Renewing a Flat Roof

babyblooz

phil24_7 wrote: »

I have a warm roof (18mm OSB board/100mm PIR borad/18mm T&G OSB)on my garage which also has 50mm PIR board in the cavity and an insulated garage door. It is toasty in there most of the year around (2 large double glazed windows in the rear projection facing East and South) and is warmer than the actual house!

I have fibreglass on it and having the extra layer of OSB on top means there is no danger of damaging the roof from walking on it. The only danger would be from dropping something on it.

Thanks for that info! Sounds like we should be going down the 'warm roof' route as this should increase the comfort of that end of the house. Did you have a vapour layer? Any idea on what we should be looking at cost-wise? The roof area is about 4m x 4m max.

phil24_7

ColinFishwick wrote: »

I have both fibre glass flat roof and several EPDM roofs. Porch, bay, small extension and two garages. Fibre glass is better but EPDM come a close 2nd and can be done yourself if your competent. I even put EPDM on my shed as 2 year old bitumen roof which came with the shed was pants and I got a decent shed tongue and groove

What are your reasons for putting fibreglass first and EPDM second?

phil24_7

babyblooz wrote: »

Thanks for that info! Sounds like we should be going down the 'warm roof' route as this should increase the comfort of that end of the house. Did you have a vapour layer? Any idea on what we should be looking at cost-wise? The roof area is about 4m x 4m max.

No idea. My roof was 3.5m x 12m and was included in the extension price. I seem to have 2-2.5k in my head though but this could equally be poppycock!

I spec'd and bought my insulation, vapour barrier and T&G board myself as this was not included in my original quote. I got some rather expensive Tyvek vapour barrier and the cheapest branded, 100mm PIR board I could source.

If you do the same as me you will need 18mm OSB3 board, Vapour barrier (make sure this is sealed properly against the wall side. I used acrylic sealant) I used a 100mm x 50mm (give or take) timber around the external perimeter of the roof and lipped the vapour barrier on top of this, laid the PIR board and folded the vapour barrier at the house side over the top, then used the T&G OSB3 board.

The perimeter timber gives you a nice sturdy edge as well as allowing facias to be fixed easily.

Make sure the insulation passes over the cavity or any current insulation to minimise thermal bridges.

babyblooz

Wow thanks for that. It's so reassuring to hear from someone who has done it and can give feedback. I can't see us doing it ourselves but at least I can show this to our roofer and let him see the kind of spec we are after. My son is a joiner so he can probably source the materials for me at a good price and hopefully just pay someone to get up and do the job! Please don't go away as I may just be picking your brain again at some point:beer:

ColinFishwick

I paid for a fairly large single garage with new osb3 boards £1.3k but I found out he charged me a little less than he should as he did my MIL too next and she paid a lot more think it was 1.6k. That was 3 years ago now

phil24_7

babyblooz wrote: »

Wow thanks for that. It's so reassuring to hear from someone who has done it and can give feedback. I can't see us doing it ourselves but at least I can show this to our roofer and let him see the kind of spec we are after. My son is a joiner so he can probably source the materials for me at a good price and hopefully just pay someone to get up and do the job! Please don't go away as I may just be picking your brain again at some point:beer:

Feel free to PM me if you require any more information.

I spent weeks researching before committing to a warm roof and especially a design and spec as my builders had never done it this way. They were quite receptive to learning a new technique so it was a win-win!