Mystery of the Cold Bedroom

[AlwaysLearning]

Apologies in advance for the length of this post, but I'm completely out of ideas ....

 

Our house is a 1970s semi. We bought it 15+ years ago in a very dated state. I've been stop start renovating it ever since.

 

My daughter's 1st floor bedroom is colder in the winter and hotter in the summer. I'm stuck for ideas where the problem might lie that would cause such a noticeable difference. When the heating is on, the room is ok, no different from the others. When the heating goes off, it cools more rapidly then the others.  

 

I'll go around the room, comparing it with others, what I've done and see if anyone can come up with anything.

 

• Ceiling. Plasterboard with pitched roof above it. Entire loft insulation was topped up after we moved in so there is no difference between this ceiling and any others on the 1st floor.
• SW wall. External with large DG window and cavity wall insulation. Out of curiosity, I drilled through the back of a socket and pushed a camera through so I know insulation is present. No evidence of failed DG units eg cracks or condensation. Window hinges replaced recently so there isn't a problem with the seals. Windows were replaced throughout the house perhaps 20 years ago in the usual slap dash manner. I've removed the UPVC strips used to hide the bodges and put frame sealant around all four edges so I can rule out air coming in around the window itself. Also inspected frame joints and beading and sealed any tiny leaks. Any remaining leaks must surely be too minor to make any significant temperature drop. Skirting to floor gap is sealed. There is a crack in the external brickwork near to the party wall which has been there since before we moved in. I've tried pushing a wire in at various places and it doesn't get very far. If it is letting air into the cavity, I wouldn't have thought it would be much, and not enough to cool the internal surface to make the room cold.
• NW wall. Internal stud. Small bedroom next to it doesn't have the same noticeable heat difference so I've ruled out this wall as being the problem.
• NE wall. Internal stud. Again, bedroom next to it doesn't feel any cooler even though it gets very little direct sunshine.
• SE wall. This is the party wall. It is plastered brick with an uninsulated cavity. Again, drilled a hole, put a camera through, and had a look. Also did the same inspection downstairs just to rule out the faint chance there was insulation but it had settled/slumped over the years. Going around with a lit candle I did find air blowing through the mains sockets so removed them and applied frame sealant to any gaps/holes in the pattress boxes. Skirting to wall gap is sealed.
• Floor. Carpet over underlay over 18mm floorboards. The floor void has 170mm rockwool which I fitted awhile back just to deaden the sound coming through from the lounge below. The ends of the floor joists run into the SE wall. They are not on joist hangers but embedded. For completeness, and in case they had shrunk or warped over the years to let air through from the cavity, I ran expanding foam over the joist/wall joint and floor/wall joint. No cracks in the bricks or mortar. Where the floor void runs under the NW stud wall, I've stuffed it with more insulation to minimise air flow.

 

The bedroom behind that also shares the party wall (our side) doesn't have this problem. The other front bedroom which shares the SW external wall, is of a similar size, has an identical window, and is even over the garage, doesn't have this problem.

 

After all of that, the room is still cool. If any of my actions has improved things, it's not been noticeable. It's like a window has been left open an inch. I'm stumped. Perhaps I'm too close to the problem and just can't see the blindingly obvious.

 

Any suggestions or questions welcome.

[BotusBuild]

Have you checked the cavity (with your camera) of the bedroom behind that also shares the party wall to see if that part of the party wall is insulated? If it is, that may provide a clue.

 

Where you know the party wall is not insulated, you have to assume that the room in the adjacent property is not heated. That could be were the heat is going.

 

You might want to consider installing insulated plasterboard to that party wall.

 

For example purposes only - > https://www.cutpriceinsulation.co.uk/products/ecotherm-eco-liner-2400mm-x-1200mm-x-25mm-12-5mm-insulated-plasterboard?variant=16705186955321&currency=GBP&utm_source=bingads&utm_medium=cpc&utm_campaign=pla&msclkid=43f17af32d6e1872f7c01b71830a6f65&utm_source=bing&utm_medium=cpc&utm_campaign=PLA | Cut Price Insulation&utm_term=4582764467987335&utm_content=All Items

[SteamyTea]

SW is the prevailing wind direction, so is it a case that air is blowing past/through the insulation?

Also how large is the window.  Real measurements help here, then theoretical heat losses can be worked out.

[Mr Punter]

Would it be worth getting an airtightness test done on the house?  It can help identify where the most leaky areas are.  A thermal imaging camera may also be useful.

 

 

[Roundtuit]

21 minutes ago, Mr Punter said:

 A thermal imaging camera may also be useful.

Or infrared thermometer.  Finding the cold spot could save you a lot of effort.  There could be differences across the party wall depending on how next door heat their rooms.

[ProDave]

Cold air blowing out of a socket is so common. It means there is an air path to somewhere cold bypassing any insulation, usually up into the loft space.  Are the walls dry lined or plastered onto the brick / block?

[Temp]

I suspect the cavity wall insulation wasn't done very well ...may not go up to the roof ... gaps etc

 

Might be worth trying to borrow an IR camera? 

 

Are there big trickle vents in the large window? Too much ventilation or do you get condensation?

 

 

 

 

Edited November 3, 2021 by Temp

[gravelld]

Does the party wall open into the loft? You could take some bricks out and fill it, although I'm not sure on the legal ramifications.

[AlwaysLearning]

8 hours ago, BotusBuild said:

Have you checked the cavity (with your camera) of the bedroom behind that also shares the party wall to see if that part of the party wall is insulated? If it is, that may provide a clue.

 

Where you know the party wall is not insulated, you have to assume that the room in the adjacent property is not heated. That could be were the heat is going.

