Suspected woodworm treatment has left a lingering smell...

[alexpp]

Hi,

We have an ancillary barn that was converted by the previous owner and it would seem that the exposed oak beams have been treated at some stage for woodworm - the beams have the tell-tale pin holes but fortunately no evidence of any ongoing infestation which is the good news...

However, ever since we purchased the property, there has been a strong and overpowering oily smell (similar to creosote) that seems to be emanate from the exposed timbers which even after 5 years now does not seem to want to dissipate. The smell builds up if the barn has been closed up for a while and we have tried airing with the windows and doors open but the smell always seems to return - although I would say the situation now is marginally better than it was 5 years ago but still bad. The beams have a greasiness to them and the timber on the surface is soft. It would seem whatever they have been treated with has impregnated the timber and that the chemicals are still present in the timber and leaching into the atmosphere. We want to use our barn as a guest block so we obviously want to sort the smell out as well as ensure it is not a health hazard. This is my best guess as to what could be the cause...

The following ideas have been suggested to me by general builders and decorators:
- Sandblast or use a handheld rotary sander to take the top surface off the timbers - messy job and wood worm treatment may have gone beyond the surface layer
- Shellac-based paint which would essentially seal them - would be a real shame to paint the beams
- Some form of sealant e.g. Sadolin woodstain, Shellac or Lacquer spray, Danish oil - concern as to how effective these products are as a sealant as well as the effect on the final finish (we want to keep as natural as possible)

I would appreciate any suggestions as to how we can best resolve the situation and make this barn liveable/useable.

Many Thanks
Alex

 

[88v8]

Hello and welcome.

It sounds as if the treatment was quite thorough. Which is good.
I treated our attic with Cuprinol 5 Star, which is about as aggressive a chemical as one can purchase otc, and the smell dissipated in a few weeks.
So your timbers presumably had a professional product. Even so, five years is a long time. Creosote, yes would be pretty bad but it would not persist that long.

Do agree that it would be ridiculous trying to take off the surface. And the end result would be a visual mess. I would be very dubious of employing a builder who is crass enough to suggest such a thing.

I would start by asking the previous owner what was used. And then ask the manufacturers for advice. I think this is an essential starting point.

Agree that it is a shame to overcoat bare timbers. Otoh a clear coat such as shellac would not obscure the colour nor the grain. However, if the impregnation is significantly oily, trying to overcoat it may be difficult as it will tend to throw off coatings such as Sadolin. An oil such as linseed might work. Or not.

Is there a small room in the barn that could be used as a test area for treatment? You would need to be able to seal it off completely to prevent the smell from leaching in.

And, realistically, if the woodworm treatment was thorough, there may be areas that are not accessible, within partitions, ceilings, structural joints, where the smell will only dissipate with time.
Permanent ventilation may be your best indeed only, solution.

Or simply to repurpose it as a garage or barn.

Ivor

 

[Anonymous]

Hi, just wanted to add some minor advice.
Evidence of woodworm is normally associated with flight holes. Flight holes = where the adult beetle exits the wood i.e. non active i.e. it's evidence that the wood had some beetle larvae at some point.

FYI Woodworm is most prevalent in wooded areas i.e. where the trees grow.

This is my long winded way of saying that no chemical treatment for timber should be applied for woodworm infestation - active or not.

The best advice is that beetle attack happens when timber is damp the best way to cure it is to remove the damp or better said remove the source of the damp by ensuring sufficient ventilation is provided.

With regard to the smell could it be the inside timbers (rather than the structural ones) have been treated with a preserver like creosote ? Creosote smell evaporates on garden sheds and fences because they're exposed to the air and have ventilation... putting 2 and 2 together and coming up with 5 perhaps, but it would seem there isnt adequate ventilation and therefore the smell stays put, if it's also damp through condensation this will also have a smell, and I should say if there are chimneys present the smell could be the smell you get from all old chimneys.

Paul.

 

[MikeG]

I'm with Paul on this. Open everything up just as soon as the weather allows and let the wind and sun do their thing for weeks or months.

If that doesn't work, then before I considered any sort of sanding, blasting or coating of the timbers, I would pressure wash them with ordinary soap and water, followed of course by another long period of maximum ventilation.