Thanks ProDave. That makes sense, and it is the >50mm from combustible materials (or rated A1) that is causing the issue. All the Fire Mastic and sealants seem to be max B1 rated. Just don’t want them cutting massive holes through my mega insulated walls and Passive Purple membrane!
Hi
Our new build home is now in the final few months but issues cropping up every day. We are ‘aiming towards’ passive house without going all the way. Triple gazing. Ultra insulated with additional Passive Purple membrane to enhance airtightness. At first fix stage. UFH pipes & screed down. Most MVHR pipes in place. ASHP in place. Will also have 22 Pv solar panels.
We are installing a wb stove (external air supply only) but stove company said they need 50mm around flue pipes to be A1 non combustible & had talked about this being a space around the flue exit. Obviously this won’t work with our airtight plans. Can’t find any A1 rated fire mastic. How do others seal the flue into wall exit?
I know from many previous threads many have views on necessity WBS in airtight home. Understand but it’s going in anyway.
Advice would be appreciated.
Thx.
Is this something we can do ourselves? Had a quote from intelligent membranes for passive purple which was really expensive. £8k+. Really wanted t use it for improving air tightness in our new build (brick & block) but costs are already spiralling out of control.