Cavity wall insulation problem

[Downcast]

I am having a small extension 5x3m built at back of garage. My builder is using earth wool loft insulation to fill the 100mm cavity between brick and block. I don’t think this is a good idea and should be a different type Such as rigid slab dritherm variety. He thinks loft insulation is perfectly fine and that using alternatives is overkill.
Can someone please advise. As walls are virtually at finished height only option now is blown in
I’m really at a loss

 

[frutbunn]

I am having a small extension 5x3m built at back of garage. My builder is using earth wool loft insulation to fill the 100mm cavity between brick and block. I don’t think this is a good idea and should be a different type Such as rigid slab dritherm variety. He thinks loft insulation is perfectly fine and that using alternatives is overkill.
Can someone please advise. As walls are virtually at finished height only option now is blown in
I’m really at a loss

He's wrong, If you are using B Control then I can gaurantee they will have something to say. I would advise you to instruct him to stop immediately and remedy the work,

 

[Downcast]

I thought so thank you, will get him to remove this and I guess will have to get a contractor in to to install blown in insulation now as walls are up to the wall plate level.

 

[martin hill]

I am having a small extension 5x3m built at back of garage. My builder is using earth wool loft insulation to fill the 100mm cavity between brick and block. I don’t think this is a good idea and should be a different type Such as rigid slab dritherm variety. He thinks loft insulation is perfectly fine and that using alternatives is overkill.
Can someone please advise. As walls are virtually at finished height only option now is blown in
I’m really at a loss

If he thinks loft insulation ok i'd watch him like a hawk with the rest of the build. Please tell me you have not paid the total upfront too. He has quoted you for an extension which should include using current regs materials so it his responsibility to rectify the issue not yours. Get a quote for the in fill of insulation and deduct off the final payment to your builder.

 

[Downcast]

Hello, yes he came and removed it all still adamant thou it’s acceptable and showing me how dry it all was inside the cavity. He said the slabs are the same stuff only compacted!
He will rectify this financially as well, cost will be deducted.
Thanks for your advice, appreciated.

 

[frutbunn]

Hello, yes he came and removed it all still adamant thou it’s acceptable and showing me how dry it all was inside the cavitIts y. He said the slabs are the same stuff only compacted!
He will rectify this financially as well, cost will be deducted.
Thanks for your advice, appreciated.

Its not the same, the cavity type is denser, which he himself agrees with, so he is contradicting himself. Its also treated with silicone to improve its weather resistance.
They've also been independently tested and have BBA certification etc for this use.
I've been inspecting this type of work since insulation in cavities became more common place, first amendment to the B regs '76 in 82ish. Only seen loft insulation used once in a cavity and they were made to remove it.

 

[Downcast]

Thanks everyone for the advice, it’s all removed, I hope that’s the last of any problems. Was letting him get on with outside due to COVID but now checking all delivery materials coming in. Lesson learned.