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Dry Rot Treatment & Control

Dry Rot Specialists,  Treatment & Control
North Wales, Chester & The Wirral

Damp Aid North Wales are specialists in Dry Rot treatment & control in buildings.  Our specialist dry rot surveys & reports are carried out in areas such as Llandudno, Prestatyn, Colwyn bay, Anglesey, Chester,  Mold, Bangor, Wrexham  and throughout the Whole North Wales, Chester & Wirral regions.  Dry rot is the timber decay of wood caused by the fungus Serpula lacrymans, which if left, can have devastating effects within a building.  Diagnosis of dry rot in a building has the ability to strike terror into the heart of the recipient of this dismal news.  However, to the untrained eye dry rot and wet rot can easily be confused. It is therefore essential that a correct diagnosis of a timber decay / fungal decay problem is formed.  By using a Damp Aid North Wales specialist damp and timber surveyor to carry out your dry rot survey, a correct diagnosis is guaranteed, and the timber decay survey/ report will satisfy the mortgage lenders if required as part of the mortgage loan process.


• Wood shrinks, darkens and cracks in a ‘cuboidal’ manner
• A silky grey to mushroom coloured skin frequently tinged with patches of lilac and yellow often develops under less humid conditions. This ‘skin’ can be peeled like a mushroom.
• White, fluffy ‘cottonwool’ mycelium develops under humid conditions. ‘Teardrops’ may develop on the growth.
• Strands develop in the mycelium; these are brittle and dry and crack when bent.
• Fruiting bodies are a soft, fleshy pancake or bracket with an orange-ochre surface. The surface has wide pores.
• Rust red coloured spore dust originating from the fruiting bodies.  Commonly described as looking like brick dust.
• Active decay produces a musty, damp odour.

A careful diagnostic survey carried out by a Damp Aid specialist timber surveyor (CTIS) is required to identify if the timber decay is dry rot or wet rot, to locate and cure the source of dampness, to control or treat in a very selective and targeted way and to re-instate with appropriately pre-treated or naturally durable replacement timber. (Also by using a specialist PCA registered damp and timber firm, like Damp Aid North Wales, to provide dry rot treatment & control, you will have the added assurance that any specialist dry rot works will not only be carried out correctly but will benefit from a long term GPI insured guarantee).


Once dry rot has been correctly diagnosed, it is necessary to determine how far the dry rot has spread. All woodwork in the vicinity of any outbreaks should be inspected by a qualified specialist damp and timber surveyor (C.T.I.S. or C.S.R.T. – and member of the Property Care Association – P.C.A.) to assess the extent of decay and the current moisture content of the timber. Extensive removal of plaster is necessary only if it is suspected that timber is embedded in  damp walls and is at risk to dry rot. ‘The secret’, in terms of early identification of dry rot, is not to look for the fungus but to look for the conditions that would facilitate its development and growth.


Removal of all timber affected by dry rot is destructive but necessary in principle. Retaining affected timber presents problems for the structural integrity of the building and falling debris can be a hazard to occupants and others if decay continues. Timber already below 20 per cent moisture content presents little risk of further timber  decay.   Special building measures are necessary if timber is to be retained, including isolation from damp masonry by way of incorporating a damp proof membrane or using metal joist hangers etc.


Liquid preservatives can be applied to the surface of sound timbers left in situ to help prevent new infections developing.

If timber infected with dry rot has to be retained for special reasons and decay cannot be arrested in the short term by drying, preservative treatments that penetrate throughout the affected part of the timber can be used.

For example:

• application of a preservative paste
• repeated addition of liquid preservative to sloping holes drilled into the wood or by pressure injection
• insertion of borate rods or tablets (these are only effective if the wood is wet).


Although the dry rot strands can travel across masonry, the dry rot fungus derives no nourishment from it. The concept of killing the fungus within masonry by wide-spread irrigation with a fungicide traditionally has provided a ‘comfort factor’, but it has to be questioned in each case whether this procedure can be justified. First, it is usually difficult to achieve a thorough treatment and, secondly, the treatments introduce large quantities of water which then needs to be removed, increasing the risk of damage to the masonry, as well as prolonging the time it takes to dry the structure.

The most important role of fungicidal treatment of the masonry is to prevent the fungus from obtaining access to a fresh food supply in the form of timber in adjacent areas, or replacement timbers being introduced into the area. For this purpose, localised chemical treatments of the masonry (cordon sanitaire) can create a useful barrier between the fungus on the wall and the wood.

Examples of such treatments are:

• surface application of fungicidal fluid
• use of fungicidal renderings
• application of preservative pastes
• localised irrigation treatments.


We are often asked by our North Wales, Chester & Wirral clients – How much does specialist dry rot treatment cost / How much does it cost to treat dry rot?

The cost of treating dry rot or the cost of dry rot control will vary with each individual outbreak of the dry rot fungus.  Firstly, a dry rot survey has to be carried out by a fully qualified PCA registered CSRT / CTIS damp and timber surveyor to correctly identify the fungal timber decay and determine if it really is dry rot and not wet rot as it is so commonly misdiagnosed by those who are inexperienced.  The extent of the dry rot has to be determined, as this timber decaying fungus can spread behind wall plaster and under poorly vented floors without being noticed until it attacks another piece of timber, such as a skirting board or door/window frame, elsewhere.  The source of the dry rot outbreak also has to be determined.  It is therefore not possible to provide a cost of treating dry rot without carrying out a detailed dry rot survey on a property.


Maintenance and monitoring of the conditions in buildings cannot be stressed enough.  Dry rot develops very slowly, so early detection and curing of moisture ingress will prevent decay occurring in the long term. Routine monitoring can be as simple as regular visual inspection to check the integrity of the building fabric against ingress of moisture. Dry rot will return to any building in which the appropriate conditions are allowed to develop. The presence of preservative treated wood and masonry may help to prevent decay in treated areas, but without these, timber is still at risk. Monitoring and an understanding of the dry rot fungus and how dry rot develops are therefore required in order to prevent problems reoccurring.  Adequate ventilation needs to be maintained throughout living areas; moisture ingress due to bad maintenance needs to be avoided etc.  The instigation of a regular building inspection policy is essential to prevent new problems from developing.

If you suspect you have a timber decay problem and need honest, friendly and professional advise from a locally based dry rot specialist company then call Damp Aid North Wales on 01492 535305, Chester – 01244 490341 or Wirral – 0151 959 0086 to speak with one of our specialist dry rot surveyors who are waiting to take your call.
Alternatively, email info@dampaidnorthwales.co.uk or fill in our enquiry form.