Expanding foam to fill holes in wood

[AndyTriumpH]

I have car port which was put up when the house was built in 1968 and uses rafters that are bolted to my house and my neighbours. There is one corner that is not bolted to my house or my neighbours and the previous owner has stuck a plastic shield over the neighbours facing side.

When going to clean the car port, I found in that corner the wood had started to rot top and bottom against that plastic shield side.

Due its position and the deepness of the holes, I used Soudal Expanding Foam to fill the holes. After 5 days the foam even though dry is still spongy.

The can says it OK for exterior use and be sanded or plastered. So how can I fix this problem?

[tabbypurr]

Remove the foam - it will always be spongy, cos that's what it is.

If accessible enough, cut out the rotten section & join new timber in.

NT

[Brian Gaff]

If it is structural, I'd certainly not be using foam. Threat the wood, cut out the rot or whatever, make sure you can still have enough left to be strong enough to hold it up!. Really I'd not want to use foam cosmetically this way. Brian

[Chris Hogg]

Didn't see the original message, but yes, dig out the foam and any remaining rotten wood, use Ronseal wet rot wood hardener to harden up the wood surrounding the cavity, and then Ronseal wood filler to fill it.

and Sand to a smooth finish, paint etc.

[Brian Reay]

Chris? advice is probably ok for small areas- the Ronseal stuff is good. However, if the holes are large enough to weaken the structure, you need to replace the wood. You don?t want the thing falling down on someone or your car.

[alan_m]

It's a light weight expanding foam designed to fill holes/voids and not to form a structural repair on a supporting beam or leg. The cured foam is full of air pockets and will be easily pushed in with a finger. Any excess can easily be cut away with a saw or knife.

As others have written you may have been better off using the Ronseal Wet Rot hardener on first on the damaged/rotten wood