chemical attack

[Anonymous]

I live in a early 16th century house and have recently discovered decay in the roof timbers. Thought at first it might wet rot, dry rot or woodworm and called in 3 firms from the treatment industry. Two said woodworm and the third said, no, its 'chemical attack' caused by a leaking chimney and that all the timbers would have to be specially treated. Does anyone have any knowledge or experience of this particular problem? Thanks.

 

[Anonymous]

Yes, its a parasite called Scammus Maximus. These people are salesmen.

NT

 

[Anonymous]

NT is spot on.

Before you get someone who knows about w/worm get someone who knows about beams in old properties.

I bet you will save money.

 

[Anonymous]

Wait a minute friend.

Chemical attck of timbers in a roof void does not normally require treatment.

However depending on how far advanced the attack is could mean some structural repair or strengthening of the timbers.

Obviously without the benefit of seeing the problem it is normally caused by pollution (flue salts , lime mortar (YES LIME) eating into the timber making it become very fiberous and having a crystal like coating over the timber.

PC

 

[Anonymous]

Thank you PC, MIDDI and NT. I am looking to get an independent specialist in to inspect the timbers - one who has no incentive to sell me some treatment, although the ones I've located on the web are very expensive too - partly because they seem to be located a long way from Sandwich.

Anyway, a question for you PC, since you are obviously familiar with the problem of 'chemical attack'. I am fairly confident that the timbers are still structurally sound in their current condition. If the original source of the chemicals.. flue, mortar or whatever ...can be dealt with do you think the timbers would continue to decay as a result of what they have absorbed already or should that halt the process?

Thanks.

Michael

 

[Anonymous]

Nice one, NT!

 

[Anonymous]

See no reason why they should as long as you can isolate source of attack. If the problem is chemical attack then you may find that its only on the surface.

If salts present then timber could wet up and dry down in relation to environment which could create seperate problems.

However what ever you do dont let ant treatment company near it with their spray gun.

Would suggest you get independant survey to ensure that it is CA.

PC

 

[Anonymous]

I'll take your advice, thanks. Would you look for general building surveyors (with experience in old properties) or am I likely to find independent specialists in timber decay?

Michael

 

[Anonymous]

try isbn 0 85125 244 3, ' Recognising wood rot and insect damage in old buildings' by the BRE.
Worthy investment, easy to comprehend, hope its still available.
I do have to say chemical attack is unlikely. It would leave the timber visibly disintegrating into fiberous strands I think. If i were a bit closer I would have alook for you.

 

[Anonymous]

Thanks Jon. Interestingly enough that was the book the man that diagnosed the chemical attack had with him. He didn't recognise it immediately and had to phone his boss who suggested he look at the page on chemical attack. I asked to look at the reference in the book which he showed me. I wasn't totally convinced by the photo. Certainly what I have is far less advanced than that, but the narrative description fits the bill quite well. I've subsequently found a copy of the BRE page on chemical attack on a website somewhere, so I have had time to study it again at leisure.

What is a bit confusing is that the symptoms of the two timbers that have the worst decay look nothing like the BRE description of chemical attack or the other timbers... you could break large, dry, crumbly bits off the worst affected areas that will turn into a red powder if you rub them between your hands... I'm wondering (hoping) whether this might simply be the remnants of damage done by previous waves of beetle infestation that died out many years or even centuries ago. In that case there is probably enough strength in the remaining timber not to have to worry too much, at least not in the case of these two timbers.

Anyway this is all very educational... you learn a lot more about things when they go wrong than when everything is operating smoothly!

Michael

 

[Anonymous]

What you are describing can be quite common in old oak buildings, especially in loft spaces etc...

I am not a chemical or woodworm specialist, but I do come across this frequently. It appears that the small type of worms, (name????), chew away at the softest part of any oak beams, ( sap wood), and these normally give up when they get to the harder section of the beams, after they have reduced the softer bits to a reddish powder.

The sructural damage occurring depends on the proportion of hard and sapwood of the beam in question, hence some are more damaged than others

the simplest way to determine how far the damage extends to is by using the good old sharp penknife test. As the section of an old timber frame are usually heavily constructed, usually there is plenty left for the structural purpose for wich it was designed.
The reason why it happens in roofs etc.. is due to the fact that they used section of timbers which contained a higher proportion of sapwood and they probably would not show anyway. It depended on the quality of the building.

There is probably nothing structurally wrong with the timbers.

 

[Anonymous]

Michael

Can you not get a picture and post on site?

PC

 

[Anonymous]

..............., as I said previous, understanding oak beams is more importand than understanding worms and fungal attack.

It would be a welcome luxury if you get someone that understands both and is not trying to sell you anything.

 

[Anonymous]

I would strongly suggest it is very unlikely chemical attack.
Middi has given you sound advice about the sapwood and its vunerability. You could even pare some sections of "frass" away to see what lies underneath.

 

[Anonymous]

Yes, I'll try and do that when I've recharged the battery on my digital camera. See what comes out.