Recommended closed-cell foam? And opinion on lower quality insulation work?

[Mmark]

The builders installed my L shaped loft conversion, but not to architect diagram spec, and plasterboard was put up very quickly. So I now have the following issues. What you see in the photos is what was plasterboarded.
1) Did not tape or seal any joins. Including the light recess cut out corners you see in the image as well as the wall sockets.
2) While there is 100mm of between timber PIR. Architect diagrams had 75mm between timber and 25mm over timber, to avoid cold bridging and make it easy to make it air tight.



I informed building control, they don't see to care too much, I think the rectification is disproportional to the cost. Although they are recommending we retrofit the recess gaps, using a spray gun through the recess light holes.

I have two questions:
1) I'm trying to find the best product for those recess corners. I think I want a closed-cell, high density and low expanding foam with strong adhesive qualities. There are so many cans, most seem medium density. Any recommendations?

2) If building control don't care, I'm assuming I don't really have any recourse and just need to accept a lower quality build? Am I worrying about this too much?

 

[^woody^]

Crap job. And it's not minor issues either.

Not taping the joints increases the risk of damp and timber rot significantly - guarantees it even.

Not insulating across the joists guarantees pattern staining on the decorated surface - dark black lines where the timbers are.

You would be a fool to accept this

 

[endecotp]

1) I'm trying to find the best product for those recess corners. I think I want a closed-cell, high density and low expanding foam with strong adhesive qualities. There are so many cans, most seem medium density. Any recommendations?

Firstly get a foam gun, don’t try to use a can with its built-in nozzle.
I don’t think the choice of foam will matter much. I don’t think you want “sticky” foam. The main thing is to put in a small amount and see how much it expands, then add more as necessary, so you don’t over-fill. You’ll work out the right amount eventually. Of course if you do over-fill you can carve it out later. Try not to get it on the cables.

2) If building control don't care, I'm assuming I don't really have any recourse

If the builders were contracted to do the build according to the plans they were given, then that is what they should have done. Have you paid them yet? What building control think doesn’t matter, unless your contract with the builders says “to the satisfaction of building control” rather than “according to the supplied plans”.

 

[Mmark]

We gave them architect diagrams they agreed to the job. We agreed to change the warm roof to cold, to give more head height. We didn’t agree with any other deviations, nor were we told they were deviating. Although we did hit problems, as the steels in the diagram where in the existing floor. This wouldn’t work, as joists we’re wrong way, so we had to lose 250mm and do steels above the existing floor.

We still owe them 25%. I have other issues, like joists not being 400 centres (all slightly under) so the GifaFloor FHB ends do not have joist support.

I have written a formal document, listing these concerns. They won’t fix anything beyond building control requirements. Tbh at this point I have no idea legally what to do. How much do I fairly with hold, if anything. Part of me has just had enough, pay them and move on - no interest a protracted legal battle. I’ve not read a single thing online that provides clarity here on what I should be doing. So unless you know a solicitor that specialises in this stuff?

So for now, just looking for the best product for the job, for the bit I can still correct. Yes definitely, I will get a gun for this, rather than straw. I prefer to lay more to get something right, than penny pinch.

I don’t want to loose more ceiling or room height. But maybe one day, I’ll redo it with 22mm insulated plasterboard over joists, probably enough to hide the cold bridging and introduce the VCL, without losing more room space.

 

[^woody^]

You have a contract and it matters not that if it is not in writing.

Implied into this contract is to build to the plans, conform to the building regulations (even if the BCO is indifferent) and to build to recognised standards.

 

[Mmark]

You have a contract and it matters not that if it is not in writing. Implied into this contract is to build to the plans, conform to the building regulations (even if the BCO is indifferent) and to build to recognised standards.

Understood, I just have no real experience in this side of things, no legal contacts etc. I have no idea what to withhold etc. last time I with held money from a builder he dragged me to court for two years. I counter sued and won. Was awarded my costs back + extra, never saw a penny, so was out of pocket for all my legal expenses. Deeply regretted that lost two years, and all the uncomfortable confrontations during mediation and our sessions.

 

[^woody^]

Get the dopey BCO out, or his manager. Or the XtraTherm rep.

Ask them if that will stop interstitial condensation and prevent rot, and how it prevents thermal bridging and meets Part L1b.

Meanwhile, it is a legitimate contract practice to not pay for work that does not meet the contracted specification.

 

[endecotp]

I just have no real experience in this side of things

On the contrary, it sounds like you have more experience than most, sadly.

 

[Mmark]

Back to the original Q. What spray foam, with gun and long nozzle, would be best to seal those light recess corners.

 

[Ian H]

I think the 25mm over is the most important bit and it would be easiest and cheapest to do it before the boards are skimmed.

I think mr neighbour had it only between on his roof and you can see where the heat gets out: