# 200mm Cavity



## bov2 (30 Jun 2009)

Hello all,

Planning permission for own house has been passed and i am researching different methods of achieving the lowest u-values for the lowest outlay.

I have almost settled on the wall build up of (EXTERNAL) 100 mm dense block with 200mm cavity fully filled with blown bead and (INTERNAL) 150 mm Quinn B5 (both walls finished with standard plaster).

Foundations / roof may also be highly insulated (if budget can stretch)

I have been told this wall build up could achieve a u-value of circa. 0.17 - 0.16.

Any comments / opinions are welcome.

Regards,
bov2


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## Superman (1 Jul 2009)

Homebond will only guarantee up to 150mm.
You will also need an engineer to design the cavity.


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## sydthebeat (1 Jul 2009)

superman is correct....

also...

why not simplify your construction with 215 block (be it concrete or aac quinnlite)... and then use 300mm polystyrene as external wall insulation...

blown-in insulation isnt the perfect solution for new builds...


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## bov2 (1 Jul 2009)

Thanks Superman,
I will be building in north so dont think Homebond will affect me.  I must check with NHBC etc.  Also, Engineer looking at this at minute.

Sydthebeat,
 i have also looked at the external insulation systems and am not overly keen on them.  I just dont like idea of having 300mm of insulation outside the building, durability issues mainly i.e. impact from football etc.  Another issue with these is the cost - i have approx 340 m2 external wall.

Why would you not consider beads for new build?

Regards,
bov2


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## house (25 Feb 2010)

Hi bov2, 

im hoping to start a similar build, have you any pointers or pitfalls you would like to pass on? thanks


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## Buildright (1 Mar 2010)

BoV, since you're in the UK jurisdiction this might interest you

http://www.greenbuildingstore.co.uk/page--passivhaus-diaries.html


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## fclauson (20 Jan 2011)

Syd  - why not use bead in a new build ?


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