ab12

Can you please advise on the most appropriate method of insulating this ceiling please. Above and between the horizontal rafters OR underneath the horizontal rafters? Current line of thinking is to have some insulation between the horizontal rafters- rockwool/PIR type and some roll type insulation above the rafters. Total depth of insulation apporx 300mm Worried about how to limit any interstitial condensation that might get trapped on the horizontal rafters and cause decay/dry rot etc. having read recent thread on this forum. There will be plentiful air on top of the insulation to wick away any condensation reaching above insulation level. Thank you for your input

Thank you for the explanation. Are you thinking of going to bare brick or installing the PIR insulation onto existing plaster? I've come across recommendations of applying parge lime coat if bare brick and then having PIR on that to allow for levelling of the wall surface but also any moisture thats travelled through to the wall can be absorbed by the lime plaster. Having said that I suppose its a bit of paradox to have breathable lime parge coat and non breathable PIR board on top. There is so much info available about the breathable vs non breathable insulation options for solid wall IWI that it can make the head spin and create lots of doubts. My main worry is interstitial condensation risk with non breathable insulation and the long term impact on the fabric of the building should the worst case scenario occur. Can I ask what sawayed you to the PIR rather than breathable insulation? Retro-fit insulation can be a conudrum to the point that it can cause paralysis in decision making

Need recommendations for products which will satisfy lime based parge coat requirements for bare bricks on external facing wall upon which breathable insulation will be fixed. Will plasterers who are accustomed with gypsum be able to work with lime or does it require a specific skill set? I have a plasterer in mind , very experienced with gypsum. He mentioned has worked with lime once last year so not sure what to make of this. Thanks for your help

The walls are dry except for some patches of condensation on 1st floor chimney breast area which I think might be due to hydroscopic salts? (not sure if that is the correct phrase) or water ingress from open topped chimney which I'm planning to cap with readily available chimney caps. Walls are mostly lime plastered although it is a bit hollow in places. Couple of walls are bare brick so thinking of getting it parge coated with lime plaster NHL 3.5. Yes with regards the insulation 50mm inditherm or other type breathable batts between timber studs with thin wood fibre board thinking about 20mm so net effect of 70mm insulation. Externally walls are brick only no work done to them. Thanks

Hi Everyone. Been lurking on the forum for a while, extremely useful resource. I'm in the process of applying IWI to externally facing solid walls, Fairly large task. Very conflicted between the natural breathable route and the non breathable route. For the breathable route- Battens filled with breathable batts of approx 50 cm thickness boarded with approx 20mm Woodfibre insulation board and then lime plastered. Confused about what paints then to apply to the lime plaster finish- certainly they have to be breathable (clay paints?) and I suspect will have to be specially sourced. Also unsure if I can applying lining paper to lime plastered walls to hide any imperfections in the plaster Also in rooms where 2 of the walls without IWI intend to use non breathable paints to keep cost down worried that there will be a mismatch of colours? The non breathable route essentially similar to Ankkers method recently posted. Thank you for your guidance

Hi Ankker. I'm in a similar predicament. How are you proposing to attached the 60 mm PIR to the wall? By foam or dot and dab or mechanically fixed? Also the service cavity created by the timber battens am I correct to assume this will be void space except of any services running through the void. What sized batten do you intend to use and are you thinking of going down the route of using tanalised battens? Thanks