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Quality Installation

Everyone pitches in to strip the roof, but after that the crew divides tasks. Two experienced roofers handle the shingle installation while the others focus on installing underlayment, stocking the roof with shingles, and keeping the job site cleaned up. It’s a team effort that keeps everyone moving at an efficient pace.

After installing aluminum drip edge on the eaves, we install starter strips both along the eaves and up the rakes. Proprietary starters are available, but we cut our own.

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Proper starters are about 7 inches wide. If you use a full shingle for a starter, the excess thickness of the first course will force the bottom edge of the second course to lift. This prevents the self-sealer from bonding properly and leaves the bottom edge of the roof vulnerable to blowoffs. Be sure to overhang the shingles beyond the metal drip edge by 1/2 to 3/4 inch; otherwise, water will follow the smooth metal surface and run down behind the gutter — a surefire callback. We always overhang the rake starters by 3/4 inch to help protect the trim.

Snap lines. With tab shingles, which produce a geometric roofing pattern, both horizontal and vertical chalk lines are a must, snapped at strict regular intervals. With laminated — or architectural — shingles, there is no vertical pattern, and we snap horizontal lines less frequently, about every 10 courses. Winding up with a wandering or tapering course against the ridge cap is the kiss of death.

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Nails. While four nails per shingle is the minimum acceptable standard, a high-wind application calls for six per shingle. This is the only way we install shingles, regardless of wind considerations. We consider it cheap insurance. As a rule of thumb, it takes about one coil of nails to fasten one bundle of shingles, so we use a coil and a half per bundle.

Nailing by hand would deliver more regular results than using pneumatic nailers, but competition and sanity preclude that option. We deal with the occasional punch-through or angled head by immediately adding a good nail alongside it. Nail heads must be flat and flush with the surface of the shingle to ensure good adhesion of the sealer and prevent pop-throughs. The acceptable nailing area on a shingle is very narrow, only about 2 inches wide or less.

It’s critical to keep the nailing within the prescriptive zone in order to fasten through and secure both layers of a laminated shingle. Nailing higher than this area forces the upper lamination to the deck, distorting the shingle and creating lateral channels that can capture water and introduce leaks. Nailing lower, of course, exposes the nail to the elements. In either case, you need to tear the shingle off and start over. The same rule goes for those nails that happen to coincide with the butt joint between the next course of shingles. Pull the shingle and either replace nails at least 1 inch away from the joint or secure a piece of flashing under the joint.

In coastal areas, premium lifetime shingles are the rule to comply with high-wind requirements. But electroplated galvanized nails are not lifetime nails. I’ve inspected fairly new coastal roofs and found completely rusty nails holding them down — for the time being. Both double-dip galvanized and stainless steel roofing coils are available at an upcharge; they can cost up to three times more than a standard case. But a premium roof deserves a premium nail.

High-wind shingles. Nails alone, however, are no guarantee that the roof won’t fail in a high-wind event. For optimal performance, select a shingle specifically offered by the manufacturer as a high-wind product, with up to a 130-mph rating. These shingles are stiffer, to resist wind uplift.

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It’s just as important to make sure that the shingle courses self-seal to each other. In winter installations, self-sealing strips may not be activated until warmer temperatures arrive in the spring. In winter conditions, you may decide to apply roofing adhesive under every shingle. We don’t, and to this date haven’t had any problems. We do apply adhesive along the rake starters to reinforce this vulnerable edge against uplift.

Scuff protection. Warm weather actually presents greater installation obstacles than winter temperatures do. Protecting shingles from damage and shoe scuffs during hot-weather installation takes a little extra care. You can keep the shingles cool by hosing them down — but only installed shingles, never the underlayment. That precaution makes watering the least desired method.

We protect walkways and work areas with rubberized carpet pad or other foam rubber sheeting, which provides good traction on the roof while protecting the granules from smearing. Ordinarily, we use a minimum of roofing brackets and staging planks. On a 10-pitch or lower, we just set a plank at the eaves and work an open roof. In warm weather, though, we stage the entire roof to prevent wear and tear in the loading zones.

Last but not least, we wear sneakers, which are the most comfortable shoes to wear on a roof and the least likely to scuff.

Speed. There are a few roofers who just want to get the job over with as quickly as possible. Speed matters to me, too, but not at the expense of a good installation. Racking — or running the shingles up the roof in vertical columns — is a slightly faster method than cutting “books,” which is starting shingles at one edge of the roof in 6-inch staggers and extending them laterally in a pyramid pattern. Racking is the technique preferred by roofers who get paid by the square rather than by the hour. I pay my crew by the hour. Racking requires you to bend shingles back to nail those fed in underneath from the successive column. But with laminated shingles, this bending can crack the shingles and separate the laminations. Racking can also create an obvious patchwork appearance in the finished roof, since it concentrates shingles from a single bundle in one area. Shingle color typically varies slightly from one bundle to the next, so it’s best to blend shingles from different bundles. Poor color blending is a common complaint and it’s not covered by any warranty.

Valleys. While there are several accepted valley types — including woven, closed-cut, and open — we prefer the method illustrated on Tamko’s bundle wrappers. It’s by far the fastest but is suitable for use only with laminated shingles, which effectively disguise the distinctive sawtooth pattern it produces.

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The technique is similar to that for a closed-cut valley, where one slope’s shingles are run across the valley and up the opposite slope by at least 12 inches. The opposite slope’s shingles overlap these and are cut to the valley line. The Tamko valley line is defined by butting whole shingles end-to-end up the divide, preferably along a chalk line. The opposite slope shingles are then started with their square bottom corner toeing the valley line, producing the sawtooth pattern.

Some roofers claim that woven valleys are the best for high-wind installations, but because both slopes must be worked simultaneously, they’re slow to install. Also, the weave is too bulky for thick, laminated shingles and doesn’t work in valleys of unequal pitch.

Shingle Manufacturers

Organic Based

Building Products of Canada Corp.

800/567-2726, bpcan.com

CertainTeed Corp.

610/341-7000, certainteed.com

Fiberglass Based

GAF-Elk Corp.

973/628-3000, gaf.com

IKO

416/781-5545, iko.com

Owens Corning

419/248-8000, owenscorning.com

Pacific Coast Building Products

www.pabcoroofing.com

RGM Products

559/499-2222, ridglass.com

Tamko

800/641-4691, tamko.com

Capping Off

I see lots of capped, vented ridges where the ridge-vent product stops about a foot short of the gable, forcing the cap to taper downward at the ends. It’s a bad look and a misinterpretation of prescriptive ridge-vent installation. For the best appearance, the venting slot should stop short by one foot and be covered by roofing material at gable ends and penetrations (such as chimneys), but the vent material should always run through.

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We fold the top course of shingles over the ridge for the first 12 inches at the ends and run the ridge vent full length, followed by cap shingles. The same method should be used at chimneys and cheek walls. Although exposed nails on a roof aren’t generally advisable, they’re unavoidable in the last cap shingle and in apron nailing. We like to use stainless steel box nails along with a dab of roofing cement to hold the shingles in place. The small heads don’t cause rust streaks and are nearly invisible in the roofing.

Jim Bennette owns J Bennette Roofing in Brewster, Mass.