Hello everyone,
I hope this is the right place for my question and I appreciate your advice.
I am currently planning to build a carport onto my house (about 6 by 6 meters (20 by 20 feet)). It will be located between the house wall and the garage.
At the moment, I am excavating a strip foundation on the opposite side of the house.
The foundation should be at least 80 cm (31 inches) deep to prevent frost damage. I am currently at about 50 cm (20 inches) depth.
The width is approximately 40 to 45 cm (16 to 18 inches).
The ground is very hard and full of sandstone rocks. Without a hammer drill, it’s almost impossible.
On top of the foundation will be a row of formwork blocks (20 cm (8 inches) high), into which the post anchors will later be set. These will also be concreted in. In front of it are pavers (including gravel and crushed stone).
My question is the following: If I leave the foundation at 50 cm (20 inches) depth, then add about 20 cm (8 inches) of gravel, 5 cm (2 inches) of crushed stone, and 8 cm (3 inches) of pavers, the total depth of the foundation below surface level would be 83 cm (33 inches). Do I still need to excavate to the recommended depth of 80 cm (31 inches)?
Is this approach acceptable, or am I missing something?
Thank you very much for your help.
Best regards
Michael
I hope this is the right place for my question and I appreciate your advice.
I am currently planning to build a carport onto my house (about 6 by 6 meters (20 by 20 feet)). It will be located between the house wall and the garage.
At the moment, I am excavating a strip foundation on the opposite side of the house.
The foundation should be at least 80 cm (31 inches) deep to prevent frost damage. I am currently at about 50 cm (20 inches) depth.
The width is approximately 40 to 45 cm (16 to 18 inches).
The ground is very hard and full of sandstone rocks. Without a hammer drill, it’s almost impossible.
On top of the foundation will be a row of formwork blocks (20 cm (8 inches) high), into which the post anchors will later be set. These will also be concreted in. In front of it are pavers (including gravel and crushed stone).
My question is the following: If I leave the foundation at 50 cm (20 inches) depth, then add about 20 cm (8 inches) of gravel, 5 cm (2 inches) of crushed stone, and 8 cm (3 inches) of pavers, the total depth of the foundation below surface level would be 83 cm (33 inches). Do I still need to excavate to the recommended depth of 80 cm (31 inches)?
Is this approach acceptable, or am I missing something?
Thank you very much for your help.
Best regards
Michael
M
michisa868885 Jun 2015 19:16Well, I believe we learned at masonry school that the minimum frost-protected foundation depth is 80cm (31.5 inches) below the finished ground level. So in this case, that requirement would be met.
Now the question is what your structural engineer thinks about it. If they calculated the structure with a depth of 80cm (31.5 inches), you should check with them to see their opinion.
Normally, a carport is quite light and the soil seems to be stable enough to support it.
Now the question is what your structural engineer thinks about it. If they calculated the structure with a depth of 80cm (31.5 inches), you should check with them to see their opinion.
Normally, a carport is quite light and the soil seems to be stable enough to support it.
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