100 80 no mould risk below the limits 90 wood protection ... · chemical into wood 14.4..2016 ......

Wood protection, coating and preservation

Wood Products: Applications and Performance

Aalto University

14th April 2016

Hannu Viitanen PhD

Senior Research Scientist at VTT

(1980 – 2015)

Docent at Aalto University 2015

[email protected]

50

60

70

80

90

100

0 10 20 30 40 50

Temperature (C)

Re

lati

ve

hu

mid

ity

(%

)

2 weeks

4 weeks

8 weeks

safe area

Mould

No mould risk

below the limits

50

60

70

80

90

100

0 10 20 30 40 50

Temperature (C)

Re

lati

ve

hu

mid

ity

(%

)

1 month

6 months

one year

safe area

Decay

No decay risk

below the limits

Outline

• Wood as a building material – use conditions and service life

• Moisture stress and bio-deterioration of wood - damage – Aging - damage - mould - decay - insects - critical conditions

• Factors of wood durability

• Durability of wood and wood based materials

• Methods for wood protection – Coating – Preservation, pressure treatments – Modification, chemical / physical – Coated plywood products

• How to achieve 100 year’s service life for buildings

14.4..2016 Hannu Viitanen 2

Definitions of use classes are based on the expected exposure conditions during the service life of wooden compounds and buildings.

Facades Cladding

Use class 3.1 (EN 335-1)

Balconies Terraces Fences

Use class 3.2 (EN 335-1)

Kutnik 2008

Kutnik 2008 14.4..2016

Building performance, performance degree (PD) during the life time of a building (ISO 15686)

Building performance and life cycle

Operation over time

Qu

ality

/ F

un

cti

on

PD 0

PD 2

PD 3

PD 4

PD 1

Performance without preventive actions

Replacement

Maintenance

Repair Refurbishment

Aging / Failure No symptoms

Slight symptoms

Medium

Strong

Totally unaccetable, collapse and malfunction

Hannu Viitanen 4 14.4..2016

Ageing, biodeteriodation, faults, damages

• During the service life of buildings, natural ageing of materials due to different chemical, physical, and biological processes can take place.

• Grey wood is a normal phenomenon in outside conditions on untreated wood (caused partly by discolouring fungi)

• In damage cases, more severe changes of material are associated (mould growth, decay damage and insects)

-> Problems in indoor air quality

• Definition of damage

– Termination of the ability of a building, building component or material to perform a specified function (strength, safety, health, durability etc.

• Smaller problems and faults:

– Reparation in time prevent the damage to develop.

Causes to water damages and decay (e.g. brown rot): Water leakage, convection of damp air and moisture condensation, rising damp from the ground and moisture accumulation in the structure


Mould growth as an indicator for performance of buildings

• natural ageing (outdoor exposure) – grey wood surface

• mould growth in structure

– indoor air problems – damages of structures

• VOCs and smell • Aesthetic problems

– load exceeds tolerance – decay – damage

People spend more time indoors and are more depended on indoor air quality


A building is subjected to different water sources, ageing processes and damages during the life time

humidity, temperature, material,

time period, organisms

MOISTURE DAMAGE tolerances are overloaded

MOULD

RH: > 75 - 95 %

Temp: 0 - 55 C

Time: d, w, m

Moisture stress

DECAY

RH: > 90 - 95 %

Temp: 5 - 50 C

Time: w, m, y

Detection the damages and

simulation the causes of problems

Ageing

Indoor

Outdoor


Mould and decay in wood materials and objects

• Spores and particles of fungi exist overall in the environment

• High humidity / moisture content of materials (water activity) / temperature lasting time will cause the germination of spores and growth of fungi.

• Mould fungi, algae and lichens may grow on the surface of many materials. Organic dust will add the susceptibility of surface to growth of micro-organisms.

• Decay will develop in high humidity / moisture conditions

Hannu Viitanen

8 14.4..2016

Different types of bugs and damages in wood material

• Brown rot decay on the surface of wood

• Insects bugs

• Brown rot spots in the sapwood

• Blue stain in the sapwood

• Less decay in the heartwood

Hannu Viitanen

9 14.4..2016

Soft rot will develope inside of the wood cell and the strenght of wood will be fast lowered

Advanced and high rate soft rot decay in a untreated wood pole

An advanced decay in wood cells analysed under micoscopy. Preservation should reached the thick sell wall layer of C2.

