Cold areas on recently built gable type extension

[GeddyMortgage]

Hi all,

I've been doing a bit of investigatory work recently on trying to improve how rapidly the temperature is falling in a recently built rear extension. It was all built to regs insulation wise as far I know and was signed off by building control.

That said, having taken my thermal camera to the room I've noticed a few areas of concern that have given me pause for thought. The main one being some really cold spots where the wall meets the sloped ceiling. I've put some photos below, not really sure what's causing this and whether I can do anything about it now? Though it's showing a difference in temperature of a good 7degrees or so, which is not insignificant, to say the least!

Photos

And an exterior shot, just from eyeballing i'd say the cold spot is prettty close to the valley if that could be related?

Wasn't sure whehter this post would be better in building or roofing to be honest but as i'm not sure what could be causing it. Any thoughts ideas and guidance very welcome.

Cheers all

Ged

 

[23vc]

Guessing a bit of cavity insulation missing at top of wall/roof celotex not pushed down right into eaves (chamfering needed to get it further down)
Is the heating/radiator sized correctly for the room size?
Top section of cover flashing’s wrong, but unless it leaks not a biggie

 

[Odds]

Is there an effective means of insulating an interior wall of a gable end?

 

[GeddyMortgage]

Guessing a bit of cavity insulation missing at top of wall/roof celotex not pushed down right into eaves (chamfering needed to get it further down)
Is the heating/radiator sized correctly for the room size?
Top section of cover flashing’s wrong, but unless it leaks not a biggie

I'll see if I can dig out some photos of when the roof was insulated, from memory it looked pretty snug. I think it had 100mm between the studs and 50mm below the studs.

Radiators are 6kw total in there, and there's an 8kw gas-fire in there too for good measure!... it gets super toasty in there, but its just not retaining the heat as well as i'd hoped it would.

The rest of the house is 1950's (suspended floors etc, crap wall insulation) whereas this is to today's standard, concrete floors with kingspanbeneath, 100mm kingspan in the walls, 150mm kingspan in the roof...and those other older rooms are out performing it, so gotta be an issue somewhere. That said it is a vaulted ceiling, 6m wide by 5.5m long large room and there's no curtains or shutters up yet etc. I'm sure they'll help. But at the moment trying to ameliorate anything that's fundamentally wrong.

 

[GeddyMortgage]

Is there an effective means of insulating an interior wall of a gable end?

We used the Kooltherm insulation/plasterboard stuff in some other rooms previously which worked well. But would rather not have to add more stuff to the interior walls in this room now if we can avoid it. Just had all the room painted, panelled, rads on etc.

 

[^woody^]

The spots with smaller temperature differences are poor design, the areas with greater differences are poor construction.

The issue at the eaves is relatively easy to investigate and potentially remedy under warranty.

The other cold spots/dots won't be rectified without significant alteration work.

If the room is not retaining heat, look for air leakage and the output of the heat emitters.

Also check the specifications, performance and actual construction of the roof structure and insulation. 150 high performance PIR insulation (100 between and 50 under) and properly sealed should be providing a comfortable internal environment and only small 1°C drops on the screws.

 

[GeddyMortgage]

The spots with smaller temperature differences are poor design, the areas with greater differences are poor construction.

The issue at the eaves is relatively easy to investigate and potentially remedy under warranty.

The other cold spots/dots won't be rectified without significant alteration work.

If the room is not retaining heat, look for air leakage and the output of the heat emitters.

Also check the specifications, performance and actual construction of the roof structure and insulation. 150 high performance PIR insulation (100 between and 50 under) and properly sealed should be providing a comfortable internal environment and only small 1°C drops on the screws.

Thanks, Can’t count on warranty unfortunately the building team that did this have left the country. Long story… to do with tax!

Steps for investigating the eaves etc, would that be removing soffits and fascia etc to take a look externally? If not what are the steps?

I’ll take a photo when I get back in but looking externally yesterday it looks like the brick work terminated where the soffits started. Which I thought was really odd. But havent verified that yet

Air leaks I’ve found a couple where the compression on the French doors and windows weren’t as tight as they should be. i found that on the thermal camera and was super easy to remedy. So hoping to keep finding the worst offenders and remedy as I go.

Thermal camera on the ceiling looks pretty hot. It is 100 between and 50 below. Can’t recall if they taped all the joints or not. Though it is a high ceiling, 9ft at the lowest and close to 13ft at the highest so appreciate the overall volume of the room might make this less than totally comfy in the winter. Hoping that’s not the case though but instead hoping it’s a sum of the parts of things I can fix/have fixed.

 

[23vc]

brick work terminated where the soffits started. Which I thought was really odd.

That’s normal. Insulation should be continuous between wall and roof tho.

 

[GeddyMortgage]

That’s normal. Insulation should be continuous between wall and roof tho.

Yeah so mitre cut to tesselate on the Angle change is what I’m hoping to see. Where the wall insulation meets the ceiling insulation.

Would that be easy to see by removal of the soffits? Or more fiddly?

 

[23vc]

The soffit (and probably fascia in order to get soffits off) are going to be a challenge to remove as they’re likely to be ringshank nailed on. Tiles likely resting on fascia too. Not trivial .. I’d be very sure that’s a contributing factor before going there.
Easier route to lift a few tiles but that’d involve cutting and patching membrane which isn’t good either

If I was sure something had to be done I’d bite the bullet and do it from inside

 

[GeddyMortgage]

I was sure something had to be done I’d bite the bullet and do it from inside

Not a chance she’ll let me do that now. Room has just been finished

It’ll have to be outside or not at all. How could one confirm this is an issue before we start pulling things off the exterior?

 

[freddiemercurystwin]

Why is the plug socket upside down?

 

[ree]

The DSS or "plug socket" as you call it, is obviously fixed that way for convenient & safe access to the switches

 

[GeddyMortgage]

Why is the plug socket upside down?

Not relevant to the post. But to easier trunk the cable directly to the projector.

 

[noseall]

Yeah so mitre cut to tesselate on the Angle change is what I’m hoping to see. Where the wall insulation meets the ceiling insulation.

We aways make sure that the eaves insulation detail, transitions to the roof insulation, robustly....

trap1.jpg

• noseall
• 11 Nov 2024

trap2.jpg

• noseall
• 11 Nov 2024

As said, external leaf masonry, ceases at the soffit.