Rising Damp is simply, water from the ground that enters a structure by capillary action.
Water that enters or affects a building through any other route can move about in various ways but is not
rising damp. Only rising damp can be cured by the installation of a chemical damp proof course.
Rising damp is a commonly encountered problem in some types of building, however it is often misdiagnosed. It is important that the investigations into dampness are undertaken by a trained
and competent surveyor who can recognise and understand the problem. The surveyor who undertakes investigations will have been awarded the CSRT qualification.
Decayed skirting boards, crumbling or salt stained plaster, discolouration and staining, decayed timber floors, peeling paint and wallpaper are all common when walls are affected by rising damp.
These defects are not always evident but when they are, a specialist inspection is always recommended.
Most types of masonry used in the walls of buildings will allow some water movement by capillary action; however, this is usually controlled by a physical barrier or damp proof course. If this
physical barrier is absent, has broken down or is damaged then it is often possible to install a remedial damp proof course (DPC) to control water rising from the ground.
If the dpc has been merely been bridged by relatively high external ground levels, then lowering the external levels will be the first course of action.
Water rising from the ground often introduces contaminating salts into the walls and plaster coats.
This contamination will often result in a need for the plaster to be removed and replaced using specially formulated salt resistant plasters.
As members of the PCA we have the skills and experience needed to diagnose report on and repair buildings affected by rising damp. Please contact us for further information.
WATER INGRESS (PENERTRATING DAMP)
The primary reason that building materials biodegrade is because they are affected by water. It is fundamental to the preservation and maintenance of all buildings that they remain as watertight as
their design will allow.
Any defect permitting access of moisture into the fabric of a building must be remedied or treated, further entry of water must be prevented, and the area affected by water dried out. In order to
identify defects that can lead to water ingress and to identify areas within the building that are at risk of fungal decay, a detailed inspection should be undertaken by a competent specialist.
If you are concerned that water ingress has taken place it is important to engage the services of a trained and competent specialist who can conduct all the necessary diagnostic investigations.
Please contact this office for further information or to arrange a site survey and a full written report.
Fungal Decay in Building Timbers
Dry rot and wet rot can affect buildings of all ages and if decay is discovered it should be identified and remedial action taken without delay.
Fungal decay occurs in timber which becomes wet for some time and is the result of the attack by one of a number of wood-destroying fungi. The most well-known are Serpula Lachrymans – the
true dry rot fungus -, Coniophora Puteana the Cellar fungus and Poria Vaillantii the Pore or Mine fungus. Many other fungi also occur and some have recently been particularly linked with decay in
door and window frames.
Dry rot is only caused by Serpula Lachrymans and is the most serious form of fungal decay in a building. It can spread onto and destroy much of the timber. Wet rot occurs more frequently, but is
less serious; decay is typically confined to the area where timber has become and remains wet.
Fungal decay always arises because the wood has become wet, usually timbers will be in excess of 20 per cent moisture content. Finding the source of dampness and eliminating the ingress of
moisture and promoting drying is always necessary.
Outbreaks of dry rot and wet rot start in similar ways. The mature fruiting bodies of wood destroying fungi that develop during an attack produce millions of microscopic spores and these
are widely dispersed by air currents. If they fall on untreated damp wood they will germinate by pushing out a hollow tube called a hypha which grows and branches to form a mass of hyphal
threads called mycelium. Mycelium can develop both on the surface and inside the timber and will break down the wood for food. The timber may darken in colour and develop a characteristic
cracked appearance. Some wet rots may result in bleaching of the wood; these are more common in doors and window frames.
Eventually, the wood loses its strength and in some situations may become dangerously unsafe.
The main differences between dry rot and wet rot are the degree of development of mycelium on the wood surface and the ability of the fungus to spread into other timbers via adjacent masonry. It
is important that the two types of decay be distinguished since they require different treatment.
Serpula Lachrymans develops extensively on the surface and within the infected timber and in still, humid conditions produces a mass of cotton wool-like growth. Water droplets are often produced
on the surface of the mycelium.
