Warm roof cold roof

Wickes sells upstands so that you can raise the boarded central section allowing 300mm of rockwool. The sloping bits are more tricky needing internal insulation as you have indicated.

If there is limited headroom, I wouldn't bother with making it a warm roof, but I would hoover up the dust after removing the existing insulation, then spreading a layer of turkey foil over the existing flat central section between the joists, before laying new 300mm rockwool.

Building Control here were very interested in us maintaining a 40mm or so air gap between the undertile felt and any inserted insulation.

Could you tack up a plastic vapour barrier and attach rigid PIR foam boards to the underside of the rafters. TNP swears by foil backed tape but I have found it necessary to first degrease the contact area.

The round plastic insulation retainers used by builders are handy for spreading the contact area of fixings.

As said above, there is little point in creating a warm loft if you don't plan on using it.

Sounds like a plan, I shall use the loft for storage but no need for warmth. Ten inches of insulation make be difficult at the walk way but doable over the rest. Can roackwool be stuffed right up to the eaves or is an air gap necessary?

By turkey foil I suppose you mean that reflective mylar multi-layer stuff?

I've been very impressed with this when it lined a delivery of salmon from Scotland, the ice packets which accompanied the fish were still solid 48hrs after it was sent.

Yes we have curved ceilings upstairs near the eaves as well. I guess it seemed a good idea in 1939, as did single thickness walls, but now it can be a very expensive space to keep warm. New windows as mine are the small airgap aluminium ones with no insulation might help. but the bedrooms and the loft near the eaves is a bit of a puzzle and really making the walls better is not easy either. Then there is the chimney.... Brian

The only way to get at the eaves in the construction that you have would be to pull down the sloping parts of the ceiling and inserting tightly- fitting slabs of PIR between rafters, while maintaining a 2 inch air gap between the top of the insulation and the roofing felt. This allows air movement from eaves (assuming that there are soffit vents) up to and into the actual loft (where you should have a ridge vent or tile vent close to the ridge).

If you go down this drastic (but effective route) make sure the side of the PIR facing into the room is flush (or very slightly proud) of the rafters and then add another layer or PIR, as thick as you can afford, re cost and headroom, then foil-tape all the joints, and also use double sided tape to make airtight seal between the PIR inserted between the rafters and the PIR that overlays this and the rafters.

No I meant the stuff the supermarkets sell at Xmas for cooking Turkeys (its cheap). It's only purpose is to add a vapour barrier between the ceiling PB and the insulation. If you can obtain the multi layer stuff, then fine, but it's an expensive vapour barrier.

!862 here so I expect the sloped ceilings were a way to save on bricks. We also have solid brick walls and small rooms and the brickwork is two tone and not something I am willing to cover up.

I did wonder what effect lining the walls with he reflective insulation inside and covering with tapestry or carpet might have but the main reason for wanting better insulation is to reduce the amount of wood I need to cut, split,stack and dry.

I replaced the windows five years ago.

Chimney breast keeps the house warm after the stove goes out.

I have experimented and glued a 75mm celotex to the ceiling and think this will work for the sloping bit.

There are no obvious vents in the soffits so I think the air must get in under the tiles and sarking. I am very wary of doing anything that may cause condensation in the roof timbers .

There is no plasterboard as it is lath and plaster, last thing I want is to trap moisture in the laths.

You won't. You are preventing water vapour *molecules* from migrating through the ceiling up into the loft where contact with the cold felt will go down to the dew point and condense. By insulating the room you will make the loft space colder, so condensation up there is more of a problem.

In the ?heated room below, you won't get down to the dew point so dampness should not occur, unless it is a bathroom and you use a shower or lot without effective ventilation.