Cold Extension - Problem Solving

[dewaltdisney]

I looked through the photos again and you can clearly see the insulation fill in the cavity walls constructed. Turning to the photos of the boarding out it looks quite a tight joint at ceiling to wall and the small void behind the dot and dabbed plasterboard, which seems from what you say to have a draft blowing through, would all seem to be illogical, so there must be an opening somewhere. If the drafts are arrested then the air will not be flowing through and it gives it a better chance to warm up. It is all very strange though???

DWD

[GeddyM]

how many days has it been heated for in a row and when was it first heated??
if the walls feel cold it may need more time to stop sucking heat out
once the structure is up up to temperature it will warm up a bit when heating is on and radiate heat a bit when off

I don’t run the heating like that in our house. I just blast it for a few hrs when the temperature gets quite cold. That goes for all the house though and the other rooms seem fine with this way of heating the house.

[GeddyM]

I looked through the photos again and you can clearly see the insulation fill in the cavity walls constructed. Turning to the photos of the boarding out it looks quite a tight joint at ceiling to wall and the small void behind the dot and dabbed plasterboard, which seems from what you say to have a draft blowing through, would all seem to be illogical, so there must be an opening somewhere. If the drafts are arrested then the air will not be flowing through and it gives it a better chance to warm up. It is all very strange though???

DWD

Thanks for taking a look through again. I can see the wall insulation but the roof insulation join is harder to judge. I can see the plasterboard roof to plasterboard wall join is nice and tight. No idea whether the insulation behind the board is that snug though.

I spoke to building control today to get their opinion. Told them about the really huge draught in the wall light holes etc. they said very common on an extension because the building reg for extensions doesn’t require air tightness testing. In real terms that means no vapored barrier layer over the insulation and dot and dab on the plasterboard rather than a full spread of plaster. They said those extents would only be covered if it was a new build. And also said draught like the one I’m noticing are really common and my best bet is to simply plug and seal the holes were the draught are coming in.

Quite surprised by their response.

Still wondering if improving the eaves insulation will negate some of this issue. Think I need to investigate that insulation join

[big-all]

my thought
lack off insulation without an actual draft will tend to be volume related, so a say 5% loss off insulation will give a similar level off heat loss where as an open path for airflow may be double to 10 times the heat loss

just make sure the internal structure is up to temperature [not cold to the touch] so when the heating goes off it gives out heat rather than suck it out

[dewaltdisney]

I was thinking off the wall here. I was wondering if somehow you could pump smoke into the dot and dab void to see if there was any obvious leak to the exterior. These machines are usually used for automotive but with a bit of ingenuity, you could perhaps use a smoke stick like in this video with a reversible vacuum cleaner. You can get a purpose built machine off ****** for £50 though. See this video to get an idea www.youtube.com/watch?v=di8cMe2CX64 My thoughts were if you see smoke escaping to the outside at least you would know where to start.

DWD

[Neelix]

I think the OP needs to change the way they heat their house as the "blasting" on then off won't allow such as extension to actually heat up the fabric of the building properly and hence the drop off of heat quickly too. It might get the air temp up but thats all

I would try the all day setting and have a slightly lower temperature setting on the room stat

[GeddyM]

my thought
lack off insulation without an actual draft will tend to be volume related, so a say 5% loss off insulation will give a similar level off heat loss where as an open path for airflow may be double to 10 times the heat loss

just make sure the internal structure is up to temperature [not cold to the touch] so when the heating goes off it gives out heat rather than suck it out

I suspect your right. Though I ran the heating on full whack yesterday for 13hrs. got the room up to 22degrees stabley, soon as I turned it off, rapidly fell. Now back down to 10 degrees over night.

[GeddyM]

I was thinking off the wall here. I was wondering if somehow you could pump smoke into the dot and dab void to see if there was any obvious leak to the exterior. These machines are usually used for automotive but with a bit of ingenuity, you could perhaps use a smoke stick like in this video with a reversible vacuum cleaner. You can get a purpose built machine off ****** for £50 though. See this video to get an idea <span class="skimlinks-unlinked">www.youtube.com/watch?v=di8cMe2CX64</span> My thoughts were if you see smoke escaping to the outside at least you would know where to start.

DWD

I thought about that too. We've done it for leaks in drains before but couldnt figure out a safe way to do it for the walls here. Instead I decided to plug all the draughty holes I could find with wool and compare to see how much the heating fell. So i plugged all those 4 wall light holes, did the same for the chandelier in the ceiling, that had a big hole all the way through the insulation. They're all air tight now (as far as I can feel to the touch) ran the heating for 12hrs yesterday, turned it off over night, unfortunately the room is still rapidly falling. Not sure what else I can try now for draughts. i've investigated and plugged all light fittings, sockets, switches, flue for gas fire, door and window compressions. Not sure what else to do!