Mycelium spreads over the timber surface by the continued growth and branching of the delicate hyphal threads growing with time. Specialised strands develop within the mycelium and these
supply water and nutrients to the growing fruiting bodies. The strands assume their real significance when the fungus spreads from infected timber onto the surface of adjacent stone or
brick walls. The tiny hyphal threads penetrate the mortar joints and plaster layers and large areas of damp wall can then become infected.
This type of rot is caused principally by Coniophora Puteana. Poria Vaillantii is another important wet rot fungus and a number of less common fungi also occur. While each fungus has its own
unique features, the general appearance of wet rot is similar – as is the treatment. Wet rot is typically confined to the area of dampness because the mycelium does not spread into walls.
Identification and Treatment
As we have shown it is very important that the type and cause of the fungal decay are correctly identified before any corrective action can be considered. It is for these reasons that it is important
that a detailed diagnostic inspection is carried out by a competent specialist. This inspection will be followed by the submission of a report that details both the cause of the decay and the proposed
Common Furniture Beetle/ Woodworm / Anobium Punctatum
The most common wood destroying beetle found in British buildings today is the Common Furniture Beetle (Anobium Punctatum). This insect commonly occurs outdoors infesting dead tree
trunks, branches and other forms of exposed timber but, the main cause for concern is its ability to infest indoor timbers in a variety of situations.
Adult beetles emerge from timber in the spring and summer. Very soon after mating the female beetle lays approximately 30 eggs, often into cracks and crevices in the timber she has just
vacated. Usually within a month the eggs hatch and the young grubs begin burrowing into the timber. Here they remain for up to four years slowly eating and burrowing beneath the surface of
the wood. Eventually the mature larva produces a chrysalis and during the winter months goes through the process of metamorphosis from a larva to a small black beetle. This process occurs in
a pupation chamber just beneath the surface of the wood. Following the pupation process the adult beetle cuts a hole in the surface of the timber and emerges to start the process once more. It is the
appearance of new emergence holes and the dust (frass) that falls from them that often indicates the presence of an active infestation of woodworm.
The woodworm beetle is significant because given the right conditions it can infest a wide variety of timber products including structural building timbers, furniture and wooden ornaments. If left unchecked
infestations can lead to severe structural weakening and eventually total collapse.
Treatments of Woodworm
Before making a decision on treatments a surveyor must consider the condition of the infested timber, the type and accessibility of the woodworm attack and the risks and hazards associated
with any work that is to be recommended.
In preparation for the application of preservatives the timbers should be cleaned down to remove any excessive dust and debris. Treatments using water based insecticides are very common and
are generally successful and cost effective. Chemicals are often applied by low pressure spraying but some insecticides can be applied by “fogging” or are brushed on.
Furniture, ornaments and small items of timber can be treated by the use of heat, freezing or gas fumigation. All these methods of treatment are highly specialised and should only be undertaken
by people who are trained and competent.
Other wood destroying insects
Death Watch Beetle (Xestobium Rufovillosum). This insect is often associated with historic buildings and usually affects the sapwood of hardwoods that are damp or have been affected by fungal
House Longhorn Beetle (Hylotrupes Bajulus). This relatively large insect affects sapwood and is predominantly associated with roofing timbers. They are limited in range to a small part of South
East England. Infestations if left unchecked can lead to severe structural weakening in a relatively short period of time.
When infestations by the Death Watch Beetle and House longhorn beetle are discovered, treatments will always be dictated by site conditions and formulated by an experienced specialist
The most common form of unwanted dampness in buildings is water from the air that forms as condensation.
The air in buildings can have a high level of relative humidity due to the activity of the occupants (e.g. cooking, drying clothes, breathing etc.). When this water laden air comes into contact with
cold surfaces such as windows and cold walls it can condense, causing water to be deposited. The point at which the water held in the air changes from vapour to liquid is known as the dew point.
