Class A blockwork?

[kingandy2nd]

Hi All,

The design spec for our extension states “All new walls to have Class A blockwork below ground level or alternatively semi engineering brickwork”.

Unfortunately the designs were done a few years back and we’re no longer in touch with the designer.

I’m trying to understand what is mean by ‘class A blockwork’. Google searches done yield much, so I was hoping someone might be able to advise?

Thanks

 

[Ian H]

I’m not sure but I bought some Class B bricks a couple of weeks ago and they are more porus than a Class A.

Class A’s were the least porus type.

 

[tony1851]

Hi,

Never come across blockwork described as 'Class A' (though I might have led a sheltered life). Blockwork is usually defined by the
crushing strength of the blocks in Newtons per mm², commonly 7N for the dense, heavy blocks and 3-3.5N for the lighter, aerated concrete blocks.
Any of these would be OK for below-ground work for domestic buildings.

Many builders now use trench blocks, which are just large blocks of aerated concrete and are usually perfectly OK for the loads involved.

'Class B' bricks are engineering bricks, usually of crushing strength of minimum 50N, and would be more than OK for below ground work.

The only case where special attention is usually needed is in chemically aggressive soils, such as where sulphates are present.

Don't be too tied down by the spec on the drawings.

 

[kingandy2nd]

Thanks guys. I was thinking they were some kind of high quality block of some sort or other, but just couldn’t find any when searching.

Will go for the 7N dense blocks.

I appreciate the quick responses.