breathing room. solutions for attawapiskat

7/29/2019 Breathing Room. Solutions for Attawapiskat

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Breathing Room: Solutions for Attawapiskat

Susan Reid

Thompson Rivers University

Architectural and Engineering Technology

2012


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Abstract

Breathing Room: Solutions for Attawapiskat is an examination of the problem of mould

growth in conventionally stud-framed residential buildings in Attawapiskat, Ontario; it proposes

solutions using resistant wood-based wall assemblies in construction. The background research

is from primary and secondary data sources, and forms the basis of selection for the suggested

solution wall assemblies.

A practical experiment of six weeks duration was used to test a standard 2 x 6 stud-

framed wall, a CLT (cross-laminated timber) wall, SIPs (structural insulated panel) wall, and a

NDW (wood- fibre) panel wall. These walls were assembled into a small shed measuringapproximately 4x4x4, mounted on an insulated 2 x 6 stud-framed base, and covered with an

insulated 2 x 6 stud-framed roof. The roof was finished with asphalt shingles, and the exterior

walls were covered in aluminum siding. A lamp and a hot-water vaporizer were mounted inside

the shed to provide heat and humidity, and both were cycled on/off at 8-12 hour periods. The

experiment subjected the selected walls to extremes of humidity with adequate warmth in order

to accelerate mould growth.

The final results show that both the NDW wall and the CLT wall had similarly low

mould growth by area, and low concentrations of mould where seen. However, although the

CLT wall showed most of its mould growth within the first three weeks of testing, the NDW wall

did not develop growth until after the three week inspection. Because of this resistance to initial

growth, the NDW wall is recommended for future residential construction in Attawapiskat, and

other comparable communities.


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Table of Contents

Abstract ........................................................................................................................................... 2

List of Figures ................................................................................................................................. 4

Breathing Room: Solutions for Attawapiskat ................................................................................. 5

Literature Review........................................................................................................................ 6

Mould Growth: Conditions and Problems .................................................................................. 6

Part One: Attawapiskat ............................................................................................................... 8

Part Two: Experimental Solutions .............................................................................................. 9

Results ....................................................................................................................................... 11

Analysis and Discussion: Part One ........................................................................................... 14

Analysis and Discussion: Part Two .............................................................................................. 24

Weather Conditions .................................................................................................................. 24

Air Leakage ............................................................................................................................... 25

Interior Conditions .................................................................................................................... 25

Conclusions ................................................................................................................................... 26

Recommendations for Attawapiskat ............................................................................................. 28

Glossary ........................................................................................................................................ 29

References ..................................................................................................................................... 30

Appendix A ................................................................................................................................... 34

Building Details ........................................................................................................................ 34

Appendix B ................................................................................................................................... 39

Photos of Mould Growth after 3 weeks .................................................................................... 39

Photos of Mould Growth at 6 Weeks with Analysed Patterns.................................................. 41

Appendix C ................................................................................................................................... 44


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List of Figures

Figure 1: Conditions for Mould Growth (Black, 2006) .................................................................. 7

Figure 2: Mold Damage to Indoor Relative Humidity (Nofal, 1999) ............................................. 7

Figure 3: Heat and Humidity over Testing Period ........................................................................ 12

Figure 4: Mould Growth by Area ................................................................................................. 13

Figure 5: Mould Growth by Intensity ........................................................................................... 13

Figure 6: Movement of water through the stud-framed wall, source (May, 2005) ...................... 20

Figure 7: Movement of water through the breathing frame, source (May, 2005) ........................ 21

Figure 8: Cross-section of standard wall ...................................................................................... 34Figure 9: Cross-section of SIPs wall ............................................................................................. 35

Figure 10: Cross-section of CLT Wall.......................................................................................... 36

Figure 11: Cross-section of NDW wall ........................................................................................ 37

Figure 12: Section of Experimental Shed ..................................................................................... 38

Figure 13: SIPs to CLT corner ...................................................................................................... 39

Figure 14: Bottom of SIPs wall .................................................................................................... 39

Figure 15: Bottom of Stud-Stud-framed Wall .............................................................................. 40

Figure 16: Stud-Frame to NDW corner ........................................................................................ 40

Figure 17: 2 x 6 Stud-framed Wall and Mould Growth ............................................................ 41

Figure 18: SIPs Wall and Mould growth ...................................................................................... 42

Figure 19: CLT Wall and Mould Growth ..................................................................................... 42

Figure 20: NDW wall and Mould Growth .................................................................................... 43


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Breathing Room: Solutions for Attawapiskat

This intent of this research is to find a technical answer for the common problem of

residential mould growth such as occurred in Attawapiskat. Currently, the ubiquitous timber-

stud-framed home, which serves well enough for urban Canada, does not succeed in this area and

similarly remote and northern locations. The failure in building performance in these areas is

due to a combination of circumstances: lifestyle differences dictated by culture and location, and

a lack of established infrastructure for skilled construction workers, supplies, and maintenance

capability (Humphreys, 2006). When the building performance failure is accompanied by the

growth of mould, the resulting presence of spores and micro-toxins lead to increased asthmasymptoms and other respiratory afflictions, depending on individual sensitivities. (Health

Canada, 2007)

Facing widespread and systemic challenges inherent in aboriginal building issues in

Canada, this research has limited scope, focusing on finding a technical solution to resisting

mould growth in the building frame. A small shed, composed of three alternate wall assemblies

and one conventionally stud-framed timber wall, has been subjected to high humidity, over 70%

RH(relative humidity), conditions and maintained at a temperature over 20 oC. It has been

finished externally in a typical residential manner, and sealed against air-leaks on the interior.

Although it is hoped that the finishing of the shed and the interior conditions of construction and

warmth will closely approximate a real-life situation, we recognize the limitations of a study of

this size, and have limited the defining condition to high relative humidity.

