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While there are several distinct types of condensation in buildings, surface condensation is by far the most common; indeed it is the most common form of dampness within domestic properties. Unfortunately, it is often misdiagnosed as other forms of dampness.
So how is surface condensation is formed?
Warm air can hold more water vapour than cold air – the warmer the air the more water it can hold and conversely the cooler the air the less it can hold. Thus, given this fact, it becomes evident that if warm moisture-laden air is cooled there will come a point at which the air is cooled to such a level it can no longer hold the moisture present. It is at this point the excess moisture starts to change from its vapour state to a liquid and effectively drops out of the air – this is what we see as condensation. In practice the effect is seen when moisture-laden air comes into contact with the cold surface, the coldness cools the air to an extent where it can no longer hold the excess water and it therefore falls out as liquid water (condensate) on the cold surface.
The visible signs of surface condensation are usually the formation of liquid water on impervious surfaces such as glass, oil paint, tiles, vinyl wallpaper, etc; these can lead to water ‘run’ marks, rust runs (water passing over metal) and where particularly severe it can and does lead to rot, this being especially significant where long-term condensation forms beneath timber suspended floors. In extreme cases water condensing at the base of walls can also decay timber skirtings; this usually causes a wet rot. On more permeable surfaces liquid water is initially absorbed, only becoming visible as dampness if the condensation is long term and severe.
However, perhaps the most common feature of condensation is mould growth: this is usually seen as ‘black spot’ mould but green, yellow and white moulds may also develop depending on the conditions and the particular surface.
There are proven health hazards associated with moulds, the most common being a trigger factor for asthma. However, it appears likely that in most healthy people only heavy, persistent moulds may potentially cause a problem although some people may be particularly sensitive. Nevertheless, prudence is dictated wherever moulds are to be found in occupied domestic buildings.
When mould growth is active the moulds emit volatile compounds which caused the distinctly ‘musty’ odours associated with dampness. This can be very important in that it is not uncommon to get such a musty smell yet there is no visible evidence of mould growth on walls. Why? Mould will grow on water sensitive materials without actual condensation occurring. This happens where the air may remain over around 75% saturated with water vapour where moulds can then develop on such materials like leather and certain cloth. What grows where depends on the numerous factors the most significant being the particular saturation moisture content of the air (relative humidity).
Where does the excess atmospheric water vapour come from? It is inevitably derived from normal living activities such as washing, cooking, bathing; indeed, just being in a building produces moisture from breathing and sweating. An individual in occupation can produce up to 10 litres of water simply from normal ‘life-style’ activities. However, contrary to most people’s beliefs the excess water is not derived from damp walls or floors unless extremely severe such as flooding; these sources are very limited compared to moisture generated from normal ‘lifestyle’ activities and only contribute a very small proportion of water to internal moisture production.
Normally such moisture is vented away but in some cases it is not – double glazing, draught exclusion, blocking of air vents and chimneys (if present) all restrict the venting of moisture laden air, especially from those areas where most water is produced such as bathrooms and kitchens. Where this occurs it inevitably leads to problems as described above.
One should also consider that condensation will occur in the non-living areas such as sub-floor voids and roof spaces; in these areas it often remains unnoticed and can lead to timber decay if sufficiently long term and severe.
At Timberwise we can correctly diagnose different causes of dampness. Indeed, it is imperative that diagnoses are correct – a misdiagnosis especially in relation to condensation and high humidities can lead to unnecessary expense and continued dampness and deterioration. We at Timberwise can offer specialist, specific advice and supply complete solutions as to the control and elimination of condensation and persistent problems of high humidities and associated mould growth, thereby reducing the potential health hazards associated with such growth in domestic properties and with our recommendations a healthy living environment may be achieved.
Condensation - Associated Links
Timberwise have been treating Dry Rot for over 4 decades and in that time have built a wealth of technical knowledge on Dry Rot. To help understand Dry Rot better we have now produced our definitive guide to Dry Rot to explain in depth Dry Rot, how it spreads and how we at Timberwise treat it.
