Vapour Check Layer

[GPHouse]

Hi All.

So the project continues and I'm a little stumped on the next bit as to what the best way forward is.... I'm hoping one of you with far more experience can help!

To paint the picture - I am about to put some insulation into the back half of the house, and in one area in particular which will in the near future become the main bathroom with a shiny new roof light so I can see (see diagram)

The roof here is a vaulted ceiling (irregular old rafters) running between the main A frame Oak beamed original roof in the front half of the house and the back wall, including a section of which is a dormer with a flat roof (and no ventilation I can see). There is breathable membrane on the vaulted/lean to section only.

A - Internal random rubble filled wall 1.5ft thick, up to 3/4 of the height is covered in clay and then old lime plaster
B - House back wall, a mix of rubble filled wall 1.5ft thick and concrete block in the dormer area. Gypsum plaster and plasterboard.
C - Will be a stud wall, construction to be decided
D - Party wall with next door, Random Rubble Filled Wall, 1.5ft Thick, up to 3/4 of the height is covered in clay and then old lime plaster on top.


Questions....

1. For the Roof, I'm intending to

• put sheeps wool between the rafers (30mm gap to breathable membrane) ,
  fibre board under,
  a Vapour Check membrane,
  utility cavity,
  Plasterboard.

Would you do this?

2. What would you do for the walls? Vapour Check membrane, Batten, Plasterboard? All Lime? Insulate? if no vapour check membrane where would you seal the VCL?

3. The Floor will be new, would you put a Vapour Check Layer under - It will be the kitchen below.

Everything I read / every conversation I have seems to contradict the other!!!!!!

Thanks

G

 

[malcolm]

The way I am going about it is probably unusual. I have yet to remove a waterproof layer without exposing some sort of moisture problem behind it (especially after the recent flood). All the stuff done over the last 50 years has caused trouble. The stuff done before they invented vapour barriers hasn't caused much trouble over the last few hundred years apart from cracking a bit and looking old.

For the roof I have gone for breathable membrane under the tiles and a minimum 40mm gap to the insulation. The roof void is ventilated. For an old barn where I can't be bothered to replace the roof I'm going for the original impermeable membrane and loads of ventilation, with a minimum 75mm gap to any insulation.

For some walls I'm looking at brick - lime - woodfibre insulation - more lime. No vapour barrier, just care for air tightness. I don't plan to take up any floors, but for a concrete floor the vapour barrier would be useful, and would tuck in to the damp proof course (or at the same height should there be no damp course).

Modern thinking is only to keep the water out. My thinking is to try to keep the water out, but also to give the water half a chance to escape after it has got in. English Heritage has some documents that might help. https://www.historicengland.org.uk/images-books/publications/eehb-insulating-timber-framed-walls/

 

[GPHouse]

Thanks.I'm tempted with that method but still have some fear...