between rafter insulation - use of sheeps wool or similar

[karenandoz]

Hi - would appreiciate any advice on this one.

Getting ready to insulate vaulted ceiling of kitchen extension. We are going to use multifoil on underside of rafters, but reluctant to use cellotex type board or rockwool type product between rafters (my dad reacts to them).

I'm having problems finding comparisons for u-values etc. if we used sheeps wool, as to what thickness we would need? Also because of breathability of it would you need an air gap, or could we do full-fill(we have 6" rafters)?

I also once saw a product that was a non itchy, batt that was squishable, so that you got a really good seal against rafters - any idea? I can't find info on it again now!

Thanks in advance for any help!

 

[mointainwalker]

also once saw a product that was a non itchy, batt that was squishable, so that you got a really good seal against rafters - any idea? I can't find info on it again now

Hmmm - funny that. I typed in non-irritating insulation and the products below were in the find line. they are made of cellulose.


Our Products...
Autex’s GreenStuf® and QuietStuf® thermal and acoustic home insulation products

You can also buy fibre-wool insulation sealed inside plastic sheeting ( Space Blanket ? ) and Knauff have a type of fibre-wool made with a material called Evose which is not irritating.

I think if you look around you will find lots of possibilities.

 

[karenandoz]

Thanks for taking the time to respond, but our BC officer not happy with a lot of these things in the roof. Also trying to find comparison tables that include sheeps wool. can anyone else help? cheers

 

[karenandoz]

oh and squishy batt was a charcoal grey kind of expanded foam...?

 

[hotrod]

but our BC officer not happy with a lot of these things in the roof. Also trying to find comparison tables that include sheeps wool. can anyone else help? cheers

If a product has a BBA cert and meets required U-values then your BCO officer has to give you a damn good reason why it's not acceptable. If you "squash" insulation you remove the air which isn't advisable - because it's altering the insulative characteristics.

Have a look through this web site for your "squishy batt was a charcoal grey kind of expanded foam". If they don't do it they probably don't make it / it'll be a very specialist product:-

http://www.sheffins.co.uk/show_subcat.asp?CatID=36

 

[mointainwalker]

I have seen the type of material you mean but seem to recall it being used in something like a child-safety seat as shock-absorbing material but don't recall as insulation.

Hotrod is right. The BCO cannot enforce his own prejudices, only statutory requirements.

Why do you need a comparison table ? For a 100 mm thickness, fibre-wool has a U value of 0.4, expanded polystyrene also 0.4 , PIR boards ( Celotex etc ) 0.25. For differing thicknesses you pro-rata but this is easier with R values which are 2.5, 2.5 and 4 respectively.


This company gives a U-value the same as fibre-wool for their sheeps'-wool.

http://www.blackmountaininsulation.com/product.htm

 

[karenandoz]

cheers for all your help guys