Hello!
I have a factory-made 18' x 8' brand new garden room. I’m making it into a fully-fitted office/studio with 2 rooms:
– studio for artists work
– kiln room (a pottery oven that gets hot)
Photos & videos: (plus attached diagram)
https://www.dropbox.com/sh/ese89vjh96y5110/AACrpI1yJpD82CDCq1SDPP1ha?dl=0
Our goal is to have a warm workspace and protect our investment.
Roof: (see picture)
– Sloped
– Shed roofing felt on timber decking
– *unvented* (some air seeping in front and back but I’ll seal it)
– 65mm rafters (not very deep!)
Ceilings – (the plan for)
– Plasterboard connected to the rafters in the kiln room (special fire-retardant board on all ceilings/walls in the kiln room)
– Wood cladding connected to the rafters in the studio room
– Ceilings are low - we don't want to make them much lower
For insulation, my research has found these as the 'best' options:
– Warm Roof solutions – not ideal for us
– Cold Roof + Closed Cell Foam – too expensive
I'd like to find the next-best thing - can you please help? :-)
Q1) Ceiling Insulation
– I've been told not to use rockwool style insulation in an unvented roof. Rockwool themselves say it's a condensation risk and that I *can* used their product, but I must usage a smart-VCL with it.
- Celotex told me not to use their product unvented.
- I've had other suggestions a thin layer of EPS across the rafters, no VCL, and either Rockwool or EPS in the rafter cavities.
Note: Ceiling covering in studio room – We want wood cladding but because it's not air tight, the general recommendation is an airtight layer first like plasterboard. However we don't want to eat into our internal space too much if possible...
What do you think we should do for the ceiling insulation?
Q2) Wall insulation – our current plan is:
Rockwool batts filling the cavity
+
Tyvek Airguard Smart (like membrain) VCL
+
interior wood cladding.
Again the wood cladding has an impact -- it is used both as the exterior wall and the interior wall, so we're especially concerned about moisture getting in there.
What do you think we should do for the walls?
I know that whatever the product, doing a great job of air sealing it and installing it properly is the most important.
But we are drowning in conflicting views - Thanks in advance for your help!