loft insulation ..... no felt under the roof tiles

[PaulineB]

We're having our attic converted but have come across a stumbling block to do with insulating the ceiling. Our contractor comes from Portugal and has very different standards to what we Brits consider normal for insulation.

I've been reading many discussions about the best insulation for pitched roofs on here. However, I assume that they all involve roofs where there is felt under the tiles. On our roof, we have nothing under the tiles, no felt, no membranes of any form, just tiles, and then a very thin layer of polystyrene (between the rafters), which will probably be removed cos it's old and breaking-up ........ and then attic space.

Am I right in thinking that this lack of some sort of membrane critically affects the type of insulation we can use?? Would we need a waterproof insulation as the first layer below the tiles? And if so, are there any waterproof ones???

Is there any point in hoping that the 50mm ventilation gap can be reduced in these circumstances, and if so, to what?

Are there any other things that we should be aware of when considering how best to insulate due to not having anything under the tiles (and above the rafters)??

Any help greatly appreciated .........

 

[Static]

Not many of us are clued up on belgium regulations, have you tried their construction boards/governing bodies?

 

[PaulineB]

That's the problem ... there are no regulations or standards that apply to us (because we are not putting in dorma windows). And where the regulations do apply, one MUST (a regulation!) have an architect to check that all the standards are understood and followed properly.

I've heard many stories of things going wrong: condensation/mould problems, contractors not bothering to put insulation in the floor of the roof.

That's why we want to follow standards that protect the house, (and that we can understand, but not perfectly!). Please let us know what you would do in this situation (apart from putting on a new roof!)