Is Your Home Suffering From Damp – Wet Rot vs Dry Rot, What’s the Difference?

Ask any damp proof specialists in London and around the country and they will tell you that two of the most serious problems that can come from a damp property is wet and dry rot.  Both come from fungal growths but have different requirements and cause different problems.  So how do you know if you have one of these problems? Be it an period home or a self build home, both will have the potential of being affected.

What is dry rot?

Dry rot might sound like the less serious of the two conditions but can be devastating once it gets hold.  Dry rot is a type of fungus that grows in areas away from sight and this makes it subtle in the early stages.  This also means spotting it can be more difficult but there are signs:

• Timber damage – if the wood beams in your home, most commonly in the loft are showing signs of brown colouring, brittle cube shaped features or crumbles when touched then you may have a damp problem that allows dry rot to grow
• Spore dust – spores are emitted from the fungus and are easy to mistake for dust but if you spot larger patches of orange or brown dust, this could be spore dust and therefore indicate a dry rot problem
• Grey strands – known as
• hyphae, these are a part of the fungus life cycle that draws moisture from the air and allows the fungus to spread to more wood
• White cotton wool – this isn’t cotton wool but something called mycelium, another part of the fungus life cycle that is used to spread further
• Fruiting bodies – these look a bit like a weird mushroom and grow when the fungus can no longer feed and needs to send spores to a new part of the room

What is wet rot?

Also a fungus, wet rot may sound worst but isn’t as destructive as dry rot and also requires a higher level of moisture before it can grow.  This means some of the signs of both wet and dry rot are similar.

• Timber damage – because the wood needs be very moist for wet rot to grow, it will be spongy to the touch and will have patches that are a darker colour
• Weak floorboards – if you walk on a floorboard and it feels soft and likely to give out, then there’s a chance there’s a wet rot problem affecting it.  The damage is often below the surface and harder to spot
• Fungus growth – the fungus follows the same lifecycle as the dry rot so you may notice grey strands, white mycelium and fruiting bodies as well as spores and spore dust around wood

What’s the difference?

As you can see, both conditions have a lot in common and you would often need a damp expert to tell you the difference once you have a problem.  The main difference is the amount of moisture required for the spores to begin growing – it needs to be at least 50% moisture content for wet rot while dry rot is only around 20%.  Dry rot is also sneakier and will grow in places that are harder to spot, meaning it can spread further before anyone realises there is a problem.

Wet rot will often see the growth of black fungus on timber while dry rot tends to be brown in colour.  Timber affected by dry rot tends to crumble while those affected by wet rot will be soft and spongy with darker areas.

Calling an expert

If you notice any of these signs or the tell-tale musty smell of dampness, it is important to call a damp proof company as quickly as possible.  Both conditions can cause problems in your home and dry rot can have a serious impact on the very structure of your home, leading to major damage in extreme cases.