garage ceiling insulation

[philkalico]

The room above my double garage is very cold in winter .There is some fibreglass insulation between the floor joists but it is not practical to apply extra without taking up all of the floor boards and skirting etc. The garage ceiling has one layer of fire resistant plaster board fitted to it.

I am proposing to fix 50mm of celotex boarding to the underside of the plasterboard on the garage ceiling in an attempt to provide a better form of insulation to the room above.

Has any one had any experience of using celotex in this way -was it successful. Will this help to keep the room above the garage warmer in winter or is there any better way of applying further insulation?

 

[foxhole]

You lose little heat thru floor, whats on the roof? whats the heat source? size?

 

[mikric]

You lose little heat thru floor, whats on the roof? whats the heat source? size?

Really ?? explain
How about the cold air bellow does this also have little impact on a habitable room above.

 

[foxhole]

http://www.lowenergyhouse.com/house-insulation.html
He has insulated floor so even less loss than example above for poor insulation.

 

[diynoob]

OP, I'd say yes give it a go and insulate the garage ceiling. Having an unheated, draughty room below is completely different to a normal ground floor room (where only 10%-15% will escape through the floor). Heat flows through the path of least resistance.

I had the same problem where the room above the garage was 7 degrees colder than the rest of the house. I insulated the ceiling but I think the main improvement came from draftproofing the garage, especially the garage doors. I put a lot of effort into it and eventually got the room to the same temp as the rest of the house. Without decent insulation you have a thermal bridge to the freezing room below, I guess you can feel how cold the floor is in the room above the garage, I certainly could.

Googling "cold room above garage" reveals it's a common problem. It's difficult to get good advice on it because people that don't have a room above the garage insist "hot air rises" and the solutiion is to insulate your loft. Even though the room above the garage is 7 degrees colder than every other room in the house...

 

[st3v3]

We have this problem. We live in a 12 mth old David Wilson Home called the Oakthorpe. Its a 4 bedroom, 3 ensuites, 'L' shaped house with main bedroom above double garage.
Does anyone have this problem with same house type??!?!?!?!?!?! We've got claim in with NHBC but the more complainants the better

 

[freddiemercurystwin]

We have this problem. We live in a 12 mth old David Wilson Home called the Oakthorpe. Its a 4 bedroom, 3 ensuites, 'L' shaped house with main bedroom above double garage.
Does anyone have this problem with same house type??!?!?!?!?!?! We've got claim in with NHBC but the more complainants the better

Claim for what? What did they do (or not)?

 

[st3v3]

long story. two issues; first the bedroom above garage is freezing. DWH said it will be "it's over the garage!". They drilled 50mm dia hole in garage ceiling pulled out a bit of rockwool and declared that it's fully insulated therefore its iaw ADL1A regs. I thought U-value requirement of all external floors was the same...so why is room above bedroom so much colder than all others when heating not on?
Second, we should have had S plan plus CH system but they say our "usable floor area" is less than 150 sqm. Because 'usable area' doesnt include the cupboards, cos they're storage like the garage, and the garage isn't heated, so "we exclude the cupboard areas".

 

[freddiemercurystwin]

How much Rockwool? What size are the joists? Any insulation under the joists.

Its not just about achieving simple U Values anymore, the whole house construction is used in the calculations.

Regarding your heating contact Honeywell directly and ask for the technical department and ask what they would use for the area determination ie if cupboards or integral garages should be included. Just play it dumb and don't tell them anything about why you are asking just say you are investigating heating systems to put in a newbuild or similar. Maybe even get them to email it to you. You could post a separate query for this in the plumbing section of the forum on here btw. Should've started a new thread for all of this in the Building Section tbh, tagging your questions onto the back of someone else's thread in the General DIY section is a bit fruitless tbh.

Frankly its probably easier to just whack some Celotex up underneath the existing Plasterboard than mess around with a fruitless claim to NHBC or try and pursue a developer. If you want to pursue the developer tell them you'll go to the press.

 

[st3v3]

thanks,
Joists are 'I' beams, prob 9inch height but web thickness is pretty small - so the heat transfer through the joists must be minimal. There's suppposedly 9inch of rockwool between joists. Bedroom floor is chipboard and garage ceiling is 12mm plasterboard. I think this should add up to a reasonable level of insulation but the room is freezing compared to all others?!?!
The idea of putting more insulation underneath the garage ceiling is clearly an option, but I begrudge paying money for something the building couldn't be bothered to do right (I'm too principled huh!) - house is only 15mths old!