Cold room above garage (did you fix yours?)

[Jon]

Hi,

We've got a bedroom above the garage in our eight year old house which is always 5 deg C colder (or more) than the rest of the house on cold days. The fact that the bedroom floor is always cold leads me to believe the insulation requires significant improvement between the garage ceiling and bedroom floor.

I've read these previous threads which seem sensible:

(Link to groups.google.co.uk)

and this:

(Link to

What I'd like to know is has anyone suffered with this cold room above garage syndrome, improved the insulation, and actually fixed the problem? If you have, can you state what you did and what materials you used please? I can't pull up the flooring as we've just had new carpet laid but would be prepared to pull down the plaster ceiling if necessary.

Thanks in advance,

Jon

[Andrew Gabriel]

Mine has fibreglass (looks like regular loft insulation) in the gap. There's probably around 6" -- certainly it's most of the 8" (IIRC) height of the joists. (That's a 1990 house.)

My parents recently had a single storey flat roofed extension insulated. (Built in 1964, originally just foil backed board and strawboard roof as insulation. Strawboard had been replaced with ply.) I wasn't there, but I understand they took down a strip of plasterboard along the centre of the room perpendicular to the joists, and slid more solid fibreglass bats along above the ceiling to the edges. Ceiling was then repaired and the room was to be decorated anyway.

[Huge]

[FX: Waves]Our bedroom is above our integral garage, and three of the four walls are external. Even though we have cavity wall insulation and D/G, it's still a cold room.

All I've done so far is whinge and contemplate the enormity of doing something about it. Oh, and use thicker quilts and a thermostatically controlled 2kW convection heater in the bedroom on cold nights.

Bear in mind the fireproofing requirements of integral garages...

[Paul Matthews]

I have not looked at the threads you mention, but remember that heat rises.

Maybe the rest of the upstairs is getting a significant part of its heat from the room below?

[TMC]

Mine has always been warm even though the long wall is north facing

Ceiling of garage is 2 x half inch plasterboard to give required fire protection ( built in 1991 to regs current at the time)

space between ceiling and floor above filled with 6" fibreglass

interior walls thermalite blocks cavity filled with rockwool bats

Ceiling of room standard plasterboard 6" fibreglass above boarded over for storage

Tony

[Jon]

I'm not too worried about the finish as the ceiling is only in the garage. The trouble is there is already some poor quality loft insulation in the void and I would have to get that out first before putting in the rockwool, which could be a problem.

Nice idea about cutting out a strip of plaster though and pushing in the new insulation. Removing all the plasterboard will be very messy and I don't fancy it at all, but it needs must ....

Thanks,

Jon

[Rod]

Possibly not quite the approach you were thinking of - but have you considered a new mattress?

We changed mattress a while ago and the difference in warmth is amazing. The one we got has a hefty layer of warm material where the old one let a breeze through. I haven't used a winter weight duvet this winter - at all.

The room itself might still freeze (ours is not over a garage) but that is less of a problem when we are toasty warm in bed.

[Jon]

The room itself is used as a study so nobody sleeps in there, but it would be nice if I could get the room to be the same temperature as the rest of the house by insulating it better.

[Andrew Gabriel]

BTW, the removed strip straddled the nogins, so they could push the bats up either side to both edges.

[TMC]

The room itself is used as a study so nobody sleeps in there, but it would be nice if I could get the room to be the same temperature as the rest of the house by insulating it better.

I wonder if the loose fill rockwool cavity insulation (the stuff that is blown in) could be used in the same way to fill between the floors

would just be a few smallish holes in the ceiling to deal with

Tony

may be worth asking a company what they think

[Jon]

I have considered this option, but for it to work properly I'd still need to remove the existing insulation which is in place which would involve cutting plasterboard out. If I'm having to cut plasterboard out, I might aswell use rockwool slabs as it would be more insulative. I'm sure someone would be able to confirm or not though.

Thanks,

Jon

[Autolycus]

This may be a deeply unfashionable thing to suggest, and may be highly offensive to some regulars on this group, but I'll say it anyway:

Have you considered putting a bit more heat into the room? Is the radiator at the same temperature (in and out) as the others in the house? Does it have a thermostatic valve, and if so, is it set and working correctly? Could you put a suitably controlled larger radiator in, or substitute a double for a single?

