historic building interiors conservation

HISTORIC BUILDING INTERIORS

CONSERVATION

Dr Donald Ellsmore

Director, Donald Ellsmore Pty Ltd

Convenor, Australasia Chapter

Association for Preservation Technology

ISSUES INSIDE BUILDINGS

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Building have

contents and

occupants

Structural issues

impact on integrity

of interiors

Building envelope isolates

outside from inside

Interior environments

have a close

relationship with the

envelope

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PRINCIPAL CAUSES OF DETERIORATION

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Apart from structural movement

buildings may be affected by other

factors, including:

Human Factors

inherently poor design

poor material selection

user actions

Atmospheric and Climate Action

meteorological factors

atmospheric pollution

Excess Moisture

Chemical, physical and biological

action

METEOROLOGICAL FACTORS

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Storms

Strong winds

Floods

Seismic activity

When a structure is weakened by damage and loses integrity, the rate

of deterioration can increase rapidly.

ENVIRONMENTAL IMPACTS

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Environmental factors include some

which may appear benign but their

incremental effects can be considerable.

Environmental factors include:

Oxidation and corrosion

Electro-chemical reaction

Carbonation

Sulphate attack

Pollutants and contaminants

Soluble salts

Biological action

In well-maintained structures these

factors may be minor but in others

they may become major issues.

PERFORMANCE OF TRADITIONAL BUILDINGS

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The design and functioning of

buildings is something that has

evolved over many years.

Traditional buildings are to an

extent self regulating in matters

such as controlling the impacts

of external climate to provide a

stable internal environment for

human comfort and longevity –

but only when the occupants

use the buildings in the

traditional planned manner.

BUILDING ENVELOPE

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It is commonly found that,

over time, traditional

buildings become ‘improved’

by changes which affect

their ability to function

properly.

Changes which alter the

traditional behaviour of

materials and structures

usually introduce problems.

WATER

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Excess moisture – such as caused

by penetrating or rising damp,

condensation, hygroscopicity, user

actions and natural or man-made

events - is the most widespread and

damaging cause of deterioration and

decay in heritage buildings.

Causes of excess moisture may be

obvious in some situations but not so

in others.

Moisture in building fabric can effect

the health of occupants and the

condition of interior fabric and

contents directly.

ENVELOPE & ENVIRONMENT

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The main difference between

environments indoors and outdoors is

water.

Indoors there is no precipitation water

to wet down surfaces or flush off salts

and contaminants.

Indoors there are fewer pollutant

gases.

Indoors the relative humidity is

normally lower (drier).

Users may introduce water in the

form of condensation and damp

through apparently innocent activities

and/or lack of maintenance.

RELATIVE

HUMIDITY (RH)

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Understanding

Relative humidity

(RH) is key to

understanding

how buildings

(and humans)

respond to

moisture.

UNDERSTANDING RELATIVE HUMIDITY

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To understand Relative Humidity think of

an inflated balloon containing air and a

small amount of water. The ratio of water to

air is the relative humidity within the

balloon (expressed as %).

If the balloon is placed over a flame the air

will expand but the water content will

remain the same. The RH will decrease.

Conversely if the balloon cools the RH will

increase.

The interiors of buildings are like balloons. If they are heated the RH will

decrease. If they are cooled the RH will increase. If water is introduced the RH

will increase etc.

INTERIOR ENVIRONMENT

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The Relative Humidity in buildings is

a function of temperature, moisture

and air movement .

Inadequate air movement or

excessive moisture can lead to

development of high RH, mould,

fungal decay, insect infestations,

condensation and deterioration of

materials.

HYGROSCOPIC MATERIALS

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Cellulose (one of the major constituents of

wood) is a hygroscopic material. It gains

moisture (adsorption) when the RH is high

and looses moisture (desorption) when the

surrounding air is dry.

Dimensional change is the most important

consequence of moisture sorption by

wood.

HOW BUILDINGS RESPOND TO CHANGES IN RH

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All hygroscopic materials expand or

contract in response to changes in

RH, causing structural changes to

building fabric - carpentry, joinery,

furniture and furnishings.

There is a value in maintaining

hygroscopic materials in their

‘historic’ environment.

When buildings are heated or cooled hygroscopic materials will respond

by changing to achieve Equilibrium Moisture Content (EMC) with their

environment, usually resulting movement and dimensional change and

causing changes to salts.

TEMPERATURE, RH & HUMAN COMFORT

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There is often a conflict between

conservation and human comfort –

and heating buildings in cold climates

or cooling buildings artificially in hot

climates is not environmentally

sustainable.

Heating or cooling buildings can also

change the micro environment in

ways that may create conservation

dramas.

A solution can be to heat or cool the

people only, not the whole

environment.

LIGHT

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Light is a form of energy.

