Differences Dry and Wet Rot Treatments Worcs Staffs WMids

What's the difference between Wet & Dry Rot?

It is important to find out is whether the infection is Wet Rot or Dry Rot. Sometimes confused as Damp Rot.

There are several species of Wet Rot but only one species of Dry Rot (Serpula lacrymans) often referred to as True Dry Rot. Generally, Wet Rot affect timbers that have a moisture content in excess of 24% whilst Dry Rot prefers a slightly lower moisture content of 18 to 22% but also prefers more humid conditions.

The dampness that causes the rot can be from a number of sources including;

a lack of sub floor ventilation,
walls being damp from
penetrating moisture
rising damp or
condensation

Water leaks from sinks, baths, showers, pipe work, guttering or poorly maintained roofs can all cause Wet or Dry Rot. The spores for all types of timber fungi are within the air, the same as viruses. The pollen or mould are generally harmless until they land on the right conditions and germinate.

Dry Rot (Serpula Lacrymans)

Dry Rot is generally regarded as the worst form of rot due to the fact that it can travel through bricks and mortar in search of its food source.

Dry Rot affects timber that has become damp from a reasons similar to wet rots. When dry rot spores come into contact with something suitable for germination they develop into a cotton wool like appearance, which form white strands that extend along timber and masonry.

After some time the cotton wool like fibres darken and produce spores that are a reddish brown dust. This is now the beginning of a fruiting body that is producing spores that are released into the atmosphere.

Dry Rot consumes all the nutrients in timber and causes large cuboidal cracking to occur, and as the food is removed the strands travel though bricks, mortar and plaster in search of more food. When a new food is found the original fruiting body dies off and a new one is grown as the infection continues.

Dry Rot unlike Wet Rots can carry its own moisture as it travels through a property in search of more food. Dry Rot is capable of causing severe damage to structural timbers.

BUT IT CAN BE TREATED!

Dry Rot Treatments

With all Dry Rot treatments the full extent of the infection must be identified.

In severe outbreaks opening up and disruption are necessary prior to being able to produce a full schedule of works and being able to give and estimate for the work. It is better to carry out a full investigation prior to starting treatments if possible, so that there are minimal surprises during the schedule of works.

All affected timbers will need to be removed and cut back to between 500mm and 1000mm depending on the situation to ensure that any signs of the infection are removed. This also applies to the plaster work, skirting boards etc.

The source of moisture should be removed and the area encouraged to dry out as quickly as possible. This is where the treatment of Wet Rot & Dry Rot changes as Dry Rot requires more extensive treatments.

Any masonry including subfloor solid below ground floor timbers requires treatment with a biocide. Thicker walls may require some drilling and irrigation. This is usually a "Cordon Sanitaire" drilled and irrigated around potential food sources within the vacinity as well as spraying wall surfaces and provide toxic boxes to eradicate the infection.

Wet Rot

There are several types of Wet Rot each showing different characteristic growths, fruiting bodies and strands, (fruiting bodies are mushroom like).

The damage to the timber causes wood to become weak and break up once the infection is well developed.

The colour of the strands depends on the two types of Wet Rot; White or Brown Rot.

Brown Rots: darken timber and break it into small cuboidal cracks
White Rots: make the colour of the timber lighter and the infection grows along the grain.

Treatments for all types of wet rot are the same.