How To Repair Panel Doors

After some 200 years of “hard knocks” and spotty maintenance in the harsh climate of coastal Maine, our Federal-period home’s frame-and-panel doors exhibited a range of problems—from gaps and loose joints to outright rot. Repairing them without compromising their integrity required patience and an understanding of their mortise-and-tenon joinery.

Six-panel doors are common on Federal, Georgian, and Colonial Revival houses, such as this 1938 Colonial Revival on Cape Cod. (Photo: Brian Vanden Brink)

Frame-and-panel (or rail-and-stile) doors became popular in the early 1700s due, at least in part, to the design’s clever solution for dealing with dimensional wood changes caused by fluctuating temperature and humidity. Because wood expands more across the grain than with it, the frame design minimizes the effect of expansion and contraction upon the door’s overall dimensions. The grain runs lengthwise in each frame member, which means that the frame contributes little to the door’s overall expansion, while the panels float freely in grooves, allowing them to expand and contract as necessary without distorting the door or altering its dimensions.

The design’s success also hinged on the fine, durable joinery used—most commonly mortise-and-tenon joints with wedges to tighten the tenons in their mortises. Wood pegs often were incorporated, too, driven through slightly offset holes to draw the joint tightly together and secure it in what’s called a drawbored joint.

Despite their deceptively simple appearance, frame-and-panel doors are fairly complex. Each of our doors has 56 separate parts, counting the various pegs and wedges that secure joints, and all of them must function in concert with one another. Being handmade, these parts are rarely interchangeable, even within the same door. Always number parts when taking apart a door to avoid problems later.

Disassembly & Repair

Repairs often require disassembling and reassembling the door.

Loose joints, cracks, rotted areas, and rodent damage often require partial or complete disassembly in order to access the damaged areas and fix the problems. This typically involves removing the pegs and tenon wedges, then carefully separating the stiles and the rest of the components.

Pegs usually can be driven out with a pin punch. If the peg is tapered, strike it from the small end to avoid damaging surrounding wood, and always use a punch that’s smaller in diameter than the peg. If a peg is very stubborn, it may have been glued. Heat and moisture can soften animal glue, while modern glue might require drilling.

Number the old wedges before removing them in case they are reusable, since each one is nearly always unique. If you can’t get a wedge out with small needle-nose pliers or a thin blade, try this technique: Drill a small hole in the wedge, put a dab of glue on a small machine screw (using a wood screw may expand the wedge, making it harder to remove), and slide it into the hole. After the glue sets, pry the wedge out with a claw hammer or nail puller.

After removing any pegs and wedges, place a softwood block (shaped to avoid damaging the finished edge of the stile) against the inside of the stile, and gently tap it to push the stile off the tenons. If the stile seems stubborn, check for anything you might have missed, like glue or brads that may have been used in an attempt to tighten up the door.

Inserting a screw into a wedge offers leverage for extracting stubborn non-glued tenon wedges with a nail puller. This method also can be used to remove blind dowels or pegs that can’t be driven out.

After you remove the stiles, the panels, rails, and mullions should separate without much effort, as long as they weren’t glued in place. If pieces are stuck together with paint, you can use a blade to clean some of the paint out of the joint, being careful not to damage the edges of the wood. Always number the panels before removing them.

Once you’ve made the necessary repairs depending on your issue (see below for common problems), reassembling a panel door basically involves reversing the disassembly steps, but there are a few other things to consider. Before driving in any pegs or wedges, do a preliminary assembly of all of the major parts, holding them together with clamps or large rubber bands (the kind that movers use) or by gently inserting tapered drawbore pins in the peg holes. (These long, slightly tapered steel pins are used to align and temporarily lock together door parts to allow their fit to be checked.)

Look for places where the fit is too tight or too loose, and whether any joints are out of square, and fix any issues before the final assembly. Remember that with any handmade door, there’s a good chance that when some joints are square, others might not be. I always aim for the best compromise in overall squareness, while bearing in mind that the door bottom and/or top might have been trimmed at an angle that will need correction later.

Use a pin punch with a slightly smaller diameter to drive out pegs.

Then prepare any new pegs and wedges you might need. I like to make new pegs from dowel stock. Some restorers start with a large-diameter dowel rod or square stock, then whittle it down to be just slightly larger in diameter than the peg hole, leaving some distinct facets on the peg to provide a better grip. You also can use a dowel plate to make the pegs.

Cut the pegs about an inch longer than the thickness of the door, and taper them smoothly for at least 1/4″ at one end to make them easier to drive in and to reduce the chance of splintering. (You can further reduce splintering by placing a piece of scrap wood with a hole drilled in it directly under the mortise hole; the hole in the scrap wood helps reduce tear-out as the dowel is driven in.)

