Timber frame house, insulation reccomendations?

[fulguros]

Right,

I have removed a small section of plasterboard to have a look in the timber frame of our house and I basically have a 4" void and the only insulation currently in the walls is a vabour barrier backed 1" (at a guess) roll that is fixed to the external side of the stud frame and then it has battens and hung tiles fixed to it.

The idea is to fix another 2" of studwork to the inside skin of the timber frame giving a total insulatable (is that a word?) space of 6".

I was originally going to use quilt but have the problem of the vertical sagging to get over. So I am now thinking along the lines of 6" of Celotex cut tightly between all the external studwork.

I have a roll of vapour barrier paper available to use if anyone would reccommend it and would anyone also think it is worthwhile using some extra foil insulation rolls between the studs and plasterboard?
Or even polystyrene backed plasterboard?

The aim is to achieve the highest possible insulation value that I can and losing 2.5" of room space in the process is not an issue.

Any input is greatlt appreciated, especially as I aim to start removing the existing plasterboard in the next couple of days.

Thanks.

 

[Deluks]

Rockwool is highly appealing for use in timber framed properties, purely for it's firestopping properties. How about fully filling the studs with RW slabs, and covering the studs with 50mm backed insulated plasterboard.

Don't know what this vapour barrier paper is, vapour barriers are of polythene or foil and must go directly beneath the plasterboard.
If using the aforementioned insulated plasterboard then this does the same job.

 

[fulguros]

Rockwool is highly appealing for use in timber framed properties, purely for it's firestopping properties. How about fully filling the studs with RW slabs, and covering the studs with 50mm backed insulated plasterboard.

Don't know what this vapour barrier paper is, vapour barriers are of polythene or foil and must go directly beneath the plasterboard.
If using the aforementioned insulated plasterboard then this does the same job.

The Rockwool might not be a bad idea as I am finding conflicting opinions regarding the U Values of Celotex etc

I am currently thinking of 75mm Rockwool betweent he studs (it is only 3" afterall ) then possibly putting 2 layers of 2"x2" studs staggered over it to give an extra 100mm and a thermal break between the studs then filling each layer with a further 50mm Rockwool each giving around about 175mm total insulation, or even a layer of Celotex if I can get the values to around the 0.18 W/m2K mark.

The vapour paper stuff is blue and I have acquired a full unused roll off a friend who bought too much, but as I mentioned, there is already a layer of barrier on the internal side of the existing insulation.

 

[Deluks]

All these layers of studs sound a bit fiddly but if you are diehard in getting those u values as low as poss...

Maybe going with 50x50's over horizontally then topping off with something like kingspan K18 plasterboard, which incorporates 50mm insulation on the back. This would give you about 170mm-ish of insulation, which by general standards is a massive amount.
As long as your roof insulation can match it though, otherwise it's wasted money.

The blue stuff could be dpm, is it basically just very thick polythene? Can put this over the studs before boarding but not strictly necessary if using the K18.

 

[fulguros]

I did the loft insulation about 2 weeks ago. It was on offer "3 for the price of 1" so I have 270mm of new insulation up there now on top of the existing layer which was the same stuff as in the walls.

The barrier I mentioned isn't DPM it is more like a tough paper, I am trying to think of something that it is similar to but can't at the moment.

I have been reading a bit more and got some values.....

If I add a 3"x2" stud on to the stud I already have then I would have 150mm of space for the Rockwool (plus the 1" on the outside) then I am thinking of fixing Superquilt on the internal face of the stud and taping all the joints and then plasterboard or battens and plasterboard.

I am assuming that the taped Superquilt will act as a vapour barrier and a thermal break and according to YBS Superquilt a 600mm spaced stud with the insulation mentioned above would equal a value of 0.15W/m2K.

This is now what I am leaning towards as the 2 layers of 2"x2" stud would have been a bugger to get a thermal break.

The internal walls are being replasterboarded and plastered so I am able to cut into any intersecting walls and continue the insulation on through to the next room without a break in the insulation.

 

[mointainwalker]

Fibre=wool rolls are generally backed with Kraft paper ( waxed or plasticised) which the manufacturers say is a vapor barrier ( whether true or not ? ) Never heard of it being sold separately though.

Not sure what the doubts on U value of Celotex is . 100 mm has a value of 0. 25 when new, although there is discussion about how this drops over time with the leaking of the insulating gas from the cell structure. is this what you refer to, OP ?

 

[fulguros]

My only concern with Celotex was that the U value calculator I used on the website said I needed to use 200mm to get a value of 0.18 and then I have the problem of putting in a Thermal Break and the cost, compared to 150mm of Rockwool, a layer of Superquilt (which will leave loads of quilt left for other rooms), Thermal Break would be included and cost wise it is a better option and I would achieve a value of 0.15 with less space.

Considering Celotex is meant to be the better insulator compared to Rockwool, fibreglass etc 200mm seems a lot to get the value I want.

 

[freddiemercurystwin]

Fibre=wool rolls are generally backed with Kraft paper ( waxed or plasticised) which the manufacturers say is a vapor barrier ( whether true or not ? ) Never heard of it being sold separately though.

Not sure what the doubts on U value of Celotex is . 100 mm has a value of 0. 25 when new, although there is discussion about how this drops over time with the leaking of the insulating gas from the cell structure. is this what you refer to, OP ?

As you say there are doubts and if you actually speak to anyone in the industry they will tell you there is some truth in it (as you’d expect) although much of the testing for these kind of things discussed on the web is not current and lambda figures quoted nowadays are based on improved manufacture design & aged insulation after any gas levels have dropped. If you search though you can find an equal amount of disparaging research to prove roll insulations and multi-foil insulation types have equally as many drawbacks.

 

[mointainwalker]

"..

lambda figures quoted nowadays are based on improved manufacture design & aged insulation after any gas levels have dropped.

"

Do you have any links confirming they are now giving aged figures, Freddy ?

 

[freddiemercurystwin]

Nope, doubt there will be any direct links to manufacturers.

Merely pointing out that there is much research carried out negative and positive for many different products and 'tis pretty difficult IMO for the layman to categorically condemn this kind or that type or whatever.

 

[mointainwalker]

Freddy

Without back-up I ( personally ) give this no credence.

Climate change, ( remember Cancun last week ? ) insulation and all the bits around it would have ensured any change in production procedures/values would have been headline news.

This hasn't happened as far as I have read so I have to say I find your post baseless.

Happy to be corrected with any verifiable contradictory data.

 

[freddiemercurystwin]

Freddy

Without back-up I ( personally ) give this no credence.

Climate change, ( remember Cancun last week ? ) insulation and all the bits around it would have ensured any change in production procedures/values would have been headline news.

This hasn't happened as far as I have read so I have to say I find your post baseless.

Happy to be corrected with any verifiable contradictory data.

Yea you would say that, now post the up to date links to tests proving products available today do not perform as their manufacturers claim, not from 2003 or for PUR available in 2001 or whenever, but today! Then find me the equivalent proof that mineral wool is all you think its cracked up to be? That's one long wait I'm gonna have too!

Your claims are equally baseless 'tis all I'm saying.

 

[Deluks]

insulation and all the bits around it would have ensured any change in production procedures/values would have been headline news.

Hardly.

Royal wedding? what royal wedding?

INSULATION BOARDS SLIGHTLY LESS EFFICIENT THAN FIRST THOUGHT!


OK, maybe the Guardian would've run with that headline