Puunsuojaus 1982)

Hannu Viitanen

10 14.4..2016

Effect of the decay on the wood cell structure (Viitanen & Ritschkoff 1989)

Brown rot Fast decay in S2 layer. Mainly cellulose will be decayed

White rot Local decay in cell wall

Soft rot Decay in the cell wall, in S2 layer

All main compounds will be decayed

Brown rot fungus in wood cell

Soft rot decay in wood cell 11

Critical microclimate conditions for the growth of organisms and biodeterioration

Humidity: RH 75 – 100 %

- Mould > RH 75 - 80 %

- Decay > RH 95 %

- Insects > RH 75 - 80 %

Wood moisture content:

- Mould > u 18 – 20 %

- Decay > u 25 – 30 %

Temperature (-5) – 50 °C

Time

Air

Temperature Water

Nutrients Organisms


Critical parts of the building for exposure

• Indoor surfaces

– Wet rooms, attic, indoor rooms

• Structural parts / envelopes

• Outdoor structures

– facades, windows, fences, balconies, terraces

• Intended use conditions

• Critical details

• Mould / decay / other organisms

RH, moisture, temperature, exposure time,

materials

Use of model organisms to simulate and modelling the critical conditions for decay development under controlled conditions

13 14.4..2016

Critical conditions for the activity of organisms and damage to develop

• For mould development, the minimum (critical) ambient humidity requirement is shown to be between RH 80 and 95 %.

– RH 80 %: sensitive building materials, like pine sapwood

– RH 75 %: other than building materials (like wheat flour)

– RH 90 - 95 %: some stone based material.

• For decay development, the critical humidity is above RH 95 % or e.g. wood moisture above 25 – 30 %.

• Mould growth have been evaluated using different methods

– The mould index is a evaluation method for detect mould growth on the surface of materials.

– Mould growth on concrete found under microscopy


Results on mould growth in static conditions in pine sapwood

(Viitanen and Ritschkoff 1991, Viitanen 1996)

75

80

85

90

95

100

-10 0 10 20 30 40 50 60

Temperature [°C]

RH[%]

Too dry

Too

cold

Too

hot

Growth

stop

t m =4 weeks

t m =8 weeks

Mould risk is high

Mould risk is possible

Critical factors for mould fungi in sapwood

(Hukka and Viitanen 1999)

20> when %, 80

20<= when ,0.10013.3160.000267.0 23

T

TTTTRH crit


Critical

conditions for start of

mould growth

and decay to develop

on pine

sapwood

70

75

80

85

90

95

100

0 5 10 15 20 25 30Time (weeks)

RH

(%

)

1 °C

5 °C

10 °C

20 °C

70

75

80

85

90

95

100

0 4 8 12 16 20 24

Time (months)

RH

(%

) 0 °C

5 °C

10 °C

20 °C

14.4..2016 16

Critical conditions for mould and decay to develop in pine sapwood, results obtained in the laboratory (isoplets)

Start of mould growth Early stage of decay

50

60

70

80

90

100

0 10 20 30 40 50

Temperature (C)

Re

lati

ve

hu

mid

ity

(%

)

2 weeks

4 weeks

8 weeks

safe area

Mould

No mould risk

below the limits

50

60

70

80

90

100

0 10 20 30 40 50

Temperature (C)R

ela

tiv

e h

um

idit

y (

%)

1 month

6 months

one year

safe area

Decay

No decay risk

below the limits

14.4..2016 17 Hannu Viitanen

Outdoor exposure conditions in different part of Europe (uncovered situation)

Modelled mass loss (in %) of small pieces of pine wood that are exposed to rain in 10 years in Europe (from Viitanen et al. 2010).

Solar radiation in Europe.

For sheltered structure, the exposure to water and solar radiation is lower.

18 14.4..2016 Hannu Viitanen

Organisms causing problems in different building components

Attics: mould, blue-stain, insects

Wet rooms: mould, blue-stain, insects


Many factors are dealing with wood durability

WOODEN MATERIAL WOOD WORKING USE OF WOOD

AND TREATMENTS

WOOD SPECIES

GENOTYPE

AGE OF A TREE

SAP / HEARTWOOD

Permeability / Resistance

- microstructure

- chemical composition

- storage - building site and environment,

- sawning environmental stress:

- drying - humidity, temperature, duration,

- transport presence of harmfull organisms

- further working - transport and storage of materials

ENVIRONMENT - wood modification - structures (planning, performing)

- climate, growth place - preservation building and the components

FORESTRY - other treatments - surface treatments

- thinning, pruning, cutting - paints / fungicides - maintenance and the way of use

Hannu Viitanen

20 14.4..2016

Bases for wood durability: Wood is a natural polymer

• cellular matrix that provides structural support:

- cellulose - hemicellulose - lignin

• resistance against microbial attack:

- lignin - some hemicelluloses - extractives: resin acids, phenolic compounds, tannins, sugars, fatty acids

• additional protection should fitted to the use conditions (exposure to water / humidity)

For organisms, the water activity close the surface is important (properties of coatings and dust on surface may change the condition!) or water activity inside the wood and withing the cells.