 

You might want to consider installing insulated plasterboard to that party wall.

 

For example purposes only - > https://www.cutpriceinsulation.co.uk/products/ecotherm-eco-liner-2400mm-x-1200mm-x-25mm-12-5mm-insulated-plasterboard?variant=16705186955321&currency=GBP&utm_source=bingads&utm_medium=cpc&utm_campaign=pla&msclkid=43f17af32d6e1872f7c01b71830a6f65&utm_source=bing&utm_medium=cpc&utm_campaign=PLA | Cut Price Insulation&utm_term=4582764467987335&utm_content=All Items

 

No, I've not drilled in that room yet. Shifting furniture has put me off, ditto getting access to it for long enough. I'll just have to bite the bullet.

 

I've no idea to what extent next door heat their bedrooms. They're recently retired so there's just the two of them knocking about it a 5 bed. I know they sleep in the end bedroom so quite probably have the heating turned down.  

 

However, their rooms being cool might not explain why my daughter's bedroom is so hot in the warmer months.

[AlwaysLearning]

6 hours ago, ProDave said:

Cold air blowing out of a socket is so common. It means there is an air path to somewhere cold bypassing any insulation, usually up into the loft space.  Are the walls dry lined or plastered onto the brick / block?

Plaster onto brick/block

[AlwaysLearning]

6 hours ago, Temp said:

I suspect the cavity wall insulation wasn't done very well ...may not go up to the roof ... gaps etc

 

Might be worth trying to borrow an IR camera? 

 

Are there big trickle vents in the large window? Too much ventilation or do you get condensation?

 

 

 

 

Thought about the trickle vent, so taped over it awhile back. 

 

Have to admit I've been tempted to buy a high spec IR camera from fleebay, use it, then sell it. Resisted the temptation so far since I know there's a high chance I'd put off selling it again and keep it "just in case". If I can't crack the problem over the next couple of months, I'll probably crack and get one for the helluvit.

 

Can't comment on the quality of the CWI as it was before we bought this place. It's another reason, in my head at least, to buy that camera.

[Iceverge]

I'm guessing airtightness for the coldness and the SW window for the overheating. 

 

Second hand Flir One on eBay for £120. Don't know if they're any good but I've been looking myself. 

[Wil]

I bought a blackview phone with IR built in to it. It's actually really good and far better than the tiny low-res dedicated jobs that seem to be at the lower price range... 

[AlwaysLearning]

10 minutes ago, Iceverge said:

I'm guessing airtightness for the coldness and the SW window for the overheating. 

 

Second hand Flir One on eBay for £120. Don't know if they're any good but I've been looking myself. 

I might have been swayed towards airtightness if the problem was more than one room. Don't forget this is a 70s house so any air tightness test would just show the entire house leaks

 

The other bedroom faces the same way, is the same size and has the same sized window but doesn't have this issue so I'm struggling to point the finger of blame at that.

[SteamyTea]

1 minute ago, AlwaysLearning said:

The other bedroom faces the same way, is the same size and has the same sized window but doesn't have this issue so I'm struggling to point the finger of blame at that

To me that points more and more towards a serious air leak or in the parlance, thermal bypass.

 

Maybe see if the room is noisier. Can get a phone app to measure it.

[AlwaysLearning]

16 minutes ago, Wil said:

I bought a blackview phone with IR built in to it. It's actually really good and far better than the tiny low-res dedicated jobs that seem to be at the lower price range... 

That sounds interesting. Could you tell me more about the phone please e.g. model and thermal features?

 

I had a plug in IR attachment years ago as part of a project at work. It did the job but the IR sensor was 32 x 32 so next to useless except for close up. 

[Wil]

5 minutes ago, AlwaysLearning said:

That sounds interesting. Could you tell me more about the phone please e.g. model and thermal features?

 

I had a plug in IR attachment years ago as part of a project at work. It did the job but the IR sensor was 32 x 32 so next to useless except for close up. 

Think it was this one, or possibly the model before. looks like they have a 6600 for $250... you can also find on Amazon.

https://store.blackview.hk/products/blackview-bv9800-pro-thermal-imaging-4g-rugged-phone

 

Edited to say- it's an absolute brick, you wouldn't want to use it as an every day phone, but with a decent FLIR and the added extras of being a ruggedised phone, it's pretty decent. As with most of these toys though, it's not out of charge at the bottom of a bag somewhere. Which reminds me I really should digit out and see how my changes have progressed!

Edited November 4, 2021 by Wil

[AlwaysLearning]

11 hours ago, AlwaysLearning said:

 

No, I've not drilled in that room yet. Shifting furniture has put me off, ditto getting access to it for long enough. I'll just have to bite the bullet.

 

Right, drilled and inspected this morning. No insulation.

[AlwaysLearning]

19 hours ago, SteamyTea said:

SW is the prevailing wind direction, so is it a case that air is blowing past/through the insulation?

Also how large is the window.  Real measurements help here, then theoretical heat losses can be worked out.

SE wall is 4m x 2.4m

SW wall is 3.25m x 2.4m with a window 2.35m x 1.2m

[SteamyTea]

3 minutes ago, AlwaysLearning said:

Right, drilled and inspected this morning. No insulation.

A 1970's house with missing insulation.

There must have been some industrial action happening.

 

Now the really messy work starts.

[AlwaysLearning]

11 hours ago, SteamyTea said:

A 1970's house with missing insulation.

There must have been some industrial action happening.

 

Now the really messy work starts.

They weren't routinely insulated in those days. Indeed, when the CWI was put in in the 80s, it was almost unheard of to insulate the party wall simply because they couldn't access it from outside and few homeowners were willing to have 1" holes drilled all over their inside walls.