kingrat wrote:Well if you decide to use bricks there, and if your new inner leaf ceiling is going to be below the ceiling joists then that means your air gap between the inner and outer leaves at the ceiling/roof will be much larger than the air gap between your walls. The larger air gap will make up for the lesser mass on your roof.
Yes, that's the plan. Build the inner leaf below the ceiling joists. We will put them a bit higher, to gain space, but the air gap will still be much larger than the gap between the walls. We will reconsider bricks... Not to bad of an option. But, as you can see, we need a lot of bricks then! Also for replacing the glass sliding door (which is already removed). I see I didn't share a picture of this yet, only of the three other sides:
https://imgshare.io/image/20201012-124553.NmuphO
Have you already sorted out how to do your roof ventilation without compromising your isolation?
What do you mean with specific roof ventilation? In the inner room are two vent pipes, in and out. They go through the concrete below the ground, next to the studio I will build two s-boxes, where the vent pipes come up. With the in --> there will be ventilator or maybe later a hvac unit.
You might want to use a breather membrane on there first before you put the drywall up tight against the wooden panels.
And where would you put the breather membrane? Behind the drywall?
The underside of the roof deck must be ventilated unless you have a warm roof design. A warm roof design is where you have thick, rigid insulation on the outside, on top of the roof, usually covered by a rubber water proof membrane or metal zinc sheets.
If you do not have that, then you have a cold roof design and it must be ventilated properly to avoid interstitial condensation building up on the under side of your roof deck causing rot, mould and water to drip down inside your room, destroying everything.
This ventilation has nothing to do with your fresh air supply & return. It ventilation for your structure, so it can breathe.
This type of ventilation requires roof vents; usually soffit vents at the eaves and a ridge vent all the way along the top. Of course, this means cutting lots of holes, which would trash your sound isolation, unless designed properly.
What you will need to do is put drywall/plywood/osb on the bottom of your roof rafters/joists, leaving at least a 50mm air gap behind it so that air can come into every bay under your roof deck, and then out again at the ridge/opposite side (in the case of a flat roof). The air must have a completely unobstructed pathway.
It will look a little something like this:
Cold roof assembly.jpg
For your other question:
The breather membrane would go between your existing wooden cladding and the drywall/plywood/osb that you're going to add. The point of it is to protect your walls just in case your cladding lets water through. It needs to be breathable so that any water vapour that does get through, or any vapour from the interior of the space can escape and not get trapped. So, the membrane is water proof but vapour permeable. Something like tyvek, or any breathable house wrap will work. You must install it properly, overlapping it correctly and sealing it with tape in the right places.
Paul