How to Build a Soffit

What You'll Need
Circular saw
Saw horses
Small knife
Screw gun
Tape measure
2 by 4s (amount TBD)

A soffit can be built for a variety of reasons. Sometimes it’s to enclose a series of ducts, sometimes it’s just decorative. In any case, you have to follow proper safety precautions to have a clean, sturdy installation.

Step 1 – Check Blocking Needs

Before installing drywall, make sure no extra blocking is needed. Blocking is used to connect the joists that run along the same length as the soffit. If it is necessary, place the blocks at 16 inch distances, using 2 by 4 inch wood.

Step 2 – Hang Sheet Rock

It’s important to follow code when you’re installing the soffit, so you must place the sheetrock on the wall and ceiling behind the location the soffit will be installed. It’s mandated by most coding laws because it functions as fire protection. A layer of joint compound, which can be bought ready mixed for application, should be laid along with tape over the sheetrock.  

Step 3 – Measure the Ceiling

It’s important that you check the ceiling’s stability and evenness before going any further. If your ceiling is not level, you will have to make adjustments to the measurement of your soffit. Generally, for every 1/2 inch of unevenness, you will need to add 1 inch of length.

Step 4 – Divide Sections

Using your 2 by 4s, divide the installation into two sections and attach them with nails. Before you begin construction, make absolutely sure the 2 by 4s are straight. Any wood that’s warped or curved needs to be replaced.

Step 5 – Build Vertical Pieces

Begin by cutting your 2 by 4s to the soffit’s length. For these instructions, the soffit is assumed to be 16 inches long. You will also want to have the measurements of the height and depth. Most likely, you will need at least 6, 2 by 4s. These need to be placed 13 inches apart to create a 16 inch high wall. When nailing the wood together, make sure you don’t overuse the nails, as they might cause the wood to split.

Step 6 – Build Horizontal Pieces

Follow the same instructions as in step 5, but instead cutting the 2 by 4s to the full length of the soffit, they should be only 11 1/2 inches long. When you are finished, attach the bottom unit by nailing it into place.

Step 7 – Attach the Two Sections

Place the vertical and horizontal pieces next to each other on the floor, and nail them together. It’s important that the 2 pieces are nailed together exactly like they will look on the ceiling.

Step 8 – Construct the End Cap

Take 1, 2 by 4 and cut it to 12 1/2 inches, and take another and cut it to 13 inches. Place the 2 pieces together in an L-shape and nail together. Next, you will use this piece as the soffit’s box end. Nail it to the edge of the frame, making sure it’s flush to the edge.

Step 9 – Hang Soffit

The soffit frame can now be nailed directly into the joists and studs. This part is too big for one person to handle, so make sure you have a couple of helpers.

Step 10 – Cover with Drywall

Once the soffit is in place, cover it with 1/2 inch drywall and you’re finished.