Identifying The Differences Between Wet Rot and Dry Rot

There are two common types of wood rot found in buildings, known as wet rot and dry rot. Both of these forms of fungal decay can result in structural damage to the property. Specialist building surveyors must be able to distinguish between the two types of wood rot to effectively address and eliminate future issues.

Dry rot is considered the most severe form of fungal decay and has the potential to cause extensive damage to the property. It can spread rapidly behide plaster to the next storey and destroy a significant portion of the timber within the building. Wet rot, on the other hand, is more prevalent than dry rot but is typically contained to areas where timber is exposed to moisture.

As specialist building surveyors, we can distinguish between the two types of wood-rotting fungi. Here are some key indicators to look out for when identifying signs of both wet rot and dry rot.

Identifying Wet Rot:

– Look out for a black fungus appearing on the timber.
– The timber is likely to feel soft and spongy to the touch, with visible discolouration.
– If the decay has dried out the timber, it will easily crack and crumble.
– Damaged paint finish could indicate wet rot fungus, even if the paint looks fine on the surface but is rotting from the back.

Identifying Dry Rot:

– The fungus leaves deep cubical cracks running across the grain, with white sheets (known as mycelium growth) often present on the wood, masonry and behide plaster.
– When exposed to light, the fungus may have a lemon-yellowish tinge.
– The timber will be brown in colour and crumble due to dry rot feeding on it.
– The presence of red dust spores.
– Damage is usually limited to the timber, but in some cases, large flat mushroom-like fruiting bodies can easily grow through finishes such as plaster or skirting boards.

How is Dry Rot Treated?

Dry Rot is the most serious of all the property care issues that can affect your building. Dry rot should be treated by a specialist and should be treated as soon as possible before any further damage can occur from this form of wood rot. The process of how dry rot is treated is:

A specialist dry rot surveyor will visit the property to identify where the damp originates from the surveyor will accurately diagnose the cause of the damp issue, whether it is due to plumbing leaks, rising, penetrating damp.

The surveyor provides detailed information on how the external defects or others are causing the damp problem. However, the full extent of the outbreak is difficult to assess until full exposure works have been completed.

The technicians will remove all fungal decayed timber and plaster within a metre of the last visible traces of Dry Rot.

– Any structural roof or floor timbers that have been affected by dry rot will be replaced with new treated timbers.

-The dry rot-affected area will be treated with fungicide dry rot treatments.

-To prevent dry rot from occurring again in the future, underfloor ventilation will be installed to improve the airflow in the property.

How is Wet Rot Treated?

It is essential for a property to conduct a comprehensive inspection of the property in order to pinpoint the source of dampness.

Following the inspection, the surveyor will accurately diagnose the cause of the damp issue, whether it is due to plumbing leaks, rising, penetrating damp or condensation.

Any structural roof or floor timbers that have been affected by wet rot should be removed and replaced with new treated timbers. External timber door and window frames can have new wood scarfed in or filled with wood hardener and redecorated to prevent future deterioration.

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By | 2025-06-11T11:56:24+01:00 June 10th, 2025|Uncategorised|