Concrete Subgrade

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Q&A: How Flat Does a Subgrade Need to Be?

Q: When you're preparing the subgrade for an insulated slab foundation, how flat does the surface need to be before you lay out the rigid foam? Is "pretty flat" good enough, or do you have to eliminate every minor hollow and high spot? More

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Super-Insulated Slab Foundations

Compacted drainage stone and a thick layer of foam prevent frost damage and keep... More

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Lowering a Basement Floor

Gaining an extra foot of headroom isn’t easy, but it can yield valuable living space. More

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That Thang Is Leanin
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Compacting Stump Holes

I'm about to pour a slab on a site where several stumps were removed, leaving 2- and 3-foot-deep holes about 4 feet across. The backhoe operator went ahead and filled in the holes with dirt from the site (sandy loam, pretty good stuff), drove over them a More

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Q&A: Is It Necessary to Compact Slab Sub-Base?

Q. We need to pour a 24x24-foot concrete slab for an attached garage next to a... More

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Q&A: Garage Slab Drainage

Q. How should a garage slab be sloped for drainage toward the overhead door? At 1/4 inch per foot on a 24x26-foot foundation, the height difference from front to back would be more than 6 inches. Do I need to grade the sand and gravel sub-base at the same slope so the slab can have a uniform 4-inch thickness? More

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Radon Vent Retrofit

A radon remediation contractor shows how to install vent pipes beneath a slab to... More

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Tips for Crack-Free Concrete Slabs

A construction superintendent from Canada explains how to prep the subgrade and... More

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Layout Under the Slab

A construction superintendent explains how to avoid costly errors under slab foundations. More

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