When a beam of light strikes a given

material, a certain amount of energy

is transferred to the surface it

contacts and several different

phenomena may occur:

- fading of colour

- degradation of material

The higher the frequency of radiation (or the shorter the wavelength) the higher the

energy of the photons – and hence the light’s capacity to induce chemical

reactions. Photons can interact with other particles (atoms and molecules).

UV is a high frequency, short wavelength, highly destructive energy.

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The term ‘light’ is used to indicate the electromagnetic radiation within the so-

called visible region – from 380nm to 780nm. However, the term ‘light’ is often

used in a broad sense to indicate all of the radiation emitted by an optical source

(UV to IR).

SOURCES OF LIGHT

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A light source is a

physical emitter of the

electromagnetic

radiation needed to

initiate visual perception.

Daylight is the most comfortable form of light for vision. It provides

uniform energy distribution over the whole visible range and offers the

best conditions for chromatic perception.

BUT it contains a considerable portion of UV as well as IR.

COLOUR TEMPERATURE

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The term ‘colour temperature’ is used to describe the quality or perceived

warmth of light. It ranges from black (coldest) through to red to blue to white (the

highest level of thermal radiation – white hot!).

Daylight varies hour by hour and day by day – and it ranges from 2,500k at

sunset to 20,000k in a clear blue sky.

DIRECT SUNLIGHT illumination can be highly damaging.

EFFECTS OF SUNLIGHT INDOORS

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Direct and reflected

sunlight can harm

indoor fabric and

contents.

For example, loss of colour may occur with light sensitive pigments. Even

reflected light can damage surfaces over time.

MEASURING (LIGHT) RADIATION

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For the conservation of light sensitive building fabric and artefacts the

parameters to be measured are; - light intensity,

- exposure, and

- ultraviolet radiation.

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The main issues indoors concern :

Corrosion (water usually exists

as vapour)

Light doses (artificial UV)

Temperature (excessive

heating and cooling)

Pollutant gases and particles

CONSERVATION

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There are not always obvious or simple

solutions for problems but there are

some reliable strategies that can be

applied to many conservation

challenges.

The following case studies illustrate

some strategies that might be applied

to other projects.

CASE STUDIES – INTERIOR WORKS

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WINDSOR HOSPITAL DEAD HOUSE

Early colonial building fabric including pit sawn timbers and hand made bricks

The object of the work was to conserve

maximum amount of authentic fabric,

using traditional methods including:

• poultice de-salination,

• lime water consolidation of brickwork,

• lime washing, and

• minimal material replacement.

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RIPPON LEA, MELBOURNE, CONSERVATORY

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The conservatory at Rippon Lea, Melbourne was added to the house in the

1890s. A series of photographs of that time indicated that the ironwork had

been painted in contrasting tones. Later it was painted green.

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The condition of the iron and steelwork had deteriorated to the point whereby it

required extensive work. The ironwork was overdue for painting in 2008.

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Although it is sometimes difficult to research ironwork, due to its hardness and

corrosion, paint sampling revealed evidence of the painting history including red

oxide protective coatings, original finishes and gilding.

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The sampling was cross referenced to the photographic record of the 1890s to

confirm the nature and placement of the colours and the gilt highlights on the iron

columns.

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The materials were repaired and the colour schemes were reconstructed

accurately. This has greatly enhanced the architectural balance of the

conservatory and re-integrated it with the polychrome detailing of the complex.

ALBERT HALL, CANBERRA 1927

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Albert Hall, 2010

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Albert Hall in Canberra was opened in 1927 to serve as the new capital’s main

assembly hall – a function that has not changed greatly, although the condition

of the place has deteriorated.

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The interior of the hall had been relatively plain. It was originally painted in

oil paint in drab tones. The latest colour scheme was a ‘restoration’ in a

latex emulsion paint system.

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Conventional paint sampling revealed details of the original paint colours and

the overlying paint colour schemes.

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Various problems were encountered in the works, including substrate

inconsistencies following paint removal, colour matching and reproduction of

appropriate gloss levels with enamel paint systems.

PARRAMATTA TOWN HALL 1881

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GOVERNMENT HOUSE, SYDNEY

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Conservation of the State Rooms

1984 - 2007

ENTRANCE HALL

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DINING ROOM

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BALLROOM

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Government House

Drawing Rooms

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SUMMARISING

• Occupied places often require works to accommodate uses or

changing uses.

• Changes should be planned to avoid impacts that would affect

authenticity and significance.

• There should not be any water inside buildings to affect the

building fabric but water often exists as vapour.

• High humidity will cause decay in organic materials and will

contribute to decay in inorganic materials.

• Works inside buildings require careful attention to the

principal causes of deterioration prior to any works to restore

decorative finishes.

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