Saturday, October 3, 2009

How to Repair a Split in a Wood Door Panel

A common problem with older wood doors is split panels. Wooden panels were typically fitted into grooves plowed in the door rails and stiles and left to float so they could expand and contract without binding and splitting (for a primer on making wooden panels, see my last post). However, varnish, wax and dirt can build up over the years and stick the panel in place so it isn’t able to expand and contract. Since the wood can’t move, stress builds up and the panel eventually cracks and splits. This common problem usually isn’t a difficult repair and can be done by any homeowner with a few fix-it skills. Below is a step by step outline of the repair process.

This white pine exterior door was built in a Minnesota millwork shop around 1863 and hung in the rear entrance of the LeDuc House in Hastings, MN (for pictures and a description of the LeDuc, see my post below). The exterior side of the door is very weathered and one panel has failed, leaving a large split which lets water and drafts into the building.

The interior side of the door is in good shape, although it appears the LeDuc family owned a large dog which badly marred the lock rail.

The first step is to remove the bolection moulding around the panel. The safest way to accomplish this is to use wooden shims. I use a razor blade to score the varnish and gunk between the moulding, door and the panel and then slowly push wood shims under the length of the moulding. Work slowly and carefully since the thin strips of moulding are fragile and can easily break. The card stock under the shims keeps them from abrading the old varnish.

Continue to slide more shims under the first ones until the moulding begins to lift. Once it is lose, carefully use a small pry bar to pry the moulding up. Be sure to place the end of bar near nails as that will put less stress on the molding. You can also slide shims under the back edge of the moulding. The trick is to keep even pressure along the length of the piece. Be sure to number the pieces as you remove them so you can return them to their original position.

Once all the moulding on both sides has been removed, gently clean the edges of the panel using mineral spirits or naptha and a soft cotton rag. Use 0000 steel wool if the dirt and grime are especially thick. Once you are done, carefully scrape away any remaining gunk and allow the panel to dry completely.

The next step is to open the split as carefully as possible. This is necessary because glue will not adhere to dirty, oily or decayed surfaces. Exposed wood oxidizes and erodes over time leaving a poor surface for gluing. Years of dirt, grime and gunk also make good glue-ups difficult. Once you have opened up the split you can use strips of cloth with solvent, dental instruments, small knives and 220 git sandpaper to clean the surfaces. BE VERY CAREFUL AND DO NOT REMOVE TOO MUCH WOOD!! If you are sloppy and sand or cut away good wood along with the dirt and grime you will not be able to close the joint completely and get good glue adhesion.

A close-up of the cleaned split which is ready for gluing and clamping.

One difficulty in gluing up a door panel is clamping it. To do this you need to glue wooden blocks on both sides of the panel along the split. Be sure to place the block on areas that will be covered by the pieces of moulding once they are replaced. I use a hot glue gun to do this because the hot glue really binds the blocks to the panel so you can clamp firmly. Once you are done the blocks can be removed easily and cleanly with a chisel because hot glue has very poor shear strength.

I used a syringe to inject glue into the crack and a bit of a shim to spread a good amount of glue on both surfaces of the split panel. I clamped the panel tightly and cleaned up any squeeze-out with a damp cotton cloth.

Once the glue set up I removed the clamps, blocks and replaced the pieces of molding using new cut nails. Be sure that the panel is floating in its grooves so that it able to move and will resist splitting in the future. Since this door was so badly weathered the split did not close up as tightly as I would hope despite clamping it quite tightly. To make the split less obvious I used colored wax matched to the stain to hide the crack.

Although you can still see the split, it is now less obvious, closed and weather tight. The key to maintaining exterior wooden doors is regular maintenance. Be sure to repair splits, refinish regularly and care for your doors as problems arise. If neglected, problems will worsen making repairs more difficult and less successful.