Step 1: Mark and trim the door bottom
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Photo 1: Trim the door
Scribe a line on the door 3/8 in. above the top of the threshold. Remove the door
and carefully cut along the line with a circular saw.
Older wood doors usually rely
on a non-adjustable threshold
to keep the weather out. If
your old door doesn’t seal tight against
the threshold, you’re wasting energy.
You could screw a surface-applied
weather strip to the face of the door,
but a door-bottom weather strip is a
less obtrusive way to create a good seal.
The door bottom we’re using is
available at most home centers and
hardware stores. If you can’t find a
door bottom that’s smooth on one
side, you can slice off the barbed
flanges from bottoms designed for
steel or fiberglass doors.
Cut the bottom of the door to allow
enough (but not too much) clearance
to install the new door bottom. The
goal is to create an even 3/8-in. space
between the top of the existing threshold
and the bottom of the door. Close
the door and measure the largest gap
between the door and the threshold. If
the gap is less than 3/8 in., calculate
how much you’ll have to cut off the
bottom to equal 3/8 in. Mark this distance
on the door at the point you
measured. Then use a scribing tool to
extend a mark across the bottom of the
door (Photo 1).
Remove the hinge pins and move
the door to a set of sawhorses. Mount
a sharp blade in your circular saw and
cut along the line. Protect the surface
of the door with masking tape. If you
have a veneered door, score along the
line with a sharp utility knife before
sawing it to avoid chipping the veneer.
Step 2: Install the new weather strip
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Photo 2: Install the new weather strip
Cut the door bottom to length with a tin snips or utility knife. Apply two
parallel beads of adhesive caulk the length of the door and nail the door
bottom to the door.
Cut the door-bottom weather strip
about 1/8 in. shorter than the width of
the door and tack it to the bottom of
the door with a staple gun. Rehang the
door to test the fit. If it's too snug,
remove the weather strip and trim a bit
more from the door. When the fit is
perfect, remove the staples and mount
the weather strip (Photo 2).