The other parameter is that all proposed solutions are limited to wood-based assemblies

that are commercially available in British Columbia. Although Attawapiskat is located in

Ontario, its problems are considered to be common to many areas of Canada, including British


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Columbia. It is not within the scope of this project to directly test materials from Ontario in a

Northern Ontario climate, and so conditions and materials must be approximate. By limiting the

research to materials and climate in British Columbia, general conclusions relevant to

Attawapiskat can be drawn, and specific conclusions can be related to the Government of British

Columbias Wood First Initiative, BC First Nation Economic Development Action Plan, and to

housing issues in regional aboriginal communities.

In doing so, not only may we find reasonable suggestions for future building materials for

our defined problem, but we may also be able to present an elegant solution that addresses

several peripheral conditions. There may be a better way to build in isolated and, often, largelyaboriginal communities; it is only fitting that in approaching this particular Canadian challenge, a

representative Canadian solution should prevail.

Literature Review

Mould Growth: Conditions and Problems

Mould growth inside a building, although it does not compromise the structural

performance of the building, can cause allergic reactions and advance existing respiratory

problems in the occupants by spreading spores and micro-toxins (Dales RE, 2006). The number

of spores inside can be increased by daily living, including cleaning activities such as vacuuming

(Black, 2006). This is not a specific problem segregated in remote locations; over 270 different

strains of mould have been identified as present in Canadian homes, regardless of area (Health

Canada, 2007). By finding reasonable solutions to particular problems facing Atttawapiskat,

these solutions may be applied with confidence in other areas of the country facing similar

issues.


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In order to understand this problem, a basic understanding is needed of conditions under

which mould develops. Mould spores are introduced into the home from outside by occupant

traffic, pets, stored firewood, and ventilation. Once inside, mould needs three conditions:

Nutrients, Moisture, and Correct Temperature.

Figure 1: Conditions for Mould Growth (Black, 2006)

Figure 2: Mold Damage to Indoor Relative Humidity (Nofal, 1999)

Stud-framed houses provide ample nutrients if the spores gain access through holes and

tears to vapour barriers in the interior of the home, and external damage to walls. A temperature

0.25 L/m2

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Indoor Relative Humidity,


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ranging between 20 oC and 35 oC provides optimal warmth, and a combination of high humidity

and low ventilation will supply the necessary moisture (Health Canada, 2007).

The above graph in figure 2 illustrates a dramatic increase in mould growth when relative

humidity exceeds 35%; noticeably, it is seen near the bottom of the wall. Other studies have

suggested that visible mould growth needed a RH (relative humidity) of over 80%, regardless of

temperature, or even 100% for results. It was proposed that while high humidity alone would

produce mould growth after several months, growth was accelerated into a period of weeks when

exposed surfaces experienced wetting (Black, 2006). From this, it can be summarized that an

indoor environment that is exposed to larger sources of mould spores (e.g. damp firewoodstorage or pet traffic), is heated continually above 20 oC, and produces large volumes of humidity

through living activities (e.g. larger number of occupants, cooking) with little ventilation to allow

dissipation will encourage conditions for visible mould growth. Any pre-existing problems (e.g.

construction with damp wood), damage to the building envelope, esp. the inside vapour barrier,

and lack of maintenance during the lifetime of the building will almost guarantee the appearance

of mould.

Method

Part One: Attawapiskat

Attawapiskat is a Cree First Nation with less than 2000 members living on a reserve near

James Bay, at the mouth of the Attawapiskat River. It is only accessible by a winter road from

January through March; otherwise all traffic in and out of the reserve is by air. Its situation is

fairly representative of other small, remote Aboriginal communities in this area and throughout

northern Canada, and as circumstances from one to another are common, it can be assumed that

the problems experienced will also be shared.


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In order to study the problem of mould growth in Attawapiskat, certain factors pertaining

to the problem of residential mould growth were examined.

1. General causes of mould growth and specifically how it grows in the building frame

2. Cultural and geographic features of life in Attawapiskat that specifically contribute to

mould growth in the building frame

3. Identifying key construction needs of this area and wall assembly types meeting these

needs

4. Identifying key characteristics of construction materials able to control causes of

mould and wall assembly materials with these characteristicsPrimary and secondary sources were reviewed regarding mould growth, building materials, and

life in Attawapiskat. As a result of this study, three walls were chosen as likely solutions to this

building issue. A practical experiment was constructed with the walls-CLT, SIPs, and wood

fibre, in addition to a standard 2 x 6 stud-framed wall- over a period of six weeks in order to

test their resistance to mould growth.

Part Two: Experimental Solutions

Objective

The objective of the experiment was to simulate extreme indoor humidity and natural

environmental conditions reasonable near those of Attawapiskat during warmer months to test

mould-growth resistance of four unique wall assemblies.

Building Construction Details

The construction diagrams can be found in the appendices. A small experimental shed

was built using four complete wall assemblies cut to 4x4 size. The walls tested were a 2 x 6

stud-framed wall (fig.20) as a control, a CLT (cross-laminated timber) wall (fig.21), a SIPs


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(structural insulated panel) wall (fig.22), and a NDW wall (fig.23). The shed was mounted on an

insulated wood-frame base, and covered with a similarly constructed roof covered in asphalt

shingle. Each wall had two nails hammered into it in the middle section to approximate

predicted damage that would normally occur during occupant use. A humidifier was installed to

produce water vapour, and a lamp with a 100W incandescent bulb was used for heat. After ten

days, the humidifier was replaced by a vaporizer. An aluminum duct was installed at the top of

the shed to house the temperature/humidity sensor and to provide access to a feed hose leading to

the vaporizer. A hole was cut above this area in the roof, under the shingles, in order to add

water to the vaporizer, and to take sensor readings with minimal disturbance to the interior.Data Compilation

Inside and outside temperature and relative humidity was recorded each day;

approximately around 8:00 am and again at 4:00 pm. Water was added at these times, and the

light was switched on/off depending on the temperature recorded.

The interior of the shed was routinely checked for the first ten days of operation and no

mould growth was seen, although some light condensation was noticed. At ten days of

operation, the cool-air humidifier was removed, and replaced with a hot-water heating vaporizer.

