revelation

Hi Peter, Thank you for your input, after much considering. I had spoken to kingspan. They had advised that they would be happy for a small amount of insulation below, I gave them the roof build up and they advised how much I could have below.

We already have the 100mm already so will be going ahead with that. I couldn’t see anything on the king span instructions.

Yes. We have 1200 gauge DPM going over the insulation the will staple our pipes down to it.

Hi all. We are laying kingspan K103 insulation boards before putting out UFH pipe on top. Normally if it’s a foil face board you tape up all the seams and joins. But the K103 that kingspan recommend is a paper faced board. Is it best to leave it as it is or to still tape it up? regards.

I have taped most of it already but will add the VCL too to be extra safe. Appreciate the help.

From what was being said I thought that the vapour barrier was going on top (of the 120mm insulation between the rafter) before the 25mm insulation. I have plastic washers that I was going to use for securing the insulation. So I get this right, the vapour barrier is on the last layer before the plasterboard goes on?

Would it be best to secure the VCL with staples? Or to use some kind of adhesive? Especially considering it will be pierced when screwing the 25mm insulation boards and the plaster boards

Just standard polythene or is there a specific material for use as a vapour barrier.

Thanks Tony, I have a fair bit off tape so I will tape the timber too. Looks like a separate vapour barrier doesn't seem that necessary.

I have foiled taped what’s in the picture. So add another 25mm layer. Then foil tape again. Then plasterboard. (when foil taping the join between insulation and timber does the whole timber need to be covered or just the joint?)

We have had a loft conversation with a dormer which has a staircase going up so no hatch. I hadn't thought of a vapour barrier until one of my builders asked if I am putting one in while I was taping the insulation. I wasn't sure I assumed the foil tape would suffice. I am not sure what you mean by airtightness layer and whether it is hermetically sealed. I have attached images which show the set up (this was before finishing expanding foam and foil taping). So I was going to just add the large insulation sheets screwing them to the timber work. Then the insulation on top.

I have had my roof re-done and also a dormer added with a cold roof. I have 120mm kingspan between the rafters of pitch and the flat roof of the dormer. We have 80mm kingspan in the walls of the dormer. I plan to add another 25mm kingspan in large 1.2 x 2.4 sheets over the ceilings and walls and tape all the joins. The plasterboard. The question I have is whether I need to have a vapour barrier added anywhere, if so where and what kind would be best?

I appreciate the advice, I have two main builders who are fairly sensible as far as the right foot gear, ear protection and eye protection when needed. I am hopping that all my plumbing work, plastering and first fix electrics are done before the stairs go in, then try to manage the rest.

True.. that will deal with dust but not massively with stones etc in the shoe tread. Regards

I have had issues before in this situation, where they say they need boots on 'health and safety" which I guess is a fair point.