We have a brick built, flat roof detached garage in our back garden that we would like to convert the rear half into a playroom. Despite being re-felted around ten years ago (the roofing company only replaced the boards to the front half) the boards on the rear half are showing signs of damp and so are the timber joists (only 100mm joists spanning around 2700mm). The existing roof falls from front to rear over a distance of around 6mtrs but looking at the wall plates internally and the puddle that forms on the rear of the roof every time it rains I believe we will need to alter these plates and replace the joists etc.
I'm not really going for building regs quality but could use some advice on insulating said area as we will probably end up with a small wall mounted 2kw heater just to keep the chill off.
Floor I was considering a DPM with only 25mm celotex and chipboard with laminate finish, the rear and right hand walls are solid brick so perhaps 35mm timber battens with more 25mm celotex between (10mm air gap?) and 12.5mm plasterboard with plaster finish. The left hand wall requires rebuilding as someone had previously cut in a window and door (rather poorly leaving wall looking a little unstable), remove what little brickwork is left and replace with a new 100mm timber stud wall, UPVC cladding externally, 100mm mineral wool insulation and plasterboard/plaster internally? The roof as previously mentioned needs replacing throughout, upgrade joists to 150mm at 400mm centres with 100mm mineral or celotex? In between leaving a 50mm air gap above, new ply or chip deck and re-felt?
Any advice greatly appreciated, I know it's going to cost a few quid hence I would like to do it reasonably properly avoiding any possible damp issues through not having air gaps etc.
I'm not really going for building regs quality but could use some advice on insulating said area as we will probably end up with a small wall mounted 2kw heater just to keep the chill off.
Floor I was considering a DPM with only 25mm celotex and chipboard with laminate finish, the rear and right hand walls are solid brick so perhaps 35mm timber battens with more 25mm celotex between (10mm air gap?) and 12.5mm plasterboard with plaster finish. The left hand wall requires rebuilding as someone had previously cut in a window and door (rather poorly leaving wall looking a little unstable), remove what little brickwork is left and replace with a new 100mm timber stud wall, UPVC cladding externally, 100mm mineral wool insulation and plasterboard/plaster internally? The roof as previously mentioned needs replacing throughout, upgrade joists to 150mm at 400mm centres with 100mm mineral or celotex? In between leaving a 50mm air gap above, new ply or chip deck and re-felt?
Any advice greatly appreciated, I know it's going to cost a few quid hence I would like to do it reasonably properly avoiding any possible damp issues through not having air gaps etc.
