How to Build an Airtight Door

Building a door is much easier when there is an element of flexibility with the spacing. Interior doors often have some excess space to play with when measuring, particularly at the top and bottom of the door. Making an airtight door, however, requires a higher level of attention to detail, and may take a few modifications and customizations to figure out the best method. Excess space around a door that is meant to be airtight can be blocked out with weather stripping around the frame of the door. This foam barrier helps make and keep a tight seal around the edge of the door.

Tape measure
Saw
2 plywood sheets, about 3/4-by-36-by-80-inches
Drill
Wood drill bits
Wood screws, 1 1/4-inch
2 door hinges
Doorknob with faceplate
Weather stripping, 1-inch
Caulking
Rubber door threshold strip

Instructions

- 1
  Measure your door frame's height and width. Subtract 1/2 inch from both measurements. Using a saw, cut out two 3/4-inch plywood boards at those final dimensions, which should be about 36-by-80-inches.
- 2
  Set the two plywood boards on top of each other. Drill 1 1/4-inch wood screws through the top plywood board and into the bottom one, spacing the screws every 6 inches in a rectangle on the door's main surface, about 3 inches from the edge of the door. Space the screws in a 12-inch grid in the middle of the door.
- 3
  Hold the door in the doorway with the help of an assistant and position two door hinges between the frame and the door. Adjust the door until it is completely even within the frame, and mark the position of the hinge attachment screw holes. Drill out each hole and attach the hinges to the door and the frame, using 1 1/4-inch wood screws.
- 4
  Position the doorknob along the other edge of the door. Mark the chosen position and drill out a hole big enough for the doorknob's internal latch section. Drill another hole through the edge of the door and into the main doorknob hole for the doorknob's latch operation. Set the doorknob inside the hole and connect it. Close the door and mark the position on the frame where the latch contacts the door.
- 5
  Position the doorknob faceplate against the frame where the latch strikes it. Mark the screw hole positions and the main hole position. Drill out all the holes and install the faceplate in the frame with 1 1/4-inch wood screws.
- 6
  Apply 1-inch weather stripping all the way around the edge of the door, excluding the bottom surface. Add 1-inch weather stripping all the way around the interior edge of the door frame.
- 7
  Position a rubber door threshold strip across the bottom of the doorway. Shut the door to determine if the height of the strip provides an airtight seal. Add weather stripping under the strip if the seal is too loose. Lay a bead of caulking along the floor of the doorway and attach the rubber door threshold strip to the doorway firmly once the correct height has been reached.

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