Critical humidity to avoid biodeterioration of wood

Coating and preservation of wood cellular matric for penetration of chemical into wood


The natural durability or decay resistance of heartwood of different wood species according to ASTM Manual 40

Durability Class

(Europe)

Durability Class

(USA)

Examples

Very durable Resistant or very

resistant

Teak (original), iroko, aphzelia, bilinga,

mesquite, junipers, redwood (Sequoia)

natural

Durable Resistant or very

resistant

Western redcedar, white oak, american

mahogany, meranti, redwood (Sequoia)

plantations, Teak (some plantations)

Moderate durable Moderately resistant Larch, douglasfir, hickory, african

mahogany, khaya, tamarack, Scots pine,

southern pine

Slightly durable Slightly resistant or

nonresistant

Pine, spruce (several species), elm,

hemlock, hickory, oaks (red and black

species)

Not durable Slightly resistant or

nonresistant

Alder, aspen, beech, birch, maple,

poplar, balsa, ramin 22

Proportion of heartwood and its effects on the durability of products

• Pine: heartwood will be produced after 20 - 40 y age. In 60 years c.a. 25 % (butt log 30 %, others 20 %) maximum c.a. 60 - 75 %

• Larch: heartwood will be produced after 10 - 15 y age. In 60 years c.a. 65 - 70 % maximum c.a. 55 - 80 %

• Also age of tree affect on the quality and durability of heartwood !

20% 50% 70%

For pressure treatment and preservation of wood, the sapwood of pine is treatability (water permeability is low). Penetration of preservative should be around 95 – 100 % in sapwood of pine.


Harvesting time and sensitivity of wood to mould growth

Mänty, kaatoaika ja homehtuminen

4 viikon altistus RH 100 %:ssa

0

1

2

3

4

5

6

Viljava Karu

Kasvupaikan ravinteisuus

Ho

mein

deksi

(0-6

)

Kuusi, kaatoaika ja homehtuminen

4 viikon altistus RH 100 %:ssa

0

1

2

3

4

5

6

Viljava Karu

Kasvupaikan ravinteisuus

Ho

mein

deksi

(0-6

)

kevät

kevät, kastelu

syksy

talvi


Keywords for durability and preservation of wooden material for buildings

• The whole production chain of wooden materials and products wood quality, processes, structures and end use conditions

• Surface treatments

several different types exists: permeability, active agents, pigments

• Wood preservatives traditional methods: wooden tar, oil treatment present methods: different impregnation methods

• Wood modification methods chemical modification: acetylation, maleic acid anhydrids, furfulation physical methods: compression, heat treatments e.g. Thermowood

• Structures the whole building but also details: keep wood dry


Wood preservation

• Moisture control – Prevent stain and

decay – Reduce damage of

insect – Reduce weight and

increase strength – Prepare wood for

treatment with chemical preservatives

• Chemical control – Chemical formulation

• Oil borne • Water borne

– Application method • Surface treatment /

dipping • Pressure treatments

– Amount of presevative • Penetration and

distribution • Content of preservative

and active agent

14.4..2016 26

Hannu Viitanen

Wood preservation with chemical

• Several preservatives and impregnation techniques available

• Pine sapwood is permeable for penetration

• No significant penetration in the heartwood

• In spruce, only partial penetration of the preservative (same effect, if moisture content of wood is too high during impregnation process)


• Wood in contact with salt sea water (ocean), use class 5, high retention and penetration throug sapwood needed (NWPC class M)

• Wood in ground contact or high exposure, use class 4 – Poles, needs of high content of preservative and penetration through the

sapwood (NWPC class A), Fence posts

• Wood exposure to weather and rain, use class 3.2 – Decking, balconies, fences, non-covered terraces (NWPC class AB)

• Wood exposure to short period of wetting and rain, use class 3.1 – Cladding, covered decking (NWPC class AB, or coated wood having low water

permeability)

• Wood exposed to occasional high humidity, use class 2 – Wood in high humidity, surface treatments mainly against mould and

bluestain

• Wood in dry conditions, covered, use class 1 – Only occassional attack of insect expected, surface treatment against insects

and termite, depending on use conditons

Use of impregnated wood


Chemical wood preservation

• Non pressure processes

– Brush and spray treatments

– Dipping

– Coating processes: paints and stains e.g. coating of wooden boards with films

• Pressure processes – Full-cell process (high retention)

– Empty-cell process (optimized retention)

– Low pressure process (vacuum treatment)


