How to Build a Knee Wall in an Attic

Adding a knee wall to your attic is a great way to increase usable space and storage. A knee wall is a short wall, usually 24-42 inches tall, that creates a separate space in your attic. With some basic carpentry skills and the right materials, you can build your own attic knee wall relatively easily.

Planning Your Knee Wall

The first step is to plan out where you want to build the knee wall and how high it should be. Consider the following:

Determine the Location

• Decide which area of the attic you want to partition off. Measure the attic space to determine the ideal placement and length of the wall.
• Make sure there is enough headroom to walk behind the wall. There should be at least 30-36 inches of clearance for an average-height person.
• Check that there are no ducts, vents, electrical wiring, or plumbing pipes where you plan to build. The wall will need to avoid these.

Choose the Height

• Standard knee wall height is usually 24-42 inches. Taller walls take up more space.
• The wall should be high enough so you don’t have to duck under but low enough to reach over easily.
• Building codes typically require a railing or guardrail if the wall is over 42 inches high.

Account for Access

• Determine if you need access behind the wall. This may require including an attic ladder, stairs, or door.
• Make sure any attic doors or ladders will still be accessible after building the knee wall.

Create a Layout

• Sketch a layout with measurements to visualize the knee wall location.
• Mark the ceiling joists where the wall framing will need to attach.

Preparing to Build

Once you’ve planned out your knee wall design, you can start preparing the work area:

Clear the Space

• Remove any insulation or debris from the area where you’ll construct the wall.
• Have a clear path to access the workspace without stepping on ceiling joists.

Gather Materials and Tools

You’ll need the following supplies:

• Studs – 2×4 lumber, standard 92 5/8″ length
• Top and bottom plates – 2×4 lumber, cut to knee wall length
• Drywall panels, plywood, or beadboard to cover wall
• Finish nails
• Drywall screws
• Construction adhesive
• Drill and drill bits
• Tape measure and level
• Stud finder
• Saw (circular, miter, jigsaw, or handsaw)
• Hammer
• Safety equipment (glasses, gloves, etc.)

Protect the Attic Floor

• Lay plywood or cardboard over the insulation to protect from debris.
• Use foam board insulation underneath for comfort when working.

Framing the Knee Wall

With your materials gathered, you’re ready to start framing:

Install the Bottom Plate

• Cut a 2×4 to the length of your planned knee wall.
• Position it along the layout marks and make sure it’s level.
• Attach to the attic floor using construction adhesive and nails/screws every 16-24 inches.

Cut Wall Studs

• Use 92 5/8″ 2x4s for standard 8 foot ceilings. For taller ceilings, size accordingly.
• Cut studs to length with a power saw.
• Space studs 16 inches on center for drywall or 24 inches for plywood.

Stand Up the Wall Frame

• Lay out the studs alongside the bottom plate.
• Secure each stud with toe nails using 2-3 nails per stud.
• Check that the studs are plumb and properly spaced as you go.

Attach the Top Plate

• Cut another 2×4 to the same length as the bottom plate.
• Position it atop the vertical studs and nail into place.
• Use construction adhesive to firmly secure the top plate.
• Brace diagonally if needed until sheathing is added.

Include Wall Openings

• Cut and frame openings for any doors or access points wanted.
• Double up studs on each side of openings.
• Add headers along the top to maintain structural support.

Adding Wall Sheathing

Once the wall framing is complete, you can begin sheathing it:

Choose a Sheathing Material

• Drywall – Creates a smooth finished wall for adding shelving/cabinets.
• Plywood – Provides easy attachment for cleats and storage items.
• Beadboard – Lightweight with a decorative, classic look.

Cut Sheathing Panels to Size

• Measure the wall dimensions and cut panels to size.
• Drywall typically comes in 4×8 sheets. Plywood and beadboard in 4×4 sheets.
• Use a circular saw or handsaw with a guide to cut neatly and accurately.

Attach Panels to Wall Frame

• Position the panels against the framing and nail into the studs and plates.
• Place vertical seams over studs for support.
• Space drywall screws every 12 inches around the perimeter and in the field.
• Countersink screw heads slightly below the surface.

