ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Sunday, March 31, 1996 TAG: 9604040014
SECTION: HOMES PAGE: D-1 EDITION: METRO
COLUMN: Hints for Homeowners
SOURCE: STEVE ELDER
Some questions sent in by readers are answered in today's column. If you have sent in a question and don't see it answered here, you will receive an answer by mail.
Q: When we had our new skylight put in, our contractor was looking at our asphalt shingles when he was up there and said we would need to get a new roof pretty soon. We didn't know what to think, because our house is only 13 years old and the shingles have a 20-year warranty. He doesn't do roofing so we believe him, but do you think our shingles could already be in bad shape?
A: Unfortunately, the concept of a 20-year roof shingle is based more on marketing than on physics. In reality, most asphalt shingle roofs do not make it to 20 years; a goodly number don't even last 15.
Asphalt shingles used to have an organic felt base, and the asphalt was derived from a higher grade of crude oil than it is currently. Nowadays most shingles have a fiberglass mat base, which makes for a lighter, thinner shingle. In other words, you should expect a shorter life span from today's shingles, even before you unwrap the bundle. After you have adjusted your expectations accordingly, you need to consider the various forces of nature that affect your roof.
The force that ages an asphalt shingle roof most rapidly is not rain or snow, but sunshine. The sun's rays dry out the oils in the asphalt base, making the shingle brittle and prone to crazing and cracking. This is what normally happens as a roof ages, and sunshine just accelerates the process. A south-facing roof slope, which gets sunshine all day, will have its life expectancy reduced by roughly 20 percent compared to the north slope; so when you're examining your roof in order to judge the remaining life, look at the south side or whichever side is most exposed to the sun.
To extend the logic, roofs that are shaded by trees will last longer than roofs that are exposed to the sun's rays all day. Ultraviolet radiation causes heat build-up in the shingle, and that hastens the drying process. This is also why roofs with a steeper slope tend to last longer than shallow-pitched roofs: the steep roof does not get as much radiation per square foot as the shallower roof. Similarly, light-colored roofs will generally outlast their darker counterparts because they reflect some of the radiation while the dark-colored roofs absorb it. This is also why keeping the attic well-ventilated to reduce heat build-up will help the roof somewhat. (The effect that attic ventilation has on roof life expectancy is frequently exaggerated, however. A more compelling reason for good attic ventilation is to reduce the amount of air conditioning required.)
The short answer to your question is therefore, "yes.'' It is entirely possible that a 13 -year-old roof can be at the end of its life span, for any of the reasons above and also because some shingles are more cheaply made than others. Standard roof shingles weigh 225 pounds per square. (A square is 100 square feet.) If you want real assurance that your roof will actually last 20 years, buy a heavier grade shingle. How can the manufacturer afford to give standard roof shingles a 20-year warranty, you ask? Simple. The statistical chance that many buyers will stay in the same house until the roof wears out (and that they won't lose their paperwork) is very small.
Q: Recently I visited a friend in her new condo. When I turned on a wall switch in her bathroom, it caused a noise in a small slotted plastic plate high on the wall. It didn't seem to do anything. What was it?
A: If it is what I think it is, it's supposed to be a vent fan. This particular device pulls air in from one side, runs it through a small charcoal filter (which nobody knows about and consequently never changes), and exhausts it out the other side back into the room. The fan is usually very small and doesn't move much air. The device does not exhaust air to the outside at all, and as a result is useless for removing hot, steamy air from a shower, just as a ventless kitchen range hood doesn't remove much smoke or odor. In some instances these ventless bathroom ``fans'' have managed to become an ``approved mechanical ventilation system.'' However, while they have the virtue of being inexpensive, they have a very high SPF (sleaze perpetration factor), in my personal opinion.
LENGTH: Medium: 75 linesby CNB