Is this a good idea for Internal Insulation?

atobin

Hi Folks,

I am building at present and am doing the following insulation internally (dry lining effect). Do people think that this is OK?

Interal Walls
100mmblock
40mm gap
60mm Kingspan in Cavity.
100mm
40mm holzflex 040 between Battens with Intello Membrane.
Plasterboard (Fermacell)

Roof (Storey and half)
280 Sheeps wool on flat portion
140 Sheeps wool on Pitch portion
Intello Membrane.

I had planned to use Actis Foil on battens internally and on ceiling under sheeps wool, but I am starting to hear a lot of worrying things about the foil.

any views would be very welcome.
Thanks

dingdong1234567

I take it the 'Internal wall' make up you have there is on the outside perimetre of the bulding? Because that make up of wall is never used on the internal walls of dwellings.

Apart from that it looks good to me, haven't had any experience of the foil being used before, so don't know much about it TBH.

sinnerboy

looks ok

- stay away from the foil

- why not stick with Kingspan on the dry lining ( I don't work for them - honest ) . Much better R value ( U value )

Builderfromhell

I understood that the BRE (Building research establishment, UK) had tested Foil insulation and found the manufacturers claims wanting. I am not familiar with the foil quoted here but have used Tri-sor, together with 300mm fibregalss in roofs.

archtech

None of the foil type insulation/membranes have Agreement Board Certificates, so I won't be relying on the manufacturer's claims of their u-values.

I wouldn't be specifying the product myself until at least an Agreement Certificate was available.

10-10-20

Have a look at this as a good reference on foils...
http://www.just-insulation.com/multifoil.html

Mellor

Considing they are selling it I would really value what they have to say on it as much as the BRE or IAB. I'd insist a cert before I even considered it.

getfit

Is the Intello membrane for airtightness or insulation?? I'm considering going with the same type of wall structure, with an airtightness membrane and thus get a Heat Recovery Ventilation system to capitalise on the (relativly) air tight structure

atobin

Thanks for the replies.
Getfit, Intello is for Air tightness. You need tapes, and an Product called Orcon from Ecological Building Soultions to complete Job properly. I believe Intello also serves as a vapour check so you don't get a build up of condensation behind insulation.

dingdong1234567: Sorry about that 'internal wall'. I was also indicating that I had insulation in the cavity.


Has anybody else used holzflex 040 as an insulation? If so are you happy with it?

Thanks

sydthebeat

atobin,
The main advantage of using a woodfibre insulation (holzflex) is that it is breathable. This will allow moisture diffusion through but very possible may allow condensation to form on the inner face of the block wall. this build up of water could cause mould and rot of the woodfibre. Plus the kingspan in the cavity is non breathable so the moisture cannot escape through this construction.
The construction should either be completely breathable or completely non-breathable. Thats why sinnerboys recommendation would make more sense if you want to persist with a cavity wall. If going with composite plasterboard, remember to fix the plasterboards with complete 'ring' gluing, and not spot daubing.

Its not a good idea to split up your insulation. It is understandable and commendable what you are trying to do, but you are trying to augment your system to suit the traditional cavity wall build. Woodfibre insulation is perfect for timber frame applications where the whole construction can be made breathable.

atobin

Hi sydthebeat,

Thanks for the reply. I think that's where the Intello comes in. It is a vapour check. Now maybe I am misunderstanding this, but if this is made airtight (in as much as it is possible to do this), would this not prevent any moisture going on to the block work. Unfortunately the walls are build with the cavity so I can't change this. It would appear from what you are saying that my two Insulations are conflicting. Is this the case? I had gone down the route of Foil/Holzflex, sheepswool for eco reasons.

thanks

sydthebeat

thats an interesting one atobin....

the membrane is a vapour check but it does allow different diffusions depending on humidity, pressure and temperatures.

I wouldnt like to comment any more than i have on its suitability or non suitability, as my opinion wouldnt be informed. But just remember that the PU board in the cavity is non breathable, so much of your efforts to use 'eco' friendly materials may be negated by the use of the PU. I completely agree with the use of sheepswool in the roof. i would even consider improving the u value standard by incorporating the wood fibre under the rafters with the fermacell, taped. If you have the room of course.