What size concrete blocks for house extension.

[BrickyBrian]

I started my apprenticeship as a Bricklayer in 1952 and have worked at my trade on and off over the years. The last extension I built was for our bungalow a few years ago and I was told to use 4" blocks for both skins. I visited my daughter today who is having an extension to her house built and they have built the foundations with 3" concrete blocks for the inner skin and a normal 4 ½” brick for the outer skin. My understanding is that the inner skin bears the load of the roof. So, should it be 3” or 4”?

 

[denso13]

So, should it be 3” or 4”?

There is no "standard" size, it depends on a number of factors which should all be taken in to account before specifying which block should be used.

 

[HERTS P&D]

Brian are you 84?

Andy

 

[BrickyBrian]

There is no "standard" size, it depends on a number of factors which should all be taken in to account before specifying which block should be used.

What factors?

 

[denso13]

What factors?

Things like the structural loading that can be expected upon them, the insulation value of the blocks (is insulation or thermal mass is more important) and the buildability of a particular block. Sustainability and availability are biggies nowadays and could be factors in choosing one block over another as well.