How many Blocks do i need to build a extension 3.5Mx3.5M x 2.4Mhigh with a cavity

Hi, the amount of blocks you would need ,would be 588. its 10 blocks per square metre. 3.5 x 3.5 = 12.25m (lenth) 12.2 5x2.4 = 29.4 m (lengh x height) 29.4 x 2 = 58.8 m (x2 for cavity so two skins) 58.8 x 10 = 588 blocks (x10 -10 blocks per squre metre) Also add 5% for wastage.

Hi standard blocks are 450mm x 225mm high so its 10 to a square mtr. so i expect your extention has 3 side so 3.5 trs x 2.4 mtrs = 8.4 mtrs x 10 blocks = 84 blocks x 3 walls = 252 blocks skin x 2 = total 502 blocks. and then you need to take away the area of your windows and door. hope this helps you. regards Tom

I would agree with Tom . If you get the higher amounts at least you will have some spare blocks to sit your spot boards on.

520 blocks will cover the job ,

you would need 50.4 metres=504 blocks less windows and doors

If i was you i would add another 3.5 +3.5 +3.5 =10.5 length 0.9 depth of footing (depending on ground conditions) sub total =9.45 x 2 skins =18.9m2 @10 block m2 =189 without waste call it 3packs @ 72= 216 allowing for waste, unless your not having any footings on your extension. Even better get someone who knows what they are doing to come round and have a measure up unless it probably will cost you in the long run.

10 blocks per m2