For Contractors


Suspended slab garages are easy to include and maintain if done correctly. Here are some common questions contractors have asked me over the past 15 years:

  • How do I waterproof the garage floor to prevent water leaking into the finished space below?

    1. Apply foundation tar over each joint no more than 9” wide and around the perimeter of the garage.
    2. Place ice and water shield no more than 9” wide over each joint and around the perimeter (half is horizontal then wraps up the wall so half is vertical).
    3. After topping slab is poured repeat steps 1 and 2 over the cold joint across the front of the garage where the topping slab meets the foundation.
    4. When pouring the topping slab, tool or saw-cut a joint directly over each spandeck joint and tool a finished edge around the entire perimeter.
    5. Fill these joints and edges with a commercial concrete caulk.  These are readily available in the concrete section at Home Depot or any concrete supply such as, White Cap or Intermountain Concrete Supply.  I use Sika-Flex self-leveling caulk from Home Depot.
    6. After the driveway is poured, use this same product to caulk the joint between the garage topping slab and driveway slab.
    7. Many contractors also epoxy the garage floor.
    8. Advise the home owner NOT to spray out their garage with a hose or leave standing water on their garage floor.  Remember, even though it is water-proofed, there is living space beneath it.
  • If I set the spandeck down in a foundation shelf, my ceiling height in the room below is too low. What can I do?

    1. Taller foundation walls (whole home or garage area only).
    2. Place the spandeck on top of the foundation rather than in a shelf.
    3. Pour the basement floor lower.  The top of the basement floor could be as low as the top of the footings for a 4” gain on ceiling height.  This could be done below the garage only.
    4. Pour the floor much lower and hide the footing in the framing to gain more than 4”.
  • Where do I need to place joints in the topping slab?

    1. Tool or saw-cut a joint directly over the spandeck joints.  You can have more joints, but you must have joints over spandeck joints or your topping slab will crack.
  • Can I core-drill through the spandeck slab?

    1. Yes.  Contact me for how and where.
  • How do I get a flue or plumbing pipes through the spandeck slabs?

    1. This is done by hiring a concrete cutting company to core drill through the slab.  Contact me for how and where you may drill a hole.
  • How do I finish the ceiling below the spandeck?

    1. Leave it unfinished
    2. Paint it
    3. Texture it and paint it
    4. Glue acoustic tile to it
    5. Fasten framing (treated 2x4s) by bolting on with 1/4” expansion type anchors.  Then proceed with drywall as usual.
    6. There are several other framing options with room for insulation, wiring, etc. contact me and I can discuss your specific project with you.
  • How do I get heat runs or other utilities into the space beneath the spandeck?

    1. You can either core-drill holes for runs or have the foundation sub-contractor block out spaces for runs.
  • Can I place window or door openings in the foundation bearing wall?

    1. Yes.  The header above it needs to be engineered.  If there’s not enough room between the shelf and the opening, it may need a piece of steel angle placed over the opening.
  • What money-saving tips can I offer my owners?

    1. Design your garage in 8’ increments plus an inch or two for some wiggle room.
    2. Avoid 45s or other angles. Any shape garage can be accommodated, but for the best pricing, a rectangle is the least expensive.
    3. If your garage size does not accommodate full 8’ slabs you can fill in 2’ or less gaps like a porch by shoring up underneath and using rebar.  This is generally less expensive than having additional pieces of spandeck custom cut to fill the gap.
    4. You can save money by removing non-bearing foundation walls between the garage and house.
    5. Spandeck becomes more expensive for spans over 31’ although it can span up to 38’.
    6. Spandeck is less expensive per square foot as the garage gets larger.
    7. Provide access within 10’ of the center of the foundation for a crane.  In doing so, you will avoid additional costs of a larger crane to reach the foundation.