So that they can look like old wood or slate shingles in size and shape. At
some point during the asphalt technical revolution, someone made a machine
that could produce 30 inch wide sheets of asphaltic bitumen... then they
were divided sliced like cheese and divided equally into 3 tabs so as to
resemble classic shingles. I think an even better question might be "how
come shingles aren't manufactured in standard 4 foot sections using 4 tabs?"
Technical limitations of the product, invented before the 4 foot measurement
became standard, or a combination of both?
During Charley millions of tabs were snatched off of thousands of roofs.
I believe the vertical slots cause weakness in the shingle.
And....the typical nailing pattern is to place the nails directly above the
top of the slot, about 1" away.
It seems to be a procedure that is doomed to fail, especially if the nailor
uses staples, that act like little knives, instead of roofing nails.
Its generally assumed around here that if the shingles are installed in the
summer, after 30 days they are *sealed*, the backing adhesive has bonded
with the shingles below. However, hurricane season doesn't end until the
beginning of Dec. and if shingles are installed in Nov and it happens to be
cloudy or cold then the shingles could be susceptible to a failure in the
event of a late season Cat 1 or 2 storm.
(My cousin counted over 700 tabs missing from his 15 y.o. shingle roof. He
got the whole thing removed and new shingles installed and made money on the
deal. The insurer paid him $13k for it and he paid the roofer $9k. He's one
of the rare people that benefitted from Charley.)
All the US shingle manufacturers I know are giving a 20-year warranty on
their basic generic shingles.
It should mean a properly installed shingle roof should last at least 25
Then, read Don reservations and make up your mind.......
You want a real long lasting good shingle roof?
Lay it over a minimum 16-18 mm thick exterior grade plywood deck (REAL
Cover the deck with a strong underlayment felt.
Use European Standards shingles, NOT ASTM.
Give preference to APP-modified bitumen shingles, not the standard oxydised
Make sure of proper ventilation.
Nail it, do not stapple it.
You got it.
Not cheap, but you got it.
Seems likely. Nothing lasts in AZ. There is no such thing here as "glue". Of
any sort. We use velcro for everything ;-). I'd expect distance between
extremes of temperature to play and even humidity. Not sure diet of
occupants comes noticably in to play.
If the roof assembly is properly ventilated, climatic conditions do not
really modify the shingles life expectancy (Beside heavy hurricanes, for
sure). Don't forget, it is small elements, so they don't suffer from
temperature, moisture, etc, as a monolithic membrane or similar.
I am doing shingles in tropical/equatorial countries since quite a while, no
specific problems beside the fungus attack risk, but we know how to tackle
Colours don't really change the life expectancy.
A light colour will reflect more heat but will be more prone to colour
fading, darkening than a darker colour, that's all.
I am talking, obviously, about good quality US or Canadian shingles, not
about..... mmhhh! I won't name "them" here, thay may sue me :-)
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