DIY Wall Frame Molding

What wall frame molding is

Wall frame molding, also called picture frame molding or box molding, is a set of rectangles or squares made from trim and attached to a wall. Each box is four pieces with 45-degree ends, so the pieces meet like a picture frame. It is a common way to add detail to plain drywall, and it is generally considered beginner-friendly if you are comfortable measuring carefully and using a saw.

Typical layouts:

• Lower third of the wall: boxes below a chair rail, with paint or wallpaper above.
• Full height: boxes running from baseboard to ceiling, often painted one color.
• Single large boxes: one box on a feature wall, which can frame art or a headboard.

Is it cheaper to make your own?

Usually yes, if you compare it with ready-made paneling kits or hiring a carpenter, since the materials are basic trim, adhesive, nails, caulk and paint. Costs depend on the molding you choose and how much of the wall you cover, and lumber prices change, so price your materials list at a local store. Time and tools are the other cost: a miter saw, a brad nailer and a level make the work easier, and you can rent or borrow tools. Buy extra trim because mistakes and miscuts happen.

Choose molding and layout

A commonly used trim is base cap molding, often sold finger-jointed and primed. Other small trims, flat stock, or MDF strips can also work, depending on the look you want. Pick material that sits flat on the wall.

Design guidance from DIY sources:

• Spacing between boxes and from baseboard, chair rail or ceiling is often around 3 to 4 inches, but there is no strict rule.
• Boxes should look balanced. They don’t need to be identical in size across a room, but they should be consistent along each wall.
• Work around doors, windows, outlets, switches, radiators, vanities and furniture before you buy material.
• If you are using a chair rail, set it at a consistent height using a level line carried around the room rather than measuring up from the floor, since floors are often not level.

Tools and materials

• Molding for the frames (and chair rail, if desired)
• Miter saw (or miter box and hand saw)
• Brad nailer and 1 1/2 inch brad nails, or a hammer and finish nails
• Construction adhesive and caulk gun
• Tape measure, pencil, level or laser level, stud finder
• Paintable caulk, painter’s putty or wood filler, fine sandpaper (about 220 grit)
• Painter’s tape, primer and paint, brush and roller
• Safety glasses, hearing protection, dust mask

Plan and measure

1. Measure the height and width of each wall.
2. Sketch the wall on paper and decide how many boxes you want and their sizes.
3. Subtract the spacing between boxes and edges to get box size. An online layout calculator can help.
4. Draw the boxes lightly on the wall in pencil, or mark with painter’s tape, to check the look before cutting anything.
5. Write a cut list. Number each box and label top, bottom, left and right pieces.

Cut the pieces

Each corner is a 45-degree miter. The measurement for each piece is typically taken along the longest edge. The direction of the cut changes for each end, so draw an arrow or mark on each piece so you cut the correct way. Cut all pieces for a wall at once and label them. Wear eye and ear protection and keep fingers away from the blade. Follow the saw manual.

Install

1. Find studs with a stud finder and mark them, but you do not have to hit studs with every nail on lightweight trim, because construction adhesive carries much of the hold.
2. Check for wiring and plumbing. Do not nail or drive fasteners where you know of electrical cable or pipes, and be aware that wires can run in unexpected places near outlets and switches. If you are unsure, use adhesive and shorter fasteners, or consult a licensed electrician.
3. Start with the chair rail, if you are using one.
4. For each box, apply a thin bead of adhesive on the back, press into the pencil line, and tack with brad nails. Many guides install the top piece first, then the sides, loosely, then the bottom, so you can fine tune the corners.
5. Angle nails in a crossing pattern for better grip when you miss studs.
6. Wipe away any excess adhesive before it dries.

Fill, caulk and sand

Fill nail holes with painter’s putty, spackle or wood filler and sand lightly when dry. Run a thin bead of paintable caulk along the seams where the molding meets the wall and into any mitered joint gaps. Smooth with a damp finger or a damp rag. Because walls and corners are rarely perfect, caulk is what makes the molding look built in.

Paint

Prime bare wood or MDF, then paint. Many people paint the molding the same color as the walls for a subtle look, or a contrasting trim color. Semi-gloss or satin is often used on trim because it wipes clean, though matching the wall sheen creates a softer look. Let caulk cure before painting, following the label.

Drywall prep and repair

Molding doesn’t hide poor walls forever, and lighting can still show problems. Before you install, patch holes and cracks, sand any raised seams, and check for nail pops or loose tape. Our guide to signs of bad drywall installation can help you find problems that are better fixed first. For deep patches, see the setting-type joint compound guide. If you want a smoother wall behind the frames, read skim coating over painted drywall and our Level 4 vs Level 5 finish guide. Frame molding also gets installed over prepared walls, so finish the walls before trim goes up if you plan a big repair.

If you must remove old trim and the home is older, be careful: paint on old trim and walls could contain lead, and some old wall materials could contain asbestos (see asbestos in drywall mud). Test before sanding or cutting, and hire a licensed professional if needed.

Safety

Wear eye protection when sawing and nailing, and hearing protection with power saws. Keep the work area ventilated, use a dust mask when cutting and sanding, and follow tool instructions. Use a stable stepladder for upper boxes rather than a chair or furniture.