Garage conversion with internal (fire) wall. Construction?

[miljee]

OK, I'm a radiographer not a builder so excuse my lack of knowledge.

We have a 4 br. 12 year old brick 'estate' house with an integral single garage, accessible from the house. A bedroom sits above it. With growing kids, we want to convert the garage into 2/3 living room, 1/3 garage 'store', retaining the up and over door.

The floor is concrete.

As the 1/3 will be a store, the dividing wall (note, no doors through it) will need to be 30 minutes fireproof and have insulating properties as the garage space beyond will be just that, cold and unheated.

What could the wall be made of? Concrete blocks have been suggested (then stuck on plasterboard on the 'room' side)- I would assume that would require more major 'foundation' works, cutting down into the concrete floor?; or could we build a frame and fire resistant plasterboard wall with a layer of suitable insulation between the 2 layers of plasterboard? Would this just need 'keying' into the concrete floor (and walls and ceiling, obviously!)?

Note I will be getting this work done professionally but I am keen to explore our options before going too much further! And building advice on here is generally more accurate than that on mumsnet

 

[^woody^]

If you keep the door, then its still a garage and relevant works will be required based on that

The separating wall between the garage and living space would need to be insulated as per an external wall. So the easiest way to do this is as a 100mm thick timber stud with 100mm Celotex/Kingspan foil board insulation between the timbers. No foundation required. Normal 12.5mm plasterboard and skim each side will be enough too

Just read up on the numerous 'garage conversion' posts

 

[freddiemercurystwin]

By the way, on a 12 year old estate house there is a fair chance that your Permitted Development rights regarding converting the garages (or essentially losing a car parking space) will have been removed (that is to say it would need planning permission) and if you care about such legalities you should check this out before you go much further.

 

[miljee]

Oh yes, I will definitely need planning permission! We do still retain the required 2 off road parking spots, though.

I am assuming the wall as woody describes would be cheaper than a block built one?

Thanks for the advice.