Framing a 45-degree Wall

A piece of cut wood next to a table saw blade.
  • 15-30 hours
  • Advanced
  • 1,000-3,000
What You'll Need
2x4 lumber
Circular saw
Power drill
16d nails
Chalk line
Table saw

One of the trickier ways of framing is joining two walls at a 45-degree angle. By far most walls meet at 90 degrees, but in some instances it is desirable or even necessary to frame a wall at 45 degrees instead. In some alternative homes such as domes or even more traditional homes with an uncharacteristic layout, a 45-degree angle wall might be called for. If you're building something a little less conventional, here's how you can get those odd angles taken care of.

Step 1 - Measure and Cut the Plates

Your 45-degree angle wall consists of a top plate, bottom plate, and vertical studs. The top plate will attach to the upper beams of the structure while the bottom plate attaches to joists at the floor level. The first step is to measure and mark the plates to the right angles, cut them, and make sure they join to make a 45-degree angle. To do this, measure along the broadside of the plates at 22 ½ degrees so they will meet and make a 45. Use the T-bevel to make an accurate angle and mark it with a pencil. With your circular saw, cut the ends off the four plate pieces. For each pair of top and bottom plates, make sure the angles are marked opposite of one another so they’ll meet to form an acute angle.

Step 2 - Join the Plates

Put two screws into one of the plate pieces for both the top and bottom. Insert the screws at a slight angle so they go cleanly into the other plate piece. Together they should form a perfect 45-degree angle.

Step 3 - Mark the “V” Studs

Lay the top plate on top of the bottom plate and align them. Measure down 1 ¾ inches from the inside apex or the point the two sides meet, and make a straight line on both inner sides of both plates at these points. This line indicates the far point of each of the two studs that form a “V” when constructed. The point nearest the tip of the angle will be the inside apex.

Step 4 - Attach “V” Studs

Lay the top plate on one side so the other goes into the air; you may want to support the floating end. Preset two 16d nails in the top of the top plate midway between the inner apex and the line you drew. Lay the first stud flat on the ground on edge and position it squarely against the plate between the inner apex and the line. Holding it in place, hammer the two nails home so the stud is secure. Then, turn the plate over to its other side, supporting the previous side and repeat this procedure with the second stud. The two studs should meet at one corner and flare out like a “V."

Step 5 - Attach Bottom Plate

Attach the bottom plate to the studs in the same manner as step four. As a reminder, the studs should already be cut to length at this point.

Step 6 - Make Marks for Corner Studs

Now comes the tricky part. Take two other 2x4s and cut them to the same length as the “V” studs. At the edges, measure and mark a 22 ½-degree angle. Again, make sure they are mirror opposites so they will fit together and make an acute angle. The line should run from one corner of the edge to somewhere between the corners on the opposite broadside of the 2x4. Where this line meets the broadside, position a chalk line and mark the entire length of 2x4 down to the other end.

Step 7 - Rip the Corner Studs

Using a table saw, set the blade to 22 ½ degrees and position the fence so that the 2x4 is held in place. Very carefully, rip the 2x4 the entire length. Set the blade to 22 ½ degrees at the opposite angle and rip the other 2x4. The two pieces should conform lengthwise and make a 45-degree pair of studs.

Step 8 - Nail in the Corner Studs

Nail the two studs into the corners between the top and bottom plates. Your wall is now cleanly framed at 45 degrees.

It will take some precise measuring and cutting, but you can frame a wall at 45 degrees with a little skill and the right tools. Note that you can use a circular saw to rip the 2x4s, but you will need sawhorses and clamps to hold it in place.