Bespoke have yet to figure out why all their rendering cracked. it’s been over 5 weeks since we noticed the cracks. Nothing has been done about it and Bespoke have more-or-less ground to a halt on the rest of the project. We’re struggling to contact them. We’re now about 22 weeks into what was supposed to be an 8 week job and we’re not happy with it. Looking on the bright side, it’s been the driest Spring in 100 years – handy for us because our roof is still unfinished!
Wishing now that we’d found a builder with experience of external insulation who may not have had the same problems when rendering over it (although we’ve noticed similar but less pronounced problems with other rendering which has no insulation under it, so maybe it’s just bad rendering?). There aren’t may builder with experience of retro-fitting external insulation – one builder we spoke to proposed to subcontract it to a very expensive specialist, another building firm did have experience in that area but we didn’t feel they were right for the rest of the job.
Hello Gavin
Just browsing website and I’ ve come across your update, back-tracked to other stuff you had done on your house.
I too finding it difficult to find a an experience builder that can fit external insulation. I too would have alarm bells in my head if Bespoke purchased the incorrect insulation material. Glad you got phenolic foam, much more dense.
I’m sure the Bespoke builders are normally very good at what they do and have got the contract on recommendation – they will be able to work it out. However, there may have been a significant error in the application or the product.
I have know experience in the application of external wall insulation but, it strikes me that there may have been some shrinkage of the base coat, top coat or both. You say it was a hot sunny day, maybe (as you say) they should have made the mix wetter. Maybe they applied the top coat too quickly. Layers drying at different times and at different rates should be known by the builder and allowed for to minimise shrinkage and cracking.
There maybe some sort of chemical reaction between the phenolic foam insulation, meshing and the base coat render. A test wall, should have been done. Was there any movement joints to minimise cracking?
About that external insulation, I suspect what you were alluding to is dense (compression resistant) rockwool slabs, I agree would be much better, it is somewhat an inert material, therefore less risk of a chemical reaction between the insulation and the render.
My heart goes out to you. I really hope it will be finished soon. Just wanted to pass a comment. Very envious that you have the opportunity to try these new products out:-).