A New Roof is More than Just Shingles
If you are doing a tear-down, or stripping the shingles to the bare sheathing of the roof deck, this is a fine time to upgrade attic ventilation and rain gutters. The best attic ventilation is to have continuous venting at the eaves and at the roof ridge. With this ventilation system, cool air is drawn in at the eaves, warmed as it moves across the insulation or attic floor, and rises. As the warmed attic air rises, it flows out of the attic through the ridge vents, carrying any moisture in the attic outside. This cool air creates a vacuum behind it as it is heated, rises and exits, and the vacuum thus created will pull in cool air through the eave vents. This natural air flow is called the "chimney effect" and is necessary to control attic moisture levels and relieve attic heat buildup. The best time to upgrade attic ventilation is when you are reroofing. Ask your dealer to suggest a brand of continuous ridge and soffit venting.

In addition to the shingles you will need a number of accessory materials. First, you will need to buy roof underlayment, usually referred to as "15 pound felt", which is a roll material made of felt saturated with asphalt. This underlayment is rolled down on the bare roof sheathing and stapled in place, so the sheets overlap by about 2 inches. The underlayment serves several purposes: It protects the roof deck or sheathing, and the house interior, from rain while the reroofing is going on. The underlayment also provides a secondary barrier to the finished shingle roof, and ensures against windblown rain entering under the shingles. Be sure to use 15-pound felt underlayment, or its equivalent: do not install any material that might be a vapor barrier. A material that acts as a barrier to moisture passage will trap any leaked moisture or frost between the shingles and the roof deck.

You will also need valley flashing. Valley flashing in the past was made of galvanized sheetmetal. In time the galvanized finish (zinc) weathered away, and the valley flashing rusted so it leaked and stained the shingles. Today, most roofers are using aluminum valley flashing. The aluminum flashing is resistant to corrosion, and it is prefinished both for visual appeal and for weather protection. Also, buy new metal flashing sleeves to fit over the chimney stack and plumbing vent pipes.

In colder climates where winter temperatures fall below 0-degrees, your building code may require that you install eave flashing. In some states in the northeast, such as Pennsylvania, a wide strip of aluminum flashing is installed at the roof eaves so that the sun, warming the metal, will melt ice and prevent ice dams from forming. In other areas, a double layer of felt underlayment is installed at roof edge to ensure against ice melting and running under the shingles. Usually this second layer of underlayment is installed so it extends at least one foot past the edge of the exterior walls on roofs with 4/12 or greater slope, and two feet past the exterior wall on low-slope roofs.

To prevent water damage at the edge of the roof, a metal drip edge is installed. The metal drip edge is intended to ensure that water that runs to the eave will drip off, not bead up and run back under the soffits or eaves.


You will also need some roofing cement to glue down shingle corners and seal any joints between roof shingles and valleys or flashings. Buy the roof cement in caulk tubes for easy, no-mess application. Buy extra tubes so you don't run out: most dealers will let you return unused, unopened tubes of roof cement.

You will also need galvanized shingle nails. Your dealer can help you figure the quantity or number of pounds of nails you will need, based on the size of your roof, in squares or in hundreds of square feet. Tip: if you are shingling over a clean deck, where the old layer of shingles has been removed, you can use 1-1/2 in. nails. If you are reroofing over one layer of old shingles, you should buy 2-in. roofing nails, to penetrate through the extra layers of shingles.

A recent consumer article we read talked about roofing, and cautioned that a third layer of shingles would add too much weight on the rafters to be safe. Actually, most building codes (all codes that we are aware of) let you reshingle over your first roof, but when you already have two layers of shingles on the roof you must tear down or remove the old roofing, down to the bare roof deck, and start anew: you cannot have three layers of shingles on the roof. Most such code prohibitions are based on common sense: The first hazard of three layers of shingles, the difficulty in finding a leak in so thick a roof, and the danger of damaging the top shingles when walking and working over so many layers of shingles are all reasons not to apply more than two layers of shingles.

If you decide to reroof and do the work yourself, and you are removing the old roofing, call your trash collector and rent a dumpster. Have the dumpster set close enough to the house that you can throw the old shingles directly off the roof and into the dumpster, to avoid making a mess on the lawn and having to handle the debris twice. After finishing the job, drag a strong magnet on the lawn around the perimeter of the house to pick up any stray roofing nails. Stray nails may be picked up by a power lawn mower and thrown with dangerous force. Such projectiles are an injury hazard to the mower operator or anyone on the lawn, so try to avoid dropping any nails on the lawn.

To remove old shingles, use a 4-tine garden fork to pry under the edge of a shingle course or row. This will lift a large number of shingles at a single pass, and will remove most of the shingle nails at the same time. I have seen a pair of workmen remove the entire shingle load off a roof in a half-day effort, using the garden forks.

After you have the roof clean and the underlayment stapled in place, have the shingles delivered. Don't try to save delivery charges by hauling the shingles yourself: Material dealers have elevators on their delivery trucks that will lift the shingles to the roof, saving you the effort of hauling the heavy shingles up a ladder. Getting the shingles on the roof is half the job, so take advantage of this special equipment and save yourself a lot of work.

Order enough shingles so you will have at least one bundle left over. These leftover shingles will ensure that you have matching shingles if the roof is damaged. I have even known people to open a bundle of shingles and lay shingles on the roof of a storage shed, so they would weather and age to match the roof shingles on the house if replacement was necessary. This precaution, while it may be a bit extreme, will avoid the problem of new shingle repairs that are new and stand out so prominently against the aged shingles on a patched or repaired roof.

Written by Gary Branson.
Reprinted with permission. Copyright HouseNet, Inc.

Back to Home Improvement Preview Lawn And Garden Preview Home Decorating Shopping Center