Built-In Bookshelves: Measure, Build, Secure to Studs and Finish

Do you build a bookcase and push it against the wall, or build it into the wall? A built-in looks custom because it fills the space edge to edge, and that is also what makes it tricky: walls are rarely plumb and corners seldom square. Measure for the worst case and the rest is carpentry.

At a glance


Skill	Beginner to intermediate; all three videos rate it DIY
Time	Paint needs a 24 hour dry time in the Home Depot build. The Weekender video says a custom carpenter would take longer than a weekend and cost much more
Cost	Not stated for the shelves. Price lumber or plywood where you shop
Tools	Tape measure, level, miter saw, nail gun, drill, stud finder, jigsaw for arches

Safety

Table saw. The Mr. Build It video warns that cutting a narrow 2 1/2 in. piece on a small contractor table saw is risky. Cut thicker stock, such as 4 in., and use jigs to hold the piece.
Wall. Before you drill into a wall, know what is behind it. See How to Find a Stud in a Wall.
Old paint. If the wall or trim is from before 1978, test the paint before sanding or removing it; see the EPA lead guidance in Drywall Repair.
Wear safety glasses with saws and nailers, and hearing protection.

Step 1: Measure three times

The Home Depot method:

Measure from the floor to the base of the molding, account for the molding height, then subtract one inch.
Measure the width at the top, middle and bottom, and use the shortest. Take two inches off for the side panels and trim.
Under stairs, expect the same: Mr. Build It measured 54 1/2 in. at one point and about 55 in. a spot 16 in. deeper. He cut for the difference ahead of time, and small gaps remained.

Four measurements for pre-built bookshelves (The Weekender): the total width of the space, the height to the ceiling or soffit, the width of the shelves and their depth off the wall. Centre the middle unit on the wall and work outward.

Step 2: Choose material

Boards. The Home Depot build uses 1×12 boards for the sides and shelves, 1×2 face plates and a plywood back.
Plywood. Mr. Build It used 3/4 in. maple plywood. He picked maple because maple and birch are easy to find at a hardware store and have the least amount of intersections when painted or stained. A reinforcing piece down the middle of the longer floating shelves keeps them from sagging.
Pre-built units. The Weekender dressed three Lowe’s bookshelves, each 3 ft wide and 6 ft tall, with 2×4 and 1×8 framing and plywood faces to make them look built in.

Step 3: Prepare the wall

Move furniture out and lay a drop cloth. Cut through the paint seal with a utility knife and pop off the baseboard and molding carefully. Mark the studs with a stud finder; see Finding Studs: Tap, Drill, Magnet or Electronic Stud Finder.

Step 4: Cut and assemble

Home Depot cut list: two 1×12 side panels, six 1×12 shelves, two 1x2s to the vertical measurement and six 1x2s to the horizontal measurements minus 1 1/2 in. for the face plates.

Mark the sides together: one inch below where the crown molding rests and one inch above where the baseboard top will sit. Square the lines across.
Mark shelf spacing on the edges and square it down the boards.
Glue the bottom shelf’s edge to a side, secure with a nail gun, and add the others.
Pre-drill pilot holes and add screws. Fit the second side with glue, nails and screws.
With the unit face down, glue the back edges and nail on the plywood back.
Glue and nail the 1×2 face plates to the front edges.

Mr. Build It mitres the face frame pieces at 45 degrees with wood glue, and pre-drills so the wood does not snap.

Step 5: Secure and trim

Slide the unit into the space and screw it into the studs. The Weekender’s skeleton fastens 2x4s into the soffit and says fasteners should go into studs; the Home Depot unit uses screws into the studs. Nail trim to blend with the existing molding and baseboard. A vertical 1×2 fits between the crown molding and the baseboard or wainscoting.

For arches: trace with a scrap piece of wood screwed at one end with a pencil hole at the other, like a hinge. Measure the shelf, divide by two, and that is the radius. Cut with a jigsaw, and smooth with a sander.

Step 6: Fill, caulk and finish

Fill gaps. Rub a round-shafted screwdriver lightly over rough corners to close seams (careful not to break the plywood), sand, and dab on wood filler. For hard corners rub filler in with a finger, then sand with 220 grit (120 if you need to remove more).
Caulk the wall gaps. Push a bead of paintable caulk deep into gaps, let it dry and paint over it. See Caulking and Sealing.
Stain. Test stains on a scrap of the same wood. Use pre-stain on woods such as pine to reduce blotching. Brush stain with the grain using a foam brush, let it soak about two minutes per the label’s typical directions, then wipe off the excess.
Clear coat. Mr. Build It uses wipe-on polyurethane with a rag for three to four coats, so the finish doesn’t land on the walls.
Paint: allow 24 hours to dry (Home Depot).

Mistakes to avoid

Measuring in one place only.
Skipping the studs. Do not rely on drywall to hold a loaded cabinet.
Spraying clear coat in the room.
Cutting narrow pieces on a small table saw.

Start with

Start with a pair of simple shelves in a single bay of one wall. Practise on a scrap of plywood: glue, nail and fill a corner, then sand it. Then do a full unit.

Sources

Shown on this site, source of the measuring, cut list, assembly and installation steps. Build Built-In Bookshelves With 1×12 Boards and a Plywood Back (video, The Home Depot) Source
Shown on this site, source of the plywood, face frame, stain and gap advice. Building Plywood Built-In Shelves Under a Staircase (video, Mr. Build It) Source
Shown on this site, source of the hidden frame and arch method. Turn Basic Bookshelves into Arched Built-Ins with Plywood (video, The Weekender) Source
Shown on this site, source of the stud-finding methods. Finding Studs: Tap, Drill, Magnet or Electronic Stud Finder (video) Source

Watch

The videos and projects this guide mentions.