Garage Conversion

[andydiynot86]

Hi All, I have a single Skin Brick Garage at the bottom of my garden with a flat roof, there is no damp course the the base appears to be a massive slab of concrete. The Flat roof is a 200mm Cavity and then plaster board ceiling.

Id love some critique on the below.

> Take down existing plasterboard, re felt roof and replace OSB if needed.
> Fill with some Rockwall insulation and reapply new moisture resistant board (any advise on the rockwall / Kanuf) ?
> Liquid DPM The Floor and Walls
> Self leveling compound for the floor
> Clotex insulation on the floor (what would be the min I can get away with) I'm a little restricted with height and budget > Then Chipboard then hard wood / laminate
> The single skin walls I plan to batten, 50mm rockwall/Kanuf, plaster board

How does all this sound?

The other issue I have is the entrance. I have attached an image of the current state and what I hope to achieve. I want the narrower French doors, I then plan to frame out either side then OSB, external membrane and glad with composite or equivalent.

I don't know what to do with the base though? So if the doors come with a 80mm deep ceil for example can I screw this directly into the existing concrete base or should I run a horizontal layer of bricks along along the base first then sit the doors and frame on that ?

 

[Bonni]

You can either create a warm or cold flat roof, so have a look into those two options.

The correct terminology is half brick, the walls are half brick thick. Any part of your new inner stud wall should not touch the brick, be it insulation and timbers.

You don't need building regs if the garage is not attached to the house, your proposed insulation level is way way below buildings regs standard. Kingspan/Celco boards are 2 to 3 times more efficient. I did one flat roof a couple of years ago and the minimum was 120mm Kingspan. I think cavities are now 100mm kingspn and floors used to be 100mm too, but it may have increased.

 

[Ivor Windybottom]

Not sure how you'd resolve that wall wrapping around to the inside in the doorway. You need to line and insulate it, you may need to somehow thicken the door/window frame to provide the space.