The Restoration UK Blog

Wood Rot Explained

How Wood Rot Occurs

Wood is an excellent material for building as it’s resistant to most biological attacks as long as it remains dry. However, if it’s exposed to water over a prolonged period, it can be vulnerable to decay from wood-rotting fungi. Symptoms can include softening or disintegration of wood, a ‘hollow’ sound when wood is struck with a hammer, discoloration of wood, a ‘mushroom’ smell and/or fungus growing on the wood.

Fungi

While not all fungi cause wood rot, the presence of any fungi is an indication that the wood moisture content is too high, making it vulnerable to wood-rotting fungi too.

Wood-rotting fungi break down the cell walls of wood, causing them to lose strength. As fungi require at least 20 percent moisture content, they are unlikely to be found in internal timbers unless design or building issues have led to water ingress or condensation.

Wood-rotting fungi found in buildings can be divided into two main categories: white rots which cause the wood to become fibrous in texture and lighter in colour, without any cross-cracking; and brown rots which cause the wood to become darker and to crack both along and across the grain. Extremely decayed wood will crumble to dust when dry.

All these rots are referred to as wet rot, with the exception of the brown-rot, Serpula Lacrymans, which is known as dry rot. As this can spread behind plaster and through wall materials, dry rot is particularly destructive and can require elaborate treatment.

The majority of cases of wood rot are as a result of rainwater entering the fabric of the building, or due to rising damp. As such, a thorough external survey is the first step. The problem could stem from missing or defective roof tiles or slates, blocked guttering, damaged roofing membranes, a defective damp proof course (DPC) or a host of other sources. Internally, problem areas can include cellars and basements, skirtings on damp walls, joists of suspended walls with inadequate underfloor ventilation and bearing ends of timbers in non-cavity walls, among others.

Recommended products to treat or repair wood rot

ProBor 20 Gel is ideal for the treatment of larger dimension timbers. It is also effective against wood-boring insects and infestations of Deathwatch Beetle

ProBor 20 Gel Wood Preservative

This is a introductory kit, with everything needed to start using the Repair Care system. Perfect for wood repairs e.g. window frames.

Wood Repair Kit

Designed as a woodworm killer and is effective against all life stages of wood boring insects

Lignum Pro Insecticide

Designed to eradicate and prevent attack by wood boring beetles and prevent wood destroying and discolouring fungi.

Lignum Pro Fungicide & Insecticide

Get problems diagnosed by a member of the PCA (Property Care Association) as there can be complex causes (sometimes multiple) and you don’t want to make an expensive mistake through misdiagnosis.