Layering Asphalt Shingles
Tips from Real-Estate-Agents.com
by Kathy Maynard, reprinted courtesy of ServiceMagic.com
Q: I would like to know if it is recommended to remove previous,
18 year old asphalt shingles before installing new shingles of
the same type?
A: Thanks for your inquiry, it is a common question.
Although it is usually legal to overlay a second (but not a third)
layer of asphalt shingles he doesn't recommend it.
The building code, and most municipalities, will allow you
to overlay a second (but never a third) layer of shingles on an
existing shingled roof. You will need to check with your building
inspections department to be sure.
If you are doing the roofing yourself, you will save the extra
labor and the problem of disposal. I know first hand, I put myself
through graduate school in Waco, Texas roofing houses and it is
hard work-no way around it! However, it is not the recommended
procedure for the following reasons:
If there's any curling of the old shingles, the new
shingles will not lay flat. Moisture can get trapped under
the heavy layers and cause premature rotting of the wood. You
do add excess weight to the roof framing, which can cause the
decking and/or roof joists to bow and cause a ripple effect in
the roof. Overlay will not work well at all with dimensional
shingles, only three tab. If you do overlay, you have to cut
off the tab of the first course which will give you a "bump"
about 6" up the roof all the way around the roof. You
must pull off both layers before you roof next time. Many times
the cost for a double tear-off is more than doing it two separate
times. Tear off will give you the opportunity to examine the
decking for any rot and make repairs now before it gets worse
(and more costly). If you do remove the old shingles, you
will end up with a nice fresh layer of felt on the roof deck.
To find several reputable roofing contractors to gather estimates
and options for installing your new roof, simply visit our site
at www.servicemagic.com, and let us match you with the ideal service
professional in your area!
Good luck!
David Radcliff, Certified Remodeler
-- Tips courtesy of Service Magic
