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How to Build a Wooden Frame Over a Concrete Slab for a Floor

By Danny Donahue ; Updated September 21, 2017
Review your plans with the local building inspector before starting the project.
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A concrete slab is a sturdy surface. But, it does not hold heat and the comfort factor is negligible. The answer to this problem is to build a wooden subfloor over the concrete slab. Once you have built a proper subfloor you can install any standard flooring you wish. Normally subflooring begins with standard lumber framing. The concrete will react negatively with standard lumber. So, common sense, and most local building codes, call for a frame made of treated lumber.

Step 1

Place a board against one wall. Cut the board with your circular saw so that it fits along the wall tightly. Stand the board on its narrow side so that it stands 3 1/2 inches tall.

Step 2

Cut a second board to match the first one. Place it alongside the first board. Drive two of your 16d nails through the boards every 12 inches to form a secure double stud.

Step 3

Repeat the process across the room on the parallel wall. Push each double stud tight against its own wall.

Step 4

Build a double stud for each of the two remaining walls. Toe nail each perpendicular double stud to the original two double studs to complete the outer band of your frame.

Step 5

Measure the distance between your last two double studs. Divide that number by 12. Cut that many rows of boards. Nail each of those boards into a double stud. Toe nail one of those double studs to the original two boards. Place one double stud every 24 inches across room.


Things You Will Need

  • Treated boards (2 inches by 4 inches by 20 feet)
  • Circular saw
  • 16d nails
  • Framing hammer
  • Work gloves
  • Safety glasses
  • Hearing protection


  • Toe nailing is the process of driving an angled nail through the end of one board and into an adjoining board. Driving each nail at a 30 degree angle with your framing hammer is sufficient for toe nailing one board to another.
  • Here is an example of the process: Build a frame of double studs around the entire perimeter of your 20 foot by 20 foot room. Measure the distance between your first two double studs and you get 19 feet 6 inches, or 234 inches. Divide the total number of inches by 12 and you get 19 1/2. So, you would cut 18 boards making each one 19 feet 6 inches long. Nail each board to another to form 9 double studs. Toe nail one of the double studs every 24 inches to fill in the gap. In this scenario the final double stud will be 24 inches from the previous stud and 18 inches from the outer band. This spacing is within the limits set forth by most local building codes.
  • Rooms larger than 20 feet by 20 feet will require a different strategy. Any time you have a distance longer than your lumber it is necessary to lay out your lumber in a double row. Arrange the two rows of boards so that the junctures between boards in one row are at least 4 feet from the ones in the other row. This staggering process insures the strength of your frame.


  • Work gloves and safety glasses are required when using hand and power tools.
  • Hearing protection is required, in addition to your gloves and glasses, when using power tools.
  • Framing a floor is a project that is covered under the guidelines set forth by most local building codes. Contact your local building inspector with a copy of your plans before beginning this, or any, remodeling project. Comply with all inspection and licensing rules in your locality to avoid prosecution and the possibility of condemnation of your home.

About the Author


After learning electronics in the U.S. Navy in the 1980s, Danny Donahue spent a lifetime in the construction industry. He has worked with some of the finest construction talent in the Southeastern United States. Donahue has been a freelance writer since 2008, focusing his efforts on his beloved construction projects.