Dry Rot in Your Home? Keep Calm and Read On

January 24, 2017
Posted in Ideas

Dry Rot is one of the biggest threats to the structural integrity of a building. It attacks damp timbers and can reduce the beams, joists and timbers of your home to a crumbling mess. In order to do its nasty work and thrive, the Dry Rot fungus needs wood with a moisture content of at least 20% to survive. It wreaks havoc in warm, damp and unventilated conditions, and is normally found in difficult-to-reach areas such as underneath wooden floors, beneath the stairs, in your roof trusses and behind the skirting boards.


So far, so bad. But there’s no need to panic. Armed with some proper information provided by Dakota Murphey alongside building professionals, Hutton and Rostron on how to recognise the symptoms of Dry Rot and how to identify it, you’ll be able to deal it swiftly and effectively.

 What is Dry Rot and how does it take hold?

Early detection and prevention is better than having to treat a Dry Rot outbreak when it’s had time to develop. Typically, timber in your home needs a moisture content of between 20% and 30% for the Dry Rot fungal spores, which usually take the form of a fine orange dust, to germinate and take hold. Once the fungus is established, your timber only needs to have a moisture content of over 20% to survive. The fungus develops strands, or hyphae, that can travel across brick and masonry until it finds more timber to infect.

 1-2-dry-rot-mucellium 1-dry-rot-spores-and-strands

Damp areas to look out for include

  • Rainwater seeping in through small gaps in windows and doors
  • Leaking pipes, guttering, and overflows from cisterns
  • Missing roof tiles, flashing or cladding
  • Damaged damp-proof course
  • Blocked air bricks

What are the symptoms of Dry Rot?

If you spot a pancake type growth that’s reddish brown in the centre, then the fungus has really taken hold. That russet colour is a cluster of millions of spores of dry rot! Other symptoms include

  • a whitish growth, tinged with yellow and/or lilac patches
  • a distinct, sour, mushroom type smell
  • crumbly, split or shrunken wood. If you poke the timber with a screwdriver and it sinks easily into the wood, then you almost certainly have Dry Rot.

 2-dry-rot 3-dry-rot-causing-cracking-in-timber

Treatment and repair to masonry and timber

There are a few ways you can repair or treat Dry Rot affected timbers in your home. But first, if there are signs that you have a damp problem, you’ll need to find the cause of this and treat it. Only then can you move on to repair the rest of the Dry Rot damage. Any new damp diminishes the effectiveness of the chemicals you apply – these chemicals are water soluble, allowing them to enter damp masonry and timber where Dry Rot is situated.

If you think there’s Dry Rot present in your house, it’s a good idea to use ‘sensor sticks’ to see just how far the rot has spread in the timbers and joists. If it is only present in exposed timber like the joists, then you will need to treat the timber itself, plus any of the brickwork or masonry that’s in close contact with the joists. Of course, if your timber’s structure has been severely damaged by the rot, you’ll have to replace it, or get a professional building contractor to do this for you.


One of the most effective ways to treat Dry Rot is by using Boron powder. It dissolves in water and can then be brushed onto the affected areas, or even sprayed on if that’s easier.

There are a few different chemical products available for Dry Rot treatment in timber. Some of these enter the timber itself, while others coat the surface of the timber. Boron gel can be painted on and comes in different concentrations. Boron rods, which are made from highly concentrated borate, can be inserted into holes drilled into the affected timbers, or Boron paste can be injected into pre-drilled holes, using a skeleton gun. If you have Dry Rot and mould, these can be treated with Boracol, a Boron and Glycol mixture. Healthy timbers near the site of a Dry Rot infection should also be treated with boron.


Once you have coated all the affected areas, you should also think about painting the areas with a special Rot Barrier’ paint – this will prevent any residual Dry Rot from travelling across the surface of bricks and masonry to reach other timbers. In addition, all affected plaster should be stripped away and replaced with a fungicidal plaster. Masonry should be cleaned with a chemical fungicide and sprayed with a masonry biocide.


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