09-06-2011, 11:29 AM
One key point to add to David's post, and to reiterate the point I made earlier, the moisture content of timber is very important. I didn't go into detail last night as I really should have been asleep 
The wood needs to be damp. Not necessarily wet to the touch, but it needs to have some moisture content to sustain life. Typically 11% or more. Of course, you can buy specialist moisture meters, but a DVM does the same job. Once I found a lookup table correlating typical values in M-Ohms to MC in % (this varies slightly with the species in question), I wish I could remember where!
So in a centrally heated house, any active woodworm will soon die or if they do pupate and leave the timber, they won't be able to find suitable timber nearby to lay their eggs. It's a non-issue IMO. Obviously it's different if you store things in the shed!
Think about their natural habitat: they ideally want a nice tree trunk - or maybe some dead wood lying on the damp ground. Look around any wooded area and you'll find lots of woodworm living in these sorts of conditions, and the flight-holes to match. Laying eggs in a radio or roof joist is a last resort for these things, and if they can get outside, they will.
Also, they only like sapwood. So decent quality joists won't be weakened significantly by an infestation (I was quite surprised at this when I replaced some joists in my front room). I've got more joists to replace in the room above the cellar, and there has been extensive attacks in the past, but since opening up the ventilation under the house and through the cellar some 6 years back, I've not caught anything emerging since the first year. Relative humidity in the cellar has gone from 100% to 60% (varies with the weather, of course) and the joists are completely dry apart from the 6-12 inches near the ends (where they sit in the walls with no damp-proof membrane).
As I mentioned above, I'm also concerned about the health risks with using chemical treatments. Just because the H&S people have approved their use, that's no guarantee in my mind. Also, no-one knows what happens when you mix these things together - easily done if a house gets a "respray" each time it changes hands (don't get me started on the sharp practice of timber "specialists" and their so-called "free surveys")
A couple of good references that I normally trot out on occasions like this:
http://www.pdoyle.net/content/view/57/79/
http://www.askjeff.co.uk/woodworm.html
Remember; spiders catch and eat the emerging beetles; they are your friend
Cheers,
Mark
The wood needs to be damp. Not necessarily wet to the touch, but it needs to have some moisture content to sustain life. Typically 11% or more. Of course, you can buy specialist moisture meters, but a DVM does the same job. Once I found a lookup table correlating typical values in M-Ohms to MC in % (this varies slightly with the species in question), I wish I could remember where!
So in a centrally heated house, any active woodworm will soon die or if they do pupate and leave the timber, they won't be able to find suitable timber nearby to lay their eggs. It's a non-issue IMO. Obviously it's different if you store things in the shed!
Think about their natural habitat: they ideally want a nice tree trunk - or maybe some dead wood lying on the damp ground. Look around any wooded area and you'll find lots of woodworm living in these sorts of conditions, and the flight-holes to match. Laying eggs in a radio or roof joist is a last resort for these things, and if they can get outside, they will.
Also, they only like sapwood. So decent quality joists won't be weakened significantly by an infestation (I was quite surprised at this when I replaced some joists in my front room). I've got more joists to replace in the room above the cellar, and there has been extensive attacks in the past, but since opening up the ventilation under the house and through the cellar some 6 years back, I've not caught anything emerging since the first year. Relative humidity in the cellar has gone from 100% to 60% (varies with the weather, of course) and the joists are completely dry apart from the 6-12 inches near the ends (where they sit in the walls with no damp-proof membrane).
As I mentioned above, I'm also concerned about the health risks with using chemical treatments. Just because the H&S people have approved their use, that's no guarantee in my mind. Also, no-one knows what happens when you mix these things together - easily done if a house gets a "respray" each time it changes hands (don't get me started on the sharp practice of timber "specialists" and their so-called "free surveys")
A couple of good references that I normally trot out on occasions like this:
http://www.pdoyle.net/content/view/57/79/
http://www.askjeff.co.uk/woodworm.html
Remember; spiders catch and eat the emerging beetles; they are your friend
Cheers,
Mark