Dry rot is the common name given to the wood destroying fungus, Serpula lacrymans. However, despite its common name it will generally only attack damp timber. Initiation of attack is by either a minute dry rot spore or cross contamination from already infected material, eg, wood, masonry.
For an infection to be initiated there needs to be a spore (or some growth that is viable already present), oxygen, a suitable temperature, a susceptible food source and water, all of which are to be found in buildings. Oxygen and a suitable temperature are almost inevitably present in the internal environment. In a normal ‘dry’ environment water will be present in timber but at a level that is not conducive the germination or growth of dry rot, ie, less than 20% (Moisture contents of between 8 – 16% may be found in a ‘normal’ dry domestic dwelling). Even when suitably damp, the natural resistance to decay of some timbers (and properly preserved timber) may prevent rot. Thus, dry rot is not inevitable if wood becomes and remains damp but timbers will certainly be at risk.
Dry rot mycelium
Omnipresent in the environment, spores will therefore be present in all properties. However, a spore will only germinate and infect when there is both dampness and a food source (ie, suitably susceptible wood or some other suitable cellulose based material). For spore germination to be successful it appears that free moisture must be present within the wood above the fibre saturation point, ie, moisture contents in excess of 30%. Thus, for the decay to become initiated the wood must usually be physically wet. This usually occurs as the result of severe water ingress in the form of rainwater leaks, plumbing defects, floods, long term severe condensation, etc. Further pre-requisites for initiation of decay are still and humid conditions. The initiation of dry rot appears less likely as the result of ‘capillary bound’ moisture such as that arising from rising dampness although once initiated such dampness will support growth.
It is recorded in laboratory culture experiments that spores can germinate between 7-10 days following suitable wetting; this may take longer if the spores are older. However, it appears that in practice under field conditions it often takes some considerable time before rot becomes noticeable.
Once initiated a minimum timber moisture content of around 20% is required for the infection to survive although the optimum moisture content for active growth is reported around 35 – 50%; however, the rate of decay at 20% and just above is likely to be very minimal. Timbers within a building are usually kept well below 20% moisture content and are therefore not vulnerable to fungal decay. However, should timbers become damp, then, given the requirements described above, dry rot has the potential to establish and develop.
Dry rot will also require a suitable temperature. The optimum temperature for growth is recorded around 22ºC and the maximum temperature around 26ºC; indeed 15 minutes at 40ºC has been shown to kill the fungus. The minimum temperature is around 3ºC. It should be noted that very slight variations on the above figures have been reported.
Once established it has the ability to spread over and through damp materials such as damp masonry, etc, and can spread to and attack timbers which are in direct contact with or in very close proximity to damp masonry under still, humid conditions, eg, joist ends, lintels, panelling, fixing grounds, skirtings, or any other timbers which can become and remain damp/wet.
Established dry rot normally infests those timbers that remain damp although it can cause wetting of ‘dry’ timber as the result of water produced from the breakdown of the wood in the process of decay. However, this appears only to occur in areas where ventilation is very limited and the humidity remains very high, probably greater than 90% relative humidity. Indeed at these humidities the moisture content of wood will rise in excess of 20% and so could be vulnerable to the support of dry rot. It also has some limited ability to wet up dry wood, but again, this will only occur where there are very humid stagnant conditions or where it may be trapped between impervious materials where water cannot evaporate.
Dry rot may spread over onto other materials such as carpets and fabrics if in contact with dampness. However, unless these materials are cellulose based it is unlikely to cause any damage although some discolouration may occur.
So, in practice decay by dry rot tends to be restricted to damp, unventilated areas and often remains unnoticed until damage is at an advanced state; frequently it can go undetected for many years. This also occurs where large dimensioned timbers are in direct contact with damp masonry but remain well ventilated in which case the decay only develops within the interior of the member, the outer surface remaining sound.
