Building a bigger room, meeting local code headaches.

[Funky Animal]

In the past I have built a shed, and in there I built my own drumroom/small home studio. Which worked good enough for my own little project and practicing drums.
The room holds up nice, but it isn't big enough to comfortable practice with a band in there.

I am building an extra room in my garden, but I'm having difficulties meeting local code AND having good insulation for this practice / live room.

First of, local government gave me these limitations
- I am limited to 30m2
- Maximum height of 3.5m
- Not a flat roof
- And they're not allowing me the way I wanted to build my walls

From bottom to top

Floor size
I decided on 4.5m x 6.5m, it fits well in my garden this way.

Foundation
Status: Approved and done.
Concrete 20cm, with around it 60cm deep (frostline) and 30cm wide so it won't freeze underneath and won't move.

Building shape
Status: Approved, framing is up.
I needed to get create on this, since I couldn't do a floot roof, but I had a maximum height of 3.5m (exterior).
I went with and idea of having a sloped roof, this way I could get the most out of the space.

Wall construction
Status: Not approved yet
They want the airtight space to be on the inside, so the T200 foil needs to be on the inside, and all the seams need to be taped. This is causing problems with where I want to seal my out layer and create a closed leaf.

My proposal (denied):
Siding | Furring strips | Polytex covering | OSB (airtight) | Insulation + framing | Airgap | Insulation + framing | T200 foil | Gypsum | Gypsum

Their proposal:
Siding | Furring strips | Polytext covering | Insulation + framing | Airgap | Insulation + framing | T200 foil | Gypsum | Gypsum

The problem occuring is that with their proposal, my outer leaf won't be properly insulated, and not really be functional as a leaf, so in this case, my building is just a single leaf built, which is not the intention I have for it.

Roof:
Status: Approved, with a sidenote however.
The sidenote is that if we can find a proper option for the walls. So I'm using EPDM, since it wasn't sloped enough for shingles, however with EPDM I needed to have EPS insulation underneath it, which does nothing for insulation. However, since there is an subsidy on having a green roof I can cover my roof as a green roof. Which help regarding heat AND sound.

I'm now looking into other options for the walls to propose so I can get the best insulation for my situation.

[John Sayers]

What if you build the outer wall as per code. The OSB becomes the outer leaf as the siding on furring channel is not airtight and therefore doesn't act as a leaf.

You then build the inner wall with a 100mm air gap with insulation and the double layer of plaster which becomes the inner leaf.

suggestion.jpg

cheers
john

[Funky Animal]

What if you build the outer wall as per code. The OSB becomes the outer leaf as the siding on furring channel is not airtight and therefore doesn't act as a leaf.

You then build the inner wall with a 100mm air gap with insulation and the double layer of plaster which becomes the inner leaf.

suggestion.jpg

cheers
john

Hi John,

Thank you. I got the news back last week that this has been approved!

Up to the next step, planning it all out and making drawnings.