How To Build a Hidden Bookcase Door

Lead Image
  • 2-5 hours
  • Intermediate
  • 15-100
What You'll Need
Carpenter's square
Adjustable trammels or string

This article will help you consider the critical points of everyone's favorite fantasy carpentry project before you attempt it in real life. If you're thinking about constructing a bookshelf door, or converting an existing bookcase, study the challenge before you dive in. That way you'll fully understand the physical requirements before you start sawing open your wall.

The main challenge is establishing a stable mechanical pivot system—one sturdy enough to withstand many years of use without showing the usual signs of fatigue and wear, all while keeping smooth and effortless operation even when fully loaded with books.

The following step by step process will provide example calculations and measurements to give you a sense of what this takes. It only relates to an inswing door (opening towards the person when facing the shelves), which is the most commonly used version, and it's also right handed, with the pivot at the right side of the doorway, but would work just as well with the hinges on the left.

Fig 1- Bookcase Hidden Door

Swinging bookcases tend to sag from the weight of the books, so they’re often equipped with a caster at the opening end to support the weight. However, that solution will eventually leave a circular mark on the floor, and it's not very practical in a room with carpeting.

Since it’s nearly impossible to conceal the joints in the baseboard on each side of the bookcase, it might be a good idea to build it higher from the floor to clear the baseboard, as the one illustrated in figure 1. Our imagined version hangs on a sturdy pivot hinge, which in turn is mounted on a built-up block behind the baseboard.

The layout used here is for a door with a net opening of 40”, but a larger case requiring a wider opening could easily be used following the same instructions. The layout of the project will be drawn in the manner of old fashioned Rod Layouts, using a piece of plywood or other sheeting longer than the door opening and no less than 16 inches wide, the case being 12” deep.

Step 1 - Lay out the Wall and Door Opening

Sub Step 1 - Size the Door Width

Line #1 is the first one drawn and represents the existing wall and doorway into which the bookcase will be installed. It's drawn parallel to the front edge of the plywood and should be almost the full length of it, and approximately 6” back from the front edge (Figure 2).Fig 2

Sub Step 2 - Size the Door Height

Line #2 comes next and is drawn perpendicular to Line #1 on the plywood at approximately 45-46” from the left side (Figure 2). For this example only, Line #2 will be the hinge side of the “hidden door”.

Sub Step 3 - Sketch the Strike

Measuring and marking 40 inches (see note below) back from Line #2, another perpendicular line (Line #3) is drawn parallel to Line #2 and will be referred to as the Strike side of the hidden door.

*Note- If a different size opening or bookcase in in the plans, proceed the same way but ensuring that the plywood is large enough to accommodate. The opened bookcase will take up to 13-1/2 or more inches of the door opening.

Sub Step 4 - Sketch the Jambs

It is now time to sketch out the door jambs on each side of the opening. They’ll be represented by Outlines #4 & #5 in Figure 3, but will not necessarily have the same shape, thickness, or proportions.

Step 2 - Add the Accessories to the Layout

Fig 3

With Step #4 completed, a rectangle has to be sketched (Outline #6 in Figure 3) representing the net depth and the ideal but impossible maximum width of the bookcase, while respecting a 1/4” tolerance on each side to let the case open without colliding with the jambs. At the front edge of each wall, a trimming (Outlines #7 in Fig. 3) 3-1/2” to 4” wide by 3/4” thick, and extending 1-1/4” over the opening is added, as shown in figure 3. The protruding part will serve to cover up the opening created when cutting off the excess material exceeding the amount of clearance, as outlined by arc #13 in Figure 5.

Fig 3

Step 3 - Determine the Pivot Location

The location of the pivot on the bookcase has to be far enough from any edges to offer adequate strength, stability, and holding power for the pivot hardware without breaking or cracking. The use of a butt hinge which unfortunately is only acceptable on an “Out” swing because being impossible to conceal, wouldn’t require any part to be cut out of the case at the hinge side, but all of it at the strike side. Figure 5 shows the actual chosen placement with the corner cut-out for the 1/4” clearance. If the placement of the pivot was to be moved back diagonally towards the center, it would only cause the side gable of the case to be moved in at the hinge side, at the same time resulting in a further increase of the gap to be covered over by the trimming.

Fig 5

Sub Step 1 - Plan Fasteners

Line #9 in Figure 4 is to be added next. Drawing it at 1-3/4” from the front of the bookcase leaves enough wood to offer proper fastening strength. Where Line #9 intersects the hinge side wall will be the point of intersection or Axis #10 and will be used as the starting point to trace the Arc #11 with a radius of the combined 1-3/4” (pivot backset) + 1/4” (tolerance) + 1-1/4” (overlap of the Facing) adding up to 3-1/4”. The intersection of that Arc #11 of 3-1/4” radius with the Line #9 will provide the Axis #12 and the center of the pivot location.

Sub Step 2 - Plan the Gables

The backset of the two side gables can be determined by tracing the arcs #13 and #14 using Axis #12 as the point of origin (Figure 5). Stretching a radius from that axis to the intersection of Line #9 with the right edge of the case, an arc traced across to the front edge shows 9/16” wide material that has to be removed in order to get the proper clearance when opening the case. This will cause the gable has to be moved by 9/16” towards the center. Likewise and still from the same axis but with a radius stretching all the way to the left edge of the case at the intersection with Line #9, the arc traced up to the back edge of the case this time, shows that the gable has to be moved 1-1/2” towards the center to clear for the required tolerance.

Sub Step 3 - Plan the Trim

The trimming #8 can now be added to the drawing to cover up the gable’s backset making sure the appearance on the finished product while closed is identical for both sides. A reinforcing cleat large enough to fill most of the space while still clearing the door frame would provide added support and strength to the trimming.