Under very humid, stagnant conditions white cotton wool-like aerial mycelium is produced. In extremely humid conditions droplets of water form on the growth. In less humid conditions the growth tends to form a silky-grey skin, often tinged with patches of lilac and yellow colouration. Sometimes the growth is more of a ‘mushroom’ colour or even sheets of a reddish growth.
The first evidence of the existence of an outbreak of dry rot is often the sudden appearance of a fruiting body (sporophore), or the shrinking/distortion of timbers. This latter feature can be quite dramatic and sudden, the change from dimensional stability to instability of the wood visually taking place relatively suddenly; this explains the apparent sudden appearance of dry rot frequently reported. It should be noted, however, that fruiting bodies are not always formed.
Unlike many other wood destroying fungi dry rot can readily grow over and through porous masonry provided that there is a nutritional source (wood) from which it can spread; this ability allows the spread of the fungus from one area to another. This generally only occurs to any significant level where the masonry is damp either via severe sources of water ingress or rising damp, etc.. Dry rot will not spread over or though masonry that is ‘dry’, ie, that does not contain free (capillary) moisture.
A further feature of the fungus is the formation of ’strands’, thick walled structures which develop in the fungal growth. These are resistant to desiccation and carry nutrients from the food source to the growing tips of the fungus when the organism is growing through or over nutritionally inert materials, eg, masonry, soil. They support the spread of the growth. However, without a source of food growth is terminated.
When the decay is advanced the shrinkage causes the wood to split in a cuboidal manner (this is typical of a number of wood destroying fungi), and it is therefore not always easy to distinguish between dry rot and other fungi (wet rots — brown rots) in the absence of fungal growth.
Should infected timbers dry out or the food source be removed the growth will cease but, depending on conditions, it can take considerably longer for the fungus to die. For example, in timbers that have dried down to below 20% moisture content the fungus can remain dormant for up to about a year at ambient temperatures before dying. However, this period may be prolonged at lower temperatures.
If infected wood is removed then the growth is very limited and quickly terminated, but the growth can remain viable in damp masonry at low temperature (eg, 7oC) for up to 9 years, and up to 1 year at ambient temperatures. Should new, untreated or inadequately treated wood be put back into direct contact with damp infected masonry, even though the original decayed wood had been removed, then fungal growth may start and spread into the new wood so initiating further decay.
It is not practical to precisely define the rate of growth of dry rot due to variation in the nutritional quality of the food source, dampness, the environment, etc., but in buildings that have been studied growth rates of between 0.04m and 0.8m per year have been recorded (Building Research Establishment Digest 299); C.R.Coggins (1980) gives a slightly higher general figure of about 1 metre per year. Savory (1971) reports figures in an experimental house of between around 1m – 1.45m. The author has reliable figures giving a growth rate of around 1.5 metres per year. In the laboratory, however, growth rates of about 2.9m to 4m per year have been recorded. A further difficulty arises in establishing growth rates in that it is not always possible to tell if the decay is the result of a single outbreak or the coalescing of several individual outbreaks. However, the use of published rates of growth may be useful to help identify if an outbreak could have possibly grown a specific distance in a given time period.
In most cases the optimum conditions for growth and decay of timber have been derived under carefully controlled laboratory conditions. In practice, however, it is highly unlikely that such optimum conditions would be present, or at least for any length of time. Thus, for growth and decay the use of ‘optimum data’ within a field situation to evaluate the growth or decay activity by dry rot is unlikely to prove valid. Furthermore, it is possible for dry rot to remain ‘dormant’ under unsuitable conditions for a while, only to become ‘active’ when such conditions become more favourable.
The procedures for the control and eradication of a dry rot infection are given in Building Research Establishment Digest 299 and British Wood Preserving Association Code of Practice for Remedial Treatment; where remedial works are envisaged then the work should be undertaken in strict accordance with the principals and instructions given within the above publications. Basically the control of all rots is a matter of good building practice but it also requires a thorough understanding of the nature of this particular organism.
