can i use thermalite blocks as trench blocks

[mommabear]

hi all

im building a large gym in my garden which is 9.7m by 3.8m
i have dug the trenches and they are 800mm deep which the building inspector is happy with.
he has said i can trench fill upto 400mm and trench block the rest.

ive been offered some thermalite blocks 3.6n could i use these as thrench blocks.

thanks for any advice

 

[big-all]

now i could be miles out
but i believe they need to be above dpm level as they are fairly light weight

 

[opps]

I used them below the DPC when I built my garage.

http://forterra.co.uk/resources/news/article/2014/12/can-i-use-thermalite-blocks-below-ground

 

[^woody^]

Yes, but not in the frost zone 225mm above and below ground level on the outer leaf.

 

[opps]

Yes, but not in the frost zone 225mm above and below ground level on the outer leaf.

According to Hanson-

Independent comparative frost resistance tests have been carried out on facing bricks, common bricks and Thermalite blocks. After 20 freeze/thaw cycles, the facing bricks were severely cracked. At 61 cycles, the Thermalite blocks showed no signs of cracking. This test was repeated with additional strength tests being carried out after 20, 40 and 60 cycles, and this confirmed that Thermalite has satisfactory frost resistance and that there is no reduction in strength under these conditions. A similar test undertaken by the British Board of Agrément (BBA) produced similar results. The inherent frost resistance of Thermalite blocks means that all products within the range are suited for use below dpc level. The mortar properties should be appropriate to the degree of frost resistance required.

My garage (8m by 4m) is the only structure that I have built. Given my lack of knowledge, I spoke to the block manufacturers and they told me that it is fine to use them throughout for each of the walls. From memory, I used the 200mm blocks and then had the exterior walls rendered.

 

[^woody^]

Did they report on the small line of block dust on the ground caused by several freeze/thaw cycles?

Presumably it gets to be a bigger line over the years.

 

[stuart45]

I built a shelter for the wife's call ducks with some old Thermalite and concrete blocks that had been lying around for quite a few years, but the Thermalite were a lot more crumbly than you would expect for a new block, so I'm not totally convinced by the manufacturers claims.

 

[opps]

I built a shelter for the wife's call ducks with some old Thermalite and concrete blocks that had been lying around for quite a few years, but the Thermalite were a lot more crumbly than you would expect for a new block, so I'm not totally convinced by the manufacturers claims.

You and Woody might be right to be sceptical. As I said, I have only used them once and the structure was rendered.

 

[tomfe]

Even if you could, you'd be left with a course of blocks on show.