Condensation Technical

Every year around the time the clocks go back another seasonal event takes place without fail. Windows start to steam up, mould growth starts to grow and you know condensation is back with a vengeance.

In the same way as condensation and mould growth make their annual appearance the remedial treatment industry as a whole tends to ignore the problem, and unwittingly lose a worthwhile business opportunity. The traditional remedial treatment business has become more difficult in recent years and the professional contractor now needs to grasp every opportunity to extend his professional services.

In the colder months condensation will occur somewhere in nearly every property, either housing, commercial or industrial, unless appropriate remedial precautions have been taken. It is the largest single complaint received by landlords in both the public and private sectors, and generally a self-inflicted problem by the owner-occupier.

The Problem

Condensation is caused when warm, moist air meets a cold surface and the water vapour "condenses" out.

The capacity of air to hold water is related to temperature; warm air holding more water than cold air. Air is saturated when it cannot hold any more water vapour at the existing temperature and therefore has a relative humidity (RH) of 100%. If the temperature of the air falls until saturation point occurs, the air is at a critical temperature or dew point where any further fall in temperature will result in water vapour being forced to condense out as liquid water.

The condensed water usua~4y~pears as droplets on windows and other non- absorbent surfaces. This is surface condensation; it is fairly obvious and always occurs on the surfaces which are at or below the dew point of the air immediately adjacent.

The water vapour inside a building also contributes to a greater overall air pressure. This results in the outward movement of warm, moist air through the structure of the building. This could eventually cool below its dew point within the fabric of building resulting in interstitial condensation.

Interstitial condensation is more complex than the surface form and presents a greater hazard. It can go undetected for long periods until serious damage has developed such as timber decay.

There are four main and interrelated factors which affect the occurrence of condensation in a building:-

Moisture generated within the building

The ventilation system provided and use made of it .

The heating provided and use made of it .

The thermal capacity and insulation

The first two factors are normally the primary causes because moisture generated by domestic activities can be significant and the fact that most buildings are effectively sealed to prevent heat loss means there is no background ventilation to allow the moist air to naturally filter out of the building. Features such as double glazing and draught excluders cause problems associated with poor air circulation, as this can lead to stale air as well as condensation.

Condensation is quite often found in kitchens and bathrooms, but warm moist air can also spread to cooler parts of the building such as bedrooms to condense on any cold surface. Here the first signs to the occupier will be mould growth.

The appearance of mould creates concern about damage to furnishings, decorations, unpleasant smells and possible affects on health.

So what does all this mean for the contractor ?

Here in UK the majority of the housing stock will suffer from condensation and mould growth -what do you do to convert this into business?

As a professional contractor the client will expect you to sort out the "damp" problem reliably -you should be able to identify the cause of the "damp" and if it is condensation deal with it -don't ignore the condensation or pass it off as rising damp. You can convert this type of enquiry into good business in the following way:-

1. Diagnose the problem properly . 

Condensation and mould growth are dynamic events. They need to be diagnosed properly at a site visit and not confused with other sources of dampness.

Surface condensation can be determined if RH, air and wall surface temperatures are measured. This can be achieved at the same time using either air/surface thermometers and/or various instruments such as thermohygrometer condensators, digital hygrometers or in some cases simply dew tabs.

Even if conditions are changing at the time of surveyor the survey is made under hostile conditions, the risk of surface condensation can still be evaluated if RH and wall surface temperatures have been determined.

Unlike surface phenomenon interstitial condensation cannot be measured directly and only the risk of its occurrence can be assessed.

Site record sheets are invaluable in this type of survey, as specific data has to be recorded. In fact some forms do allow an estimate of costs to be made quickly which will save time and money.

The Professional Approach

The remedial work to be undertaken to control condensation and mould growth depends very much on the extent of the problem. The work will range from a sale of antimould or anticondensation coatings (sometimes in a kit form) to solve isolated mould problems through to minor building works and major refurbishments. By applying the correct remedy you can convert tentative enquiries into hard business whilst improving the general reputation of your company, which will in turn lead to other damp or remedial related work.

You should also remember that local authorities and housing associations are now seeking "best value" rather than competitive tendering and this, again will help you develop more business provided you diagnose the problem correctly and apply an effective remedy.

What do you offer?

In most cases the use of antimould coatings and ventilation products will satisfy the situation. Your own knowledge and experience, coupled with the survey will tell you the extent of the risk of condensation and mould growth.

Low risk

Isolated mould growth but no obvious signs of condensation. You will find this quite often on "call backs" during or after drying out following replastering. The answer here is the use of antimould paints (available in kit forms for sale to householder) to prevent mould growth.

If you have experienced a number of call backs like this a more effective solution will be to use antimould microporous or breathable replastering

paints. They have been specially formulated to allow the substrate to dry out after replastering without mould growing on it. These paints are generally available and meet the recommendations in BS 6576 and the BRE Good Building Guide 3 (Damp proofing existing basements).

Medium risk

Mould growth and condensation in kitchen/bathroom and some other rooms. Apply biocidal washes, antimould and anticondensation paints and install ventilation products. There are various options with ventilation products from passive ventilators (air bricks, black holes), local extraction fans and PIV

(Positive Induced Ventilation).

A habitable room should be ventilated so that all the air is replaced at least once every hour. Air replacement in high risk rooms such as bathrooms and kitchens should be much greater than habitable rooms. Building Regulations now recommend that this is achieved by having permanent ventilation of at least 8000mm2 ( equivalent to a 4 x4" hole in an outside wall) and rapid mechanical extraction in high risk rooms.

High risk

Severe mould growth and condensation throughout the property. Essentially the same action as for medium risk cases but with recommendations for insulation, heating and even double glazing (provided trickle ventilators are part of the unit) as well as minor works such as fitting door closers to kitchen and bathroom doors to prevent moist air migrating into other parts of the property.

