Frame a Floor

Most modern single-family homes are constructed from dimensional lumber framed in a consistent pattern. This type of framing, often called "stick framing," is lightweight and economical. The first part of any structure to be framed is the floor, which rests on a concrete foundation or on piers. This article explains the process of framing a floor.

Steps

1. Look up the building code for your area. Your city will have building code, or basic requirements that homes and buildings are required to meet. If your floor isn't up to code, you might get fined and will probably be required to pull up the entire floor. Know what the code is for your area before you start, because it can affect everything from the materials you need to use to the measurements you use. Your area might even require a permit for a floor to be considered up to code!
2. Plan your floor framing layout. Before installing anything, use a pencil and paper to design your framing plan. Draw the plan to scale and check all your calculations carefully so that you know exactly how many members you need and what length they need to be. Extremely long spans, staircases, or interior load-bearing walls complicate the framing plan by necessitating lapped joints and additional support columns. These complications are best handled by a licensed contractor.
   • You should space your floor joists at 16" center-to-center to be as structurally sounds as possible. The length can vary depending on the size of your room and what lumber is available to you, but generally you will at least want support for longer boards from below, such as an extra pillar and horizontal board.
3. Cut all the wood members to size. Once you have formulated your framing plan, use it to determine the length of lumber you will need and what sizes to cut the lumber into. Use a pencil to mark each piece after you cut it, which will help you determine where that pieces needs to be installed later.
4. Install the sill plate. The sill plate (sometimes called the sill, or the mud sill) consists of lengths of dimensional lumber that are laid directly on top of the foundation wall. The boards should be laid horizontally, with one edge flush with the exterior of the foundation wall. Use either 2x6 or 2x8 (50x150 mm or 50x200 mm) lumber for the sill plate. Because the sill plate contacts concrete directly, you must use pressure-treated wood. Drill holes in the boards to accommodate the anchor bolts in the foundation, and secure the boards by fastening nuts and washers onto the bolts.
   • To avoid problems with moisture and air circulation, you should place a sill gasket before installing the sill.
5. Install the band joist. The band joist, also called a rim joist, sits vertically on top of the sill plate. Use the same size lumber for the band joist as you will for the main floor joists; 2x10s (50x250 mm) are an appropriate size for most applications. Position each board vertically so that its edge is flush with the outer edge of the sill plate, and then toe-nail the board to the sill plate with framing nails.
   • You can also get a metal brace to keep the sill and band joist extra secure. The brace screws into the wood at one end and the foundation at the other.
6. Mark the position of each floor joist. Floor joists should run parallel to each other and be spaced evenly, at no more than 16 inches (40 cm) on center if you want the floor to be properly secure. Use a tape measure to find the position of each joist along the sill plate, and mark the position with a pencil.
7. Install the floor joists. Set the floor joists onto the sill plate and position them over your pencil markings. The joists should fit flush against the band joist. After setting each joist in place, toe-nail it to both the sill plate and the band joist.
   • If you want to make your joists more stable and make installation a breeze, use joist hangers.
8. Add the bridging. You'll need to put in X or solid bridging between the joists, if the length of the joist is greater than 9'. There are different schools of thought on which is better, but having it at all is what is really important. If you know you're going to have to run a lot of cables or utilities beneath the floor, then the X bridging is probably better in the long run.
9. Install the subfloor. Once the bridging is in, you can go about installing the rest of the floor. Just be sure that you thoroughly glue the plywood or other subfloor material to the joists. Only apply the glue in one small section at a time. You do not want the glue to have time to start drying before you get the chance to lay down the subfloor. The subfloor panels should be places perpendicular to the line of the joists (across the joists).
   • Tongue-in-groove subfloor, as well as subfloor which is at least 3/4" thick, will make a floor much more secure.

Tips

• Always wear safety glasses and work gloves when operating a circular saw.

Things You'll Need

• Pencil
• Paper
• Dimensional lumber
• Tape measure
• Circular saw
• Drill
• Anchor bolts
• Nuts
• Washers
• Hammer
• Framing nails
• Safety glasses
• Work gloves

Sources and Citations

See also

• Buff Floors
• Install Baseboards
• Prepare a Subfloor for Hardwood
• Measure for Stairs
• Protect Laminate Flooring
• Lay Laminate Flooring
• Install Linoleum Flooring
• Sand Hardwood Floors
• Install Floor Tile
• Clean Linoleum Floors

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What links here

• Pour a Garage Floor