Deciding About a Metal Roof

Deciding About a Metal Roof
Using metal for one's roof material appears to be gaining in preference these days. Of course, the
metal roof tends not to be selected for original roofs by contractors building on spec because
trying to recover the higher cost is risky. But it is a common choice for custom jobs and as a
replacement roof. When metal is being considered, the owner should understand certain of its
characteristics. This article is intended to review such characteristics and make both an initial and
long-term comparison across roofing materials.
The metal roof is about middle of the range in terms of quality. The roofs that last the longest,
perhaps as much as three hundred years, are constructed from clay or slate. They also are the
most expensive. At the other end of the spectrum are roofs made from asphalt shingles, the most
commonly used material. These are the least expensive and last about fifteen to twenty years. A
notch above asphalt in quality are wood roofs, whether in shake or shingle form, with a lifespan
of up to thirty years. Metal is better yet, with roofs fabricated from it having a life expectancy of
up to fifty years.
Weight is an aspect that cannot be ignored. A house foundation and structure has to support all its
loads, both live (people) and dead (including roofing materials). When original structures were
designed to hold composition roofs, they are unlikely to support the much heavier materials of
clay, slate, concrete tile, and fiber cement as replacements, at least not without reinforcement.
Metals, on the other hand, have the advantage of being relatively lightweight.
The various roofing materials have their characteristic problems. Both asphalt and wood roof
shingles tend to deform over time, affected by weather and sun. Asphalt loses its protective
coating and breaks down, while wood cracks, splits, and curls. With clay and slate roofs, the
issue is breakage. Of course, fire threatens the wood roof, though applications of retardants are
available.
When it comes to metal, the issues are dents, corrosion, and buckling. Falling limbs and other
debris cause dents. Most metals are susceptible to oxidation and manufacturers take great pains
to fight this by coating shingles and panels with protective treatments. The buckling issue arises
from the significant expansion and contraction inherent in metal. To counteract this tendency,
manufacturers limit panel widths to twenty inches and installers know to provide plenty of
spacing at the joints.
An attractive roof is always desirable; it is pleasing to the eye and enhances resale value. The
metal roof has a poor reputation in this department, but industry innovations have led to
improved designs, flashings, and fasteners to the point where derision is a thing of the past. To
explore these concepts further, and for a glossary of trade terminology, visit
HomeInspectionWA.net.

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