Timber Treatment After Spray Foam Removal
Once spray foam is removed, the exposed roof timbers are inspected for moisture damage, fungal decay and woodworm. In most UK homes, the timber is sound. Where treatment is needed, here's what's involved.
What inspectors look for
- Moisture content above 20% (decay risk)
- Soft or spongy areas (rot present)
- White or brown fungal growth
- Woodworm flight holes
- Splits, sagging or fixings pulling out
Treatment options
- Borate-based timber treatment — sprayed onto rafters; £400–£900 typical
- Sister rafters — fixing a new timber alongside a damaged one; £80–£150 per rafter
- Resin repair — for localised end-grain decay
- Full rafter replacement — rare; only where structural failure has occurred
Frequently Asked Questions
No — in around 70% of UK homes, the timber is fine and no treatment is required.
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