Condensation is often associated with poor heating and ventilation in buildings, but this simple view can be misleading. Condensation is chiefly a winter problem, as the external air temperature
is low and external walls and windows are cold. The usual sequence of events is as follows:
• Cold air enters the building
• The air is warmed for the comfort of the occupants
• The warm air takes up moisture
• The warm, moist air comes into contact with cold surfaces, walls, windows, etc. and is cooled
below its Dew Point
• Condensation occurs as the excess moisture is released
Walls in kitchens and bathrooms (where atmospheric moisture levels are usually highest), solid external walls, un-insulated solid floors and cold bridges such as concrete lintels set in cavity walls are commonly the areas in which condensation takes place. Intermittent heating and cooling of the property can aggravate condensation problems, since it allows warm damp air to cool, reducing its capacity to hold water. Dew points are reduced allowing
condensation to occur. When the air is reheated water is taken back into the air only to be deposited again when the air temperature drops again.
Problems caused by condensation
Running water on windows and walls is perhaps the most immediate indication of a condensation problem. If ignored this can lead to a deterioration in the decorative condition of the property, stained curtains, decay in window frames and the appearance of moulds on the surface of wallpapers and paints in poorly ventilated areas. Condensation can occur under suspended floors greatly increasing the chances of fungal decay in floor timbers.
A much less common form of condensation occurs when the Dew Point is reached, not on the surface of a wall but within the structure of the building itself. This is known as interstitial condensation and can easily be mistaken for rising damp or penetrating damp.
Condensation is a real problem and where it persists a specialist surveyor should be engaged to explore the cause of the problem and provide advice or propose solutions. We have listed just a
few of the possible methods of controlling condensation below.
Simply heating the air is unlikely to be a satisfactory solution, not only on grounds of cost, but also of practicality. Unless cold surfaces are eliminated, condensation is almost inevitable. Any remedial
action, therefore, must involve both a lowering of moisture levels and the elimination of cold surfaces.
Improved heating and ventilation coupled with specific action in relation to cold spots will usually result in a significant improvement in conditions, although there may be circumstances in which
alternative methods are required. A modest but constant background heat is preferable to intermittent heating since this will help to maintain a higher ambient temperature in the fabric of the
The installation of effective extractor fan in a kitchen or bathroom will carry away moisture-laden air from the two areas most responsible for condensation with minimal running costs. This is now
required by the Building Regulations in new constructions. Extractor fans are now available which incorporate a humidistat which will control the operation of the fan within certain humidity limits. It
is also possible to install fans that have an integrated heat exchanger. These have the advantage of providing effective ventilation while reducing heat loss from the property.
Where an open fire or fixed gas fire exists, a certain amount of “natural” ventilation will occur and where additional ventilation is provided it is important that this is not blocked off.
The use of specialist insulation materials fixed to the outside of the building and insulation in cavity walls will help to improve the thermal dynamics of the building and may help overcome condensation.
An alternative to heating and ventilation for the control of moisture in the air is a dehumidifier. This is a device which draws in air, cools it to remove moisture which is collected in a reservoir and
reheats it to an acceptable temperature before re-circulating it. However, while this is effective it can be a costly solution that requires electricity and will probably be turned off at night and
therefore only a temporary option.
We recommend the installation of Passyfier vents. The best way to describe this products is it’s a one way air brick that allows water vapour to escape (around 2.3 litres of water per 24 hour period),
but prevents cold draughts coming in.
However for the permanent reduction or elimination of condensation, this will usually require a combination of changes or upgrades and advice. For this we would recommend a personal survey specific to your lifestyle and property type.
We can install Passyfier vents, extractor fans on request. Please contact us for prices.
Tony Flower and Associates have been members of the PCA formally the BWPDA since 2007.
Selecting a professional and trusted tradesperson for damp-proofing and building preservation work can be a daunting process.
Help is at hand with the Property Care Association (PCA), which represents the UK’s dampproofing and timber preservation sector, as well as the structural waterproofing, and structural repair industries.
The Association’s UK-wide list of contractor members are all carefully vetted before being awarded membership – and are then subject to rigorous auditing procedures once admitted to the PCA.
