18 Jul 2023
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United Kingdom
Hello, I was looking in the loft of a 1900s house we've recently moved to, and noticed some tracks in the rafters that look like some kind of wood boring insect (images attached) - is that correct and is it possible to tell if old or recent? There's insulation below the beams so difficult to tell if there's fresh dust. We have some info that the timbers of the lower two floors were treated for woodworm about 30 years ago (after woodworm found under stairs on ground floor), but not the loft I don't think.

There are quite a lot of tiny light coloured bits over several beams - is this related or innocent-looking?

Also any advice on whether any rot is visible in these pictures, or mould? I am a bit worried about the whitish areas visible on some beams, especially the far ends.

We have had work done to replace flashing and broken tiles on the roof here and improve guttering, so hopefully any previous damp issues should be improving.

Thanks very much for any help!!


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Around about February next year, string some clean paper or card under the area you suspect most - a bit like a hammock. Then see if any frass collects on it over the coming months.

PS, you need to improve ventilation through your loft, and probably insulation as well.
Thanks @jeds for the reply - when we viewed the house this space was full of suitcases etc, so indeed probably not much airflow; since then it does at least seem to get enough to rattle the hatch a lot when it's windy or another window is open, so hoping this is an improvement. We plan to put more insulation down in the autumn.

Would you be concerned about the mould and whether this could be rot? And any idea what the tiny white bits are everywhere, is that the frass? It can't be eggs can it?
It's very hard to tell from a distance but it does look like worm trails. Impossible to tell how old they are? Poke around anything that looks soft with a screwdriver and see what gives? You can't do any damage. If it's soft enough to fall out, it's not adding anything structurally anyway.

The white stuff is just white mould or efflourescence. It isn't dry rot - you don't need to worry about that.
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The reason for using a flat-tipped screwdriver, rather than a pointed implement, is that it will not leave holes that will be mistaken for insect damage.
Those tunnels in photo 1 look too big to be woodworm (common furniture beetle). It also looks like there may have been some attached bark which has fallen off exposing the tunnels rather than just seeing the usual flight holes. If there was bark attached the tunnelling might be confined to the outer layer of sapwood. You should never use timber with the bark attached as it is vulnerable to beetle attack as the adult beetle lays eggs under the bark, but the good news is that if there has been an infestation it is probably localised to just the timber with the bark rather than common furniture beetle that can spread between timbers irrespective of any bark remaining.

Also the reason you use a flat head screwdriver rather than a pointed tool like a bradawl is it is relatively easy to push a bradawl into sound timber so it doesn't really tell you anything. You cannot push a screwdriver into sound timber so if manage it you know it has been softened by rot or wood boring insects etc.
If it were woodworm, I would have thought that there would be exit holes in the sides of the timber. I am however, only guessing.

Since the advent of central heating, the only case of active woodworm that I have seen was my mum's house, she purchased a new oak nest of tables. A few weeks later she noticed bore holes and wood dust on the floor. The supplier gave her a replacement set.
Thank you everyone! Will investigate further but feeling less worried about it. I think most of the damage I can see so far looks old, maybe some fresher looking bits further in that need exploring, but the main thing is that we have already taken steps to sort damp and improve ventilation, which it sounds like is the first step anyway if there is still a live issue.

Many thanks again :)

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