On November 5, 2012, at three weeks of operation, the interior of the shed was inspected in

order to replace the light bulb and secure the vaporizer to the floor. Heavy condensation was

present, and substantial surface wetting was noticed. Large areas of mould growth were seen on

the floor. All walls, excepting the NDW wall, had visible mould growth, as well. This was

documented with casual photos and video. No analysis of the data was done at that time.

On November 24, 2012, the vaporizer and lamp were removed from the shed, and a series

of staged photos were taken of each wall. These photos were taken from the shed interior, and


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each wall was photographed from 6 positions which were as nearly identical as possible for each

side. Gaps in the photography are consistent for each wall, and do not represent areas of

substantial, if any, mould growth on the walls. Inadequacies in the photography that reduce

precision in measurement, should not affect the overall accuracy of comparison.

Data Analysis

Heat and humidity for outside conditions and th e shed interior were recorded

over the six week period and the results were graphed with averages and medians.

Each photo was opened in AutoCAD software (Figures 17-20, Appendix B), and scaled

to the correct size as indicated by the tape measure in each. The six photos for each wall (seeprevious note) were visually point matched by wall feature and tape measure positioning. Each

composite image was then opened in ImageJ, a scientific image processing software, and the

areas of mould growth were highlighted. These areas were compared by pixel to the total area of

analyzed photo and the results recorded. The photos sizes were not identical, and any difference

in size is reflected in number of pixels per image. As the growth represented by pixel area is

expressed as a percentage of the total area analyzed, conclusions based on percentage can be

considered valid. Charts (Appendix B) were generated to represent the amount of mould growth

on each wall as a percentage of total area and to show the intensity of that mould growth in terms

of average size of connected particle by pixels.

Results

Heat and Humidity

During the testing period, outside temperature ranged from a low of 1 oC up to a high of

18oC, averaging at 7.5 oC. The outside humidity ranged from 36% up to 91%, averaging at 62%.

Inside the shed, temperatures fell as low as 7 oC during a period of two days and rose as high as


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50oC during one afternoon. However, these were anomalies, and the overall average

temperature, 22.6 oC, was close to the median of 22 oC. Humidity ranged from a low of 42%

during the first week, to 81% after the hot-water vaporizer was introduced. The average was

76%, close to the median of 77% relative humidity.

Figure 3: Heat and Humidity over Testing Period

The outside temperatures did not appear to have a significant effect on inside

temperatures. This is believed to be due to heat generated by the light bulb in the first ten days,

and the insulation of the walls, roof, and floor, and later, because of the high temperatures

maintained by the water-heating vaporizer. As well, outside humidity did not appear to have any

noticeable effect on the inside humidity. The most significant factor for the inside humidity was

the introduction of the hot-water vaporizer which was able to maintain higher, and a more steady

level of relative humidity than the cool-water humidifier.

0

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Outside % Relative Humidity


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Mould Growth

It is noted that when the mould growth was seen after three weeks, there appeared to be

substantial surface wetting inside the shed on the floor and all walls. The wetting is believed to

be partly from spills from the unsecured vaporizer during filling, and from the heavy

condensation produced by the vaporizer. The other observation noted is that the NDW wall did

not develop mould growth until after the three week inspection.

Figure 4: Mould Growth: Area of Mould as a Percentage of Wall Area

Figure 5: Mould Growth Intensity: pixel cluster size per area of mould growth

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At the end of the testing period, the NDW wall had both the lowest percentage of

coverage at 0.82% and the lightest coverage as represented by cluster size of mould areas. The

CLT wall was slightly higher, but comparable in both area coverage and intensity of growth.

The real differences were seen with the 2 x 6 stud-framed wall and the SIPs wall. In area

coverage, the SIPs wall was double that of the 2 x 6 stud-framed wall, and triple the CLT and

NDW walls. In heaviness of mould growth, however, the 2 x 6 stud-framed wall showed the

greatest intensity of mould growth, over double that of the comparatively light growth shown on

the CLT and NDW walls and over 80% higher than the SIPs wall.

Analysis and Discussion: Part One

Attawapiskat Case S tudy: Conditions and Problems

For Attawapiskat, and for similar remote reserves, it can be seen that the conditions optimal

for indoor mould growth are the norm and that as a result, serious problems from this condition

are more likely to be seen. Itemized, these conditions are (Humphreys, 2006):

1. Pre-existing problems due to inadequate construction

a. Materials stored on-site, leading to damage over time, e.g. torn poly sheets used

as vapour barriers allow moisture and mold spores to access the building frame

b. Wood materials not kept dry, construction with wet materials introduce moisture

into the building frame; vapour and moisture barriers do not allow diffusion

c. Lack of skilled labour in area, hurried construction with imported trades people

can lead to the previously noted problems, as well as improperly sealed building

envelopes

d. Construction not meeting the National Building Code minimum standards

2. Lack of adequate maintenance to the building


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a. Necessary knowledge lacking in occupants to do repairs

b. Limited knowledge resources available in area for maintenance

c. Difficulty in obtaining necessary equipment and supplies, and prohibitive expense

3. Problems with humidity due to occupant use

a. Higher number of occupants per dwelling unit on average compared to urban

areas

b. Longer period of cold weather with closed windows

c. Preparing game inside the home and boiling as a primary cooking method

d.

Storage of firewood, leading to moisture given off by wet woode. Laundry left to dry inside the home

f. Inadequate or non-functioning mechanical ventilation

4. High concentrations of available mould spores indoors through daily activities

a. High occupancy leading to continual introduction of spores from vegetation,

animal waste throughout the day

b. Storage of firewood as a source of mould spores

As well, poor construction cannot be overemphasized as a cause of mould growth; Chief

Theresa Spence reports:

(Residential) units were built using untreated wood for foundation materials, which was prone to

mould, rot and collapse, vinyl siding (prone to breakage in extreme climates), and generally very

cheap construction.