At Timberwise we first undertake the fundamental procedure to control and eliminate the rot and that is to eliminate the source of water, to remove infected timber if the rot is active, and propagate and maintain drying conditions. Without either food or water the fungus cannot grow and will eventually die. However, where decay is limited and wood/masonry is now dry, or will rapidly dry once the source of water has been eliminated, then we may leave such timbers in situ if deemed appropriate and structurally sound thereby minimising the amount of repairs necessary and maintaining the structure of the original building; this is particularly important in the case of historic and listed properties.
We regard ancillary chemical measures as secondary to the above in the control of dry rot. It should also be considered that chemical treatment of timber and masonry must be capable of resisting the rot for at least the period of drying down; this could take several years in some cases otherwise it will be of little value. It is these factors which Timberwise fully appreciate.
Finally, Timberwise fully appreciate it is imperative that all areas of dampness are identified as timbers within these areas will be at risk to rot developing if such timbers are not fully protected from either the moisture or the rot itself. We are also aware that where dampness is identified and where there may be hidden timbers these may have already rotted. However, previously decayed wood where rot is now dead may sometimes be found in areas that have dried out and if structurally sound or of no importance these may be left provided they can be maintained dry.
Dry Rot – Associated Links
Download our Dry and Wet Rot Solutions Leaflet
When an ASDA store in Liverpool needed some help with some nuisance birds Timberwise were called in to provide an ideal solution. Pigeons and gulls were nesting on the facade of the store causing problems and health issues for shoppers as a result of bird droppings.
The Timberwise solution for these troublesome birds was to utilise bird spikes along ledges and other possible landing sites for the birds on the building making the building a bird free area. Bird spikes are a humane deterrent that stop the birds from landing.
The pictures below show the front of the store, the birdspikes going into position and a close up of the birdspikes in situ.
For more information on the range of bird proofing solutions from Timberwise visit our bird proofing page or click here to arrange a survey.
Property maintenance is one of those jobs that most home owners tend to forget about or put off until another day. Every day our surveyors come across properties in need of remedial treatments as a result of neglecting property maintenance. Below we have an example of one such building.
This property in the West Midlands needed our expert attention as a result of prolonged rain water ingress as a result of defective and blocked external guttering. The rain water ingress caused moisture inside the building which helped provided the ideal climate for dry rot fungus to grow. Dry rot requires 3 things for growth: water, air and a source of food – all of which were present in this property and caused the dry rot fungus to take hold. (To learn more about the life cycle of dry rot click here or to view our on line CPD seminar on the life cycle of dry rot click here.)
The floor boards, walls and skirting are all showing signs of water ingress damage.
The dry rot sporophores are clearly visible on the skirting board above.
To help keep your property in top condition there are a few simple checks that can help:
If you discover any problems with damp, water ingress or dry rot in your property simply give Timberwise a call on 0800 99 11 00 or request a survey on-line.
Timberwise are well know for their skills in the treatment of dry rot, woodworm and damp proofing but we are also skilled in the control of troublesome birds using a range of humane bird proofing solutions that are harmless to the birds yet effective in solving the problem. Bird problems can occur on a whole range of properties – even Wimbledon has problems keeping the pigeons away!
With our range of bird netting, bird spikes, bird coils and bird wires we are able to provide a solution to the problem caused by troublesome birds.
Problems caused by birds include:
To find out more about our humane range of bird proofing solutions click here
For the latest news on the tennis at Wimbledon visit the offical Wimbledon website
People expect their basement waterproofing system to keep their basement dry day after day, year after year but without an annual inspection of the waterproofing system can you really rely on your sump and pump unit to keep your basement dry?
At the heart of a Timberwise basement waterproofing system is a sump and pump unit. Think of the pump in the same way as you would the engine of a car. To keep a car in good running order it requires regular servicing and so does your pump.
