How much to panic about woodworm spreading….?

[BatNic2000]

We have discovered a very bad case of woodworm in some decorative reclaimed oak beams in our bedroom and need help knowing when to panic about how far it may have spread.

It’s a modern extension and a vaulted ceiling, so no loft space or access. The beams touch the roof trusses at the edges behind the plasterboard. The beams were old but structurally sound when they went in four years ago. As they are pretty high up, we have totally missed them being munched pretty badly, only realising when we’ve found the little beetles around the room

I have treated the beams with three generous coats of permethrin and will probably repeat this is a few weeks. However…. I know the beams touch the roof trusses behind the ceiling. Should I panic about this? The trusses are also only 4 years old, are modern trusses pre-treated to prevent woodworm? The room is always very warm and always well ventilated (we sleep every night with the windows open) so a little surprised we have woodworm at all.

I’m worried that we would have to pull down the entire ceiling to treat the trusses when it might not even be a problem. Should I cut some away to inspect it? Am I overreacting? Will treating the oak be enough?

Does anyone have any reassuring (or non reassuring!) advice? Thank you

 

[Kearn]

Treating won’t solve the issue. And it’s not nice for you humans, particularly in a bedroom.

If the timber came in damp with infestation, by now you’d expect it to have dried adequately so that it was no longer appealing.

If it came in dry with no infestation, then it’s no longer dry.

I’d say you may have in room ventilation, but maybe not within the roof structure itself. Possibly even a leak that has increased the moisture level enough to be worth munching on.

 

[jamest]

For some reason people tend to get quite panicky about woodworm (which is almost always common furniture beetle), but in oak they are nothing but an aesthetic problem (if you find the holes offensive) as they only eat the sapwood and so have no structural effects. In pine, a bad infestation might cause minor structural problems (in floorboards, for example), but that's not your issue.

Assuming yours are common furniture beetle, then you do not need to do anything (insecticide is not needed). They will only spread to other timbers if those timbers are sufficiently moist, which seems unlikely, but even if your trusses are green oak and still drying out, the beetles will only attack the sapwood.

If your timbers are getting wet, they could be at risk from attack, but the real enemy of damp timber is not woodworm but fungus/rot.

If it were me, I would just open the windows and let the adult beetles fly away

 

[Drayton]

The chemicals are likely to cause far more damage to you than the beetles to your house...

 

[BatNic2000]

Thank you for the replies, these were really helpful. There is definitely no damp in the roof and no leaks, I’m not concerned that that could be an issue. But the roof trusses are modern and therefore not oak, so the whole ‘they’ll only eat sapwood’ doesn’t really apply here. But, they are kiln dried and pressure treated so hopefully that means we’ll be okay.

Re the chemicals, I’m afraid that’s already done so no going back. But, I have no intention of licking the beams so hope that risk is minimal.

As for just leaving the woodworm be…. I guess you could but aesthetically speaking they are absolutely ravaging the beams and they aren’t as beautiful as they once were. If I were to leave them, I’m sure it wouldn’t take too long for the sapwood to be gone. I really don’t think leaving them to fly away is an option.

 

[Matt Green]

As for just leaving the woodworm be…. I guess you could but aesthetically speaking they are absolutely ravaging the beams and they aren’t as beautiful as they once were. If I were to leave them, I’m sure it wouldn’t take too long for the sapwood to be gone. I really don’t think leaving them to fly away is an option.

What would change your mind on this?

Kind regards,

Matt Green B.Sc M.Sc Ph.D (Wood Science, Brunel 2004)

 

[BatNic2000]

Do you mean changing my mind on seeing the beauty?

I love character and put reclaimed bashed up old beams in a new extension because I think there is lots of merit away from perfection. However there is a point where it tips into disrepair and decay, which is very much where this is heading. Nevermind seeing bugs literally crawling out of the wood above my bed….

 

[Kearn]

Do you mean changing my mind on seeing the beauty?

I love character and put reclaimed bashed up old beams in a new extension because I think there is lots of merit away from perfection. However there is a point where it tips into disrepair and decay, which is very much where this is heading. Nevermind seeing bugs literally crawling out of the wood above my bed….

Back to my point regarding why they are there and the moisture content of the timber … this is the symptom, you need to find and fix the cause.

 

[jamest]

I reckon that the beetles being seen now were newly hatched larvae when the beams were put in the house. The larvae take from 3 to 5 years to mature and pupate, so young larvae in the wood when it was installed would be expected to be emerging as adults now (plus or minus a year). You cannot treat an existing infestation by treating the surface of the wood with insecticide, you just have to make sure the wood is too try for re-infestation.

 

[BatNic2000]

Hmm. I understand fully but I’m at a loss. It’s a super warm room (the heat very much rises in this house) and it’s so warm we never even have the radiators on, even in winter. Windows are always open and there is zero problem with damp in the house. If this is an old infestation that is clearing out, could they still do that in dry wood? And not return as it’s dry? Or is does this mean it’s still damp enough to support them finishing their life cycle and therefore there is still an ongoing problem? I don’t know what else to do to dry the beams

 

[Cubist]

Too often when considering the source of possible damp as a cause of woodworm infection our minds turn to the external sources only and we go in search of leaky pipes or penetrating/rising damp from some other external source. This can often be a mistake because we end up neglecting the other, and sometimes more significant, cause in the shape of our own activities - in particular heating, cleaning - the house and ourselves - and simply breathing. It may be worth considering that in the absence of any obvious source of damp that the problem you're seeing is the product of moisture from the atmosphere in your home accumulating in the old worm burrows that may have stood vacant for years making these very attractive dwellings for new tenants.

In your shoes, and being one of those not averse to the odd use of permethrin, I would be tempted to use a syringe to 'inoculate' some/all of the old galleries and then plug the openings with some coloured beeswax and then wait until any further evidence surfaces.