It is also important to offer guidance to any occupier in order for them to minimise the risk of condensation by taking sensible precautions such as the venting of tumble driers to the outside and maintaining some low background heating.

Who can help?

You should be aware that there have been amendments under COPR with regard to anti mould paints. If the product makes a claim as a fungicidal or antimould paint it should be HSE approved, as it is now a treatment against biological growth. Under these circumstances the anti mould paints or coatings have become recognised as treatments and this will help you develop the business.

Most chemical manufacturers will have available the survey equipment,

anti mould paints and a range of ventilation products. They will also invariably run training courses to introduce and fully explain how you can deal with condensation and mould growth.

Take advantage of these services as remedial treatment contractor should be dealing with condensation and mould growth as a major damp problem and not leaving it to "non -experts" from other business sectors.The first two factors are normally the primary causes because moisture generated

by domestic activities can be significant and the fact that most buildings are effectively sealed to prevent heat loss means there is no background ventilation to allow the moist air to naturally filter out of the building. Features such as double glazing and draught excluders cause problems associated with poor air circulation, as this can lead to stale air as well as condensation.

Condensation is quite often found in kitchens and bathrooms, but warm moist air can also spread to cooler parts of the building such as bedrooms to condense on any cold surface. Here the first signs to the occupier will be mould growth.

The appearance of mould creates concern about damage to furnishings, decorations, unpleasant smells and possible affects on health.

So what does all this mean for the contractor ?

Here in UK the majority of the housing stock will suffer from condensation and mould growth -what do you do to convert this into business?

As a professional contractor the client will expect you to sort out the "damp" problem reliably -you should be able to identify the cause of the "damp" and if it is condensation deal with it -don't ignore the condensation or pass it off as rising damp. You can convert this type of enquiry into good business in the following way:-

1. Diagnose the problem properly . 

Condensation and mould growth are dynamic events. They need to be diagnosed properly at a site visit and not confused with other sources of dampness.

Surface condensation can be determined if RH, air and wall surface temperatures are measured. This can be achieved at the same time using either air/surface thermometers and/or various instruments such as thermohygrometer condensators, digital hygrometers or in some cases simply dew tabs.

Even if conditions are changing at the time of surveyor the survey is made under hostile conditions, the risk of surface condensation can still be evaluated if RH and wall surface temperatures have been determined.

Unlike surface phenomenon interstitial condensation cannot be measured directly and only the risk of its occurrence can be assessed.

Site record sheets are invaluable in this type of survey, as specific data has to be recorded. In fact some forms do allow an estimate of costs to be made quickly which will save time and money.

The Professional Approach

The remedial work to be undertaken to control condensation and mould growth depends very much on the extent of the problem. The work will range from a sale of antimould or anticondensation coatings (sometimes in a kit form) to solve isolated mould problems through to minor building works and major refurbishments. By applying the correct remedy you can convert tentative enquiries into hard business whilst improving the general reputation of your company, which will in turn lead to other damp or remedial related work.

You should also remember that local authorities and housing associations are now seeking "best value" rather than competitive tendering and this, again will help you develop more business provided you diagnose the problem correctly and apply an effective remedy.

What do you offer?

In most cases the use of antimould coatings and ventilation products will satisfy the situation. Your own knowledge and experience, coupled with the survey will tell you the extent of the risk of condensation and mould growth.

Low risk

Isolated mould growth but no obvious signs of condensation. You will find this quite often on "call backs" during or after drying out following replastering. The answer here is the use of antimould paints (available in kit forms for sale to householder) to prevent mould growth.

If you have experienced a number of call backs like this a more effective solution will be to use antimould microporous or breathable replastering

paints. They have been specially formulated to allow the substrate to dry out after replastering without mould growing on it. These paints are generally available and meet the recommendations in BS 6576 and the BRE Good Building Guide 3 (Damp proofing existing basements).

Medium risk

Mould growth and condensation in kitchen/bathroom and some other rooms. Apply biocidal washes, antimould and anticondensation paints and install ventilation products. There are various options with ventilation products from passive ventilators (air bricks, black holes), local extraction fans and PIV

(Positive Induced Ventilation).

A habitable room should be ventilated so that all the air is replaced at least once every hour. Air replacement in high risk rooms such as bathrooms and kitchens should be much greater than habitable rooms. Building Regulations now recommend that this is achieved by having permanent ventilation of at least 8000mm2 ( equivalent to a 4 x4" hole in an outside wall) and rapid mechanical extraction in high risk rooms.

Hiqh risk

Severe mould growth and condensation throughout the property. Essentially the same action as for medium risk cases but with recommendations for insulation, heating and even double glazing (provided trickle ventilators are part of the unit) as well as minor works such as fitting door closers to kitchen and bathroom doors to prevent moist air migrating into other parts of the property.

It is also important to offer guidance to any occupier in order for them to minimise the risk of condensation by taking sensible precautions such as the venting of tumble driers to the outside and maintaining some low background heating.

Who can help?

You should be aware that there have been amendments under COPR with regard to anti mould paints. If the product makes a claim as a fungicidal or antimould paint it should be HSE approved, as it is now a treatment against biological growth. Under these circumstances the anti mould paints or coatings have become recognised as treatments and this will help you develop the business.

Most chemical manufacturers will have available the survey equipment,

anti mould paints and a range of ventilation products. They will also invariably run training courses to introduce and fully explain how you can deal with condensation and mould growth.

Take advantage of these services as remedial treatment contractor should be dealing with condensation and mould growth as a major damp problem and not leaving it to "non -experts" from other business sectors.