Block and beam

[mrrusty]

Take a digestive biscuit and support it on two pencils. Press down in the middle (representing weight of wall on top) - biscuit snaps easily. Now place a piece of biscuit same thickness as pencils and fill the gap underneath. Now press down - it is MUCH tougher. QED.

 

[Nathan110]

Point made.

But let's say the inner cavity wall is 15 blocks high. With each thermalite block weighing 5 kg and taking into account the roofing how much weight is actually going to be directly above the edge block..

I'm labouring the point because all the other blocks along the span could have any weight directly above them too when walking or placing a permanently large heavy object.. Is that not a worry too?

 

[Dad'n'lad]

Probably because the weight of all those blocks, cement, plasterboard, anything fixed to wall, and a bloody heavy roof, which all the forces are transmitted down the outer walls, will be pressing on partially unsupported areas. I will be doing this same job in the spring. It would never occur to me to leave the slips out. I'm sure ive read that the solidity of the floor is based on its fully joined up structure.

 

[Nathan110]

True but even 15 blocks for a 3m height wall is around 100kg. Let's say the roof if 1 ton, the weight is spread along a span of 12 blocks on each side (not taking account the front facing wall)..doesn't add more than 40kg... Even with all the cement and plasterboard the weight on the edges per individual block could be anywhere between 150-200kg..

 

[Nathan110]

440x100x7/9800 = 30 tonnes per block in silo as compressive strength from readings

If the tensile strength of concrete is 8-10% of the compressive strength, does that now follow that each block can't withstand tensile 30t x 0.08 = ~2.8t