STOPPING
FLAT ROOF LEAKS AT SKYLIGHTS AND PARAPETS:
The flashing around the curb of a skylight on a flat roof seldom
has to be replaced, but the flashing can pull away from the curb
due to the expansion and contraction of the wood that forms the
curb. This causes leaks. If the gaskets sealing the skylight are
okay, look for the leaking problem at the flashing. You
will have to remove the skylight (probably) from the curb to get
to the flashing. Once the skylight is off, the job is easy. Clean
away all debris with a broom.
With
roofing nails, reset the flashing against the curb, driving the
nails flush with the flashing and asphalt building paper and roll
roofing that is lapped up against the flashing. Just drive the nails
flush to the surface of this material. Then trowel asphalt roofing
cement over the area in a fairly thick coating.
If
the roofing is damaged where it "folds" or laps up against the curb,
you may be able to replace it with a patch. Clean away the stone/gravel
next to the curb and lay a piece of asphalt roll roofing in a fairly
thick bed of asphalt roofing compound. Fold the roofing gently and
lap it up the curb. Then nail it in place. Cover the patch and nails
with the compound. Then add stone/gravel and embed it slightly into
the compound with the flat of a trowel or shovel.
The
wooden curb could be rotted, causing leaking. If this is the case,
the curb has to be replaced along with the flashing and the roofing
that overlaps both. This is really a job for a professional since
the curb may be tied in structurally with the roof framing.
PARAPET
FLASHING:
If the roof has a parapet, chances are the parapet is flashed along
its top with metal (although sometimes the flashing is just roofing
lapped up and over the top).
If
flashed and the flashing is damaged you can replace the damaged
section easily.
-
Remove any stone/gravel from the area.
- With
a prybar padded with a piece of scrap wood which also acts as
a fulcrum, loosen the nails that hold the flashing into position.
Then pull the nails. You should be able to lift off the flashing
cap now.
- Clean
the area under the cap.
-
Cut a piece of asphalt roll roofing for a patch to fit under the
flashing. The patch should overlap the spot that you are repairing
at least 4 inches. Embed the patch in roofing compound troweled
on fairly thickly. Press the patch in place.
- Cut
another patch that overlaps the first patch by about 6 inches.
Coat the first patch with compound and press the second patch
in place. Add extra compound at the joints. Use plenty of compound.
- Replace
the flashing over the patch. You'll probably have to bend the
flashing for a tight f roofing nails and then seal the nail heads
with roofing compound. Replace the stone/gravel to complete the
project.
VENT
STACK FLASHING:
If the flashing is leaking around a vent stack, you may be able
to replace this flashing with new flashing you can buy at many building
material outlets and home center stores. The cost is not prohibitive.
- Remove
the stone/gravel around the stack. With a utility knife, cut the
roofing membrane at the old flashing. You'll be able to see the
outline of it through the roofing. Then with a prybar and scrap
wood fulcrum, remove the old base plate of the flashing.
- With
a piece of roll roofing (or buy pre formed), make a patch to cover
the area of the old base plate. Cut a round hole in the patch
ing material to fit down over the stack. Make this hole a tight
ft so the roll roofing laps up the stack slightly. Cover the patching
area with compound and embed the roll roofing into it.
-
Now slip the new flashing over the stack, embedding the base of
the flashing in a thick layer of compound. Nail the flashing to
the roof decking and with pliers crimp the top of the assembly
into the opening of the stack. Coat the base of the flashing with
plenty of roofing compound and replace the stone/gravel around
the repair.
