Wooden floor onto concrete slab

[aaron1987]

I am converting my garage to a playroom and am looking to install a wooden floor over my concrete slab.
I am wondering how best to secure the joists before I put the floor boards down.
It's a single wall on the outside so I am a bit dubious about using joist hangers.
I was going to put a visquine sheet down in slab to protect joists and then use rock wool insulation between joists.
Any help, comments, ideas regarding what I'm doing wood be appreciated - especially regarding how to secure the floor joists.

 

[catlad]

I would not recommend rock wool for the floor and how much gap will there be under the joists.

 

[aaron1987]

There is about 160mm drop from my kitchen to garage floor so I think the joists will pretty much be on concrete. Some packing to level the floor up.
I could use the rigid foam insulation if that would be best.
Do you think using 90 degree angle brackets would be sufficient to fasten the joists to the concrete floor?

 

[catlad]

You are supposed to have a few inches of clear space for ventilation under your wooden floor, but if thats not possible then I would recommend buying treated joists. Yes to the brackets but try and get something rustproof and make sure the joists are packed well and use slate or similar for a dpc.

 

[aaron1987]

Is there any particular size joist which is require?
Or just what ever fits?
The room is only about 5m by 3m and I will span the 3m section.
If I'm using brackets (and noggins to provide support) should I leave gaps at the end of the walls? Or cut the joists tight to the walls?
I have also just thought of attaching a piece if timber all the way round the walls if the room and then attaching joist hangers to this (rather than fixing to concrete floor) does anyone think this would be better/worse?

 

[catlad]

You could probably go down to 4"x 2" if you pack it a couple of times across the span, as to bolting timber to the walls thats ok as long as the wall are dry, and put a couple of air bricks either end for ventilation.