Carport slab thickness and subbase.

Old 07-14-20, 03:05 PM
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Carport slab thickness and subbase.


I have a 26 feet carport I wish to make it 12 feet longer. I live in Québec, Canada, so we have pretty rough winters. I want to pour a slab that will be 12x13. I see a lot of 4in on the internet, some advocate for 6in thickness. What would be the compacted thickness for the subbase? Is it better to you 0-3/4 stone or gravel? The wall of the carport won't be on the slab, the only weight on it will be a car.

Thank you
Old 07-15-20, 05:01 AM
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Thicker is generally better. I think 4" (actually 3 1/2") is common just because of the lumber size. Research if you want an air entrained mixture or anything else for spalling/freeze protection.

The base depends on what you have. Often carports and driveways are poured right onto dirt and without any base. Crusher run or 0-3/4 can work well for a base but it will require proper compaction before pouring. Clean gravels can be used and don't require compaction.

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