It should be noted that the housing was built in 1985 to the Indian on Reserve building

code, and not to the National Building Code. In addition, because the houses were built without

accommodation for building services, adding electricity and plumbing later caused structural


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damage to the homes and reduced available living space, accentuating already crowded

conditions. Due to poor design and installation, the sewage lines often backup and flood

basements, spurring the growth of mould spores (Spence, 2011).

The building design itself, imported from southern Canada, is often at odds with the

geographic and climate conditions in which it is built. Large differences between outdoor and

indoor temperatures during winter can produce condensation on the surfaces and interior of walls

(Said, 2006); this wetting action activates mould spores quickly (Black, 2006).

Maintenance, even of an adequately constructed home can be difficult in these areas.

Experts from southern Canada are normally flown in temporarily and infrequently to manageprojects; there is little in the way of community or business infras tructure to provide the after -

market know -how. The remoteness of location poses its own set of challenges: "We don't have

a Pro Hardware storethe closest place we can order [materials from] is Moosonee," (220 km

south of Attawapiskat by air) "We still have to bring those in by air, and it's not cheap," (Stastna,

2011).

Occupant use can increase the numbers of indoor mould spores, and produce the high

humidity and moisture on surfaces ( wetting conditions) needed to initiate active spore growth.

Often wood-burning appliances are used. As the firewood may be stored nearby, radiant heat

from the appliances can activate spores in the wood. Preparing game, cooking by boiling,

washing and drying clothes inside, all contribute to inside humidity. Air circulation and natural

ventilation can be limited during several months due to continuously closed windows. As

overcrowding is commonplace, all of these factors can be considered to be increased. (Said,

2006)


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Defining the Solution

In order to determine a reasonable solution to the problem of mould, the elements

underlying the problem must be identified in terms of the building frame, and specifically in

regard to the composition of the walls in the frame. The solution is not concerned with suitable

design, but with improved construction and maintenance of the building, and should allow for

occupant use of the building that contributes to the presence of mould and high humidity.

Difficulties with construction can be minimized by using a wall system that resists

damage on the construction site, or can be quickly put into place once it arrives on site. Ideally,

it should be simple and fast for less-skilled workers to assemble with supervision, if a skilledworkforce is not available locally. Hiring and training locally is less costly for the construction

company, less demanding logistically, and provides additional income to the community.

For ongoing maintenance, a solution wall that is resilient and/or easily repaired will need

less maintenance and be more likely to be maintained by the occupants. This self-sufficiency for

maintenance should extend to resisting immediate conditions of high humidity through its own

material performance, rather than through reliance on mechanical services. As the occupant use

of the building is fundamental in creating these high-humidity conditions, any wall assembly

within the given parameters will be suitable for discussion.

In this report, three walls are evaluated for suitability:

1. NDW (Naturally Different wood-fibre) wall panel

2. CLT (cross-laminated timber) wall panel

3. SIPs (structural insulated panel) wall

All three walls are wood-based and commercially available in British Columbia. Because

they are pre-constructed panel walls, each allows ease and speed of installation and maintenance.


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The NDW wall and the cross- laminated timber wall can each be considered breathing walls,

while the structural insulated panel shares some of these characteristics.

Solution Elements

Construction with Panel Walls

Inherently, panel walls provide ease and speed of installation on-site. As they are

manufactured to order specifications, quality control is ensured and costs can be better

controlled. The panels are complete and do not require additional construction before use; they

can be erected in place upon delivery. Eliminating or reducing storage time also reduces the

possibility of damage to materials, especially by water. In conventional construction, walls thatare erected with wood that is less than completely dry will introduce moisture into the interior of

the building frame, and later provide conditions for mould growth. And finally, workers with

minimal training can successfully construct a residential building quickly with experienced

supervision and using basic construction tools. For a remote area where transportation costs are

high for construction materials moved by barge, panel walls can offer long term savings by

consistent levels of quality control and reduction in waste.

Maintenance with Panel Walls

Maintenance can be defined by any actions the occupants must take to ensure the

continuing function of the building in general, and the wall in particular. Maintenance for a wall

susceptible to mould would include keeping it dry and avoiding or repairing breaches to moisture

barriers. When the health of the wall is dependent on working mechanical systems, more

variables can increase barriers to successful maintenance. A panel wall that will perform well

against moisture, and therefore mould growth without need of mechanical aid will have a distinct

advantage over conventionally stud-framed walls which depend upon the continuing integrity of


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the inside vapour barrier to repel moisture away from the wall interior. This dependence

requires a fully functioning mechanical ventilation system to be successful. If the wall assembly

chosen has the ability to minimize as many variables, and therefore impediments to maintenance,

it will have a greater chance of contributing to the long-term building performance.

In this case, a panel wall which is able to process large volumes of water vapour will

have the greatest chance of success for resisting mould growth. The breathing wall is an

example of a particular assembly that, by its inherent characteristics, is able to contribute to its

own maintenance by its ability to process water vapour.

The Breathing Wall as a Panel Option

Any wall can be considered in terms of its vapour permeability- how fast vapour will

travel through a material, its hygroscopic ability-how water vapour is managed by cellular

absorption and release, and capillarity- how liquid is managed by absorption and release. In the

standard 2 x 6 stud-framed wall used in Canadian construction, there is a vapour barrier behind

the gypsum wall board on the interior face of the wall, and mineral wool insulation inside the

wall. The walls performance hinges upon the vapour barrier remaining intact and the initial

construction using wood that is completely dry. Unfortunately, at the time of construction, wood

can get wet on site during storage, and vapour barriers can be damaged by work done by trades

people. Once in use, a well-meaning resident can puncture the barrier by using large nails to

hang pictures, or by DIY repairs. The following diagram illustrates the resulting action of

moisture that promotes mould growth (May, 2005).


