13/09/2026
Dry rot ☠️
This is one of our lime render projects in Bristol. The team worked extremely hard to remove the cement render (which was the hardest to date 😭). We discovered the end of this triple beam had suffered the dreaded dry rot. There had been a leak at the abutment of the mono pitch roof, soaking the timber for years. This, combined with the impervious cement render, provided the perfect conditions for dry rot to thrive. We opened up the wall inside and drilled a core sample through the middle. The timber beam seemed ok, so it was agreed an end repair with some steel c section was sufficient. We had a structural engineer design from Swan Structures and proceeded with the repair. However when we started prep work, we found the dry rot had travelled much further than first thought. Consequently, the only fix was to replace the beam with a UC steel.
We’ve shared this to reiterate what we are always shouting about: impervious renders ruin historic buildings - masking problems, holding moisture and causing damage which costs thousands to remedy 👎
Dry rot needs around >18% moisture to live. It will travel through masonry to find new damp timber to feed on. It is crucial that masonry and timbers are allowed to dry, and this is done by using vapour permeable systems and maintaining good ventilation.
With the recent boom of fitting external wall insulation on solid wall properties, we are going to see so much more of this kind of damage, with the EWI systems turning solid wall property into a ticking damp time bomb.
