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The shingles and other materials should be kept dry until installation. If materials are stacked on the ground, the materials should be placed on pallets or other type of raised platform and covered with a weather protective covering. Inspect the bundles for moisture upon delivery. If the bundles are wet, the shingles should be allowed to dry completely before installation. If they are installed wet, then problems will occur later on such as blistering, mold, mildew, etc. all of which expedite roof deterioration.
We do not recommend the use of staples! A really good type of nail to use in roofing applications is a "Hot-Dipped Galvanized" nail. This type of nail is dipped in a bath of molten zinc.
Two layers of underlayment should be used on slopes less than 4:12. Nails should be long enough to penetrate the wood decking a minimum of 3/4". A general rule of thumb is to use 1-¼" nails in re roof applications when the old roof is torn off and to use 1-½" nails when overlaying the old roof. Use a minimum of four (4) nails per unit, or six (6) nails per unit in high wind areas and six (6) nails per unit on slopes exceeding 12:12, or 12 inches of rise for every 12 inches of vertical "run" (a 45 degree angle).
When replacing decking material, it is recommended that it be replaced with half sheets (4'x4'). You want the decking to span 3 rafters. A 4'x4' sheet will span 3 rafters spaced 24 inches apart. Do not "piece" in decking and use a dense nailing pattern for installing the underlayment. That way, if the shingles blow off, then the felt should still be there to help provide protection. When placing decking over rafters set on twenty-four inch (24") centers, it is recommended that minimum 5/8" decking be used.
When installing shingles on a roof with a slope that is less than 4 in 12 (33%), it is recommended that two (2) layers of number fifteen (#15) asphalt saturated felt underlayment be installed in shingle fashion.
Ice and water protection membranes should be installed in regions where the average January temperature is below freezing (32° F, 0° C). The membrane should extend from the bottom edge of the roof, past the interior wall line a minimum of twelve inches (12"). It is always a good idea to place an ice and water protection membrane in all valleys.
For Starter courses, you can use the 3-tab, self-sealing with the tabs cut off. Cutting of the tabs is not mandatory and you can simply turn it 180 degrees and use it for the starter course. Always nail on the factory nail line!
Galvanized edge metal (drip edge, nosing, etc.) should be cleaned with vinegar prior to priming and painting. Paint your roof penetrations and flashing the same color as your fascia to improve the looks of your new roof.
Ventilation devices are installed at the very top of your roof. Installing roof vents between the intake and exhaust vents will cause a ventilation short circuit. For proper ventilation, you should have an under-eave soffit ventilation and ridge ventilation installed at an area ratio of 1:1. In other words, for every square inch of soffit ventilation you should have a square inch of ridge ventilation.
If installing gutter, try to use straps instead of nails and furrels. Nails can pull out of the fascia if your gutter fills up due to plugged downspouts and dirt and debris build up.
Never install wood decking directly over old wood decking. Wood needs to be able to "breathe" on one side or else severe warping can occur.
You shouldn’t install in temperatures less than 40° F because shingles are brittle and can crack. However, there are some currently on the market that have been installed in 0° temperatures. These shingles are manufactured from modified asphalt.
Install the drip edge material over the underlayment along the rakes and under the underlayment along the eaves. Keep all oils, greases, and chemicals off of the roof. The nails you use to install your hip and ridge cap should be approximately 1/2" longer than the nails used on the main sections of the building. This is because the hip/ridge nails generally have at least two extra layers of material to go through.
Again, inspect the bundles for moisture upon delivery. If the bundles are wet, have them returned and exchanged for new ones. If they are installed wet, then problems will occur later on such as blistering, mold, mildew, etc. all of which expedite roof deterioration.
To start with you must get the old roof ready for he overlay. Remove any curled tabs. You want the substrate of the new roof to be flat. Use a flat square nosed shovel as it works the best. Make sure the existing roof is dry before you shingle it. Trapped moisture such as dew will shorten the lifespan of your shingles. Don't overlay a roof with algae problems unless you clean it first.
Before you start, cut the existing shingles back approximately ½" to 1" from the edge of the roof all the way around. If you install new drip edge, make sure that it covers the old drip edge material or else it will look ugly. Install a starter row along the eaves. When overlaying an existing shingle roof, do not install a layer of felt between the systems. Tear off the hip and ridge cap before you start or else it will cause a large hump in the roof along the hips and ridges.
Next, nails should be long enough to penetrate the deck a minimum of ¾". 1 ¼" to 1 ½" nails are generally used in overlay applications. The nails you use to install your hip and ridge cap should be approximately 1/2" longer than the nails used on the main sections of the building. This is because the hip/ridge nails generally have at least two extra layers of material to go through.
Install all new flashing. Remove the old flashing and fill in the void that it causes with shingle material. Use four (4) nails per shingle minimum, six (6) nails per shingle in high wind areas.
Check with your local building codes department prior to overlaying the existing roof. Some cities / regions allow only two layers of roofing while others allow three layers.
Each layer of roofing adds a great deal of weight to your homes roof structure! The best way to re-do your roof is to remove it completely down to the decking and apply the new shingles. You get a better finished product as well as the full life expectancy of the shingles.
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