To remain effective your basement system needs to be inspected and cleaned regularly – in most cases only once a year.
With a 10 point basement ‘Clean & Check’ you will have the peace of mind that your basement waterproofing system is working efficiently. If left unchecked silt and deposits along with limescale can decrease the effectiveness of the pump and the waterproofing system.
With a Timberwise waterproofing solution the system is designed so that it can be serviced easily. The sumps benefit from easy to remove lids to allow easy access to the pumps whilst the perimeter drainage has inspection ports fitted to allow the system to be ‘flushed’.
The ‘Clean & Check’ routine comprises of the following:
The ‘Clean & Check’ service is provided by The Basement Sump & Pump Co
The Basement Sump & Pump Co are experts in the maintaining and servicing of basement waterproofing systems and are a strategic partner of Timberwise.
To arrange a survey of your basement simply call 0800 019 9949 or visit www.basementcare.co.uk
11 July 2008
The attraction is German U-boat U534. The U-boat which was sunk on May 5th 1945 is one of only 4 full size U- boats left in existence. At it’s new home the U-boat will be split into 3 sections allowing tourists to have a glimpse of what life in the cramped conditions of a German U-boat was really like whilst also exploring the link between ferries and underwater warfare.
The pictures below show the U-boat and site under construction.
The problem for the owners of the new attraction though was how to potentially keep troublesome birds away from the attraction. As the attraction is outdoor based it was vital that bird proofing was taken into consideration, especially as the attraction was based in a coastal location. Due to the shape and size of the structure conventional methods of bird proofing would have proved difficult to utilise – audible bird proofing devices may have proved too noisy whilst netting may distract from the aesthetics of the attraction. Through a careful study of the location we are now monitoring the bird situation on a regular basis to keep the area free of troublesome birds.
For further information on the Timberwise range of bird proofing solutions click here
The Association represents the UK’s damp-proofing and timber preservation industries, as well as structural waterproofing and structural maintenance.
Mr Edwards’ key roles include promoting the expertise of the PCA with regard to flood damage and raising awareness of its profile in the consumer sector. He holds the post of chairman until May 2010. Mark is currently also chairman of the GPT as well as holding directorships in the GPI and BWPDA.
The Property Care Association (PCA) has been in existence for four years as part of the British Wood Preserving and Damp-proofing Association (BWPDA) but last year officially became an independent association, along with the Wood Protection Association.
The new Associations have been created to concentrate on their own areas of expertise – namely for the Property Care Association damp-proofing and timber preservation, structural waterproofing and structural maintenance.
Although a relatively new trade body, the Property Care Association has inherited the stability and professional strengths of the BWPDA and its 75 year history.
This includes the choice of a long-term FSA regulated specialist insurance policy, and a UK-wide list of contractor members who are all carefully vetted before being awarded membership – and are then subject to rigorous auditing procedures once admitted to the Association.
The Property Care Association is also a member of TrustMark the scheme supported by Government, to help property owners find reliable and trustworthy tradespeople to make home improvements.
At Timberwise we are experts in the treatment of all forms of fungal decay from well know rots such as dry rot and wet rot to lesser know ones such as Plaster Fungi.
Plaster fungi comes in various forms and tends to be found in damp habitats such as brickwork or plaster.They are very similar in appearance to wood rotting fungi and produce large fruiting bodies and mycelium growth.
Peziza ssp:
This is a small, light brown or flesh coloured fungi. It has cup shaped fruiting bodies with no stalks present. When fresh they are flexible but harden over time and become brittle.
Pyronema domesticum:
With it’s bright orange jelly like fruiting bodies Pyronema domesticum is easily identifiable. The mycelium produced is very similar to that of Serpula lacrymans – Dry Rot.
Timberwise are experts in the eradication of plaster fungi. If you find plaster fungi in your property don’t panic! Simply call Timberwise on 0800 99 11 00 or click here to request a survey.
