Cold bedroom above integral garage

[Phil Pascoe]

It's surprising how much draught is is stopped ad insulation gained by covering the the floor with hardboard.

 

[Jameshow]

It's surprising how much draught is is stopped ad insulation gained by covering the the floor with hardboard.

Even better a layer of 25mm celotex if you can live with the step up into the room.

 

[Agent_zed]

56oz Luxury Wool Carpet Underlay from £4.00 Per m2 no idea what 3.6tog equates to in U value but this is eco friendly and same tog as the foam one they sell. Assuming the room is carpetted and doesn't already have an underlay.

 

[TomGW]

Forgive me if I’ve missed this - how many external walls? What is the orientation of the room - is it to the north side of the house or well exposed to prevailing winds?
If there are two or even three external walls and this part of the house is to the north or particularly exposed I would expect it to be the coldest part of the house. Additionally, if at the end of the central heating loop the water in the system will likely be cooler by the time it reaches the room and, if not balanced correctly, the flow through the rad is not sufficient. Any combination of these factors will result in a room that’s harder to heat.
All of the suggested insulation improvements will help but, if there happens to be three external walls, to a vaulted ceiling room, on the north side of a house with an unheated garage below it will be a massive task to keep it at the same temperature as the rest of the house.
One thing to consider after all the insulation upgrades is to go for an aluminium rad. In comparison to a steel rad the output improvement is phenomenal.

 

[seanf]

Firstly, thank you so much again all for all the thoughts and suggestions. I am not ignoring the latest questions that have been raised but am away for a few days so will reply when back home

Sean

 

[seanf]

Ok, so coming back to this. Thank you again for assistance. To answer some of the questions:

• The room has carpet and a standard underlay
• It has one dormer window at the front that faces north-east
• The room has three exterior walls
• The radiator is a quality one that is a double convector

Over the summer I have put a DPM down, fibre insulation boards and then a vinyl flooring to make the workshop more comfortable and will see if that happens to makes any difference come winter. I have also fitted a rubber strip to the bottom of the garage door. I think I will use the foil insulation on the existing garage door as that is a very cheap and quick thing to do and I can see if a small improvement there makes any difference to the room above

I have recently spotted that a house of the same type but from the first phase of building has changed their garage door. I will try and catch the man who lives there to see if he fitted an insulated one and get his feedback on that

Sean

 

[rafezetter]

I've not read all the replies so I might be repeating it but insulated plasterboard just isn't going to cut it. - in the USA where this happens a lot the MINIMUM R value of insulation between a garage and a room above is roughly TWICE the thickness of insulation used elsewhere because the only thing between the garage roof and the bedroom floor is timber.

There's no brick or blocks that provide at least some form of thermal break / cavity, and unless that garage door is hermetically sealed, which it won't be, it will have constant circulation of air adding a windchill factor that isn't even present on a cavity wall that doesn't have insulation - that constantly moving air will drop the temperature at least 3-4 degrees which makes a helluva difference.

This is not the same as a house with airbricks to the cavity under the floor, because the volume of air moving is much lower. A gap of just 10% can allow up to 50% airflow. Stand behind the closed garage door and put your hand to the gap, you'll be surprised at the volume of air moving, it won't be a "draft".

If by some chance the floor of that bedroom is made of concrete beams and blocks with a layer of chipboard, then whatever floor covering, then you've basically got a built in heatsink sucking the life out of any heating you have. The only time solid "outside" surfaces can "insulate" internal heating is when they are 18 inches or more thick such as in old stone houses, so the external cold penetrates in only so far, and the heat internally penetrates out only so far, a concrete beam floor about 4-6 inches thick will essentially be the same temperature as the outside, and being physically linked to the walls, will suck heat out of them as well.

While the rad might be rated for that size room, I'll bet the person that told you doesn't understand that the ratings of radiators are set for rooms that are better insulated; cavity walls or internal rooms, or maybe you didn't explain that the room essentially has 1 external single skin surface, which is probably also the largest one./

What you've essentially got is a room with one major surface area with a single skin to the outside, and half or less of the insulation rating required for the conditions of a single skin surface. If you had more, it wouldn't be cold.

If the insulation on the plasterboard was 2 inches, that's not enough; even if it was 4 inches all that's done is add enough insulation so the floor is now the same R value as a cavity wall with no insulation inside.

you need more.

a LOT more.

You need to either drop the ceiling, add battens, then more insulation - I would suggest a combination of 100mm of celotex first directly under the bedroom floor, then a layer of rockwool for fire retardancy, then fire rated (pink) plasterboard; Or just add battens and then 75-100 mm of rockwool, depending on the thickness of the insulated plasterboard, then more pink plasterboard over that.

I would STRONGLY recommend NOT using celotex directly under the pink plasterboard because of the fire risk, even with using pink plasterboard.

Spend the money now - from the sounds of it, it's already cost you a fair bit in extra heating and the cost is only going to get higher.

If the builder you used only added insulated plasterboard 2 inches thick, DO NOT have him come back to do the work, he clearly doesn't know what he's doing and understand what's required.