Impregnated wood products after NWPC and CEN

NWPC EU Penetration Concentration

M P 8 95 - 100 % from sapwood, Depending on the preservative

A P 8 95 - 100 % from sapwood Depending on the preservative

AB P 8 95 - 100 % from sapwood Depending on the preservative

B P 5 lateral 6 mm and 50 mm from edges

Depending on the preservative


Chemical preservation - preservatives

• Water based preservatives for impregnation – Chromated copper arsenate, CCA (not in Europe anymore)

– Chromated copper compounds, CC

– Acid Copper Chromate (ACC)

– Alkaline copper quaternary compounds, ACQ (quaternary ammonium compounds)

– Copper azole: Cu + organic triazoles (tebuconazole, propiconzole)

– Other copper compounds ( eg. CuHDO, micronized copper technology)

– Borate preservatives (Inorganic Boron and Boric Acids)

– Sodium silicate based preservatives

– Alkyl Ammonium Compounds (AAC)


• Oil-borne preservatives for impregnation – Coal -tar creosote (treated wood not allowed to be used in

Finland), different types of creosote exist – Hot-oil heat treatments – Tall oil and it's distillates (many different applications) – Different formulations for vacuum treatment (not in Finland)

• Surface treatments – Linseed oil, tung oil (actually only protection against water) – Light organic solvent preservaties (permethrin, bifentrin)

– Propiconazole (organic triazole), against decay (not insect) – Tebuconazole – 3-Iodo-2-Propynol Butyl Carbamate (IPBC) – Alkyl Ammonium Compounds (AAC)

Chemical preservation – preservatives (2)


List of approved wood preservatives in Nordic Wood Preservation Council

Marking of the impregnated wood according to NWPC

quality marks

33

NWPC wood preservation classes in relation of EN 351-1 and EN 335-1

34

Use class

General service situation

Wood durability class (1 – 5)

1 2 3 4 5

1 Indoor dry 0 0 0 0 0

2 Above ground, covered 0 0 0 (0) (0)

3 Above ground, not covered 0 0 (0) (0)–(x) (0)–(x)

4 In ground contact 0 (0) (x) x x

5 In salt water (ocean) 0 (x) (x) x x

Treatments support the durability (EN 350-2) of wood products in different use classes (EN 335-1), EN 460 (1994)

Key and explanations 0 = natural durability is sufficient (0) = natural durability is normally sufficient but for certain end uses treatment may be advicable (e.g. surface treatments (0)–(x) = natural durability may be sufficient , depending on the wood species, treament may be necessary (impregnation, surface treatment) (x) = preservative treatment is advicable, but for certain end uses natural,

durability may be sufficient X = preservative treatment is necessary

35

Standarisation and testing of wood durability Task of CEN TC 38 Wood durability

• CEN TC 38 task: development of standards on durability / resistance of wood against biological agents and bio-deterioration

• Working groups (WG 21 – 28)

• Standards – Durability / resistance of wood products against bio-deterioration – Use classes – Natural durability of wood – Fungal testing – Insect testing – Field tests – Preconditioning prior testing and external factors – Analyses of preservative and treated wood – Performance classification / service life of wood products


Standards and norms on wood durability

• EN 335 Definition of use classes. Part 1-3

• EN 350 Natural durability of solid wood. Part 1: Guide to the principles of testing and classification. Part 2: Guide to natural durability and treatability of selected wood species

• EN 460 Guide to the durability requirements of wood / use classes

• EN 599 Performance as determined by biological tests

• EN 351 Preservative-treated solid wood -Part 1: Classification of preservative penetration and retention.

• ENV 1099 Plywood – Biological durability. Guidance for the assessment of plywood for use in different hazard classes

• EN 152: 1 - 2 Blue stain in service – Preservatives, primers and coatings

• EN 113 Wood destroying basidiomycetes – Treated wood

• ENV 839 / CEN/TR 14839 Wood destroying basidiomycetes – Surface treatment

• ENV 12038 Wood destroying basidiomycetes – Wood-based panels

• ENV 807 Soft rot fungi – Treated wood

• prCEN/TS 15083-1 / -2 Determination of the natural durability of solid wood against wood-destroying fungi. Test methods - Part 1: Basidiomycetes / Part 2: Soft rotting micro-fungi.

