Woodworm in roof timbers

19 Feb 2014
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United Kingdom
We're currently in the process of moving home and the Homebuyers survey on our new property has thrown up a couple of issues, one of which was signs of posibly active woodworm in the original roof timbers.

We'll be getting a professional company to quote for treatment but what should I expect them to be doing. ie Is current practice to treat all woodwork whether it shows signs or not, should they lift insulation to spray etc Any ideas of how much the job should cost given that it's a 4 bed detatched house dating back to 1860.

I'm also investigating the DIY approach, lookes like you can buy the appropriate chemicals online eg


I know this contains Permethrin but there seems to be conflicting info on using this product safely. The safety data sheet just says that a respirartor should be worn but gives no indication of what sort, is anyone able to give me some pointers ?

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We are recovering from a severe infestation - had to remove walls, floors and 1/2 a stair case...

So - I'm not qualified - but months of research and conversations gives me a little experience. Time will tell if I am right or not :confused:

In your position, I would go for a professional company... above all else, they will offer a certificate and industry backed insurance/guarantee. DIY treatment would not allow this. Your mortgage company would probably require some form of certification & guarantee/insurance anyway.

I would also advise the Permetherin as opposed to boric acid based treatments. Some companies will swear by the boric acid (mostly the ones that invested in it's R&D I might add...)

The larvae live well below the surface of the timber - so the current treatments - no matter what the base - will not reach the live insects. It is when they pupate (turn from Larvae to the beetles) that they come to the surface and burst out, the beetles apparently don't even eat. So the boric acid (requiring ingestion) is less effective when compared to the contact based permetherin.

I have done a mixture of DIY and professional treatment - for an entire underfloor space, floorboards, staircase, garage and all visible (and treatable) timbers on the ground floor it came to £450+vat. But it was a near-empty house and I made access as much of a breeze as possible (removed carpets, cladding, opened gaps to the sub-floor, etc etc)

Where I exposed new timber - I either DIY sprayed with Woodzone - wearing gloves and a mask - but I did very small areas at a time - usually the tops of a few floor joists, or the newly uncovered sides of floorboards.

The pro's are really good at blanket covering really large areas for very cheap - and you own DIY top-ups will get the bits no professional could be expected to cover.

and yes - all insulation should ideally be lifted; it may also help if you hoover up and dust too - then the pesticide is soaking into the wood and not the dust/muck thats accumulated over the last 100s of years!

Depending on the severity of your infestation - you might want to consider any remedial works, as well as using treated wood when replacing timbers.

To be honest - mine was exacerbated because of a previous bathroom set-up allowing them to conquer otherwise sound wood on my ground floor - and my belt and braces approach. We'd just moved in and had no particular care for the previous decor - so it was an easy decision to tear out all wood that even came near the infected timbers.

One final piece of advice - get quotes from local and national firms - the locals have a suprising amount of knowledge that the nationals don't have. The BCPA (British Pest Control Association) have an index of accredited controllers which could be a starting point!

Lots of info there - feel free to ask more questions if you have any :)


In an 1860's house there will have been wood boring insect visits from time to time over the years, therefore most, if not all, your signs of infestation will be long dormant. How can you tell? Simply by prying or gouging out the suspect areas, and if live bugs or larvae are seen then its active - no live bugs, and its inactive.

If the wood is so damaged that it requires replacement, then thats all it needs - it does not require spraying. Nor do you tear out all the adjacent wood.
Neither does any area require "precautionary" spraying.
Permetherin is undoubtedly the best, but most dangerous, chemical to use if spraying is necessary.

Damp and rot will attract the bugs.

These "professional" chemical sprayers and their associations are qualified in one thing only - relieving you of all the money they can gouge. This spraying business is easy for any fit DIY'er.

Perhaps, go in your loft and identify any affected joists or rafters, gouge out the holes, and come back here for further advice. Pics would help.
An interesting and informative answer, ree . In my latest ( and last ;) ) house I have had to remove and replace aprox. 4 metres of 4x2 wallplate timber on the ground floor ( sleeper wall ) and one whole 3 metre length of T=G floorboard . House built in 1962 - just these timbers totally destroyed by the worm - the rest of floors , a few random holes and literally a dozen or so in one roof timber . Yes there is a lack of underfloor ventilation ( 1960`s regs probably required fewer air bricks) but the evidence is that certain timbers were better for the larvae :idea:
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Nige F,

Thanks for the complement. I am surprised that a 1960's house had such beetle damage without collateral damp and rot to assist. Guess, as you say, it must have been lack of ventilation.

The bugs definitely pick and choose what they munch up - i wonder if its connected to the acid content of the timber? Research claims that certain moisture contents will deter the little mechanics, and other moisture contents will encourage them.

Again, for a 1960's property you seemed to have had well dispersed attacks.
Of course, the larvae can already be in the wood at the Timber Merchants.
I've traced Termites tunnelling through from mud cill to attic before they launched out, so to speak. But not furniture beetles.
i remember doing a job a few years back all t&g boards and they were totally eaten,the joists had little evidence of infestation.
They Sussex worms be choosy b`ggers , reckon ;)

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