How to Make an Exterior Door

Knowing how to make an exterior door does not require a lot of expensive tools or expert woodworking skills. All that is necessary are a basic table saw, drill press and router.  As for woodworking skills, patience, attention to detail and careful measurements will fit this bill.

Required Materials and Tools

• Table saw
• Safety glass
• Waterproof glue
• Silicone weather proof caulking
• Caulking gun
• Spar varnish
• Approximately 18 board feet of hardwood (Oak, Cherry or Walnut) at least 1-1/2 thick 
• Approximately 30 board feet of similar hardwood, ¾ inches thick

Step 1. Designing the Door

Measure and cut lumber for an outer frame of two 84 inch upright stile pieces, approximately 4 inches wide, a top rail 3-1/2 inches wide and a bottom rail 8 inches wide. When fitted together, these rails and stiles should comprise a square of a standard sized door opening of approximately 36 inches by 80 inches. Cut and fit two inner horizontal rails approximately 2-1/2 inches wide and two vertical mullions of the same width. 

Panels of wood or glass may be placed between the inner and outer rails and stiles as desired. It is usually the custom to include taller, wider panels for the bottom of the door, and either a single, centered safety glass panel, sandwiched between two solid wood panels for the upper portion of the door. Alternatively, these three panels can be comprised of a single safety glass panel, or three panels in a row.

Step 2. Construction Joinery

Keep in mind that when making an exterior door it should be weather-proof and as flat as possible. For these reasons, weather-proof glue and mortise and tendons are used for joinery. It is extremely important to apply sufficient glue to all joints before final assembly. Equally important is ensuring that construction takes place on a very flat surface. These two facts must be considered before applying the final clamps and cinching them down tightly. The structure of the door stiles and rails can be completed without worrying about the panels, which will be built while the glue for the door frame is drying.

Step 3. Installing Raised Panels

Construct a series of raised panels and accurately fit them between the rails and stiles of the exterior door frame after clamps have been removed and glue has thoroughly dried. Single raised panels can be constructed out of thicker wood or pairs made out of thinner wood. Machined molding can be used to hold the panels in place. Glue, nail and apply silicone caulking along the inside wood molding and glass panels to provide for insulation.

Step 4. Weather-proofing an Exterior Door

Exterior doors are subjected to a lot of weather abuse. Hot sun, cold weather and rain can take a toll on exterior doors. To protect doors from this kind of abuse it is essential to apply a good finishing coat on both sides of the door. Begin by sanding with a 100 and working up to 220 grit sandpaper. Apply a primary coat of 50-50% of Spar varnish and mineral spirits. When thoroughly dry, apply two more coats of 100% varnish. Finish with 0000 steel wool.