[GeddyM]

I think the OP needs to change the way they heat their house as the "blasting" on then off won't allow such as extension to actually heat up the fabric of the building properly and hence the drop off of heat quickly too. It might get the air temp up but thats all

I would try the all day setting and have a slightly lower temperature setting on the room stat

But to be fair - I run all the property like that and all the other rooms are comfortable for me and my family. All those other rooms are on suspended floor, older windows, and insulation that was best practice in the 1950's.And they're all fine. This room is not, and really it isn't that much larger than some of the others. Hence why I still suspect there's an underlying problem here. Not to say I couldn't be more efficient in the way I heat the whole property, but at this point I do believe that's not the issue here.

[GeddyM]

Small update - Plugged all the draughty holes I could find. And decided to whack the heating on and observe with the thermal camera from the exterior and see, these shots were taken perhaps an hour after the heading had gone off. Found some confirming (and worrying?) things. Images and thoughts below:-

• There's a shaped pane of glass that was showing as a good degree or so colder than the others on the inside, sure enough from the exterior it was much warmer than the others, by almost a full 2degrees, so that's definitely a problem that needs sorting.

WhatsApp Image 2025-02-15 at 11.55.13_89ef762a.jpg (75.83 KiB) Viewed 640 times

WhatsApp Image 2025-02-15 at 11.55.13_9fe4345c.jpg (73.53 KiB) Viewed 640 times

• Also from above I noticed that some of the parts of the tiled roof were wayyyy warmer than others, Suggesting that's where the warm air is coming out? and in turn likely where the cold air is getting in? that's not normal, surely?

WhatsApp Image 2025-02-15 at 11.55.13_5c4bb606.jpg (112.8 KiB) Viewed 640 times

WhatsApp Image 2025-02-15 at 11.55.13_519ec381.jpg (72.28 KiB) Viewed 640 times

WhatsApp Image 2025-02-15 at 11.55.13_cb630cd5.jpg (112.35 KiB) Viewed 640 times

WhatsApp Image 2025-02-15 at 12.09.22_cf2a50ba.jpg (64.44 KiB) Viewed 640 times

WhatsApp Image 2025-02-15 at 12.09.22_26aee54f.jpg (71.35 KiB) Viewed 640 times

• this is what that portion of the wall/ceiling look like from the interior.

WhatsApp Image 2025-02-15 at 12.09.22_d75e0b1e.jpg (158.16 KiB) Viewed 640 times

Those are the worst offending bits I could find. What do you guys think I should do?

[dewaltdisney]

They are interesting thermal images. That glass panel is strange, I wonder if it fitted the wrong way around as glass has reflective layers. However, the heat loss seems very high and there must be a logical reason. One thing I thought of is that you have a volume ceiling and the hot air rises. Perhaps a roof fan might help blow the warm air down to a lower level and help warm the lower walls. This is very strange.

DWD

[Neelix]

The OP , I think still under estimates the fact that their extension is pretty much all outside walls

[GeddyM]

They are interesting thermal images. That glass panel is strange, I wonder if it fitted the wrong way around as glass has reflective layers. However, the heat loss seems very high and there must be a logical reason. One thing I thought of is that you have a volume ceiling and the hot air rises. Perhaps a roof fan might help blow the warm air down to a lower level and help warm the lower walls. This is very strange.

DWD

Perhaps, I think we're going to get an air test done to see if i've missed any obvious air leaks. That roof thermal image has really confused me. There's a good 4 degrees diff in temp, how all the warm air is finding its way out there but no where else, I dont understand. Unless it's not insulated at all there where the flashing is.

[GeddyM]

The OP , I think still under estimates the fact that their extension is pretty much all outside walls

I'm trying not to. But to be fair the thermal image doesn't show the walls as the main offender. To add to that, the internal wall doesnt appear to be any warmer than the external walls adjacent. Losing my will (and hair!) to live with it.

[Neelix]

The OP , I think still under estimates the fact that their extension is pretty much all outside walls

I'm trying not to. But to be fair the thermal image doesn't show the walls as the main offender. To add to that, the internal wall doesnt appear to be any warmer than the external walls adjacent. Losing my will (and hair!) to live with it.

Our TV room is similar to this extension, single story, mainly outside walls, built about 7 years ago to a similar standard, and we constantly have issues to keep it warm - and our radiator is oversized too