Garage Conversion Help

Hi,

I am about to start turning my single brick garage into a room.

My plan at the moment is to stop the door from opening then lay a DPM (the plastic sheet kind) down over the concrete floor, up the walls and over the back of the garage door. What's the best way of attaching the DPM to the walls?

Then create a rised timber floor with 150mm of insulation and Plywood boards ontop. This floor should stop 5-10mm from the garage walls is this right? Also is it OK to lay the wooden battons for the floor frame onto the DPM? How should I attaxh these to the floor?

Next the walls - leave a 30-40mm air gap between the wall (with dpm) and the insulation. Build a timber stud wall and fill with insulation and cover with plasterboard. My questions here are what's the best way of attaching these stud walls to the floor? Do I need a breathable membrane in there somewhere?

Finally I will insulate and board out the ceiling.

Is there anything else I need to think about?

I think I'm ready to go but just worried about damp getting through.

Thanks in advance for any help.

 

Thanks Anth

I was talking to a builder today and he said it would be fine to just attach CLS battens to the brick wall, fill with insulation slabs and then run a DPM over the top before adding the plasterboard.

This will save space loss but will it be OK? The conversion is just a 5-10 year temp solution un till we can afford to repalced the garage with a 2 floor extention. So it's not like I'm making something to last forever.

Thanks