How To Frame An Addition

A framed in room
  • 240-300 hours
  • Advanced
  • 2,000-4,000
What You'll Need
Chalk line
Concrete slab
Measuring tape
2 x 4 studs
Chop saw
Table saw
Nail gun
8 penny nails
16 penny nails

Putting an addition on your home begins with the framing process. If you're going to build the addition yourself, these steps will help you get the framing done right.

Step 1 - Obtain Permits

You must meet a variety of local legal requirements and obtain building permits before you begin work on your addition. Meeting these requirement is handled through the permitting process with the county. You should expect to provide copies of your plans or blueprints, exact specifications for any drainage you’ll be adding, and distances from side yards, sewer lines, etc. This initial process can be expensive and time consuming, so figure it into your planning.

Step 2 - Foundation


Before you begin framing you’ll need to build a foundation. Most people pour a concrete slab, even if they have a full basement under the rest of the house. The slab needs to be construction quality, meaning it will need to be made of a thick concrete material poured to a precise depth. It is advisable to consult or hire a professional for this job.

You can also build a raised subfloor with stone or wood supports. Be sure to research code requirements for your area.

Step 3 - Lay Out Your Walls

Using the chalk line, mark the wall lines on the foundation. Make sure to lay out any windows and doors as you go so that you will remember to frame them in.

Snap your chalk line around the exterior measurement of the walls (where you want the exterior walls to be). Measure at each end of every wall so that the wall lines are straight. Having walls that are not square causes problems both on the exterior and interior later on.

Step 4 - Cut Studs

Determine how high you want your finished walls to be. Standard ceilings are 8 feet off the ground, but you can decide on higher ceilings if you like.

Whatever you decide, make sure to subtract 41/2 inches from that height to determine the height of your wall studs. This allows for the bottom seal plate (1 ½ inches) and the double top plate (3 inches).

Step 5 - Tag Top and Bottom Plates

Put the top and bottom 2 x 4s together and mark them as to where you want your studs. Standard interior walls have studs on 16-inch centers. If you mark the top and bottom plates together, you’ll have straight studs and the framing can go quickly.

Step 6 - Construct Walls

Framed walls

Using the nail gun, construct walls while they are lying down. Once you complete the wall, lift it into place and attach to the adjoining wall. Attach carefully to the existing wall of the home where you are building the addition. Use braces to give extra support and keep the walls plumb.

Be sure to measure for doors and windows as you go, following the markings on your floor.

Step 7 - Place Extra Pieces

Place jack studs, cripples, headers, and fire blocking—all types of 2 x 4 extra pieces running horizontally from floor to ceiling in spaces where you have doors or windows. Install these pieces according to code. If you do not know the rules, consult a professional or have the building inspector come out and instruct you.

Step 8 - Install Double Top Plate

Nail top plate all around the top of the wall. Line up the nails with the studs below. All top plates are doubled for support.

Now you are ready to begin finishing the room and adding a ceiling and roof.