New build - cold bedroom

[saveasteading]

1 hour ago, Radian said:

the cavity insulation guy is saying

....whatever excuse they can think of. It probably works most of the time.

[Littlebig]

In all fairness this was the first time a someone has given such a detailed explanations about his findings. He also mentioned that instead of 8 bags of insulation material(as per specification) the used 9 so he was very confident in saying there is no problem with insufficient insulation.

I also mentioned he suggested draughts as the main issue, this was after he finished his inspection and the 2 main points of draughts was the main front door and the loft hatch and this was concluded after the thermal imaging survey and it was obvious on the pictures.

Also in the small bedroom and bathroom was noted that the loft insulation has been pulled too far back to unblock the vents and has caused an issue where cold air could penetrate the cavity and all it needs doing is to fold the loft insulation into the cavity.

(The attached picture is just an example of what I was able to see on his camera.)

But I’m not sure this is the reason for the cold air in there, so again someone knowledgable maybe will be able to say what is the cause. 

[MikeGrahamT21]

2 hours ago, Littlebig said:

In all fairness this was the first time a someone has given such a detailed explanations about his findings. He also mentioned that instead of 8 bags of insulation material(as per specification) the used 9 so he was very confident in saying there is no problem with insufficient insulation.

I also mentioned he suggested draughts as the main issue, this was after he finished his inspection and the 2 main points of draughts was the main front door and the loft hatch and this was concluded after the thermal imaging survey and it was obvious on the pictures.

Also in the small bedroom and bathroom was noted that the loft insulation has been pulled too far back to unblock the vents and has caused an issue where cold air could penetrate the cavity and all it needs doing is to fold the loft insulation into the cavity.

(The attached picture is just an example of what I was able to see on his camera.)

But I’m not sure this is the reason for the cold air in there, so again someone knowledgable maybe will be able to say what is the cause. 

Thats an excellent thermal image of why dot and dab is so bad!!

 

Without ripping it all off, you could drill holes along the perimeter all way round, but only where it sounds hollow, the solid bits will be where the dots are, and inject some FM330 airtight expanding foam, but not silly amounts, this should seal the gaps up.

 

In my experience though, its slightly pointless, you would need to do top, bottom, and corners, but even then, a crack in the mortar or blockwork (very common with most traditional masonry construction methods), will again let air circulate in the cavity between plasterboard and blockwork. Its a very hard problem to solve without taking everything off and wet plastering. You may be lucky and get a parge coat which would possibly solve the cracking issue, but if its a developer house, i wouldn't expect that. Expanding foam top bottom and corners inbetween the dots may give you some resolution.

[Littlebig]

4 hours ago, MikeGrahamT21 said:

Thats an excellent thermal image of why dot and dab is so bad!!

 

Without ripping it all off, you could drill holes along the perimeter all way round, but only where it sounds hollow, the solid bits will be where the dots are, and inject some FM330 airtight expanding foam, but not silly amounts, this should seal the gaps up.

 

In my experience though, its slightly pointless, you would need to do top, bottom, and corners, but even then, a crack in the mortar or blockwork (very common with most traditional masonry construction methods), will again let air circulate in the cavity between plasterboard and blockwork. Its a very hard problem to solve without taking everything off and wet plastering. You may be lucky and get a parge coat which would possibly solve the cracking issue, but if its a developer house, i wouldn't expect that. Expanding foam top bottom and corners inbetween the dots may give you some resolution.

I guess your explanation is confirming my first thought. The constant ribbon of adhesive along the top that should prevent airflow and thermal bypass is basically not there? Unfortunately like your saying not an easy fix and will have to contact the builder and see what their proposition will be to resolve it.

[Littlebig]

9 hours ago, PeterW said:

Definitely not ok !!!! Should be full to the top..!!

 

installation will be warranted by the CWA (Cavity Wall Association) so they should take this up  

Are you saying I get in touch with the CWA and explain my problem so they can come and have a look and get it sorted free of charge and hopefully in a much more professional manner than the contractor/builder?

