How to deal with cold bedroom above garage

eyeofthetiger999

Hi.  I have a large bedroom above a double garage which is approx 22m2 and hence large.  The double garage has recently been upgraded to a sectional insulated door.  There is a single radiator 175 x45cm situated below the window(  in my opinion is woefully small for size of the room).  The room is colder then the rest of the house, esp in winter.  I am looking for solutions to make the room warmer.  I have 3 possible solutions:

1.  Insulate garage ceiling.

2.  Upgrage existing radiator.

3.  Add another radiator to the existing room.

Or possibly a combination?

Any advice , particularly on people who have found solutions to this already, any ideas on costs invloved?

Thanks

Robin9

I had the same issue   -   took down the garage ceiling, installed 150mm insulation in the rafters, double overlapping plasterboard to meet fire regs (that was 1997 !)

Solarchaser

Hi, I would definitely say the first suggestion.i have a carport under our bedroom with a single radiator and it's possibly the warmest room in the house because there is around 300mm of insulation under our feet and about the same in the loft above.

Reed_Richards

If it's a single panel radiator then the output at Delta T = 50 would be 660 W according to the calculator here https://www.castrads.com/uk/resources/calculators/panel-radiator-outputs/  .  That is not enough to heat a room of 22 m2 floor area (unless everything except the floor is extremely well insulated).  So although "floor" insulation is an obvious thing to do, you may well still need to upgrade your existing radiator.  

Meatballs

I have a 20m2 room above double garage, the floor may not be the only issue as the room is likely on the end of the house with potentially 4, 5 or even 6 sides of the box being "external/unheated spaces" whereas most other rooms in the house are likely to have 2 or 3.

I have one wall connected to the house, but it's an insulated cavity wall so the above garage space is almost completely isolated from the house barring the door.

To make it worse if it's built into the garage roof space you likely have stud wall partitions into roof space rather than an insulated cavity wall like the rest of the house? My walls had 100mm EPS between timber but lots missing, especially where the roof is sloping. I've tried to fit 100mm PIR where it's been missing (one whole wall!).

So you need to check all the walls and roof are properly insulated. Mine also had no loft access so I had to fit a hatch to check and do remedial work with all the poorly rolled out loft insulation (and added more).

I added another 100mm under my chipboard flooring on top of the existing 100m. I also added a layer of thermafoil over the top to prevent drafts where I had cut the chipboard and taped to the skirting boards.

Also put some roof breather membrane at the end of the floor where it went into roof space to prevent airflow running from one side all the way to the other.

Insulated rad pipework whilst there.

Upgraded radiator from a 500x900mm single convector to a 600x1000 double convector. You should do heat loss calc to work out best size rather than guessing on room dimensions.

So that's all been a bit of a mission, and it's still easily the coldest/least efficienct room in the house, but the radiator can get it up to temperature quickly as we only use it as a guest room so mostly unheated.

It still does ideally need 50mm insulated PiR plasterboard to get it up to a decent specification tbh.


Anyway to sum up:

Easiest/cheapest should be upgrade the radiator, which will increase comfort for limited cost, but keep long term heating costs high.

For underfloor:

Just adding insulated plasterboard would be the quickest/easiest if doing from below. Think you could screw straight through existing plasterboard into joists with long enough screws and not have to take anything down.

Best approach take down ceiling and fill cavity with either fibreglass/rockwool, followed by plasterboard + insulated plasterboard (I think its supposed to be double plasterboarded so may need to check building regs how its supposed to be constructed!)

Martyn1981

I grew up in a bedroom like that. The rest of the family insisted I kept my bedroom door shut in the winter so it didn't cool the rest of the landing. I liked it, but looking back it's kinda nuts. It also had a tiny little rad, about 1,500mm by 300mm.

I'd definitely do as others have suggested and insulate the garage ceiling with PIR. I've used plasterboard backed PIR in a cold room in my house and it works great. You might also be able to put insulation under the fllorboards if they can be lifted easily .... big 'if', and even a super thick layer of underlay will help.

Rad sounds too small, is it a single panel, if so then moving to a double panel, with two sets of large fins too, might be relatively simple?

Rodders53

Define cold.

NB You may already have insulation in the floor space (it almost certainly should have had some installed to meet Building Regs unless done a very long time ago)? Our master bedroom over the double garage certainly has a good amount of rockwool in the space... as does the rest of the house a circa 2007 build.

You need to do the heat loss calcs for the rooms making some assumptions and work out the correct radiator size and temperature you want the room to be.  Ours has three external walls but they are modern cavity wall insulated.

SWMBO has both the double panel-double convector radiators in the room on frost setting.  It was unusually cold in there last night 14.5 C  (- 1.5 C outside).  Often enough we can't get it below 18 C for sleeping without using aircon.

eyeofthetiger999

House was built 1981, it has 2 external walls and the garage underneath.  I will try to get a temperature reading but it is cold to me and Im heat intolerant!  I can feel the carpets are cold which i cant feel in other rooms.  

Exiled_Tyke

I've done this recently.  We decided it was better to go into the void from the bedroom rather than bring the garage ceiling down. The floorboards were stuck-down chipboard so we took a circular saw to them and cut strips out of them. Then packed the void with fibreglass (or whatever the model equivalent is). it's still the coldest room in the house but a vast improvement. 

jimjames

You might need to increase the radiator size but there is little point doing that on it's own without insulating the floor as you'll just be heating up cold air from the garage. Our garage roof had to have 12.5mm fireproof plasterboard (or double normal plasterboard) plus Celotex 50mm panels and also has rockwool insulation above the celotex. 

Spies

I have a similar issue with my front room which is floating over the road into the carpark behind, once the heatings off, the temperature drops at an alarming rate.