New tenon wedges should match the angles of the originals, but cut them about an inch longer and trim about a half inch from the sharp end so they won’t bottom out when driven in. Don’t drive the tenon wedges in too tightly, as this can cause damage. They should be just tight enough to hold the joint firmly without crushing the tenon. After all of the pegs and wedges are installed, trim them flush with the surface using a flush-cutting trim saw.

Common Problems

Tenon wedges often can be tapped in further or replaced with larger wedges to tighten joints.

Problem: Gaps & Loose Joints
Over time, shrinkage in door components typically causes small gaps to appear in the joints. Some shrinkage is part of a door’s natural aging process as it “settles in,” and a narrow visible joint gap on the face of the door doesn’t always mean that a joint is significantly loose. If a door isn’t sagging or wobbly, the joints may still be reasonably tight or just slightly loose, in which case a simple task like tightening the tenon wedges often can keep the joints secure for years to come.

Solution: Tightening Joints with Wedges
For doors that are still reasonably tight, or just beginning to loosen, try the following: Square up the door if necessary, and clamp the stiles against the rails with bar clamps under light pressure, then gently tap in the tenon wedges to tighten the tenons in their mortises, being careful not to crush the fibers in the tenons. (Note: Sometimes a joint might not close up completely, depending on its design and wood shrinkage factors.)

It’s often possible to tighten a blind fox-wedged joint by installing a screw through the outside edge of the stile and into the tenon. When the screw is tightened, it should push the tenon back into the mortise and close or reduce the visible joint gap. (This approach, while not perfect, may be adequate.) The pilot hole, shank hole, and countersink drill sizes must be correct—screw manufacturers publish tables that can help determine the correct drill sizes based on the size and type of screw and the wood type (hardwood or softwood).

Damage to the lower corner and joint of this door (top) was repaired with patched-in new wood (bottom). This door will be painted, so the color of the replacement wood is not critical.

Problem: Wood Damage
Rot is often caused by water collecting at the bottom of panels in rail and mullion grooves. Other rot-prone areas are the exposed ends of door components, since end-grain cuts absorb water more quickly than surfaces parallel to the grain. Priming end-grain areas before reassembly is a good idea, especially for exterior doors.

Solution: Repair or Replacement
Wood replacement is my first choice when the damage involves a joint or threatens a door’s structural integrity. (Depending on the location and extent of wood damage, you may or may not have to disassemble the door to carry out a repair.) I may replace an entire component, such as a rail or stile, or splice in a new section of a component using a strong splice joint (such as a scarf or half lap), which also can be doweled if desired.

For damage that’s less likely to affect the door’s structural strength, I may simply replace the damaged area with a Dutchman patch. If the door will be painted, there are more options: If decay is confined to a small, non-structural area, you can treat it with a wood consolidant, such as a two-part penetrating epoxy, then use a bit of epoxy or polyester filler to bring the surface back flush. If the door is going to receive a translucent finish rather than paint, fillers (even a stainable filler that matches the color of the surrounding wood) will almost always show to varying degrees.

To fix a loose drawbored joint, drill peg holes to a slightly larger size using a doweling jig (top), then fill and re-drill the holes with a slight offset (bottom).

Problem: Loose Drawbored Joint
Shrinkage, poor maintenance, or abuse can distort the holes and pegs that draw the parts of a drawbored mortise-and-tenon joint tightly together, resulting in a very loose joint. Repairing loose joints requires care, but it’s not difficult.

Solution: Fill and Re-Drill Peg Holes
Remove the stile, and drill the existing peg holes to a slightly larger size—just enough to clean them up—using a drill press or doweling jig to keep the holes perpendicular. Next, fill the existing peg holes in the tenon by gluing in wood dowels and trimming them or using an epoxy wood filler.

Then, temporarily reinstall the stile on the rails without pegs, clamping it in place with the joints tight and square, and mark the position of the stile’s mortise peg holes on the tenon with a sharp pencil. (Alternately, you can use a brad-point bit the same size as the peg hole to mark the centers.)

Finally, remove the stile and drill the rail’s tenon holes with a slight offset of about 3/64″ to 1/16″ closer to the shoulder of the tenon from the marked stile hole locations. If working with all-hardwood joints, you should reduce this offset slightly (harder woods generally aren’t as compressible as softwoods).

Online exclusive: Get step-by-step instructions for repairing a knocked-out panel.

Tags: A.R. Bowes doors OHJ June/July 2013 Old-House Journal

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