Curling happens on the corners of shingles, where the ends
appear to be bent. They can curl either upwards or under themselves.
Like most roofing problems, curling is do to moisture or an improperly
ventilated attic space. However, there are other causes that result
in curling as well. Lets discuss them all.
- High Nails: Curling can
occur when the nails that are securing the shingles to the decking
are sitting up. Through expansion and contraction of the roof
decking nails can inch themselves upward. The way the nailing
patterns are set up when installing shingles, this can cause a
curling effect on the shingle tabs.
- Lack Of Back Coating: Each
shingle has a tar line or what some call an adhesive strip. This
strip adheres the shingle tabs to the shingle row below it. If
shingles are not installed according to manufactures suggestion,
this adhesive will not line up properly - and cause the tabs to
- Lack Of Ventilation: If
a roof is poorly ventilated and in many cases not ventilated at
all moisture will build-up in the attic. This lack of ventilation
prevents the moisture from exiting the attic space. The moisture
will become condensation and begin to cause damage to the homes
framing and roof decking. The moisture needs to go somewhere!
Slowly and surely it will become trapped between the underlayment
and the roofing shingles. This can cause the shingle tabs to curl
from the underside.
- Improper Nailing: Curling
can also happen when a roof is not installed properly. A nailing
pattern is designed in a certain way. If an installer deviates
from that, many problems can occur. The industry calls it "skip
nailing." An example may be that the manufacture recommends
four nails per shingle - however, the installer wants to move
along faster and takes it upon himself to use only 3 nails per
shingle. This causes the shingle to slip downwards, causing a
If curling is noticeable then you may have a ventilation
problem. Add ventilation to the attic space by adding a ridge vent
and making sure you have adequate soffit ventilation an baffles
(rafter vents). The minimum requirement is one square foot of net
free vent area per 150 square feet of attic floor space if a vapor
retarder is not present. If a vapor retarder is present, the amount
of required ventilation can be reduced to one square foot of net
free vent area per 300 square feet of attic floor space.
Another solution is to simply do an inspection of the singles that
are curling. Carefully lift a curling shingle tab and inspect the
cause underneath. In many cases a nail may be protruding up that
can simply be re-nailed. You may notice that the adhesive strip
is damaged or in the wrong place. If so, use roofing cement to adhere
the tabs down. If there is moisture and condensation under the tab
the you may indeed have a ventilation problem. Usually fixing the
ventilation in the attic will allow to curls to sit back down after
a few weeks or months.
A better solution is to remove the shingles that are affected.
This is done by removing the shingles and inspecting the cause of
the curling underneath them. Cut out felt or underlayment that may
be causing the curling as well. Then replace the area with new shingles.
Depending on the size of the area to be fixed you may elect to replace
all the shingles for symmetry and appearance. Make sure to apply
shingles in accordance with the shingle manufacturer's recommendations.
For a more permanent solution, re-roof with Owens Corning Shingles.
They are specifically designed to withstand North and south Carolina
moisture conditions for extended periods of time and are backed
by our strongest product warranties* available to homeowners.
For the average homeowner this process can be difficult and dangerous
to do on their own. Patton General Contracting* is a certified installer
of Owens Corning roof products as well as RoofLock - a product designed
to clean and protect your roof from this type of issue. Visit
here for more information.
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Other Issues You May Have
with any type of work you personally do on your home or in this
case inspecting your roof, please use caution and safety equipment.
If you do not feel comfortable inspecting your roof or you have
trouble knowing what exactly to look for, please feel free to contact
us for a free consultation.
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home photos using Owens Corning Roofing System.
Feel free to contact
us at any of our North and South Carolina
locations with any questions or concerns you may have about
your roofing needs. We will be happy to assist you in any way we