Page 147 - 2018 National Home Improvement

2018 National Home Improvement Estimator, All Rights Reserved Page 122

Premature roof failure is usually caused by fungus, high winds, roof deck deterioration or failure of the
flashing. In some climates, portions of a roof can develop fungus that discolors and eventually
deteriorates the shingles. After a high wind (over 50 miles per hour), it’s common to see shingles blown
off. Replacing a shingle takes only minutes, but that’s seldom the extent of damage. High winds create
a vacuum above portions of the roof, lifting and flexing the surface like the wing of an airplane. Such
movement of the roof deck will cause seals to break and fasteners to work loose. It’s this unseen
damage you have to watch out for – it may not be apparent until the next rain.

When a roof is approaching the end of its useful life, you’ll see obvious signs of weathering. Asphalt
shingles lose granules, curl on the edges and get brittle. Wood shingles break, warp, curl and blow off in
high winds. A good wood shingle roof forms a perfect mosaic. A worn wood shingle roof looks ragged.
Excessively worn roofing loses the ability to shed water, making it a candidate for replacement – even if
it hasn’t begun to leak.

Choosing a New Roof Material
The roof is a major design element of most homes. If the roof cover has to be replaced, be sure to select
material that fits the character of the building. You don’t want to put Spanish tile on a Tudor house.

A major consideration in choosing a new roof covering is the weight of the material. You can’t replace
lighter roofing materials (such as wood shingles) with heavier roofing materials (such as concrete tile or
slate) unless the owner is prepared to reinforce the roof to support the additional load. Select materials
that are similar in weight to what you’re replacing.

Wood shingles and composition shingles are still the most popular roofing materials for pitched roofs,
though in an increasing number of areas in the U.S., wood shingles untreated with fire-retardant may not
be installed. Both of these can be applied directly over some types of roofing without doing a tear-off.
But there are limits. First, ask your customer if the house has been previously reroofed. When in doubt,
you’ll need to get up on a ladder and peel back a corner of the existing shingles to see what’s under
them. Be sure you understand your local building department’s requirements regarding layering and
tear-offs.

Here are some other tips to help you decide whether or not you can avoid a tear-off. You can’t install
fiberglass strip shingles over hexagon, Dutch lap or T-lock shingles. However, you can install laminated
fiberglass strip shingles over asphalt shingles without cutouts and over wood shingles, assuming the old
surface is smooth or can be made smooth. T-lock asphalt shingles can’t be installed over hexagonal,
Dutch lap or wood shingles, or on a roof with 2 in 12 or 3 in 12 pitch. But T-locks can be installed over
3-tab shingles and shingles without cutouts. Slate, tile, wood shakes and cement fiber roofing must
always be removed before reroofing.