• EN 252 Protective effectiveness in ground contact - Treated wood

• CEN/TR 14723 Field and accelerated tests out of ground contact. Wood-based products, treated wood

• CEN/TS 12037 Horizontal lap-joint method. Wood material, treated and coated wood

• EN 330 L-joint method, treated and coated wood

37

Field test of wood preservatives in Nordic Countries (Larsson-Brelid et al 2011)

Example of results on EN 252 test in Simslångsdalen, Sweden, started in 1989

Fielt test sides in Nordic countries (Viikki is not anymore for test side)

38

• Water: ambient humidity and liquid water

• Weathering: solar radiation and outdoor exposure, rain water, driving rain, surface erosion, discoloration (mould, bluestain)

• Change of dimension of wood caused by moisture variation

• Microbes: mould, bluestain and decay fungi, bacteria

• Color shange of wood and coating itself

• Dirt: different type of dust and compounds

• Wood properties affect the performance of coating and vice versa

Coating of wood, protection against


Penetration types and coating thickness of different types of coatings (paint types) for wooden materials (Anstenius 1990)

Preservatives Wood oils,

Opaque paints, Arylate, Alkyd Oil paints

Primers Opaque stains


Paint type Paint film Water permeability

Life span

Wood oils, varnishes

Transparent, low protect for UV

High 1 – 2 years, repaint easy

Red, yellow ochre

Open Film forming, protect of UV

High 6 - 12 years, dont change paint type, repaint easy

Pigmented stains

Semi transparent protect of UV

High - Moderate

Water / oil borne products. 3 – 6 years, repaint easy

Opaque stains

Film forming, protect of UV

Moderate - Low

Water / oil borne products. 5 – 10 years, repaint easy

Dispersion paints


Moderate - Low

Primer needed, 10 – 20 years, repaint needs work

Oil / alkyd oil paints


Low (as new) Colour may be changed, 10 – 20 years, repaint vary

Coatings (paint types) for wooden materials


Durability and use of Norway spruce and Scots pine

• Norway spruce – Picea abies

Water permeability

Very low

Low

Moderate

High (Scots pine sapwood)

Use for building components

Use classes 1 - 3 (EN 335)

structural timber, claddings,

fences, windows (coated)

1 Very durable

2 Durable

3 Moderate durable

4 Slightly durable

5 Not durable (pine sapwood)

Scots pine Pinus sylvestris


Sensitivity of wood to mould growth can be found on the coated surface of wood

Heartwood Strip of wood during kiln drying 43

Protective action of coatings: prevention of mould growth on painted wood, effect of wood quality and fungicide on

pine sapwood (Viitanen & Ahola 1999)

• 26 weeks incubation at RH 100 % and 20 C

• S1 is kiln dried surface

• S2 resawn surface (sawn 10 mm from the original surface)

• acrylate primer (prim)

• top coat (top coat)

• preservative (dipped)

• no fungicide (-)

• fungicide added (+)

0

1

2

3

4

untrea

ted

prim

- / top

c -

prim

+ /

topc

+

dipp

+ /

prim

+ /

topc

+

Mo

uld

in

dex (

0 -

4)

Pine, S 1

Pine, S 2

Hannu Viitanen

44

14.4..2016

Protective action of coatings: prevention of mould growth on painted wood, effect of wood quality and fungicide on

spruce sapwood (Viitanen & Ahola 1999)

• 26 weeks incubation at RH 100 % and 20 C

• S1 is kiln dried surface

• S2 resawn surface (sawn 10 mm from the original surface)

• acrylate primer (prim)

• top coat (top coat)

• preservative (dipped)

• no fungicide (-)

• fungicide added (+)

0

1

2

3

4

untrea

ted

prim

- / topc

-

prim

+ / topc

+

dipp

+ / pr

im + / topc

+

Mo

uld

in

dex (

0 -

4)

Spruce, S 1

Spruce, S 2

Hannu Viitanen

45 14.4..2016

Mould growth of the outer surface of wood can be cleaned using washing methods


Exposure time, surface treatment (water-borne wood oil), sap and heartwood / decay resistance / Water absorption

Decay of uncoated and coated (water-borne wood oil) pine and spruce,

sap / heartwood, Coniophora puteana, 6 and 10 weeks 'minitest'

0

10

20

30

40

50

Pine

sap,

Unc

oate

d

Pine

sap,

Coa

ted

Pine

hear

t, Unc

oate

d

Pine

hear

t, Coa

ted

Spr

uce he

art,

Unc

oated

Spr

uce he

art,

Coa

ted

Ma

ss

lo

ss (

%)

6 weeks 10 weeks

Water uptake (g/m2) in water absorption test, EN 927-5

0

1000

2000

3000

4000

Pin

e sa

p, u

nco

ated

Pin

e sa

p, c

oat

ed

Pin

e hea

rt, u

nco

ated

Pin

e hea

rt, c

oat

ed

Spru

ce, u

nco

ated

Spru

ce, c

oate

d


Heat treatment of wood, Thermowood

Effect of heat treatment on antiswelling efficiencies,

strength decrease and decay resistance of pine

-40

-20

0

20

40

60

80

100

0 5 10 15 20

Weight loss in heat treatment process (%)

