Are there any resources available online that would tell me what sort of
groundwork should be done prior to laying a block drive and concrete garage
I had a quote from a local guy recommended to me and want to get some
details down about depths of aggregate and sand etc before he comes to
finalise and go ahead with the work.
I think its because I saw some 'builders from hell' programme and got all
For my 24 x 12 garage on clay sub soil, I dug out and laid about 9" of
hardcore (using a mechanical wacker), followed by 5" of concrete laid
as a single slab. I made the concrete a little thicker around the
perimeter of the slab.
It developed a small crack several years ago, but I suspect this was
due to laying too large a slab in one piece. It causes no problems.
Doing it again, I would probably be inclined to add a small amount of
steel reinforcing to the slab. Make sure the top of the slab is at
least an inch or two above ground, so that water doesn't flood in and
that the fall is either away from the front, or there is a drain
channel in front of the door. Especially if it is a prefab type, add a
2" web of cement around the inside edges to help prevent water flowing
in. Prevent the cement sticking to the walls by laying plastic sheet
along them, otherwise the cement will crack as the slabs move slightly.
For the blocks, lay a 6" of harcore with a good bed of sand on top.
I've seen drives where blocks have been laid without foundations and
grooves soon appear where the car wheels run if the sub soil is soft.
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