Insulating garage conversion floor

[CaptainJack88]

I'm redoing our garage conversion, however just wondering what the correct/best way of insulating the floor would be

Option 1:

1. Concrete Floor
2. Insulation Board
3. Chipboard/Plywood

Option 2:

1. Concrete Floor
2. Battons every 600mm
3. Insulation board between battons
4. Chipboard/Plywood on top of battons

Is a membrane or anything required at any point? The concrete floor is the existing garage floor

 

[Doggit]

As long as the garage floor is dry, then a membrane isn't required; any questions over it, then use a 1400 gauge membrane, and take it up the walls to the height of the floor. As long as it's just general usage, and the floors flat, then option 1 is okay. The chipboard can just go on top if the PIR (I assume) insulation, and you glue the P5 chipboard joints together to make a floating floor, then a small skirting board to keep it in place. Option 2 won't work out much cheaper.

 

[CaptainJack88]

Thanks, that makes sense.

Do you have any suggestions about what I could do here:

The blue is the wall (sticking out bit it breeze block support column)
Green is the insulation board, and white being the plasterboard.

I can't really afford to bring the plasterboard in anymore, and there is a 15mm void between the breeze block and the plasterboard.
Only issue is that it will probably leave me with a cold spot

 

[Tigercubrider]

Possibly the thin quilt/foil stuff?
Use a wide chunk and foil tape it to the celotex

 

[Doggit]

You can get 20mm PIR boards, but 25mm is more common.

 

[^woody^]

You always need a dpm with garage conversions whether the new floor is touching the concrete slab or not - there will be moisture moving through the slab or evaporating off.

Option 2 all the time.

10mm or so of celotex on that pier.

 

[CaptainJack88]

You always need a dpm with garage conversions whether the new floor is touching the concrete slab or not - there will be moisture moving through the slab or evaporating off.

Option 2 all the time.

10mm or so of celotex on that pier.

Assuming the DPM goes down first, how do you fix all the battens in place without puncturing the DPM?

 

[^woody^]

Hang them off the walls or make a frame that sits on the dpm.

 

[CaptainJack88]

Hang them off the walls or make a frame that sits on the dpm.

Hmm, I thought the DPM had to come up to at least the door sill, which is at the same height as the existing DPC.

Not sure I can hang it off the walls so might be the frame way

 

[^woody^]

A dpm goes across the floor as the up the wall and you lap it with the vertical wall membrane on external walls or seal it with the dpc on the internal walls.