The warm floor is created well below the level of the screed.  Insulation of 100mm Jablite (or equivalent) should be under the concrete floor slab.  

If the insulation needs to go directly under the screed then you need 75mm screed (mesh reinforced) on top of 100mm insulation.

That's 7 inches..................................  

But where did you think this 'warmth' was going to come from?

Has your slab even got a dpm?  ???

Could you lay a few courses of bricks around the edge and put the sectional garage on top of that. This would raise it up enough to fit in the insulation and screed floor. Not sure where the dpc would have to go - perhaps a layer over the whole slab before you start?.

I'm not sure if you need to comply with building regs ??? it is not an habitable room so probably not. In which case you could lay 25mm Xtratherm or Kingspan, not sure if you can get 25mm Jablite. The Xtratherm is about £14 per 8x4 sheet. Then lay minimum 1000 gauge dpm over the insulation and 150mm up the walls; then lay 18mm t&g flooring chipboard, glueing all the joints and leaving a 10mm minimum expansion gap round the edge.

This does end up being 43mm without carpets but does have the advantage that the floor has little thermal mass so the room will warm up quickly. You would be advised to fit a 2x1 tanalised batten at the door reveal to support the chipboard floor and anywhere else round the edge where the floor may have to take a particular load.

Hope this helps

Keith

I think Building Control Approval is required if the floor area is bigger than 30 (or is it 36?) square meters.

What are you intending for the walls and ceiling regarding insulation?  Most heat goes out through the roof, then through the walls.  The floor looses the least (as heat rises).

John, timber frame internal wall sounds OK but the vapour barrier goes between the plasterboard and the studding. The vapour barrier is there to prevent warm moist air from inside the room condensing on the cold inner face of the outer wall not to prevent moisture from outside affecting the insulation.

The wall I would build is as follows;

line the inner face of wall with breathable membrane, (Ruberoid or Tyvek) pretty expensive at about £100 a roll!!

3x2 stud wall from tanalised timber

Use 70mm Expamet(I meant  Xtratherm   well it was early) or the like to insulate between the studs, you need to get a good a fit as you can then fill ALL the gaps with expanding foam.

Then lay a vapour barrier over the studding, before applying 2 layers of 12mm plaserboard, staggering the joints to aid sound-proofing.

The studding can be attached to the outer wall for strength or leave a gap for better sound insulation, but then it may need bracing on the long wall.

One simple job, so many ways of doing it

Keith

[quote author=JerryD  link=1123786176/0#14 date=1123919656]Woody, I didn't know Expamet made insulation  

[/quote]

Neither did I, I think it's news to them too

I was actually thinking that John could use a metal stud wall rather than timber and in the early hour got my Xtra mixed up with my Expa .

Thanks for spotting the cock up, good job we are a team round here

Ok guys, now for the roof, I am planning to have a flat roof put on to replace the asbestos sheets, how would "you "do it and take into consideration the insulation and how to tie it to the concrete sections of the garage walls.
Regards.
John.

Not easy to explain 'how to do it' without a three page post  

There will be many website showing how to construct a flat roof.  The insulation must be continuous with the wall insulation (no gaps) or else you'll get cold spots where condensation can occur. Go for a 'warm roof' design as this avoids the need for cross ventilation. (warm roof = insulation on the top, just under the felt)

For felt, ensure the felter uses HT felt.  This will last minimum 20 years (maybe longer) if done properly.

EPDM has had many bad reviews.  In addition, that web link you gave shows a headline price of £7.38 m² but if you read it further you cannot buy it for that price (as far as I can see). The cheapest method comes to £9.40 m² + vat (£11.05) + delivery.

The slightly thicker, self adhesive range costs nearly double @ £20.18 m² (inc vat but again + delivery)

Finishing the edges is always a problem, I've seen some awful diy attempts at this.

If I had a new flat roof deck to cover I would get a reputable firm in and insist on ht felt.

Fibreglass is another option.

Well I'd go for a pitched roof every time.  Costs about double the flat roof method but lasts minimum 100 years (my last one did anyway  ).

Walls have to be able to take the weight though...........

Iv'e just had a terrible thought! will the garage walls support a proper felt roof? what with the joists boards and felt, after all they are only concrete panels bolted together. Maybe I should contacy a manufacturer of sectional garages and ask them. If not then would building an inner skin with blocks be the answer.
Regards.
John

Thanks CWatters.
Iv'e had the roof guys around and they said it will hold, they even took me to one that they had done  and it looked fine.

this is the stuff I'll be putting on my garage roof & they are only about an hr from the house

http://www.planwell.co.uk/

i don't know if there is a distributer near you

[quote author=woodsmith  link=1123786176/0#7 date=1123827442]I'm not sure if you need to comply with building regs ??? it is not an habitable room so probably not. In which case you could lay 25mm Xtratherm or Kingspan, not sure if you can get 25mm Jablite. The Xtratherm is about £14 per 8x4 sheet. Then lay minimum 1000 gauge dpm over the insulation and 150mm up the walls; then lay 18mm t&g flooring chipboard, glueing all the joints and leaving a 10mm minimum expansion gap round the edge.


Hope this helps

Keith [/quote]

Ok back to the floor, (the roof is going on very soon)
Keith you said put the 25mm Xtratherm down first, but the concrete floor is quite rough could this damage the  Xtratherm when there is weight on it? If that is the case then what would you put down first.
Regards.
John.

Thanks Keith.
Will do what you say regards knocking off proud bits (ooh err mississ   ) maytbe some self levelling compound would help as well.
Rgards.
John.

[quote author=john59  link=1123786176/0#0 date=1123786176]Hi all, At the moment I am erecting a concrete sectional garage onto the existing concrete garage floor. The purpose of the garage is not for the car but as a home cinama.  I know the proceedure regarding screeding and such to make the floor warm and level ready for the final covering (carpets) but I have a problem, the door that I am fitting is 81 inches tall (frame) and from the base of the garage to the top of the  wall plate that I will be putting on measures 82 and a half inches so I only have inch and a half for the screed and the carpet, are you with me so far. Apart from sand and cement screed is there any other method I could use to creat a warm sound floor.
Regards.
John. [/quote]Hi I am from the states. florida actually and we do not need heated floor systems here so I am not familuar with heat flooring. this might sound crazy to you but why can't you buy a custom door and frame that is the exact height you need. when you build up your floors your door is allways one of your first consideration. here we tile mostly on concrete and when we install carpet it is right to the concrete with tac strips and tile infront of door way.is tiled no frozen toes here. I read your post again. can you pull the header board at the top where the top of the frame will go and build a higher support so the door will fit, I had to do this when I added french doors to my bedroom after talking out a single door. I hope this is not confusing to you.

[quote author=sailfishoney  link=1123786176/30#35 date=1124680432]
Hi I am from the states. florida actually and we do not need heated floor systems here [/quote]

Oh I am soooo envious but welcome to the forum

I don't know about John's door situation but custom doors are expensive, or is it that factory made doors are so cheap ...yes.... definately the latter

Keith