Lost in Insulation

[Morpheus Cane]

Hello all,

In the throes of starting our single story extension and hunting around for the best prices and materials needed, and having a headache finding the best match for our bricks at sensible money, I have got a company to dig and fill the foundations lined up and a builder to do the brick work.

I need to source some cavity wall insulation of 100mm thick, our architec put
EARTHWOOL DRITHERM 32 ULTIMATE (100MM) in the build specs, do I have to go with what he has put in the specs or can I source others and if so what would people recomend, the prices seem to jump around a lot and i am getting confused by all the figures, I need enough for 14m2

Thanks

 

[londoner1]

My opinion is you can find your own material, as long as it is 100mm+ and fulfills the thermal requirements.

My loft spec specifies celetex, but builder put in IKOTHERM, cheaper in price but same performance. Also plans say 150mm insulation on rafters, builder but in 110mm due to size of rafters, Building control did not say anything.

As a guide aim for over 100mm as it will benefit you in the long term.

 

[Morpheus Cane]

Thanks Londoner1 for the reply, this insulation is for between the external and internal wall and looking at the plans the void is 100mm, so not sure if I could fit anything thicker but I guess it would compact slightly.

 

[tomfe]

Dritherm 32 is horrendously expensive for what it is, can you get a 150mm cavity and then use a 0.37 batt?
100mm of 32 has a u value of 0.26 which is pretty poor with a brick outer skin and light inner.
150mm of 37 has a u value of 0.21 with the same make up as above, which is still not great but ok.