Screen Door Corner Joinery

Advice on wood choice and joinery for a custom wood screen door replacement. August 15, 2011

I need to build a screen door to replace one that is old, worn out, and badly sagged. My thoughts are to use 1 1/8" thick thermally treated poplar, or possibly Spanish cedar or mahogany, depending on the availability at my local supplier. What joint would be the strongest at the four corners to provide a sag free door? Mortise and tenon comes to mind but is time consuming. I am pondering using a biscuit for alignment at each corner, then drilling holes through the stile into the rail and hammering in a few oak dowels in each joint. Would lap joints suffice? Any thoughts would be appreciated.

Forum Responses
(Architectural Woodworking Forum)
From contributor G:
If you are not going to do mortise and tenon then the half lap with an epoxy joint would suffice. Not going to be a 50 year door, but it should last 15-20 years before the epoxy finally fails. Biscuits will fail soon. A tongue and groove joint using a 1" tongue would work well too. You could always use a couple of 3/8" x 3" long dowels in the ends of the tongues to help keep it together.

Down and dirty dowels with a long screw and a plug would work. It would be less expensive and quick, and also give a ten year service. The screw will be the weak point as the wood moves around with the humidity. The screw will loosen and become ineffective after a few years leaving the joint relying on the dowels.

From contributor A:
I concur with Contributor L; however, he is 50% conservative on his failure projections. Do not use poplar.

From contributor U:
One of the benefits of mortise and tenon joints is that the joint is using the same wood as the rest of the door. One problem with biscuits and dowels is the wood they are made from will rot or fail before the rest of the door. Even though they are encased in the wood rails and stiles, they do get wet and when the joint opens up some, they will deteriorate. I would go with the lap epoxy suggestion if youíre not willing to do the mortise and tenon.

From the original questioner:
I will probably do the mortise and tenon joint, I just needed some validation. I have a mortising attachment for my drill press that hasnít seen much action for awhile. I am not sure about using the thermally treated poplar, the sawmill that I usually buy my lumber from is talking it up a lot. I might still use Spanish cedar or mahogany as I know these will be stable and last a while outdoors.

From contributor O:
A bridal joint can be made at the bandsaw, tablesaw, jigsaw in a pinch, at a drill press, or with hand tools surprisingly quickly. Stick with mahogany or cedar.

From contributor C:
If the poplar youíre talking about is what I have known as roasted poplar, then that would be a fine choice. Itís lightweight and insect and rot resistant. Itís chocolate in color and smells like a house fire. The only negative experience I have had with it is checking. It is remarkably stable though. I would definitely do mortise and tenon joints for the one door.