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Other stories by Alan Gibson

  • 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?

  • Super-Insulated Slab Foundations

    Compacted drainage stone and a thick layer of foam prevent frost damage and keep the heat inside the building.