Insulating concrete floor with rockwool?

Hi!
Im about to embark on a big project (well, big for me being a rank armature builder!) to covert part of a garage into my 'Man Room!'
I'm starting with the floor (seems like a good place to start) and was wondering what's the best way to go about it...
It's a single skin brick garage with concrete floor and I was thinking of laying a damp proof membrane, 50x50mm battons, rockwool between the battons then chipboard sheets on top. I know rockwool is probably not the best thing to use to insulate a floor but I've got rolls and rolls of the stuff and want to keep costs down to a minimum! Also, chipboard sheets are probably not the best thing to use either but I can get them for next to nothing too!
Are there any major flaws with my plan?
Any suggestions would be greatly received!
Thanks, Bruce!

Doing this to Building Regs?

I see no flaws, and I'd do it the same way if I had a supply of free materials. make sure you have the battens close enough together that the floor doesn't flex.

I'm not sure of the legal aspects, as per planning laws blah blah.

I'd probably do the walls the same way too, and use the membrane to keep damp out as well.

It may not be the best way, but it will do the job and not cost a fortune.

Thanks for the replies!

Not really that fussed about the building regs to be honest! It's just a place for me to retreat to! I'll rip it all out if I have to if we ever move!

I was thinking about the same for the walls but was a bit concerned about damp...

Would the DPM go directly onto the wall, battons over that, rockwool between the battons then plaster board? If this is the right way of doing it, wouldn't it leave loads of holes in the DPM from screwing the battons through it and into the wall?

You could make it a 'suspended wall', so it doesn't actually screw to the wall in any place, but just rests against it or hovers a half inch away. Or at least no screws anywhere near the bottom of the wall where it'll be damp if anywhere. That way no holes in the membrane.

Tie it into the floor boarding at the bottom to keep it all in place, maybe have a ceiling the same materials to locate the top. A room within a room.
Just a thought.

There's probably far superior 'expert' ways to do such things, but I'm a rank amateur.

Just thought....

If i'm laying a damp proof membrane onto the floor, then battons on top of that, I'm going to have to screw the battons down, through the membrane, making holes in it!

I'm going to used treated timber so would I be better laying the battons first then the DPM over the top of them?

I'd not even screw the floor battens down. Just lay them out over the DPM and screw the chipboard over them. Maybe put something down so they don't cut the DPM, some felt or that green board they use under laminate flooring.

I'm not sure if condensation would be an issue under the DPM. Maybe some ventilation would actually be better. If the floor is not actually damp to the touch maybe you don't even need a membrane.

When I insulated our old concrete outhouse a few years back I screwed 2 x 1 batten to the walls, then put 1" polystyrene sheet between them, then screwed 1/2" chipboard over that. No membrane was used. And I just laid carpet on the floor as it never actually felt or looked particularly damp.

When winter came it started to show a little mildew or black mould in the very lower corners, on the paint, so I put a small electric radiator out there and set it to maintain about 24C.

I wiped the mould off and it never came back again, so I think a little heat would help any damp issues.

The man room is coming along! Slowly but surely!

Just encountered a bit of a problem though!

I got some recessed 70mm LED lights so I borrowed a 70mm cutter, cut the holes in the plasterboard ceiling only to find out the overall diameter of the lights is 70mm, not the recess!

Is there such thing as a ring spacer I could use to reduce the diameter of the holes I've already cut!?

Cheers people!