(%)

improvement of antiswelling in 24 h water immersion

decrease of bending strength

improvement of decay resistance (EN 113 test)

Thermowood process Hannu Viitanen

48 14.4..2016

Durability of Thermowood D and untreated pine sap- and heartwood after 6 years’ field test (modified double-decking test, Espoo Otaniemi,

(Metsä-Kortelainen & Viitanen 2015)

Hannu Viitanen 49

0

1

2

3

4

Untreated ThermoD Untreated ThermoD

Pine sapwood Pine heartwood

De

cay

rate

(0

-4)

Decay rate after 6 years' field test

Ground contact

Middle part

Upper part

14.4..2016

Wood moisture content and decay rate after 6 years’ field test (Viitanen et al. 2013)

Decay rate as percent value -> 4 = 100 %

0,0

20,0

40,0

60,0

80,0

100,0

Pine sapwood, untreated

Pine sapwood, Thermo-D

Pine heartwood, untreated

Pine heartwood, Thermo-D

Moisture

Decay

Correlation: 0.970


Coated plywood products

• Performance of coated plywood product is not dependent on the durability of wood material: – Coated and edge sealed birch plywood perform well

• Outdoor weathering and lab test at VTT

• Performance of coated plywood products, important factors: – wood species: surface quality and hardness (edges)

– coating types and edge sealing

– protection against water uptake: edges, fixing types

– design and execution of structure

– environmental conditions

– maintenance


An example of field test of coated plywood Test at Otaniemi, Espoo Finland, after 19 years exposure

(Viitanen et al 2002 )

• Phenol film coated birch

plywood

Paint film coated and painted

plywood, PU paint and oil paint

(oil + alkyd)


Coating and edge sealing of plywood. Untreated birch and spruce plywood (Viitanen et al 1984)

0

10

20

30

40

50

60

70

Birch SprucePlywood

Ma

ss

lo

ss

(%

) Uncoated

Phenol film, No edgesealed

Only edge sealed

Coated and edgesealed

Effect of coating and edge sealing (3 x acrylate). Soil jar test, 12 weeks,

Coniophora puteana . 1 w leaching, samples: 20 x 20 mm

Hannu Viitanen

53 14.4..2016

Field testing

Accelerated outdoor set up for coated plywood products

Adapted accelerated test for coated plywood products, VTT Otaniemi,

Finland.

Modified EN 927-3 test to expose plywood specimens for weathering.

Test simulate use of plywood products in UC 3 (not covered).

Edge sealing with acrylate paint. Specimen dimensions 100x500 mm.

54 Hannu Viitanen

Moisture content of birch plywood, field test

Wood moisture content (%). Birch plywood. During 2 years (2007-2008)

outdoor weathering (EN 927-3). All edges sealed (Acrylate paint).

0

10

20

30

40

50

60

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Ma

y 0

7D

ec

07

Ma

y 0

8D

ec

08

Uncoat PF Film

120

PF Film

220

Mel

Film

PB+

AcrAlk

PB+

Acr

PB+ PU AcrAlk

Paint

Acr

Transp

Epox

Paint

Wo

od

mo

istu

re c

on

ten

t (%

)


0

1

2

3

4

5

6

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

20

07

20

08

20

09

20

11

Uncoat PF Film120

PF Film220

Mel Film PB+AcrAlk

PB+ Acr PB+ PU AcrAlkPaint

AcrTransp

EpoxPaint

Cra

ckin

g (

0-5

)

Cracking (amount/size) of surface. Birch plywood. After 3, 4, 5 and 7 years outdoor weathering (EN 927-3). All edges sealed (Acrylate paint).

Surface condition of birch plywood, cracking (additional results from October / November 2011, after 7 years)


X-ray analyses of birch plywood after wet period (5 years’ outdoor weathering)

uncoated 120 PF 220 PF PBF+AcrylAlkyd paint AcrylAlkyd paint 57

Conclusion of the results on coated plywood products (Viitanen & Nurmi 2010 a,b)

• Performance and ranking of different plywood products • UC 3 conditions, not covered by design

Spruce plywoods 1. Phenol film coated, 220

2. Phenol film coated, 120

2. Painted, 3 mm veneer

3. Varnished, 3 mm veneer

4. Uncoated, 1,4 mm veneer

4. Uncoated, 3 mm veneer

Birch plywoods 1. PBF + painted

1. Epox painted

1. Melamine film, 440


3. Painted, AlkAcr


4. Varnished

5. Uncoated

58 Hannu Viitanen 14.4..2016

Examples on long lasting coated plywood products Traffic signs, reflecting film is the limiting factor

