Purlin wall insulation

[FRAN1870]

For my loft conversion the spec says 100mm celotex on the purlin wall ...

Because there's space behind then can I just use 200mm Earthwool stuffed between and behind the studs ? Quicker easier and same u value ?

 

[^woody^]

Do you have 200mm thick studs?

Is the quilt suitible for vertical use?

 

[FRAN1870]

Do you have 200mm thick studs?

Is the quilt suitible for vertical use?

The way the wall is constructed ( basically its got a recess in it 200 deep ) it would be very easy to create a void behind the studs using battens.
I was looking at Rockwool flexi 100mm behind and 100mm between ? just seems quicker and easier than cutting celotex?

The purlin wall is only 1.2m high

 

[FRAN1870]

would also make life a little easier for cutting electrical back boxes etc.

 

[foxhole]

I would not skimp on insulation, my daughters loft conversion was done without the correct insulation and she had to get the company back in to do it correctly after a freezing winter in the loft bedroom.
My own loft has 100mm celotex in purlin wall and 40mm insulated plasterboard over the top.Immediately below the loft the ceiling have a further 100mm celotex and perimeter eaves have over 400mm of rockwool. [just for insulation purposes not a loft conversion.]
Celotex seams all need taping over to maintain complete coverage, how are you going to match that with Earthwool?

 

[FRAN1870]

I would not skimp on insulation, my daughters loft conversion was done without the correct insulation and she had to get the company back in to do it correctly after a freezing winter in the loft bedroom.
My own loft has 100mm celotex in purlin wall and 40mm insulated plasterboard over the top.Immediately below the loft the ceiling have a further 100mm celotex and perimeter eaves have over 400mm of rockwool. [just for insulation purposes not a loft conversion.]
Celotex seams all need taping over to maintain complete coverage, how are you going to match that with Earthwool?

I'm not really worried about the performance because the u-value of 200mm fibre is comparable to 100mm celotex ..... I might also skin the front wall with insulated PB yet and the spec also calls for OSB on the face too, so that adds sealing further. I just want to know if its ok for building control.

 

[^woody^]

As long as the relevant u-value is achieved, and a suitable product is used in accordance with the manufacturers instructions, then you can use whatever you like

 

[foxhole]

How are you going to get the insulation to stand up without compressing or any sagging? , ruining the u-value?

 

[FRAN1870]

How are you going to get the insulation to stand up without compressing or any sagging? , ruining the u-value?

Ive put battens across the back of the insulation with long screws into the studs..... then just adjusted in/out so it holds the insulation firm but without squashing it

 

[FRAN1870]

Might put some foil across the battens too ... just to give it a bit more ..

 

[foxhole]

How are you going to get the insulation to stand up without compressing or any sagging? , ruining the u-value?

Ive put battens across the back of the insulation with long screws into the studs..... then just adjusted in/out so it holds the insulation firm but without squashing it

Won't hold unless very tight destroying the u value.Does not stand on end.

 

[FRAN1870]

How are you going to get the insulation to stand up without compressing or any sagging? , ruining the u-value?

Ive put battens across the back of the insulation with long screws into the studs..... then just adjusted in/out so it holds the insulation firm but without squashing it

Won't hold unless very tight destroying the u value.Does not stand on end.

Are we talking about the same product ? flexi slabs ? ..... seem to be standing up just fine or the last 72 hours ?

 

[foxhole]

No mention of slab insulation in previous posts?

 

[FRAN1870]

Sorry yeah ..... It's the slab stuff and it's stacked on its side not on end.

I agree that loft roll would just fall over