When building a new home it is up to the roofing contractor to follow the recommendations of the designer. In wintry areas of the country metal, especially aluminum sheet roofing, is popular because it sheds the heavy snows before the build-up can cause structural damage. In southern areas, where snow is a non-entity, clay tile roofing both reflects and dissipates the heat before it can get into the home.
In Canada over 70% of the roofs are shingled with a three-tabbed asphalt shingle and many of these projects are completed with the top-of-the-line, 25-year product. However, the date on the package and the actual life may not always coincide. For many homes installing an asphalt-shingle roof is a job that is done every 12 to 15 years. Because even with the long-lasting types of asphalt shingles longevity depends upon where you live in the country and how the material is installed. For example, in areas with seasonal hail the ceramic aggregates that coat the external surface will wear off well before the expiry date. As well, a home under large, shady deciduous trees will see moss colonies that will breakdown the shingles.
Fiberglass shingles are almost like regular asphalt roof shingles except a fiberglass matt forms the structure. They are lighter but they can rip off easier in the windstorm than the paper matt so their advantage is in areas with less wind.
Deciding What Roofing Is Best
When deciding on a roofing system for re-roofing a home it is always tempting to go with the material on the roof even though it might not be best for the structure. Asphalt is the most inexpensive but does it do the job? And although cedar shakes match the decor of the home is the expense of having to redo the roof down the road worth the aesthetics?
Architectural roof shingles, also called laminate shingles, add a shake-like appearance with the durability of the higher-end material in that they are less prone to snapping off in a strong wind like the thinner, three-tab variety. Like the regular shingles architectural shingles can be have a paper or fiberglass core.
The roofing process is quite straight forward but finishing the roof so that it doesn't leak is the tricky part. All eaves and valleys have to be flashed, which means that a metal strip has to be inserted to direct water away from the roof and, ultimately, the home. Roof flashing goes around chimneys, skylights, vent pipes and electrical conduits. In fact anything that sticks out of the roof has to be finished in this way.
There are more roofing contractors familiar with the asphalt roofing system than all the other materials put together. The great thing about asphalt shingles is that they are inexpensive and there are a lot of contractors who do the job. In other words a homeowner can get a break because, although the shingles cost the same, the labor cost can be ground down. The rule-of-thumb for a roofing cost is double the price of the roof materials. So if you know how much the materials cost you will get a rough idea on what is a fair price for the roof.
A big cost of asphalt roofing is removing the old shingles. Years ago frugal homeowners put new shingles over old thinking that the roof would be more stable. However, this process shortened the life of the new shingles because the shingles did not sit flat and the curving exposed the shingles to uneven wear. In addition, if long nails weren't used then the outer shingle wasn't fastened properly and could come off in a storm.
Roofers scrape the old shingles off the roof deck with a roofing shovel, a short-handled spade with a fulcrum to allow the roofer to pop out the nails. Every nail has to be taken out of the roof deck to avoid piercing the new roof at a later date. When the roofing process is being done the contractor has to watch the weather reports especially if the roof is going to take a few days. This is why most bungalows are completed in one, long day by a large crew to avoid the chance of rain.
Once the roof deck has been cleaned off the eaves and the gable edges are lined with the drip-edge, a metal strip that protects the edges from water. Then an ice-and-water shield is installed. This is a rolled roofing membrane that prevents wicking water and ice from getting up under the shingles and causing rot in the roof deck. Tarred felt, or tar paper, is run up a portion of the roof from the eave and put in place with a stapler. This will provide a barrier between the roof deck and the shingles in case of a leak. In some cases tar paper is put down after a 5th course of shingles is installed. This is placed just over the top of the shingle so that in case of a leak the water will only travel underneath five shingles before it is expelled outside.
The bottom course of the shingle, the one that starts on the eave, is flipped 180 degrees and put on upside down. This so that the slots of the tabs from the next course will not expose the tar paper. The next course is placed directly above the shingle and then each successive row is placed further up. A mark on the shingle gives the accurate distance.
As the shingles are installed a succession of chalk marks from the peak are followed. When the peak is reached from both side (on a normal gabled roof) then a ridge vent is installed. This will prevent water from coming in but will allow moisture and heat to escape. This vent is then shingled.
Old shingles and tar paper are usually recycled and begin their new life as part of the asphalt paving industry.
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