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Figure 6: Movement of water through the stud-framed wall, source (May, 2005)

Typically, moisture will move from an area of high vapour pressure to a low pressure

area: from high humidity inside toward the outside (Acker, 1998). If the vapour barrier inside

has been breached, any moisture that moves past it into the building frame will not return to the

interior due resistance by higher vapour pressure. Once in the frame, moisture will not dissipate

through the outside plywood building sheathing; on average, the resistance of plywood to

moisture is 100 times that of mineral wool insulation. However, as the insulation does not have

the hygroscopic ability to absorb moisture, it will, through vapour permeability, enable the

trapped moisture to diffuse into the timber frame where it is available for the development of

mould (May, 2005).

On the other hand, a breathing wall will capitalize on its natural abilities to create an

environment in which water can move freely from inside to outside faces. This dynamic

condition, because it does not allow the water to collect at any point, will discourage spores from

developing into mould. The following figure illustrates this movement of vapour through the

breathing frame.


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Figure 7: Movement of water through the breathing frame, source (May, 2005)

This illustration (Fig.6) shows OSB (oriented strand board) on the inside face of the wall.

Both OSB and plywood have higher resistance to moisture than GWB (gypsum wall board)

commonly used in residential construction; plywood s moisture resistance is 80 times greater

than GWB and has superior performance longevity and resistance to mould growth under

prolonged conditions of high humidity. Natural fibre insulation in the building frame will

provide hygroscopic absorption of moisture, avoiding pooling of water by gravity, and vapour

permeability. When a wood fibre rigid insulation board is provided on the exterior for sheathing,

water vapour has the avenue to continue moving out of the frame. Provided all exterior finishes,

such as siding or brick work are attached with an air barrier, moisture will not be trapped in the

frame (May, 2005).

The Breathing Panel Solution


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If it is possible to combine the moisture handling characteristics that define a breathing

wall with the construction suitability of the panel wall, a reasonable solution may be proposed

for housing in Attawapiskat.

Comparisons of Panel Walls

This report evaluates three panel walls for their appropriateness as residential building

solutions for Attawapiskat. For initial construction, all three walls offer similar benefits for ease

of construction, and level of achievable building quality directly related to comparable

manufacturing controls and installation requirements. The second area of evaluation must be to

compare how each wall contributes to its own maintenance over the lifetime of the building. Asthe focus of this report is mould-resistance, maintenance in this context will refer to how each

wall can be expected to behave under the particular conditions expected in Attawapiskat, or other

related community.

Types of Panel Walls

The NDW wall is a manufactured stud wall where the spaces between the studs are

insulated with wood fibre insulation, and covered with structural wood fibre insulation inside and

out. Significantly, there is no poly vapour barrier installed on the interior face, and no moisture

barrier on the exterior. An air space is provided between the exterior insulating panel and the

protective siding to prevent trapping moisture. The wood fibre insulation combines good

hygroscopic absorption of moisture with vapour permeability (May, 2005); because the

construction is consistent throughout the wall, there are no impediments to the transmission of

water vapour from the interior to the exterior. It may be expected that the NDW wall, if used

exclusively with materials compatible in hygroscopicity and vapour permeability, will contribute


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to its own maintenance in preventing water collection in the building frame and therefore mould

growth.

The CLT (cross-laminated timber) wall is constructed from timber panels stacked and

glued into a solid mass panel; its behavior will approximate heavy timber construction. When it

is combined with a wood fibre rigid insulation on the exterior, and finished in the same manner

as the NDW wall, it should provide a degree of hygroscopic ability and vapour permeability

necessary to allow the free flow of moisture throughout the assembly. Although the vapour

permeability of a solid wood can be expected to be less than that of wood fibre, it can be

postulated that a comparable ability for hygroscopic absorption (May, 2005) would showequivalent results. The increased density of solid wood should allow more water to be absorbed

than through wood fibre, balancing the slower rate of absorption.

SIPs (structural insulated panel) walls are composed of two sheets of OSB with an EPS

(expanded polystyrene) core. As they are composed mainly of insulating foam, do not have the

hygroscopic abilities and permeability of the wood fibre and CLT walls. Moisture that is

absorbed by the OSB will not be passed through the EPS and can only be absorbed by the OSB

to be released under lower RH conditions. This expectation may be problematic under continual

high humidity conditions, and lead to degradation of the OSB face. Performance may be

enhanced if an additional layer of plywood is added to the inside face. Due to its higher moisture

resistant rating (ISO, 2007) an added layer of plywood may be able to offset potential moisture

problems faced by the OSB by resisting vapour absorption. The additional bulk of added

plywood would also increase the amount of facing material able to absorb excessive moisture.


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Analysis and Discussion: Part Two

One of the problems considered when this experiment was initially built was if the semi-

arid (Government of British Columbia, 2011) outdoor conditions in Kamloops, BC would have

an effect on the levels of humidity in the shed interior. Specifically, it was speculated that

humidity might not reach optimal levels for mould growth if 1- air leakage promoted loss of

moisture to drier outside conditions, and if 2- the bare wood fibre and CLT walls, through vapour

dispersal, skewed the results for the SIPs and 2 x 6 stud-framed wall.

Weather Conditions

Environment Canada statistics for Moosonee, Ontario were considered from the monthsof April through October. Moosonee is located 220 km south of Attawapiskat and is a similarly

isolated community also located near James Bay. Its weather conditions can be considered

comparable and are used as records for Attawapiskat are not available. Through these months

there was an average temperature variance of 17.8 oC, and an overall average temperature of

8.3 oC. During the six week testing period, the outside temperatures in Kamloops varied by 17 oC;

the overage average temperature of 7.5 oC. The outside humidity ranged widely in Kamloops

from a low of 36% to a high of 91%, averaging at 62% RH. This is somewhat comparable to the

spring and summer months in Moosonee where humidity will range from 50% to 95%, averaging

around 70% RH.

Analysis of outside weather conditions as compared to inside rooms conditions do not

show any immediate correlation beyond the observation that when there were no heat sources

inside the shed, i.e. when the vaporizer and lamp were turned off, the interior lost heat over a

period of several hours. As this loss amounted to only 3 oC over 48 hours, it can be reasoned that


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BREATHING ROOM 25

the insulation of the structure contributed greatly to maintaining the established interior

conditions.

