Significant heat loss from plasterboard wall, damp or uninsulated?

[karam94]

Recently moved in to a 1920s typical 3 bed semi that has had the kitchen extended (over 20 years ago) & the wall between the kitchen & diner has been knocked down (4-5 years ago) to create an open plan kitchen diner. Talking roughly 5m x 7.5m altogether.

There is one vertical radiator for the space & a gas inset fire in the chimney breast. I am convinced that the single panel vertical radiator is significantly undersized (1500w MAX at a guess) which is why the room sits at 11-13'c every morning even after the heating has been on for > 1 hour. It is never hot to touch & both myself & a plumber have tried to balance it with the conclusion being that it is undersized. Probably does an ok job at heating the ceiling though...

The gas fireplace costs a lot to run in comparison to the central heating so running it every day isn't really a solution. The rest of the house heats up slowly but fine (whacking my flow temp to 75-80 helps), I attribute this to the high ceilings & old imperial radiators without fins. I suspect that if I could improve temps in this huge chunk of the downstairs that it'd help the rest of the house retain heat better overall.

I have a small 2kw electric heater which can roughly being the temps of the room to 18-19'c after 45mins-1hour (longer in these minus temps). The issue is that the heat loss then happens at roughly 2-2.5'c a minute which is very fast in comparison to the rest of the house where it's max 1'c a minute. Plus electric obviously costs more.

I borrowed a thermal imaging camera and it is clear to see that a main contributor to the injury is the attached external wall where the patio doors are as attached in the images.

Both sides of the internal (ORIGINAL) wall (cavity insulated) & the plasterboard (NEW work pictured under the french doors that meant this area of the original wall was destroyed to create it) under the french doors/windows have paint peeling & I believe it's because the bricks outside had barely any mortar in them. After getting them pointed their temperatures have improved, humidity is also improved (used to struggle to get below 60% now I can get 45%) so I hope that they are hopefully on the mend damp wise. There are raised ground levels outside above the DPC (assuming the DPC is actually still intact...) due to garden decking from the previous owner which I should remove & may have led to this penetrating damp problem from rain.

HOWEVER there are two plasterboard walls as attached in the images (note: I have had the cavity wall insulation checked and it's the wool) either side of the patio door which sound hollow & always record 8'c-10'c. When I put the electric heater on, the ground the temperature in the room increases at 3x the speed than when placed on the kitchen top. I believe when the heater is on the ground it's counteracting that particular injury.

I am unsure if my problem here is damp (I have spots where I get 17-22% readings with a pin damp meter - main ones actually being close to the electric sockets either side - surveyor told me before purchasing that there was damp in that area but that removing the raised ground levels i.e. decking outside + ventilation + pointing so rain can't get in, would get rid of it over time - no high damp readings higher up) or whether the previous owner did this work by dotting & dabbing uninsulated plasterboard to the external brick wall.

How can I address this problem? Obviously I'm exploring upsizing the radiator & seeing the feasibility of running new pipes for a second radiator (LVT makes it a big job). But I don't see the point in upsizing the radiator if the heat just escapes! Or maybe if it's damp, on the contrary I need heat to dry things out?

I'm really confused as to what the root cause of the issue is. It can't be healthy to keep this area un-heatable like this & it's such a shame particularly considering energy prices.

Thanks

 

[jeds]

I would say most of your heat loss is the glass, rather than the relatively smaller area of wall. I got a bit lost with what you are describing. Do those dwarf walls have cavity insulation? You don't mention the roof - how well insulated is the roof? The radiator sounds undersized and may not be flowing correctly. Either fit an additional rad or upgrading the existing would be relatively cheap to do.

 

[karam94]

I would say most of your heat loss is the glass, rather than the relatively smaller area of wall. I got a bit lost with what you are describing. Do those dwarf walls have cavity insulation? You don't mention the roof - how well insulated is the roof? The radiator sounds undersized and may not be flowing correctly. Either fit an additional rad or upgrading the existing would be relatively cheap to do.

Those dwarf walls don't have cavity insulation as far as I'm aware, they were done by the previous owner to fit the french doors/windows on.
I suspect that they could just be plasterboard directly on the brick, hence the low temperatures as seen in the thermal images.

However the real walls either side of them do have some paint peeling off (which is explained by some higher damp areas) as pictured in the opening post. As you can see, the ground levels are raised & the brick all needed pointing. I think this led to rain creating some penetrating damp. Now that the pointing has been done however, the thermal images show that the dwarf walls are the freezing ones rather than the CWI ones.

I understand why the heat loss could be the glass however again the thermal images shows that the heat is being held in & they are modern with argon gas inside as far as I am aware.

The roof is old, needs work (that roofers & surveyors have said does not need to be immediate), however the rest of the house holds heat absolutely fine, including the bedroom above. I've also had extra loft insulation fitted in, so I don't think it's the roof.

