How to Box in Ductwork

Converting a basement area into a home theater may include building a soffit around the ductwork.

Many homeowners have unfinished basements that they desire to turn into finished living areas. For homes with heating and central air conditioning systems, the remodeling project usually requires concealment of the exposed ductwork used for air distribution. Remodeling contractors usually create a box around the exposed ductwork. This box, or soffit consists of a wooden frame made from a series of 2-by-3 or 2-by-4 inch stud-grade lumber, which envelop the ductwork in an "L" or "U" shape. Finish the box with drywall and painted.

Things You'll Need

• 2-by-4 inch stud-grade lumber
• Carpenter's level
• Screws

Instructions

1. Install a U-shaped box to cover ductwork that is not located close to a wall. Install any ductwork insulation before taking measurements and starting the construction. Measure the space from the bottom of the ceiling joists to the bottom of the ductwork section in the middle of the ductwork system. Add 1/2-inch to the measurement.

2. Locate the floor joists in the ceiling near the ductwork. Screw 2-by-4 inch boards along the length of the floor joists, on each side of the ductwork. These "support studs" will provide the support for mounting the soffit former. Use a miter or table saw to ensure precise, 90-degree cuts and create a straight level soffit. Cut two pieces of wood from 2-by-4-inch board, also called "formers." Make the length the same as the measurement from the ceiling joist to the bottom of the ductwork system.

3. Measure the ductwork width. Add the width of the supports and two former components together. Cut a 2-by-4 inch board this length. Position the formers vertically and secure this board, horizontally, to the formers to create the "U" shape.

4. Position the former under the duct and slide it in place. The former should hug each side of the duct and fit flush with the outside surface of the supports attached to the joists. This part may require an assistant or the use of a wire to hold the other side in place temporarily. Secure one side of the former to the support with a screw. Check the former to ensure it lines up properly and screw it into the other support.

5. Repeat this process along the length of the ductwork. Place the formers 16 inches on center. This interval helps to line up the drywall edges on the formers and prevents the drywall compound from cracking. Use a carpenter's level to ensure each former is level with the next. Proper alignment makes for a straight soffit with a professional appearance.

6. Install "L-shaped" formers for ductwork along the edge of a wall or other structure. Secure one end of the former from the joist and the other end from a support stud secure to the wall. Verify the support studs, attached to the joist and the wall, drops to the same level.

References

• DIY Home Theater Design: How To Build A Soffit
• Home Addition Plus; How to Hide Basement Ductwork; Mark J. Donovan