[PeterW]

Contractor has a legal responsibility to resolve if this is a new build but also CWA will hold the warranty so if not resolved then they will act.

[MikeGrahamT21]

1 hour ago, Littlebig said:

I guess your explanation is confirming my first thought. The constant ribbon of adhesive along the top that should prevent airflow and thermal bypass is basically not there? Unfortunately like your saying not an easy fix and will have to contact the builder and see what their proposition will be to resolve it.

absolutely, there should as a minimum be a continuous bead of adhesive along both top and bottom of the plasterboards, pretty sure that’s been the official guidance from PB manufacturers for a good while

[Littlebig]

50 minutes ago, PeterW said:

Contractor has a legal responsibility to resolve if this is a new build but also CWA will hold the warranty so if not resolved then they will act.

Thank you. It is a new build (just over a year old) and I will contact the builder tomorrow and inform them of my findings. I assume they will conduct some sort of investigation but from my previous experience dealing with them I’m not optimistic.
In my opinion if there is a part of the cavity with such big gaps of no insulation I assume the whole house could be like this and will request a full cavity survey. No idea whether they will even acknowledge there could be a problem with the cavity insulation as the heat survey would suggest otherwise. I guess then I either contact the NHBC or the CWA  or both, but I wouldn’t know the name of the company that has done the insulation.

[Radian]

Your thermal image appears to show a poorly sealed window trickle vent. I suspect that if you apply finger pressure to it, you'll notice a reduction of noise coming from outside. Maybe not fitted correctly, or in common with most trickle vents, just crap.

[AliG]

On 27/02/2023 at 13:16, Littlebig said:

Also in the small bedroom and bathroom was noted that the loft insulation has been pulled too far back to unblock the vents and has caused an issue where cold air could penetrate the cavity and all it needs doing is to fold the loft insulation into the cavity.

This is the problem with eaves ventilation, made worse by the house not being timber frame. At least that would ensure insulation to the top of the wall and not have dot and dab plasterboard.

 

Looking at the picture, it appears that you have cold air getting behind the plasterboard at the top and the insulation ends before the end of the ceiling. The question is can you actually get it into the cavity without blocking the vents. Also if those vents were working you wouldn't;t have condensation in the roof.

 

Sealing the top of the dot and dab should be relatively easy. If you can access the top edge of it you could seal it with spray foam from there or by drilling small holes and injecting foam. It won't be perfect but should make a big difference.

 

Clearly the loft insulation has to extend to the edges also. Due to the issue with the eaves being ventilated, I wonder if cutting pieces of PIR to sit between the ceiling joists would be a better idea.

 

Looking at the pictures it also appears that despite their claims there is not enough insulation in the walls. If there was you wouldn't be able to see all those voids.

 

 

[Littlebig]

Thanks for all the replies. Currently the house is wrapped in scaffold as I’m hoping to get the roof fixed finally.

I am also diverting my attention to the front door that will highly likely need replacing.

I’m in the process of assessing the best location for a light in the loft so I can then either tuck the insulation behind or use PIR as recommended.

Either way I think I will do it all myself as chasing the builder seems like a waste of time and effort.

With regards to the voids in the cavity insulation hopefully they will send someone competent to get it all done and we feel the full benefit of a well insulated new build next winter.

[j_s]

If youve got scaffolding up, can you remove/push up the first row of tiles and fix the entire perimeter of wallplate to ceiling junction and cavity to loft insulation join. I did this when we were replacing the soffits and facias. Hell of a job but worth it.  I taped and used airtight expanding foam between wall plate and plasterboard. We then added Dritherm 32 cavity batts to the cavity where it was missing as well as enough to over lap the wall plate. We used wall ties to hold the insulation tight in those areas. In the hard to insulate areas where the hip sat on the wall plate I added pir board and foamed it in. We took all the plasterboard off the external walls and used airtight paint and foam from below and overboarded the ceiling. All made a massive difference.