partial garage conversion

[GTA120903]

Hi, im weighing up the job of partially converting my garage to habitable space.

i've read lots of different threads and seen some progress photo's to give me some guidance but i have a few fundamental questions that i cant find an answer to by surfing the net... can anyone help?

1. I plan to build up the floor with joists and chipboard to the level of my living room but the concrete floor has a slight gradient, do i simply need to 'shim' the joists at one end of the floor structure with thinner timber to achieve a level finish or is there more science to it?

2. There is already a bedroom above the garage and the garage ceiling is plastered so im not planning on touching it, will building regs suggest otherwise?

3. As mentioned, i have sketched the job, and to me the natural order would seem to be 1. fit stud wall, 2. install floor structure to butt upto stud wall and breeze block walls 3. fit wall batons to breeze blocks and plasterboard.

Reading other posts, it seems that the walls are finished prior to starting the floor structure, is there a reason for this that my naivety is causing me to miss?

4. Im planning on building floor joists 600mm apart, is this acceptable or should i aiming at 450mm spaces?

Any help would be welcomed as this will be the most complex project i have encountered so far and would love to not screw it up just to listen to the mother-in-law tell me how she did tell me to hire a professional builder in the first place!!!!

Thanks in advance.

Glenn

 

[^woody^]

Normally you would use 4x2 joists suspended from each side, so it is the gap below the joists which gets bigger, and the joists are not cut where the floor is highest

Then pack centrally under the joist down to the concrete to take any bounce out. And then noggins at mid span to strengthen the whole lot. You can use 600mm spacing

The ceiling wont need to be touched due to the bedroom

You can do the wall or floor first. IMO its better to form the stud wall and hang the floor off this. But there is logic in doing all the walls and messy plastering first before doing the floor. You just need to be careful with the DPM and laps/joints if doing the floor last - you would put a DPM skirt around the edge and up the walls first, and then tape the floor DPM to this when you come to do it

But if you are putting services in the floor then it needs to go in before all the messy work