Woodworm - replace wood or treat

johnstown

Hi,

I have an old outhouse that needs re-roofing. It has the traditional slate over timber rafters.

I am not sure how old the roof is, but the building shows up on the 1847 ordinance survey map.

Anyhow, the rafters, collars etc have woodworm. Whether they are active or not, I am not sure. I suspect yes. The slates are slipping a lot and thus the wet was getting in a little over the years.

Anyhow, the builder thinks most of the wood is in fairly good nick and just needs to be treated. Some replacement rafters would be required (where extensive wet damage). I intend to use new slates, laths and felt. The wood is a good hardwood, rafters all fairly big and close together.

In general would treating wood get rid of the woodworm? Having spoken to a few woodworm experts, they say yes (but they would say that for business??). One guy recommended Microtech which treats and prevents. It also treats fungal infections (wet ~& dry rot). Micortech is one of these eco friendly products which can be applied using a knapsack. “It is based on the pyrethroid insecticide permethrin”.

The building is 94 ft long x 14ft either side of the ridge. Replacing the timbers would cost a bit, but would it be cheaper in the long-term?

Thanks

DoneDL

If the timber is still strong then treat it for the woodworm. If the damage is so bad that you can see that the remaining timber has lost its abillity to provide support then replace it.

cnocbui

I would treat, but I would chose a product that was not environmentally friendly and was toxic as possible.

I would use something like Cuprinol Trade Low Odour 5 Star Complete Wood Treatment as it contains zinc - which fundamentally disrupts the metabolism of insects, and being a metal, will likely not degrade and will persisit in-situ.

jimkayak

I know it's a lot of timber but when your going to all that trouble and cost of new slates, felt etc, If you change the timber you'll know it's a good finished job.

whizbang

You say the slates are slipping, is this caused by nails not holding in the wood?, or how are the tile fixed?
if the tiles are not holding, the wood needs replacing. might look great from underneath, but rotten on top

cnocbui

If it's anything like a roof I have, the lime/sand 'glue' is no longer doing it's job and has/is falling from the underside of the slates and the nails have simply rusted away.

I just patch mine as needed, using copper nails where possible and adhesive where not.