Cold bedroom above integral garage

[seanf]

Thought it would be useful to pick the brains of the knowledgeable people here before we go into the colder months. We have been in our new build house for a bit over a year now. It has an integral garage (my workshop!) with a bedroom above. Last winter we had very low outside temperatures and found this bedroom was constantly much colder than the rest of the house. On the coldest night of the year we kept turning the heating up and up but the room temperature was dropping and I resorted to sticking an electric radiator in to keep my Son warm and this did work but cost a fortune to run. So far the builder has:

• Covered the garage ceiling with insulated plasterboard, plastered and painted
• Used a thermal imaging camera to confirm no cold spots in the bedroom
• Changed the landing wired thermostat for a wireless one so that we can keep it in the bedroom and let it control the upstairs heating zone
• Had Worcester Bosch visit to confirm the heating system is working as expected

The room is large with a vaulted ceiling, but Worcester Bosch have confirmed the single radiator is adequately specced for the size of room. They have also confirmed the heat output from the boiler and from the radiator are as expected

The builder is now trying to say they have tried everything possible and the solution is to essentially blast the heating to keep that one room warm and turn down the TRVs on the other radiators to stop other rooms upstairs becoming too hot. When complaining about this I have been told to report it to NHBC “if I want”

There are several other houses of the same design on the development and they all have the same issue as us, so it seems something is fundamentally wrong. I have asked the builder about them installing an extra radiator in the room, but they won’t because of the feedback from Worcester Bosch. I have also asked them about installing an insulated garage door to replace the very flimsy metal one, but they say that is not an option for them

I have seen some people on the Internet have posted about lining the garage door with foil insulation and this would be a quick and cheap project to try and see if it makes any difference. Do people think this worthwhile or are there any other suggestions please? I have noticed that the exterior wall of the garage has weep vents starting around couple of meters up, so assume that wall only has cavity wall insulation around the bedroom part and not around the garage (though happy to be corrected if this is an incorrect assumption)

Thanks

Sean

 

[Spectric]

The room is large with a vaulted ceiling,

Always uses more energy as hot air rises, they worked back when we used big open fires as they could put the required heat into the space. If the insulation is ok and there are no obvious heat losses then you do need more heat to keep such a room warm. It also sounds like you are not keeping your workshop warm as that heat would rise. Have you got thick insulating PIR battons between the joist in the bedroom floor ? Another question is have you actually done any heat calcs to work out what energy is required based upon the size / volume of the room, this will tell you if

Worcester Bosch have confirmed the single radiator

this is really true, what size is this rad ? It could well be that replacing the rad with a larger one would solve the issue, if you need more heat then you need a radiator with a bigger surface area or even think of a large cast iron rad.

 

[Woody Alan]

My work colleague has a house new build as you describe built by a local reputable builder and he has the same issue. I would guess even though it's insulated the style of construction with all but one elevation being external it's not cocooned in the same way as the rest of the house. I had this with a study on the back of my garage and put 2 inch insulation on the inside and solved the problem. I'm not suggesting you do that though.
What I would suggest is possibly eliminating any air movement in the garage. Heat is escaping and then causing a circulating air current in the garage and any gaps to outside losing more heat from that air. Just a thought.

 

[Jameshow]

Could you blow loose fill insulation into the floor joist cavity.
If the garage is unheated and cavity wall construction then it will act as a heat sink drawing energy down out of the bedroom.

 

[williams1185]

i would check to see if theres enough insulation between the ceiling and upstairs floor when i built my house i had to put three layers of 4 inch rockwool in and double layer the ceiling plasterboard whats the bet its not that well insulated

 

[Jacob]

Roof/ceiling is top priority. You need 100mm or more of Kingspan or similar, properly installed with no gaps or draughts.
second is external walls 50mm ditto
Third would be floor 50mm well fitted with no possibility of draughts or leaks.
The garage itself less important, though draught free would be good.
The big prob with insulation is that it doesn't take much of a gap for cold air to bypass it, say behind the ceiling plaster board, which means the insulation is ineffective. Good draught proofing around insulation and any voids behind plaster board etc is essential

 

[ian33a]

We had a similar problem in our last house - a double garage and utility room on the ground floor and our bedroom and ensuite on the floor above. The bedroom was OK but the ensuite was constantly cold in the winter.