Air Leakage

In response to the second considered problem of air leakage, the interior of the shed was

heavily sealed with construction caulking in wall corners, and bottom seams where the walls met

the floor. The top of the shed was covered with a layer of poly, another lightweight tarp, and the

insulated roof. These three layers provided some sealing against air leakage. On the outside, the

corners were sealed with building tape before adding the aluminum siding. As the exterior

conditions were not seen to be influential on interior results, air leakage, as well, was notconsidered to have been a significant factor. Therefore, the exterior conditions for the shed were

considered to be reasonable and applicable to the Attawapiskat area.

Interior Conditions

The interior conditions of the shed were kept at levels sufficient to promote mould

growth. There was no concentrated attempt to simulate real life conditions in this project due to

time constraints and the limited research scope prescribed by the program of study. The limited

simulation involved hammering two nails into each wall, and cycling the periods of light and

humidity. The damage caused by the nails was intended to approximate typical damage done in

a residence by the occupants. The intermittent periods of light and humidity simulated occupant

related activities at different times of the day. Due to the small interior size of the shed, a steady

room temperature of 20 oC was easily maintained, and extreme conditions of humidity quickly

developed. The extreme humidity and wetting was considered desirable to accelerate mould

growth within the limited time available. In addition, this excessively wet condition suggests

possible conditions most likely to occur in a poorly ventilated residential washroom where


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mould is often seen, and any success in this specific area can be assumed to be valid for other,

less moisture-prone areas of the building.

Conclusions

With correct construction, proper maintenance, and average urban conditions, all walls

tested are serviceable for daily living and are used in residential and commercial applications. In

Attawapiskat, standard construction has failed to resist mould growth on a wide-spread basis,

due to extreme conditions to which it is subjected. The purpose of this investigation has been to

propose a commercially available alternative that promises to meet the particular requirements of

the area and test that hypothesis under extreme conditions.The extreme conditions used were interior surface wetting and humidity in excess of

what would normally be expected on a consistent basis in an Attawapiskat residence, but which

could be expected to occur occasionally. In addition to extreme conditions, minor surface

damage was inflicted upon the walls to simulate the type of day-to-day damage likely to occur in

the home.

In the 2 x 6 stud-framed wall, the results were consistent with prediction. By

puncturing the vapour barrier with the nail, moisture was able to able to enter the wall structure

where the mineral batt insulation was able to transfer, but not absorb, moisture. As a result, most

moisture wall was pulled by gravity to the bottom of the frame, where it was absorbed by the

wood frame. With the warm air, mould spores were in an ideal state of heat, moisture, and

nutrients, and were able to develop into mould that spread through the interior face.

In the SIPs wall, the moisture was absorbed by the OSB, but was unable to pass through

the solid foam core. As the mould growth was concentrated in the lower half of the wall, it can

be assumed that much of the moisture was absorbed from the bottom of the wall where


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BREATHING ROOM 27

condensation may have pooled. The rate of transference of moisture from the lower to higher

areas of the wall appeared to be lower than the rate of mould spore development. Under these

circumstances, the SIPs wall would have better resistance with a securely sealed vapour barrier;

holes in the vapour barrier would allow mould growth to occur, but over a much smaller area.

The CLT wall showed good resistance to mould growth. It is expected that the

hygrothermal qualities of the wood allowed the wall to absorb much of the moisture; any

moisture transferred to the outside of the frame would have been able to be evenly dispersed by

the wood fibre external insulation to the surrounding environment. However, it did show some

mould growth within the initial three week period. It is speculated that the adhesive content of the CLT wall inhibited full hygroscopic functioning of the wood, allowing moisture to become

trapped and available to developing mould spores. Vapour barriers would not be recommended

for the CLT wall, as its superior resistance is dependent on the ability of the wood to freely

absorb, and release moisture.

The NDW wall exhibited full resistance to visible mould growth within the initial three

week period. It can be assumed that during this time, the wall structure was able to absorb all

contacting moisture and freely transfer it through the assembly to the exterior wood fibre

insulation where it was dispersed to the surrounding air. By the end of testing, however, it did

show some mottling over the surface. This could have been due to the excessive condensation

from the roof, which showed signs of pooling on the top and front surfaces of the wall. It is

possible that this pooling effectively concentrated large amounts of water in the inside layer of

the wall, leading to mould spore development. A vapour barrier would not be advised for the

NDW wall, due to its high rate of absorption and transference of moisture. Compatible


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BREATHING ROOM 28

construction with like materials would enhance its natural abilities by limiting areas likely to trap

moisture.

Recommendations for Attawapiskat

Both the NDW wall and the CLT wall exhibited limited areas and light concentrations of

mould growth on their surfaces after six weeks of extreme humidity and wetting conditions. In

addition, both walls have low maintenance requirements. However, the NDW wall is the first

recommendation for Attawapiskat due to its resistance to mould growth within the initial three

week period, and its greater ease of construction. The standard 2 x 6 stud-framed wall and the

SIPs wall are not recommended because of their susceptibility to mould growth from surfacedamage and adverse conditions.


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Glossary

1. The term 2 x 6 stud-framed wall or conventionally framed wall refers to what

is known also as a stick frame wall in the construction industry . See appendix for

diagram

2. NDW or Naturally Different Wall refers to a type of wall manufactured in Alberta,

composed of wood framing and wood fibre insulation inside and out. It does not use 6

mil poly for a vapour barrier or building papers for moisture control. See appendix

for diagram

3.

SIPs wall refers to a structural insulated panel wall comprised of 2 OSB panels oneither side of a rigid foam core. See appendix for diagram

4. CLT wall refers to a cross-laminated timber wall composed of layers of wood panels

stacked and glued at 90 o angles, then vacuum pressed into a solid mass. See appendix

for diagram

5. Poly refers to 6 mil polyethylene sheet material, commonly used as a vapour barrier

in construction.