 

[seanf]

Thank you so much @rafezetter for your detailed response and thoughts, it’s really appreciated. The floor to the room is made of wooden joists that are filled with rockwool type insulation, the insulated plasterboard was added to the garage ceiling by the builder (the company that built the house) to add a second layer of insulation

Since I last updated this thread, I have fitted a curved heat deflector to the top of the radiator to try and move heat out into the room more rather than just allowing it to rise into the dormer window. This does seem to have helped the room feel warmer. We are also making sure to keep the wireless thermostat at the far end of the room and away from the radiator, which is also helping

Yesterday I bought some foil insulation for just £12.99 a roll. My plan is to stick that to the garage door and see if it makes a difference to the garage temperature and then if that is reflected in the room above. If it does make a difference then I will likely proceed with changing out the garage door for an insulated one (probably with a fight from the builder if I try and argue they should pay/contribute). I have had some quotes and a door will cost about £1900 fitted, so want to experiment with cheap insulated foil first rather than just take a gamble on it helping

Again, thoughts and comments are very appreciated

Sean

 

[rafezetter]

Thank you so much @rafezetter for your detailed response and thoughts, it’s really appreciated. The floor to the room is made of wooden joists that are filled with rockwool type insulation, the insulated plasterboard was added to the garage ceiling by the builder (the company that built the house) to add a second layer of insulation

Since I last updated this thread, I have fitted a curved heat deflector to the top of the radiator to try and move heat out into the room more rather than just allowing it to rise into the dormer window. This does seem to have helped the room feel warmer. We are also making sure to keep the wireless thermostat at the far end of the room and away from the radiator, which is also helping

Yesterday I bought some foil insulation for just £12.99 a roll. My plan is to stick that to the garage door and see if it makes a difference to the garage temperature and then if that is reflected in the room above. If it does make a difference then I will likely proceed with changing out the garage door for an insulated one (probably with a fight from the builder if I try and argue they should pay/contribute). I have had some quotes and a door will cost about £1900 fitted, so want to experiment with cheap insulated foil first rather than just take a gamble on it helping

Again, thoughts and comments are very appreciated

Sean

Depending on the type of garage door it might be possible to contrive your own insulation system - a standard up and over is largely just a flat pressed steel surface with raised sides. If the locking mechanism is one of those twist handle types with two bars that go either side, it might well be possible to fill the voids above and below with rockwool / celotex adhered using expanding foam adhesive from a gun, then gun in any missed bits.

even a sectioned one you could do the same thing.

For draughts at the sides and top, rigid rubber long strips attached to the door itself both sides and the top, then add soft rubber strips along the top and sides of the garage door frame, so when the door is closed the rigid rubber strips on the door itself, mates onto the soft rubber on the wall.

Add a brush type draught excluder at he bottom and you'll have eliminated the majority of the airflow, which is what's causing the temperature differential - still air causes a lot less heat loss than moving air.

Make sure to insulate the back of the garage door to the home if there is one.

Keep an eye on facebook marketplace for insulation, and even plasterboards, there's nearly always some going cheap - get enough of that and you could make a false ceiling from 2x2's just a little below the current one and that would make a massive difference.

Behind radiator insulation as well.

 

[Bingy man]

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

Is this rad a single panel - if so it can be changed without any major alterations for a double panel / double convector rad of the same size , the extra panel and convection grills will give a much higher output . I’ve seen many new builds and the rads always look undersized but of course the materials used and the level of insulation usually balance this out . If you opt for a wider/ taller rad then again the double panel / double convector is your best bet . Just bear in mind the additional weight if it’s a plasterboard wall .they are also known as a type 22 rad.

Also by any chance does this room have 2 external walls ie a corner ..

 

[okeydokey]

I hope the walls of the garage are cavity and filled insulated/built in the same way as the rest of the house as it will be reasonably insulated, if the walls are single skin you will never get it warm

 

[Richard_C]

For draughts at the sides and top, rigid rubber long strips attached to the door itself both sides and the top, then add soft rubber strips along the top and sides of the garage door frame, so when the door is closed the rigid rubber strips on the door itself, mates onto the soft rubber on the wall.

I put rubber strips on the bottom of my garage doors - unheated double garage which gets used as a workshop - and the difference in general comfort was HUGE. Screwfix do some, doubtless others do as well. Stormguard Garage Seal Aluminium 2.5m - Screwfix

Won't cure the problem by itself but it look like you are making incremental changes each of which helps a bit.

 

[TomGW]

.................Also by any chance does this room have 2 external walls ie a corner ..

See post #26 - it has 3 external walls, a vaulted ceiling and a north east facing dormer, so basically a northerly aspect. Also on top of an unheated garage.
The vaulted ceiling increases the external surface area and results in a larger volume for any given floor area. This plus 3 external walls and a floor exposed to an unheated, ventilated void all adds up to maximum potential for heat loss. Also a dormer increases the external surface area, potentially has substandard insulation and is likely to have cold bridging.
Trying to keep it at the same comfortable temperature as the rest of the house will be virtually impossible.
This is a fundamental design issue rather than any shortcomings on the builders part.

 

[TomGW]

.........

Also by any chance does this room have 2 external walls ie a corner ..

Sorry, repeat post.