Depending on how long you intend to live there, and how much of the day you need the room to be warm, it may even be more cost-effective than buying lots of insulation. A quick look at the calculations for the system I've just put in suggests that the most heat loss you could hope to save would be perhaps a couple of hundred watts.

There, I've said it.

At least you say you've got a carpet in there, which will help: better than a solid-copper-with fins-underneath floor, or whatever is fashionable today.

[Jon]

Yes, and it works fine. The rad gets as hot as the rest in the house.

It's already a double. Larger rad = more load on boiler which is only just the right size for a 4 bed house (cheap ass persimmon).

You're not wrong. And I intend staying here for quite a while yet.

The floor will always be cold in the room as long as the lack of insulation between the garage and the room above allows it. No matter how much heat I throw in, the garage below will act as a heat sink.

Maybe I'd be better off insulating the garage. But the garage door has so many gaping holes letting cold air in through the gap between the frame that it'd not be cost effective either unless I changed the door (expensive).

I'm just looking for a sensible solution to the problem.

Thanks for your reply.

[Autolycus]

With fins?

Is the boiler really running flat out, firing continuously, even on a very cold day? I'd be surprised if the builder had calculated it that closely. Older boilers can often have their maximum gas rate tweaked (within defined limits, of course). Is it at its maximum rate?

It's true that insulating the floor will raise the temperature of its upper surface, but I'm suggesting it may not be enough to raise the room temperature much. The world acts as a heat sink for your roof and walls, too, but you design accordingly. The energy transferred through the floor is a largely function of its area, its thermal resistance, and the temperature difference between the room and the garage. The thermal resistance is the sum of the resistance of the elements of the floor, including the surface effect. Unless the garage has a howling gale through it, your bedroom floor is therefore no different to the suspended timber ground floors found in many houses.

So do the sums: you'll find a range of values suggested for the thermal conductivity of suspended floors, but take a sensible stab at it, and play with the effect of different values of added insulation. Then compare the cost with that of providing extra heat input, even if you have to use supplementary heating occasionally.

Insulate it iff you want a warmer garage for other reasons. Even if insulating it pushed its temperature up 5 degrees, it will only make perhaps 100W difference to the heat loss from the room, so perhaps a degree or two to the room temperature.

[Jon]

Yep, it has fins.

Fair point, but the boiler already works hard to get the temperature up. Thankfully the rest of the house is reasonably well insulated (as you would like to expect for a house of this age) and the boiler will not need to fire again for quite a while due to heatloss. I'm not going to mess with the gas rate.

I understand the basic physics of heat transfer and the fact that any form of energy will want to take the path of least resistance to reach a lower value. The most fundamental thing I also realise is that these days, the houses which are bulk built by the big boys of the housing estates like mine will only pay the minimum necessary to get a house to stand up, pass the regs, and sell. That means using materials which might be lesser to the ones we would choose.

Again, your point is simple and correct. Over time it'll probably be cheaper to add supplemental heating. But sometimes, if a job's worth doing, it's worth doing right. The concept of supplimental heating doesn't give me that fuzzy feeling inside. I'll always feel like I should have done the job properly.

This discussion is of great interest. But I'm still waiting for someone to actually reply with "I've done to my house and it was/ wasn't worth the effort" which would prove or disprove if the job's worth pursuing.

Thanks for everyones replies so far.

Jon

[Doki]

Hot air does.

[Doki]

I'd be inclined to do the garage. OTOH if it's particulary small, you'll probably not be able to open car doors when you've lost 6" or so off the walls for insulation. Could you not use foam tape around the door?

[George (dicegeorge)]

why not leave the insulation which is there, though you say its not very good, and add another layer on top of or below it?

(depending on height of rooms)

george

[Jon]

I think I'll start off with some 50mm celotex on the back of the garage door and insulate any draughts coming through the gaps at the side this weekend.

Is there any reason why I can't just attach a layer of celotex over the plastered ceiling in the garage? I know it won't be as pretty as white plasterboard, but the flame retardent barrier would still be in tact, albeit covered with celotex. It will also save me a lot of work removing/replacing plasterboard yet provide a thermal barrier between the garage and room above.

[Clot]

Is the garage ceiling just plasterboard? Are the garage walls plastered? If not with all the issues re the garage door, then are you getting a draft distributed round the edges which funnel under the bedroom skirting around the edge of the carpet? Are there also gaps around any pipework from the garage into the ceiling space?