We had the ensuite redone and I got the installers to rip up the floor and put insulation down. The filled it with rockwool. It was better, quite a lot better, but still cold.

An unheated room below is always going to be a cold source for rooms above unless the insulation is very well done and with no gaps and very few new houses are that well constructed.

 

[Valeboy]

Thought it would be useful to pick the brains of the knowledgeable people here before we go into the colder months. We have been in our new build house for a bit over a year now. It has an integral garage (my workshop!) with a bedroom above. Last winter we had very low outside temperatures and found this bedroom was constantly much colder than the rest of the house. On the coldest night of the year we kept turning the heating up and up but the room temperature was dropping and I resorted to sticking an electric radiator in to keep my Son warm and this did work but cost a fortune to run. So far the builder has:

• Covered the garage ceiling with insulated plasterboard, plastered and painted
• Used a thermal imaging camera to confirm no cold spots in the bedroom
• Changed the landing wired thermostat for a wireless one so that we can keep it in the bedroom and let it control the upstairs heating zone
• Had Worcester Bosch visit to confirm the heating system is working as expected

The room is large with a vaulted ceiling, but Worcester Bosch have confirmed the single radiator is adequately specced for the size of room. They have also confirmed the heat output from the boiler and from the radiator are as expected

The builder is now trying to say they have tried everything possible and the solution is to essentially blast the heating to keep that one room warm and turn down the TRVs on the other radiators to stop other rooms upstairs becoming too hot. When complaining about this I have been told to report it to NHBC “if I want”

There are several other houses of the same design on the development and they all have the same issue as us, so it seems something is fundamentally wrong. I have asked the builder about them installing an extra radiator in the room, but they won’t because of the feedback from Worcester Bosch. I have also asked them about installing an insulated garage door to replace the very flimsy metal one, but they say that is not an option for them

I have seen some people on the Internet have posted about lining the garage door with foil insulation and this would be a quick and cheap project to try and see if it makes any difference. Do people think this worthwhile or are there any other suggestions please? I have noticed that the exterior wall of the garage has weep vents starting around couple of meters up, so assume that wall only has cavity wall insulation around the bedroom part and not around the garage (though happy to be corrected if this is an incorrect assumption)

Thanks

Sean

 

[Valeboy]

I would suggest removing the ceiling in the garage, this is the least disruption and the cheapest thing to reinstate. The floor/ceiling void then needs to be tightly filled with the maximum Kingspan/Celotex or similar rigid insulation possible, with no gaps! Kingspan/Celotex etc is around twice as efficient as Rockwool. No matter what one does to walls and ceilings/roofs, all rooms revert to ground or floor temperature! The garage must be freezing compared to the rest of the house and so will be acting as a heat sink. Once the floor/ceiling void is filled you then need to put as thick a layer of insulated plasterboard as possible across the whole of the underside to prevent thermal loss through the joists. Attention needs to be made to the usual cold void between the outer joists and the blockwork, there is often a sizable gap which again becomes a very efficient heat sink. Don't skimp on insulation and don't use inefficient mineral wool! I've run many projects similar to this and the general understanding of the vital need to remove every small gap is seldom understood. Tight fit is essential!

Best of luck, it will be worth all the effort, don't expect your builder to understand insulation to any great detail! As a retired developer/builder I can say this... This film is great, shows an easy way to get a tight fit in PIR boards.

 

[seanf]

Thank you so much for the replies everyone, lots to think about. So a little more detail:

• The radiator in the cold bedroom sits underneath the window in a dormer. The radiator is 800mm but the internal width of the dormer is 1200mm, so could be increased
• I have not done my own calculations on heat requirements for the room. I have spoken to a designer from Worcester Bosch who assured me they do take the vaulted ceiling into account, not just the floor area. Probably worth me doing some work on this
• The floor joists of the bedroom are stuffed with Rockwool insulation. I think the bottom of the joists are then just lined with fire resistant plasterboard and the extra insulated plasterboard was installed directly over that

The general theme of all your replies is along the lines of what I am thinking, namely to increase the radiator size so more heat is put into the room and then ensure the cold garage is not sucking it all away

