How to insulate?

[RF Lighting]

Here is a cross section of my parents house.

As you can see, it's a bit of an unusual design.

Currently there is a small amount of insulation in the loft, but that is it.

Understandably the heat loss of the house is massive. Not only is it expensive, but it can be really quite cold in winter.

I'm trying to work out how best to insulate this for them with minimal disruption. I don't want to be removing plasterboard if at all possible.

I'm also a bit unsure about bunging everything up with insulation, how this'll effect the ventilation of the voids and loft.

Anyone come across this sort of thing before? What did you do?

Any ideas greatfully received.

 

[Norcon]

Brother did his loft conversion last year and building regs made him put 100mm of insulation on the roof and the sides.
You could heat it with a candle.

If you want to do it right then rip off all the plaster board and start again.

 

[RF Lighting]

I had a feeling that might be the case

Maybe I could slide some kingspan up the back of the plasterboard, but leave a gap between it and the roof tiles to keep the loft vented?

There is access into the first floor void.

 

[catlad]

Minimum disruption would be to put insulated plaster board over existing plaster board and re decorate or take the roof tiles of and put kingspan between the rafters, unless you think it is possible to work in the voids you have.

 

[mikeey84]

Its not that unusual a design. its a fairly standard Chalet style build. My parents live in one very similar, and it too is very cold and expensive to heat!!

 

[rocky_robin]

I stay in a house like that shape. Late 1800's 1.5 storey croft.

Personally, plasterboard off is the only way to achieve the correct compactness and draught proof method.

I have 150mm deep trusses so I put in 100mm Kingspan, then stuck up new plasterboard.
Sorted.

 

[noseall]

Are the roof tiles in good nick?

 

[noseall]

Are the roof tiles in good nick?

 

[noseall]

What is it with this forum and double posts, it's happening frequently and it aint just me.

 

[stuart45]

What is it with this forum and double posts, it's happening frequently and it aint just me.

Never happens to me.

 

[stuart45]

What is it with this forum and double posts

Never happens to me.

 

[stuart45]

What is it with this forum and double posts.

Never happens to me.

 

[RF Lighting]

Are the roof tiles in good nick?

Yes they are, so I think realistically, the sloped ceilings need to be dropped to get the insulation in properly.

The timbers between the plasterboard and the roof battens is 3"x2" iirc, so if I use 50mm kingspan, would a 1" gap between the kingspan and the roof felt leave sufficient ventilation to the loft?

 

[AdamCH]

I've been allowed to reduce the ventilation gap to 25mm in a recent extension because there is a breathable roof membrane. Normal would be 50mm.