Which concrete blocks?

[flanagaj]

Our vague regs drawings just state the walls will achieve a U value of 0.18W/m2k and consist of high strength 7 concrete blocks.  I went back to the TA, who wasn't much help and he said "when you know what blocks you you are using, I'll run it back through the SAP calcs".  I can't be bothered with the faff and want to know if 7N blocks can be used across the whole build.  Thermalites are expensive and will they really reduce the U values, or would another layer of insulation in the loft offset their better thermal performance.

 

I need to get materials ordered as footings are scheduled to be pulled in 3 weeks time.

[JohnMo]

No one could answer your questions without more information.

 

Ideally your wall build-up drawings are needed, but you sound like you don't have the drawings down to a detailed enough spec, to even consider buying let alone building yet.

[crispy_wafer]

We used plasmor fibolite blocks , don’t seem to be bad blocks to be fair!

[flanagaj]

51 minutes ago, JohnMo said:

No one could answer your questions without more information.

 

Ideally your wall build-up drawings are needed, but you sound like you don't have the drawings down to a detailed enough spec, to even consider buying let alone building yet.

But isn't that what the technical architect is supposed to do?  Building control have signed off the drawings, but still so many questions.  Now I'm beginning to understand why the original architects wanted 10k and this guy only charged 2k

[Nickfromwales]

26 minutes ago, flanagaj said:

But isn't that what the technical architect is supposed to do?  Building control have signed off the drawings, but still so many questions.  Now I'm beginning to understand why the original architects wanted 10k and this guy only charged 2k

Depends on who's wearing the Principal Designer hat?

 

How could you think there was £8k of meat to shave of this role???

[Temp]

What have you agreed with the Architect? Some contracts are limited to getting Building Control Approval, others include construction drawings. These are sometimes the same drawings but not always. The minimum required by Building Control is less than required for construction drawings. 

 

On our house we had to use denser blocks in a few key areas like pillars supporting steel beams and between two windows where loads were higher than normal.

[torre]

You can get a good idea of the difference by going on ubakus or similar, configuring your wall build up and swapping the block type and seeing how the u value changes. 

 

Switching out thermalite for something like fibolite could take you from say 0.18 to 0.19 and if you switched to a dense block even worse. Might sound a small difference for SAP but houses have a lot of wall area so it will suffer. 

 

If you're talking about dense blocks, you'll save on materials but lose some of the difference paying more for labour.