 

[jeds]

The thermal image just tells you where the heat is - heat rises! Argon filled low-e glass is still a poor insulator compared to the average wall. If you're concerned about the dwarf walls, have them insulated.

You are misunderstanding my question about the roof. How much insulation is in the bay? Above the doors and windows in the thermal images!

 

[karam94]

The thermal image just tells you where the heat is - heat rises! Argon filled low-e glass is still a poor insulator compared to the average wall. If you're concerned about the dwarf walls, have them insulated.

You are misunderstanding my question about the roof. How much insulation is in the bay? Above the doors and windows in the thermal images!

I understand what you now mean! Apologies, I am very new to all of this & this is my first property so I am a bit overwhelmed (& surprised) trying to fix this sort of stuff!

So, I am concerned about the dwarf walls. I guess I'm just unsure how to insulate them?
I read a lot about PIR boards, celotex etc but am not sure how it will all come together.
Do you think their temps essentially confirms that they are uninsulated plasterboard dotted & dabbed directly on to the brick?

I am not sure there is any insulation above the doors & windows in the thermal images. I think it's just glass with lead on top!

What's your take on the idea that the dwarf walls are damp due to the raised ground levels & therefore leading to the heat loss?

 

[jeds]

I don't know if the walls are damp, but I doubt it if they are cavity walls. Either way, the contribution of the dwarf walls to making the room cold is minor compared to the glass - and maybe the roof from what you say. I would aim to insulate both as much as you can. Internal insulation may be the best option. How much work are you prepared to do?

 

[karam94]

I don't know if the walls are damp, but I doubt it if they are cavity walls. Either way, the contribution of the dwarf walls to making the room cold is minor compared to the glass - and maybe the roof from what you say. I would aim to insulate both as much as you can. Internal insulation may be the best option. How much work are you prepared to do?

The dwarf walls aren't cavity walls.
Don't think I can insulate the roof of the doors as it's glass.
I'm prepared to internally insulate the dwarf walls if I understand what needs to be done.
Assuming that right now it's just dotted & dabbed uninsulated plasterboard directly on brick...

 

[oldbutnotdead]

Your kitchen rad that's never hot to touch indicates a flow problem (assuming the rest of the radiators do get hot to touch). Often on extensions you end up with an up, across and down for radiator pipes- excellent way to trap air and thus massively reduce flow.
I'm assuming you've bled that rad and tried it with lockshield and control valve wide open? With heating running, close all other rad control valves, see if anything changes.

 

[noseall]

How can you judge external wall heat loss by thermally imaging frim the inside? The heat signature will be predictable and show warm high - cool low.

 

[karam94]

I don't know if the walls are damp, but I doubt it if they are cavity walls. Either way, the contribution of the dwarf walls to making the room cold is minor compared to the glass - and maybe the roof from what you say. I would aim to insulate both as much as you can. Internal insulation may be the best option. How much work are you prepared to do?

So I've had a look through the dwarf walls. As suspected, the previous owner built them as single brick walls & looks to have just put uninsulated plasterboard directly on the timber frame built in front of the bricks.

This means that not only are those walls uninsulated, hence their temperatures, but it also explains why moisture levels were high prior to the pointing being done.

I assume the best solution now is to remove the plasterboard back to brick & then rebuild with insulated plasterboard.

Your kitchen rad that's never hot to touch indicates a flow problem (assuming the rest of the radiators do get hot to touch). Often on extensions you end up with an up, across and down for radiator pipes- excellent way to trap air and thus massively reduce flow.
I'm assuming you've bled that rad and tried it with lockshield and control valve wide open? With heating running, close all other rad control valves, see if anything changes.

So the radiator isn't actually within the extension. I've had two plumbers look at it, we've tried bleeding etc & the conclusion is simply that, vertical radiators are only very good at heating the ceiling & that the radiator is just significantly undersized. It's a single panel trying to heat an area that requires 3kw when itself is probably barely 1.5kw.

How can you judge external wall heat loss by thermally imaging frim the inside? The heat signature will be predictable and show warm high - cool low.

You are correct however no wall should be 7-9'c regardless.

 

[^woody^]

Damp meters and thermal imagers should not be sold to people without a licence or training certificate.

"20% moisture. I have a damp problem".
"Red walls. I have an insulation problem"

 

[noseall]

Damp meters and thermal imagers should not be sold to people without a licence or training certificate.

Correct. Always wondered why those DP Injection company 'surveyors' (armed with damp meters) managed to sell so much of their product, lol. Trouble was, mortgage lenders were on board with them too. Incredible con.

 

[JohnD]

Don't think I can insulate the roof of the doors as it's glass.

I don't understand that.

 

[jeds]

I don't understand that.

Not 100% sure but I think he is saying the roof is glass - conservatory style. If so' I'd insulate it anyway.

 

[catlad]

I went to a house just before Christmas. It had a new extension 7x8m I would estimate, and on the garden side had 7m bi- fold doors.
The customer was complaining that they couldn't keep it warm!
I think grand designs has a lot to answer for on what is practical.