6. OSB is oriented strand board- a structural engineered wood product.


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ReferencesAcker, W. G. (1998, June). Water Vapour Migration and Condensation Control in Buildings.

Retrieved November 2012, from Stanford University: http://www.stanford.edu/group/

narratives/classes/08-09/CEE215/ReferenceLibrary/Moisture%20Control/Water%20

Vapor%20Migration%20and%20Condensation%20Control%20in%20Buildings.pdf

AWPA Technical Committee P-6. (2012). STANDARD METHOD OF EVALUATING THE RESISTANCE OF WOOD PRODUCT SURFACES TO MOLD GROWTH. AMERICANWOOD PROTECTION ASSOCIATION STANDARD. Retrieved 2012

Berglind, H. D. (2007, 10 30). Measurement of moisture content profiles in coated and uncoated Scots Pine using Magnetic Resonance Imaging. Retrieved 07 18, 2012, from Cost ActionE53: http://www.coste53.net/downloads/Warsaw/Warsaw-presentation/COSTE53-ConferenceWarsaw-Presentation-Eksted.pdf

Black, C. (2006). Mould Resistance of Full Scale Wood Frame Wall Assemblies. Retrieved 082012, from University of Waterloo Library: http://hdl.handle.net/10012/2839

Bodycote Materials Testing Canada Inc. (2004, 04 01). Fungal Mould Resistance Testing(FMRT) of Common Building. Retrieved 07 11, 2012, from Canal Block:http://www.canalblock.com/index_files/fungal.pdf

Canada Mortgage and Housing Corporation. (2005). CMHC Corporate Information. Retrieved07 31, 2012, from Canada Mortgage and Housing Corporation: http://www.cmhc-schl.gc.ca/en/co/reho/upload/66002.pdf

Canada Mortgage and Housing Corporation. (2011, 04 26). First Nations Mold RemediationCase study Membertou First Nation. Retrieved 07 31, 2012, from Canada Mortgage andHousing Corporation: https://www03.cmhc-schl.gc.ca/catalog/productDetail.cfm?cat=15&itm=35&lang=en&fr=1343790028187

Canada Mortgage and Housing Corporation. (2011, 04 29). First nations mold remediation casestudy: Wikwemikong Unceded Indian Reserve. Retrieved 07 2012, from CanadaMortgage and Housing Corporation: http://www.cmhc-schl.gc.ca/odpub/pdf/67296.pdf?fr=1352090568668

Canada Mortgage and Housing Corporation. (2011, 05 24). Publications and Reports. Retrieved07 11, 2012, from Canada Mortgage and Housing Corporation: https://www03.cmhc-schl.gc.ca/catalog/productDetail.cfm?cat=15&itm=41&lang=en&fr=1342053708071

Canada Mortgage and Housing Corporation. (2011, 11 15). Publications and Reports. Retrieved07 11, 2012, from Canada Mortgage and Housing Corporation: https://www03.cmhc-schl.gc.ca/catalog/productDetail.cfm?cat=15&itm=35&lang=en&fr=1342050443578


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Canada Mortgage and Housing Corporation. (2011, 05 11). Publications and Reports . Retrieved07 11, 2012, from Canada Mortgage and Housing Corporation: https://www03.cmhc-schl.gc.ca/catalog/productDetail.cfm?cat=15&itm=35&lang=en&fr=1342050443578

Canadian Mortgage and Housing Corporation. (2011, 05 17). Publications and Reports .

Retrieved 07 11, 2012, from Canada Mortgage and Housing Corporation:https://www03.cmhc-schl.gc.ca/catalog/productDetail.cfm?cat=15&itm=35&lang=en&fr=1342050443578

Dales RE, M. D. (2006, 08). Moldy Houses: Why They Are and Why We Care & Additional Analysis of Wallaceburg Data: The Wallaceburg Health and Housing Studies. Retrieved07 31, 2012, from CMHC Research Reports: http://www.cmhc-schl.gc.ca/odpub/pdf/62950.pdf?fr=1343784119669

Environment Canada. (2000). Canadian Climate Normals 1971-2000 for MOOSONEE UA

Ontario. Retrieved from National Climate Data and Information Archive:http://www.climate.weatheroffice.gc.ca/climate_normals/results_e.html?stnID=4168&lang=e&dCode=0&province=ONT&provBut=Search&month1=0&month2=12

Evrard, A. (2006, 08 24). Sorption behaviour of Lime-Hemp Concrete and its relation to indoor comfort and energy demand. Retrieved 07 11, 2012, from http://edoc.bib.ucl.ac.be:81/:http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-05192008-140409/restricted/PhD_AE_Appendix_4.pdf

Gatland, S. K. (2007). The Hygrothermal Performance of Wood-Framed Wall Systems Using aRelative Humidity-Dependent Vapour Retarder in The Pacific Northwest. ASHRAE Transaction , 1-8. Retrieved 07 19, 2012, fromhttp://www.ornl.gov/sci/roofs+walls/staff/papers/148.pdf

Government of British Columbia. (2011). Climate, Kamloops, BC. Retrieved from BC WildfireManagement: http://bcwildfire.ca/AboutUs/Organization/Kamloops/Climate/#Climate

Hameury, S. (2006, 11 30). The hygrothermal inertia of massive timber connstructions. Retrieved 07 16, 2012, from KTH Publication Database DiVA: http://kth.diva-portal.org/smash/record.jsf?pid=diva2:11208

Hameury, S. (2012, 02 29). KTH Publication Database DiVA. Retrieved 07 11, 2012, fromKTHB Electronic Library: http://kth.diva-portal.org/smash/record.jsf?pid=diva2:11208

Haughton, L., & Murphy, C. R. (2003, June). "Moisture Exchange" Performance of OSB and Plywood Structural Panels. Retrieved November 2012, from RCI: http://www.rci-online.org/interface/2003-06-haughton-murphy.pdf


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Health Canada. (2007, 03 31). Residential Indoor Air Quality Guidelines: Moulds. doi:H128-1/07-508E