The fitted garage door is truly rubbish, very flimsy, thinner that tinfoil and has holes in the side where sections have been joined together during manufacturing. I would like to replace this anyway for a decent sectional one to increase security. Making this a good insulated door seems like a no-brainer

I'm stuck in a position of tackling this myself or trying to force the developer to do more, perhaps through raising with NHBC, and that does make things trickier

I am thinking of the following improvements:

1. Increase the size of the radiator to the maximum possible that still allows you to comfortably bleed it, etc. This is the quickest, easiest and probably cheapest step
2. Get quotes for fitting a quality insulated sectional garage door. I can possibly take this along the lines of pushing the developer to at least contribute to the work, but need to think if that is worth the fight
3. Review the bedroom over winter and see if a difference is felt
4. Look at options for further insulation as required, such as cavity wall insulation in the bottom half of the exterior wall, and redoing the garage ceiling with much thicker insulation that is properly taped and sealed, etc.

Sean

 

[Spectric]

An unheated room below is always going to be a cold source for rooms above

A good excuse to keep the workshop warm and cosy.

 

[Agent_zed]

depending on what radiator has been fitted you might not need to go wider as you can get double convector if yours is only single. You might also try adding a radiator shelf to push the airflow into a different part of the room or even a fan system - eg (quick google returned this) https://www.currys.co.uk/products/m...+Shopping&sv1=affiliate&sv_campaign_id=259955 which will be much cheaper than running electric heating.

In addition to this another thing you can do (again depending on what you already have) is fit more insulating underlay. Carpet and underlay often has a U value so you can choose a better one.

I'm not sure from what you've said that the builder has done anything wrong as such, unless they fitted the cavity insulation badly with gaps, which is easily done as they know nobody is going to see it again. Everything else should be up to code so not a lot you can do.

I may well be wrong but I would have thought the lower section of the cavity wall would also have insulation as I would expect it to hold up the insulation batts above, although I guess it could just be on the wall ties.

 

[Valeboy]

Whatever you do, take plenty of photos if you strip out any insulation that looks below-par or dodgy, this evidence could be used in a claim via NHBC.

 

[Sideways]

This film is great, shows an easy way to get a tight fit in PIR boards.

That's a really useful video and a handy looking product. Thanks for the link.

 

[HOJ]

Just making a quick observation, The Worcester Bosch calcs will be based on "assumed" values of insulation/ "U" values, (a bit like the pointless con the EPC certificate is) however if these values are wrong, and to be honest it will be difficult to establish without an element of invasive inspection to check if the insulation is where it should be, (Dormers are always a liability) the calcs are pointless, one option would be to get someone with a thermal camera to do a survey, and then perhaps go back to builder/NHBC to resolve.

handy looking product.

It is, we looked at using it on a barn conversion last year, but far too pricey, we just make sure we cut the insulation accurately, one of these is ideal: Insulation saw

 

[Richard_C]

A couple of thoughts. First radiators. I had a cool end of the living room, odd shaped house, when I got the boiler replaced I asked the plumber to put a bigger radiator in. No need, he said, just a different radiator. I thought I had a double convector, but no it was a double radiator single convector. With double-double I could boost that by about 20% from the same overall size, which was fine and solved the cool spot. Second thought is about air temperature and perceived comfort. The room always heated up to what we set the thermostat to but that end never felt comfortable. We don't run the stat any higher but it feels better. All the calculations in the world won't help if your left shoulder tells your body it's chilly, so you have to go with a pragmatic blend of what the sums deliver and what you feel. Next, throwing more heat in, e. g. via a new rad, might help comfort but won't help fuel bills. Finally, a trial, next time heating is on stand on a chair under your vaulted ceiling. Head hot bottom cold? Is there a way to get that big stable lump of hot air sitting above your head to move around the room to where you want it?

An aside, I think NHBC guarantees are pretty useless unless the builder has done something stupid like forget the foundations. You can try but it's a scheme run by the industry to give the paying public a modest if false sense of security.

