Dry Rot, Wet Rot & Woodworm
Dry Rot
Dry rot is the common name given to timber decay caused by the fungus Serpula lacrymans.
Dry rot decay can result in extensive damage and typically occurs in timbers built into or in contact with damp masonry. Other causes include water ingress such as that caused by plumbing or roofing defects as well as rising and penetrating damp. Dry rot often germinates during the drying out process following the water ingress.
Dry rot fungus develops an extensive root system comprised of cotton candy like sheets of mycelium and thicker white to grey strands. This root system can grow through masonry and mortar beds resulting in damage spreading to adjacent timbers and often large areas. This root system also allows the transport of nutrients and water to support further fungal growth essentially making the fungus self-wetting meaning that once germination occurs a constant source of moisture is no longer required.
Dry rot attacks typically occur in timbers with a moisture content of approximately 20% and as the fungus is sensitive to high temperature the initial germination process often occurs in timbers within wall, floor or roof voids. Following this germination evidence of attacks is often seen in exposed timbers such as door frames and skirting boards.
The occurrence of dry rot fruiting bodies on exposed timbers or wall / floor junctions is often the first sign that people notice of a dry rot attack. Dry rot fruiting bodies can be large and are flesh and pancake / bracket shaped. They range in colour from yellow ochre to dark brown and have white edges. The fruiting bodies emit large volumes of fungal spores into the atmosphere and these settle as a rusty red to brown dust on surfaces such as window cills and mantlepieces. Other signs of a dry rot attack include a damp, musty mushroom like smell and as the fungus draws nutrients from the timber it is attacking large cuboidal shaped cracks occur and the gaps between these often contain tufts of mycelium.
Typical specialist remedial works will involve identifying and removing any source of moisture / water ingress, removing all timbers from within the outbreak area and applying chemical treatments to the masonry to destroy the fungal route system. Following this pre-treated and further protected replacement timbers are installed. For structural repairs this will often involve a specialist engineering detail to ensure timbers are connected to existing correctly and structural strength is retained.
The Dry Rot Gallery
If you think that there is a dry rot outbreak affecting your property contact us to book a property survey following which we can provide a detailed specific report outlining recommended treatments and associated costs.
Wet Rot
Wet rot is the collective name given to timber decay by a group of fungi including Coniophora puteana, Fibroporia vailantii & Phellinus contiguous.
As clued by the name wet rots affect timbers that have a higher moisture content than dry rot, typically greater than 30%. Common sources of moisture / water ingress resulting in decay by wet rot include external defects such as slipped or missing slates, cracked or missing cement work and blocked or overgrown rainwater goods. Internal defects such as plumbing leaks can also be the source of wet rot decay and so can rising or penetrating damp. Another common cause is when unprotected timbers are built into or in contact with damp masonry, often below the external ground level.
Wet rots also require a constant source of moisture to continue fungal growth and will therefore only spread to affect adjacent timbers that are also wet. As wet rot does not grow extensively through masonry the effects of an outbreak can be less severe than a dry rot outbreak and are typically restricted to areas where the dampness is located. Caution should still be taken as large scale damage can occur where the dampness is widespread.
Signs of wet rot can include a damp musty smell, small cuboidal or horizonal cracks occurring in affected timbers. Affected timbers often feel soft and spongy and this can result in a noticeable movement or bounce to a floor. In painted timbers the paintwork of affected timber can appear damaged as a result of shrinkage to the timber below.
The Wet Rot Gallery
Woodworm And Woodboring Insect Infestations
Woodworm is the common term used to refer to infestations by woodboring insects affecting timbers within a property.
The most common insect involved is the common furniture beetle (Anobium punctatum). During their larvae life stage these insects live within timbers and if left unchecked can lead to extensive damage including the need to replace timbers. For infestations caught at an earlier stage a chemical treatment can be applied to eradicate the infestation and protect against future reinfestation. The most common areas where woodboring insects are found are within roof and floor voids.
Signs of infestation include visible flight holes in the timbers, piles of frass (sawdust) around flight holes or on surfaces below the affected timbers and finding the adult beetles within the property.
The beetle typically pupate during warmer months of May to September and this is when insect activity is most likely to be seen.
Other types of woodboring insect that can affect timbers within properties include woodboring weevils, Lyctus powder post beetles and Ptilinus beetles.