I have an old hayloft about 130 sqm from the year 1920. Under the hayloft, there is an insulated storage and garage. The roof trusses are considerably sturdy and built on cc 120. The roof consists only of a sheet metal roof.
I want to use the "hayloft" for an office, party room, or maybe even a simple apartment.
I have two alternative ideas regarding the construction itself.
1. My idea is to build a "cage" of insulated inner walls in the middle of the loft with about 100 sqm of floor space to avoid a lot of sloped walls and to maintain some kind of "cold attic" around the entire new room except towards the gable where I will install windows. I've never heard of anyone building this way, maybe there's a reason for that, but I'd love to hear your opinions..?
2. If instead, you build on existing roof trusses and inner walls, how do you then create an air gap? What material do you use from inside the room out to the outer roof? First gypsum, then insulation, then plastic?
All comments are welcome!
I want to use the "hayloft" for an office, party room, or maybe even a simple apartment.
I have two alternative ideas regarding the construction itself.
1. My idea is to build a "cage" of insulated inner walls in the middle of the loft with about 100 sqm of floor space to avoid a lot of sloped walls and to maintain some kind of "cold attic" around the entire new room except towards the gable where I will install windows. I've never heard of anyone building this way, maybe there's a reason for that, but I'd love to hear your opinions..?
2. If instead, you build on existing roof trusses and inner walls, how do you then create an air gap? What material do you use from inside the room out to the outer roof? First gypsum, then insulation, then plastic?
All comments are welcome!
Okay, anyone see any problem with building according to option 1?
alt 1 - that's how almost all upstairs levels are decorated in old houses (like ours, for example) with knee walls along the sides and a small attic above, so it shouldn't be a problem?
Plastic or boards or something similar are probably smart to have on the outside partly as wind protection and partly to protect the insulation from falling debris and possibly a leaky roof. However, I don't know if there could potentially be condensation problems if the plastic is installed to be completely diffusion-tight; plastic is generally not recommended as a vapor barrier in houses that weren't originally built that way. But some kind of protection for the insulation on the outside is probably a good idea.
Plastic or boards or something similar are probably smart to have on the outside partly as wind protection and partly to protect the insulation from falling debris and possibly a leaky roof. However, I don't know if there could potentially be condensation problems if the plastic is installed to be completely diffusion-tight; plastic is generally not recommended as a vapor barrier in houses that weren't originally built that way. But some kind of protection for the insulation on the outside is probably a good idea.
Would, for example, masonite or asfaboard work as protection?
Will return with pictures 
