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How Long Will It Last?

Buying a house is a costly investment, and one of the first questions you may ask of your home inspector is "How long will it last?" "It" usually refers to the roof. No one has a crystal ball, but most home inspectors can provide some "guesstimate" for the remaining service life of a roof.

One relatively accurate way is to rely upon the manufacturer's warranty and the date of installation. Unfortunately, shingles themselves carry no visible markings that will indicate either the warranty life or date of installation. Suppose that you are buying a 25 year-old house with the original roof. Most roofing shingles come with a 20-year warranty, though the best may have a 30-year warranty. In the case of the 20-year shingle, you may wish to walk around with an umbrella or a prayer shawl after you move into the house; with the 30-year shingle, the only showers you'll have will probably be in the bathroom.

Let's assume that your home inspector tells you that the roof will require replacement very soon, one to three years, depending on how cracked and weakened the shingles are. Just because there are no attic drips or bedroom ceiling stains during the heavy rain on the day of the showing, do not assume that the roof is satisfactory. Water may be leaking through the top layer of roofing material onto an intact area of shingles in the roofing underneath; during the next storm, water may leak through to the old shingles with the holes, the very ones that made the previous owner install the new roofing.

Very worn shingles are brittle and subject to failure during unexpected weather extremes such as wind, hail or ice. Why bet discomfort and ceiling damage against roof replacement, just to squeak a few more months out of a roof? The small monetary savings are unlikely to compensate you for even slight interior damage from leakage.

Are your worries over if the roof is new? Just because a house has a new roof, don't assume that it needs only a cursory inspection or none at all. In a small percent of fiberglass shingle roofs, manufacturing defects occur that can result in premature failure beginning as soon as two years after installation. The type of cracking that occurs can only be seen from the roof surface or from the ground with powerful binoculars; recent fiberglass shingle roofs actually need closer scrutiny (particularly the south side) than older, asphalt organic felt roofs. Before you hire an inspector, insist that he look at the roof either with binoculars or from a ladder; if the inspector refuses, find another one! Most premature failures that I have discovered were repaired by the manufacturer under the seller's warranty prior to sale.

When you have the new roof installed, should you strip off the old shingles? If there are two layers already present, the answer is yes, you must. With only one layer, you have the choice. It's a little more expensive to strip first, about 25% more, but an advantage of stripping is that your roofer will have the opportunity to replace damaged sheathing. Shingles nailed into splintered sheathing may not hold well. Another reason to strip old roofing is appearance; new shingles directly over sheathing instead of warped and weathered shingles lie flatter and last longer. Always insist that roof paper be installed under the shingles first; failure to do so voids many manufacturer's warranties.

No shingle roofing is waterproof and one upgrade well worth considering when reroofing is installation of waterproofing membrane at the edge of the roof. These products prevent winter water build-up at the edge of the roof, called ice damming, from entering the soffit and wall. Even though ice damming is infrequent, the additional expense of waterproofing is well worth it when you consider the damage to ceilings and walls done by water from ice damming. If the home you are purchasing has had severe ice damming, and there is less than 12 inches of overhang, consider lengthening the roof overhang.

Reroofing offers an excellent time for improvements to attic ventilation. One purpose of ventilation is to reduce the attic temperature in the summer; this protects the life of the roof shingles and makes the bedrooms more comfortable by reducing the ceiling temperature. The other purpose is to let moist house air out of the attic in winter; excess moisture in the attic can lead to condensation on the sheathing and, in severe cases, to wood decay. Of course, be sure that your attic is insulated before you increase attic ventilation, or you will be letting your heating dollars leak out of the attic!

Soffit ventilation reduces the humidity in the soffits, and allows the air temperatures to change along with the outside temperature. Insect pests such as carpenter ants and cockroaches prefer moist environments with constant temperatures. Not many people realize that these insects often populate soffits; soffit vents make the soffit less desirable for these pests.

In general, homes over 40 years old, with plank sheathing, (individual boards) tend to have fewer attic moisture problems because the gaps between the sheathing boards provide some ventilation; in newer homes with plywood sheathing, far less air escapes around the sheathing. In addition, the glue in plywood acts as a "vapor barrier," trapping moisture in the attic, whereas wood planks allow moisture to travel through them.

If your home was built within the last 20 years and the attic is well insulated, be sure that there is attic ventilation. One way to tell is to look into the attic on a cold winter day (or night); if there is a lot of frost on the plywood sheathing or the ends of exposed nails, the ventilation is inadequate. If the plywood is blackened and warped, repairs may be needed.

Older homes generally have either a window or louvered vent at the top of each gable-end of the house. In new homes, you will find soffit vents combined with ridge vents. Look for soffit vents at the bottom of the roof overhang (in the soffit) just behind the gutter. A ridge vent looks like a long "bird house" roof, about one inch high, on top of the roof at its peak; it lets air out of the attic from the ridge, usually along its entire length, but has a "roof" of its own to prevent entry of rain.

Remember, there are four things that destroy a house: water, water, water, and neglect. Start your maintenance where it counts: at the roof.

From "JUST PROPERTY"


By J. May
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