 

[Jameshow]

Thank you so much for the replies everyone, lots to think about. So a little more detail:

• The radiator in the cold bedroom sits underneath the window in a dormer. The radiator is 800mm but the internal width of the dormer is 1200mm, so could be increased
• I have not done my own calculations on heat requirements for the room. I have spoken to a designer from Worcester Bosch who assured me they do take the vaulted ceiling into account, not just the floor area. Probably worth me doing some work on this
• The floor joists of the bedroom are stuffed with Rockwool insulation. I think the bottom of the joists are then just lined with fire resistant plasterboard and the extra insulated plasterboard was installed directly over that

The general theme of all your replies is along the lines of what I am thinking, namely to increase the radiator size so more heat is put into the room and then ensure the cold garage is not sucking it all away

The fitted garage door is truly rubbish, very flimsy, thinner that tinfoil and has holes in the side where sections have been joined together during manufacturing. I would like to replace this anyway for a decent sectional one to increase security. Making this a good insulated door seems like a no-brainer

I'm stuck in a position of tackling this myself or trying to force the developer to do more, perhaps through raising with NHBC, and that does make things trickier

I am thinking of the following improvements:

1. Increase the size of the radiator to the maximum possible that still allows you to comfortably bleed it, etc. This is the quickest, easiest and probably cheapest step
2. Get quotes for fitting a quality insulated sectional garage door. I can possibly take this along the lines of pushing the developer to at least contribute to the work, but need to think if that is worth the fight
3. Review the bedroom over winter and see if a difference is felt
4. Look at options for further insulation as required, such as cavity wall insulation in the bottom half of the exterior wall, and redoing the garage ceiling with much thicker insulation that is properly taped and sealed, etc.

Sean

That rad is tiny for a double? Vaulted bedroom.

Fine for a single box room but not for your situation esp with the garage rather than a lounge under....

 

[Dave Moore]

I would suggest removing the ceiling in the garage, this is the least disruption and the cheapest thing to reinstate. The floor/ceiling void then needs to be tightly filled with the maximum Kingspan/Celotex or similar rigid insulation possible, with no gaps! Kingspan/Celotex etc is around twice as efficient as Rockwool. No matter what one does to walls and ceilings/roofs, all rooms revert to ground or floor temperature! The garage must be freezing compared to the rest of the house and so will be acting as a heat sink. Once the floor/ceiling void is filled you then need to put as thick a layer of insulated plasterboard as possible across the whole of the underside to prevent thermal loss through the joists. Attention needs to be made to the usual cold void between the outer joists and the blockwork, there is often a sizable gap which again becomes a very efficient heat sink. Don't skimp on insulation and don't use inefficient mineral wool! I've run many projects similar to this and the general understanding of the vital need to remove every small gap is seldom understood. Tight fit is essential!

Best of luck, it will be worth all the effort, don't expect your builder to understand insulation to any great detail! As a retired developer/builder I can say this... This film is great, shows an easy way to get a tight fit in PIR boards.

Hi,
Ive fitted this gapotape to a vaulted ceiling in this type of build and as good as it is at sealing gaps it’s not as easy as this video shows. You need the joists well placed so they are as parallel as possible and I had the joy of trying to fit the gapotape after the electrician had put cables in which should have been as high as possible on the joists as it’s a pain fitting the gapotape where the cable is in the way. The cable needs to be in the air void to prevent clashing with the gapotape. I told my daughter in law that the garage ceiling needs really well insulating with Celotex to prevent the cold coming up. They haven’t done this yet and I think this next winter will be the first in this bedroom So I’m expecting a call for next year!
Regards,
Dave

 

[ChaiLatte]

I may have missed it in the replies above, but what flooring is in the room? Is there any kind of thermally-reflective underlay available that could assist? On the same note, what about underfloor heating in that room only?

 

[Grandad455]

I may have missed it in the replies above, but what flooring is in the room? Is there any kind of thermally-reflective underlay available that could assist? On the same note, what about underfloor heating in that room only?

I lived in a rented flat in an old Victorian property, landlord was quite amenable to me doing what I liked if it improved the property. Not having much money then, and having a cold room below our lounge, when I replaced the old carpet, I pasted a double layer of lining paper over the floor boards to seal the gaps, then applied a layer of heavy duty turkey foil with PVA adhesive followed by another layer of lining paper. Laid the new carpet with rubber underlay to finish the job. The results were surprisingly good, so it might help you.