24 years

20 years

16 years

Hannu Viitanen 59

14.4..2016

To achieve 100 years’ service life of wood in building,

following facts should be taken care

• use dry and CE marked wood material, – correct glue type and glue class should be used for engineering

components

• good detailing and design to avoid malfunction of the structure and protection of the structure from weathering – good execution and protection against weathering during building

process – take care the effect of natural loading for the longer service life

• proper maintenance during the use and manual of maintenance for the users

• guarantee proper condition for material in building during the service life (ventilation, protection, drying of accidental water damage

Hannu Viitanen 60

14.4..2016

Example: Isoplets on critical conditions for mould and decay, for protection of wood (Viitanen et al 2008)

Start of mould growth Early stage of decay

50

60

70

80

90

100

0 10 20 30 40 50

Temperature (C)

Re

lati

ve

hu

mid

ity

(%

)

2 weeks

4 weeks

8 weeks

safe area

Mould

No mould risk

below the limits

50

60

70

80

90

100

0 10 20 30 40 50

Temperature (C)R

ela

tiv

e h

um

idit

y (

%)

1 month

6 months

one year

safe area

Decay

No decay risk

below the limits


References (1)

• CEN TC 38 Wood Durability. WG 28 Performance classification. Performance standards for wood in construction - delivering customer service life needs – Perform Wood.

• Englund, F. (ed). 2008. COST Action E37. Task Force “Performance Classification”. FINAL REPORT.

• Hukka, A, and Viitanen, H. 1999. A mathematical model of mould growth on wooden material. Wood Science and Technology. 33 (6) 475-485.

• ISO 2007. ISO 15686-1. Buildings and constructed assets – Service life planning – Part 1: General principles International Standard. 32 p.

• ISO 2007. ISO 15686-7. Buildings and constructed assets – Service life planning – Part 7: Performance evaluation for feedback of service life data from practice. International standard. 35 p

• Kokko, E., Ojanen, T., Salonvaara, M., Hukka, A. ja Viitanen, H. 1999. Puurakenteiden kosteustekninen toiminta. VTT tiedotteita 1991. VTT Rakennustekniikka. 160 s.

• Kääriäinen, H., Rantamäki, J. ja Tulla, K. 1998. Puurakenteiden kosteustekninen toimivuus. VTT tiedotteita 1923. 63 s + liitt. 14 s

• Lahdensivu J, Suonketo J, Vinha J, Lindberg R, Manelius E, Kuhno V,Saastamoinen K, Salminen K, Lähdesmäki K. 2012. Design and execution instructions for low energy and passive house structures and joints. Tampere University of Technology. Department of Civil Engineering. Structural Engineering. Research Report 160, 121 pages + 1 appendix.

• Lappalainen V, Sohlberg E, Järnström H, Laamanen J, Viitanen H and Pasanen P. Epäpuhtauksien kulkeutumisen simulointi kosteusvaurioituneesta rakenteesta sisäilmaan. Sisäilmastoseminaari 2014. 13.3.2014. S 111 – 116.

• Luotonen, P. & Viitanen, H. Rakennusten mikrobi- ja hyönteisongelmat. Vantaa 1995, Tikkurila Oy. 49 s

• Luotonen, P., Paajanen, L. and Vihavainen, T. 1980. Lattiasienen aiheuttamien vaurioiden korjaaminen. Seurantatutkimus. Espoo. VTT Puutavaralaboratorio, Raportti No 4. 30 s. + liitt. 37 s.

• Metiäinen, P. et al. Rakennusten ilmanpitävyyden pysyvyys. VTT Rakennetekniikan laboratorio. Espoo 1986. Tutkimuksia 422. 136 s. + liitt. 29 s.

• Metsä-Kortelainen , S. & Viitanen H. 2015. Durability of thermally modified sapwood and heartwood of Scots pine and Norway spruce in the modified double layer test. Wood Material Science & Engineering.

References (2)

• Ojanen, T; Viitanen, H; Peuhkuri, R; Lähdesmäki, K ;Vinha, J; Salminen, K. 2010. Mould growth modeling of building structures using sensitivity classes of materials. Proceedings of Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference (CD). DOE, BETEC, ASHRAE, Oak Ridge National Laboratory (ORNL) (2010), 10.

• Paajanen, L. & Viitanen, H. Korjattujen lattiasienirakennusten seuranta. Espoo 1987. VTT Tiedotteita 749.

• RIL 2011. Kosteus- ja homevaurioiden estäminen. Suomen Rakennusinsinöörien Liitto RIL ey. 2011.

