Russell griffiths

Wall build up U values

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Can somebody do some rough number crunching for me please. 

There has been a bit of talk lately about block walls with just external eps insulation, so wondered where it comes out U value wise. 

 

From the inside out. 

 

12.5 plasterboard 

25 mm service batten

150mm dense concrete blocks

130mm eps 100

25mm batten

timber cladding. 

 

Thanks,  oh clever ones. 

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i get it calculated to 0.21, you can get it to 0.19 if you use a lightweight block of R value 0.25.

 

image.thumb.png.c0ca7c342663339586a36af928bdffe0.png

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Since the cavity (layer 5) is fully ventilated layers 5 & 6 are by convention not included but the external resistance, which is actually at the outside of layer 4, can be increased to 0.13 because the reduced average air movement increases the thickness of the external surface layer. See page 12 of attached pdf.

 

 

BR_443_(2006_Edition).pdf

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53 minutes ago, A_L said:

Since the cavity (layer 5) is fully ventilated layers 5 & 6 are by convention not included but the external resistance, which is actually at the outside of layer 4, can be increased to 0.13 because the reduced average air movement increases the thickness of the external surface layer. See page 12 of attached pdf.

 

Cheers, that ups the U-value to 0.22.

 

image.thumb.png.afa549c2c0855cbca0ec58344c003b34.png

 

Edited by Moonshine
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Another one for you with a few more facts and figures

 

image.thumb.png.a15f9c64daa9a7070f401c784f9a539c.png

 

Also another config with Aircrete:

 

image.thumb.png.c85b7f47fd178fe78459e9d7bd96c27b.png

Edited by MikeGrahamT21
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