Holm, A. K. (1995, 10 24). Moisture Buffering Effects on Indoor Air Quality- Experimental and Simulation Results. Retrieved 07 18, 2012, from Oak Ridge National Laboratory:

http://www.ornl.gov/sci/roofs+walls/staff/papers/new_119.pdf

Humphreys, D. (2006, June). The International Housing Coalition (IHC) Case Study 3. Aboriginal Housing in Canada: Building on Promising Practices. Retrieved July 10,2012, from Aboriginal Canada Portal:http://www.aref.ab.ca/resourcelibrary/documents/case_study_ENGLISH.pdf

ISO. (2007, January 9). Building materials and products Hygrothermal properties Tabulated design values and procedures for determining declared and design thermalvalues. Retrieved August 2012, from Universita luav di Venezia:

http://www.iuav.it/Ateneo1/docenti/architettu/docenti-st/Fabio-Pero/materiali-/corso-tecn1/_mat-_ISO_FDIS-10456--dati-materiali.pdf

May, N. (2005, April 16). Breathability: The Key to Building Performance. Retrieved May 2012,from Eco Timber Frame:http://www.ecotimberframe.ie/pdf/BreathabilityinbuildingsNBT.pdf

Nofal, M. (1999, 03 01). Predicting Mold Growth in Walls. Retrieved 07 11, 2012, from Institutefor Research in Construction: http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc43134.pdf

Nore, K. (2011, 01 26). Hygrothermal performance of ventilated wooden cladding. Retrieved 07

18, 2012, from Norwegian University of Science and Technology (NTNU):http://www.ntnu.no/c/document_library/get_file?uuid=3722fd33-c9fa-4762-9bf1-653d627236cd&groupId=10380

Premier Building Systems. (2011). Premier General Brochure. Retrieved 06 2012, from PremierSIPs: http://www.premiersips.com/brochures/PremierGeneralBrochure.pdf

Said, P. P. (2006, Dec). Task 2: Literature Review: Building Envelope, Heating, andVentilatingPractices and Technologies for ExtremeClimates. doi:irc_id:1846

Spence, C. T. (2011, Dec 15). Affidavit of Chief Theresa Spence. Retrieved 11 05, 12, from

Attawapiskat: http://www.attawapiskat.org/wp-content/uploads/2011-12-15-Affidavit-of-Chief-Theresa-Spence.pdf

Stastna, K. (2011, 11 28). First Nations housing in dire need of overhaul . Retrieved 12 2011,from CBC News Canada: http://www.cbc.ca/news/canada/story/2011/11/25/f-native-housing.html


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Vainiokaila, T. M. (2008, 02 01). Multifunctional properties of wood in interior use. Retrieved07 18, 2012, from Engineered Wood Products Association:http://www.ewpa.com/Archive/2008/june/Paper_122.pdf


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Appendix A

Building Details

Figure 8: Cross-section of standard wall


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Figure 9: Cross-section of SIPs wall


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Figure 10: Cross-section of CLT Wall

Exterior Face


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Figure 11: Cross-section of NDW wall


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Figure 12: Section of Experimental Shed


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Appendix B

Photos of Mould Growth after 3 weeks

Figure 13: SIPs to CLT corner

Figure 14: Bottom of SIPs wall


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Figure 15: Bottom of Stud-Stud-framed Wall

Figure 16: Stud-Frame to NDW corner


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Photos of Mould Growth at 6 Weeks with Analysed Patterns

Table 1: Mould Coverage and Intensity

Wall ExaminedCount Total Area

Ave.SizeParticle % Area Mean

2 x 6 Stud-framedWall

162 8263 51.006 1.299 61.434

SIPs Wall 497 13919 28.006 2.629 255

CLT Wall 277 5057 18.256 0.92 255

WF WALL 180 3156 17.533 0.824 255

Figure 17: 2 x 6 Stud-framed Wall and Mould Growth


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Figure 18: SIPs Wall and Mould growth

Figure 19: CLT Wall and Mould Growth


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Figure 20: NDW wall and Mould Growth

Table 2: Average Temperatures for Moosonee, ON-abridged (Environment Canada, 2000)

Temperature : Apr May Jun Jul Aug Sep OctDaily Average(C)

-2.4 6.2 11.9 15.4 14.4 9.4 3.4

Daily Maximum(C)

3.7 12.7 18.8 22.2 20.8 14.6 7.6

Daily Minimum(C)

-8.6 -0.3 5 8.5 7.9 4.1 -0.8

Rainfall (mm) 20.6 46 70.4 101.3 75.8 88.7 59.1

Snowfall (cm) 19.2 6.9 0.7 0 0 1 14.9

Precipitation39 53.7 71.1 101.3 75.8 90 73.3

ExtremeHumidex

29.6 36.8 39.3 44.7 43.4 40.8 28.8
http://www.climate.weatheroffice.gc.ca/prods_servs/normals_documentation_e.html#ND1http://www.climate.weatheroffice.gc.ca/prods_servs/normals_documentation_e.html#ND1http://www.climate.weatheroffice.gc.ca/prods_servs/normals_documentation_e.html#ND1


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Appendix CTable 3: Advisers and Sponsors

Advisers

Mindy Marshall

Dan Bissonnette

Tom Haag

Shannon Smyrl

Duane Svendson

Jaret Nield

Bill Billups

Dave Gardner

Dr. Jieying Wang

Faculty of Science Mentor

Faculty of Science Mentor

Carpentry Mentor

Writing Mentor

Project Sponsor & Advisor

Project Advisor

Project Advisor

Project Advisor

Research Advisor

Company/Department

Architectural & EngineeringTechnology

Physics & Astronomy

School of Trades &

Technology

English and ModernLanguages

Trout Creek InternationalHomes

In & Out Water and

Construction

Technical Advisor, CanadianWood Council WoodWORKS! BC

Heavy Timber SpecialistStructurlam Products Ltd.

Senior Scientist,FPInnovations WoodProducts Division


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