• RakMK1988 B1 osa. B1 Suomen rakentamismääräyskokoelma. Rakenteiden varmuus ja kuormitukset. Ympäristöministeriö, Rakennetun ympäristön osasto

• Ritschkoff, A-C.,Viitanen, H. and Koskela, K. 2000. The response of building materials to the mould exposure at different humidity and temperature conditions. In: Seppänen, O. & Säteri, J. (ed). Healthy Buildings 2000. Vol. 4. FiSIAQ, s. 317 – 322

• Samuelson I. 1985. Mögel i hus. Orsaker och åtgärder .Statens provningsanstalt. Teknisk rapport 1985:12.

• Sedlbauer, K. 2001. Prediction of mould fungus formation on the surface of/and inside building components. University of Stuttgart, Fraunhofer (IBP), Doct Thesis. Stuttgart. Germany.

• Thelandersson, S,; Isaksson T,; Früwald, E. and Toratti, T. 2011. Woodexter – Engineering Guidline, version 7. Slides report. C.E.I.Bois, Building with wood

• Tikkanen et al. Kosteus- ja homevaurioituneen rakennuksen korjaus. Ympäristöopas 29. Helsinki 1997. Ympäristöministeriö. 79 s.

• Toratti, T. & Arfvidsson J. 2013. Service life and moisture safety. In: Kuittinen, M, Ludvig, A. & Weiss G.(eds) Wood in carbon efficient construction. Tools, methods and applications. CEI-BOIS.pp. 99 – 109.

• Tunnista ja tutki riskirakenne, opetusmateriaali. Hometalokoot. Insinööritoimisto Savora Oy, Crafical.fi, Ympäristöministeriö.

• Vesikari, E; Rautiainen, L; Häkkä-Rönnholm, E; Silvennoinen, K; Salonvaara, M; Viitanen, H. 2001. Julkisivujen ja katteiden käyttöiän ennakointi. VTT Rakennus- ja yhdyskuntatekniikka, Espoo. 158 s. VTT Julkaisuja - Publikationer : 850

References (3)

• Viitanen, H. Vuosina 1978 - 1984 tutkitut lahovaurionäytteet . VTT Tiedotteita 593. Espoo 1986. 31 s. + liitt. 6 s.

• Viitanen, H. 1995. Biologiset rasitukset. RIL 183-3-3...4. Rakennusmateriaalien ja rakenteiden käyttöikä. Rasitukset: 3.3 Biologiset rasitukset. Helsinki: Suomen Rakennusinsinöörien Liitto RIL r.y, 56 s.

• Viitanen, H. 1996. Factors affecting the development of mould and brown rot decay in wooden material and wooden structures. Doctoral Thesis . The Swedish University of Agricultural Sciences (SLU), Department of Forest Products. Uppsala (1996), 58 p. + app. 230 p.

• Viitanen, H. 1997a. Modelling the time factor in the development of mould fungi in wood - the effect of critical humidity and temperature conditions. Holzforschung 51 (1): 6-14.

• Viitanen, H. 1997b. Critical time of different humidity and temperature conditions for the development of brown rot decay in pine and spruce. Holzforschung 51 (2): 99-106

• Viitanen, H. 2004. Betonin ja siihen liittyvien materiaalien homehtumisen kriittiset olosuhteet – betonin homeenesto. VTT Working Papers: 6

• Viitanen, H., 2014. 100 years’ service life of wood in service class 1 and 2 - dry and moderately humid condition. VTT Research Report VTT-R-04689-14. VTT. 32 p.

• Viitanen, H. and Salonvaara, M.. Failure criteria. 2001. In Trechsel, E (Ed.). Moisture analysis and condensation control in building envelopes. 2001. American Society for Testing and Materials ASTM MNL40 pp. 66 – 80

• Viitanen, H; Vinha, J; Salminen K; Ojanen, T; Peuhkuri, R. Paajanen, L; Lähdesmäki, K. 2010a. Moisture and bio-deterioration risk of building materials and structures. Journal of Building Physics. 33 (3) 201-224.

• Viitanen, H; Ojanen, T; Airaksinen, M. 2013. Kosteus-, home- ja laho-ongelmien ja -vaurioiden detektointi ja korjaus. Mitä on opittu viimeisten 30 vuoden aikana?. Sisäilmastoseminaari 2013, Helsingin Messukeskuksen kongressialue, 13.3.2013. Espoo, Sisäilmayhdistys ry.

• Ympäristöministeriö. Kosteus- ja homevaurioituneen rakennuksen kuntotutkimus. Ympäristöopas 28. Helsinki 1997. 143 s. Opas uudistettavana vuonna 2014 - 2015.

• Wufi (Wärme und Feuchte instationär - Transient Heat and Moisture) 4.1 Pro software, The Fraunhofer Institute for Building Physics IBP

100 80 no mould risk below the limits 90 wood protection ... · chemical into wood 14.4..2016 ......

Documents