Thermalite Shield blocks

[Grandad Gaz]

Just a quickie..

Can you use these underground?

Architects drawings do not specify anything different for footings, so I'm assuming they are ok

Cavity is now 100mm. Used to be 50mm some years ago!

[anonymous-user]

Pretty sure(99%) the new builds around here are doing just that.

[D14 AYS]

Not for use under ground, Concrete blocks or trench blocks.
100mm cavity? Normally 75mm.

[Stegel]

According to their website they can be used below DPC level, so fine - I've specified lightweight blocks below DPC before, but checked as they do vary. Cavity width will depend on insulation type and thickness, 100mm no longer rare.

[RedLeicester]

AFAIK you can use them underground, but it's cheaper not to.... I just used boggo concrete block. below the DPC, Thermalite above.

[Grandad Gaz]

Because of the varying answers, I thought I had better check with Building Control (always the best option, although not as much fun!)

It's ok to use Thermalite blocks underground.
Cavity walls can be 75mm although, a specific type of insulation and innner skin has to be used.
Therefore, it's easier to just have 100mm cavity and bog standard insulation etc. After all, what's another 25mm on the size of the extension

This is North Norfolk Council, but should apply all over the country.

Edited by Grandad Gaz on Friday 12th March 18:45

[Busamav]

Shield can be used under ground in most situations according to the thermalite brochure , I won't spec them for that purpose, I prefer to see trench blocks or just plain old 100mm concrete blocks.

Minimum cavity size you can sensibly have with a normal block is 85mm , then you need Dritherm + ( the + is very important )insulation batts