The PCA Promise
Homeowners looking for a professional tradesperson to carry out building preservation work are now able to add another level of reassurance under a new guarantee scheme launched by the PCA.
The PCA Promise is a new type of warranty which covers timber treatment and damp-proofing works, as well as structural waterproofing, and remedial wall ties. It covers contracts placed with
PCA members for;
This is for domestic premises where the contract price (including VAT) is more than £250 and up to £50,000.
The PCA Promise meets the criteria required by TrustMark.
Under the scheme, the Association gives blanket coverage to its contractor members, so they can
offer a guarantee on behalf of the PCA to cover their customers for work in progress and deposits.
There is no additional cost to customers for the guarantee, which ensures that should any contractor
member of the Association go out of business while work is being done, then another PCA contractor
will complete the work to the original specification at no extra cost to the customer.
The PCA Promise is in addition to customers’ statutory rights and provides that in the event that a
PCA member fails to commence or to complete the contract because they have ceased to trade
due to liquidation, receivership, administration or the winding up of the business due to bankruptcy
or death of the principal(s), PCA will either:
(a) arrange for another PCA contractor to complete the contract with the customer paying the remaining
balance of the original contract price less the amount of deposit and/or stage payments
that were paid to the original contractor; or
(b) provide a PCA voucher to the value of the amount of deposit and/or stage payments already made. This voucher will be accepted by any other PCA member contractor as payment against a new contract.*
*The maximum liability in respect of any one contract shall not exceed 25% of the original contract price or £10,000 whichever is the less.
Customers who believe that their contractor member of PCA has ceased to trade and wish to take advantage of The PCA Promise should contact PCA without delay: 0844 375 4301 TrustMark PCA is a member of TrustMark, the scheme supported by Government to help property owners find reliable and trustworthy tradespeople to make home improvements. TrustMark helps customers find reputable firms to do repair, maintenance and improvement work inside and outside the home. As a trade body accredited with the TrustMark logo, the PCA has met stringent criteria, verifying that the tradesmen it represents can be depended upon to do a good job. Technical skills, financial position, insurance provision and customer care policy are just some of the areas in which the Association has set demanding standards. For further information about TrustMark visit www.trustmark.org.uk
Further Warranty Protection As well as The PCA Promise, customers choosing a PCA member can also benefit from an additional warranty. On completion of the contract and full payment being made to the relevant PCA
member contractor, they will issue a warranty covering both materials and workmanship. Insurance protection of this warranty is available from Guarantee Protection Insurance Ltd (www.gptprotection.co.uk). A one-off payment will be made for providing this insurance which is valid for a period of 10 years.
Why we charge for a Survey?
With over 45 years experience in the damp and timber remedial treatment industry, many situations only require some good advice and referral to perhaps a plumber or roofer. To make the charge allows us to pay for general office cost, contribute to travel and supply of a professional survey report. With the travel the site visit and report, we probably spend around 2-3 hours on average per appointment. Even if the property has no issues to report we will report on this. This may be helpful for someone purchasing or selling a property. Our local reputation is held in high regard by estate agents, letting agents, landlords, architects, building surveyors and local authorities as well as many, many members of the general public.
Plastering and rendering,
Why we offer a plastering service.
Water contains minerals that it absorbs from the ground. When water enters the property by rising or penetrating damp these minerals will also be present. When the water reaches the surface (the plaster, wall paper) it then evaporates and deposits the minerals at or just below the surface. These minerals then crystallise and cause damage to the surface structure. Paint may start to flake, wall paper begin to peel and even plaster may eventually start to crumble. Some of these minerals will be hygroscopic and attract surrounding atmospheric moisture. Until the salts are removed the salt-contaminated materials will always remain damp. The dampness will fluctuate with surround relative humidity levels. In this instance, it will be necessary to remove the contaminated plaster and then reapply using a salt resistant plastering method. This can be done in several ways and will vary with each property.
We can offer advice, plastering specifications and carry out the re-plastering if required.