Finish Drywall Seams

• For drywall, cover seams with joint compound and fiberglass seam tape.
• Apply 2-3 coats feathering out from the center to create a smooth finish.
• Sand lightly between coats when dry.

The sheathing provides structure, insulation, and a surface for finishing.

Adding Trim and Molding

Trim pieces give the knee wall a polished, complete look:

Install Corner Bead

• Use metal or plastic corner bead to protect and strengthen drywall corners.
• Attach with drywall screws into the stud or seam underneath.

Attach Baseboard Molding

• Cut 1×4 or 1×6 boards to frame the bottom of the wall.
• Miter corners at 45 degrees for a clean finish.
• Nail through the backside of the baseboard into the wall.

Add Door/Window Trim

• Mark and measure any openings to size trim pieces.
• Miter cut 1x4s or 1x6s to border the sides and top.
• Use window and door casing for a finished look.

Caulk and Fill Gaps

• Run a bead of paintable caulk along seams and joints.
• Let dry completely and then sand smooth.
• Fill nail holes with wood filler and sand flat when dry.

Painting and Finishing Touches

The final step is painting and adding any finishing details:

Prep the Wall Surface

• Fill holes and imperfections with drywall compound. Sand smooth.
• Lightly sand drywall with fine grit sandpaper to help paint adhere.
• Clean dust and debris. Wipe with a damp cloth.

Choose a Paint Color

• Opt for a light neutral color to keep the attic feeling airy and spacious.
• Add bold colors on trim or doors for an accent.
• Use ceiling paint for flat overhead surfaces to avoid drips.

Apply Primer and Paint

• Prime drywall with PVA or high-build primer before painting.
• Use an interior latex paint with a brush, roller, or paint sprayer.
• Apply 2-3 coats allowing proper dry time between coats.

Add Decorative Touches

• Install shelving, cabinets, or cleats for storage.
• Add lighting, flooring, or baseboard heaters if desired.
• Furnish with storage bins, totes, or organizers.

With some carpentry skills and the right process, you can create a functional and stylish knee wall storage solution. Enjoy your new attic space!

Frequently Asked Questions About Building an Attic Knee Wall

Building a knee wall is a common attic renovation project. Here are answers to some frequently asked questions:

How high should an attic knee wall be?

The typical height is 24 to 42 inches. The standard is to build it just high enough so you don’t have to duck under, usually around 36 inches high.

What kind of wood should be used?

Knee walls are typically framed with 2×4 studs and plates, using standard 92 5/8 inch construction lumber. Pressure-treated wood can be used for bottom plates that rest on concrete.

Does a knee wall require insulation?

Insulating a knee wall is recommended to control attic temperatures. Fiberglass batt insulation fitted between the studs is a common solution. Foam board insulation also works well.

How far apart do the studs need to be spaced?

For most residential knee walls, studs are spaced 16 inches on center when using drywall, or 24 inches on center if using plywood sheathing.

What’s the best way to attach drywall to a knee wall?

Use drywall screws spaced every 12 inches around the perimeter and through the field of the panels. Countersink screws slightly below the surface.

Should trim or molding be added to a knee wall?

Trim and molding are not mandatory but they give the wall a cleaner, more finished look. Baseboard, door casing, and corner bead are commonly used.

How are openings framed on a knee wall?

Doorways and access openings require doubled-up studs on each side. Headers along the top maintain structural support. Custom framing keeps openings looking neat.

Can storage shelving be added to a knee wall?

Yes, many people attach shelving brackets or cleats to the knee wall for storage. This maximizes the usable space created behind the wall.

Does a knee wall require permitting?

In most cases knee walls are exempt from permit requirements because they are non-structural. But do check local codes for any restrictions.

Conclusion

Adding a knee wall is a great way to carve out additional usable space in your attic. By following the proper design, framing, and finishing steps, you can create a functional storage area safely. Use quality materials and neat workmanship for best results. With some carpentry practice and these tips in mind, you’ll be ready to build an attic knee wall like a pro.

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