Putting up new roofing and making it last for as long as possible at its highest level of performance is not nearly as easy as it might at first seem. It's not nearly so easy as just "throwing on a few shingles," but instead, it requires an orderly, step by step process of applying multiple layers of material to the roof decking in the proper manner. Anything less can compromise the longevity and integrity of the finished product.
Here is a basic overview of how roofing shingles should be installed, in 4 steps:
1. Prepare The Roof Deck
If your roof currently already has old roofing on it, it will have to first be removed before installing the new shingles. Roofing over old shingles prevents the new shingles from laying flat to the roof deck and seriously weakens them, shortening their life span.
Also, all old nails must be pulled out of the roof decking so they won't punch holes in and/or crack the new shingles. And the roof deck should also be swept clean of all dirt, dust, shingle dust, and debris. If any plywood is broken, weakened, or molded, it must also be replaced. And all possible leakage points should be caulked.
2. Install Underlayment & Flashing
The second step is to cover all roof decking with water resistant underlayment. This will help with moisture control plus act as a reinforcing backing to the shingles themselves. No gaps should be left uncovered by underlayment, and it should overlap and be nailed firmly down at all points.
The valleys bear the brunt of rain erosion and are the most likely leak points. They, therefore, need to be protected by flashing and/or ice & water guard. Flashing and/or caulk also need to be installed around chimneys and vents. Drip edge is also installed at the eaves to prevent water from wicking up the roof under the shingles.
3. Apply Shingles In Correct Sequence
Aluminum roofing nails (which will not rust) only should be used to fasten shingles to the roof deck. At least three or four nails are placed an inch or so in from the top of each shingle, and then the next shingle overlaps to cover the nails, provide extra protection for the roof, and to seal to the shingle below it along a special tar strip.
Shingles must be run from the eaves up so as to overlap properly, row by row. Where necessary, shingles are cut to size to finish each run, and extra nails are put on the ends to prevent the wind from getting underneath.
Where shingles align diagonally in roof valleys, no nails should be placed closer than six inches to the valley centerline to prevent punching a hole in the middle of the flashing or ice & water guard.
4. Install Hip & Ridge Caps
Finally, when the shingles reach the peak of the roof or sloping peaks called "hips," specialized hip & ridge cap shingles are used to cap the roofing. For hips, you have to overlap going upwards, while flat ridges should be overlapped with creases facing away from prevailing winds.
You can use regular shingles for hips and ridges if you cut them to size, but you can't just bend the shingle over the top.
For more tips and advice on sound roofing practices, or for a free quote, contact Sheegog Contracting today!