How do you calculate the requirements of a structural wall built from concrete blocks approx 12 x2.5metres?
Question:sloping back garden cut into slope(30degs)with approx 1 mtr height to be increased to approx 2.5mtr with the aid of the said wall
Answers:
From what I gather you are building a 12 meter [about 40 feet]long retaining wall that will be 1.5 meters [about 5 feet] high.
You are imposing quite a force on a wall that tall. You will likely need as much mass below grade, on an oversized footing, as above and just a guess you should have #4 [1/2" ]vertical rebar like every 32" with horiz. reinforcement on every other course. You might want to look at installing deadmen or pilaster at regular intervals, too.
You might want to have a local engineer or building offical look at you plans, you don't want to have to do it twice.
Good luck and be careful
30 block , 5 bags of sand 1 bag cement
You get 10 blocks per sq metre. So 12 x 2.5 = 30sq metres x 10 blocks = 300 blocks. Due to weight of soil behind the wall and size of wall it will need extra support ie. pillars building into it or it will have to be double skinned with wall ties.
you would need 300 blocks for a 12 x 2.5 ordinary wall but if it is being used as a retaining wall they would have to be laid flat, hence double the amount.
10 x 25kg bags of cement, 5lt of cement plasersiser (febmix) 1 tonne bulk bag of building sand, again all doubled if retaining wall.
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