Woodwork - how cautious

[stevepalace]

Hi any help would be appreciated. We have been having a new roof on a 1920s house. In the ripping out stage we have come across a beam which has signs of woodworm (small holes dotted over it in one section). I got some specialists in and they said that I needed to treat the beam and then have them spray every rafter in the loft space as a preventative. There is no sign of any other action and all trusses and rafters are in good shape. Is this overly cautious as there is no clear way to tell (unless I’m wrong) whether this woodworm could be long gone Or is this standard procedure? Can the permethrin spray damage the new roof underlay that has just been installed if the spray goes on it?

Any comments would be helpful

 

[Burnerman]

In an 1920's house I'd be very surprised if there wasn't evidence of the woodworm.....
The chances are the holes are historic and the beetle long gone, but the treatment is effective and doesn't interfere with the felt underlay - hence its a good move just in case!
On occasion where I wasn't sure about beetle activity, I filled all of the visible holes with polyfilla and then waited for more to appear......simple enough where the timber is visible, much less so in a roof void, of course. Thankfully they didn't but I still check from time to time.
John