By Kathy Danforth / Published April 2017
Consideration of your roof’s trials and travails can help you protect it and your finances. By maintaining your roof in good condition, you may be able to extend its life and keep the same roof far longer than if it is left to fend for itself. Additionally, understanding its stresses and condition will enable you to budget appropriately, so any replacement or coating is expected and more financially palatable.
Steep roofs are most commonly constructed with either shingle or tile, according to Mike Shephard with Advanced Roofing and Sheet Metal. “Shingles are very predictable,” Shephard advises. “Whether you buy a 25-year shingle or a 40-year shingle, they’re all going to last about the same amount of time, an average of 18 years. The primary deterioration comes from ultraviolet (UV) rays from the sun.” As to why shingles are promoted as having different lifespans, Shephard surmises, “I don’t think the manufacturers account for the stronger UV rays in our area.”
Damage, workmanship issues, and areas that age more quickly necessitate routine inspection and maintenance. “Damage can be caused by hail, though that doesn’t normally happen here,” Shephard reports. “Excessive foot traffic also causes damage, though that is not as common on a shingle roof. If improper fasteners are used, they can begin to back out, which we see from time to time. The worst case of premature failure we have seen occurred within five to six years because the fasteners had backed out.”
With routine inspections, however, corrections can be made before water ruins the building materials. “Inspect the roof at least once a year,” advises Shephard. “If any fasteners are backing out, reseal the penetrations and replace the fastener. Check for clogged gutters, which can back water up under the roof. Inspect all flashing details, vent stacks, curves, and roof-to-wall junctions. Sealant or roofing cement may need repair, either from damage or poor workmanship. Caulk is always a maintenance item, though typically it will last five years before needing attention.”
“Tile roofs usually last 25 years or more if they do not fail prematurely due to poor installation,” notes Shephard. “We see more premature failure from installation problems occur with tile than any other roof type, particularly if it is mechanically fastened. However, 12 years ago the market switched to self-adhesive peel-and-stick underlayment, and we have not seen any premature failure of those.” The natural deterioration of a tile roof comes from weathering of the underlayment. “Heat causes the underlayment to become brittle,” according to Shephard.
One of the main causes of damage to tile roofs is pressure washing. “This damages the tile in two ways,” explains Shephard. “The foot traffic jostling the tiles elongates the seal between the fasteners and the deck, creating openings. Also, the pressure washing can remove the tile’s ‘skin,’ leaving it more porous and prone to getting dirty faster.”
Shephard points out, “The pressure washing industry has evolved so that now the roof can be cleaned once and then treated every other year to prevent soiling. This method takes very little foot traffic, and the roof stays clean. With a new roof, initial treatment can be done any time after nine months and before the roof becomes dirty.” Shephard observes, “There is no danger in leaving a tile roof dirty; the cleaning is just for visual effect. We don’t have the types of mold that exist farther north which can extend roots that expand and crack tile.
“As beautiful as tile is, it tends not to be as resistant to wind damage as other roofs,” Shephard states. “Any time there is a significant windstorm, the roof should be checked because damage may not be visible from the ground. If you just see one or two tiles cocked, that is a red flag that numerous tiles may have been lifted and settled back down.”
As with shingle roofing, inspections should be made annually. “You are looking for cracked tiles, flashing details, roof-to-wall junctions, and gutter cleanout,” states Shephard.
Flat roofs are most often constructed with a single-ply thermoplastic olefin (TPO) membrane or modified bitumen, with TPO garnering 70 percent of the market currently. “Many years ago, gravel surface built-up roofs were most common, but modified bitumen took over the market about 35 years ago; then 15–20 years ago single-ply membranes were introduced and became dominant,” reports Shephard.
“Modified bitumen has two or three plies, is redundant, and is tough,” Shephard relates. “The redundancy makes them the least likely to leak. Sunlight degrades the material, but the roof will last 20 years, and some are going on 30 years. A well-maintained modified bitumen roof provides a good substrate for coatings, most commonly silicone. In effect, the coating becomes a new weathering surface, so with a good maintenance program and coatings, the roof could last indefinitely.” Modified bitumen can be damaged by ponding water or excessive foot traffic, but Shephard advises, “They’re tough. With two or three plies, you have to make an effort to damage it.
“Single-ply membrane roofs should last 20 years,” explains Shephard. “They have been in the market that long and have performed well. Warranties used to be shorter until they proved themselves, but a very important part of membrane roof warranties is the requirement for an annual inspection, typically documented with photos and a written report.
“Routine aging is caused by sunlight,” shares Shephard. “Premature roofing failure can be caused by poor workmanship or cuts in the membrane. Left unchecked, water can leak in and destroy the roof from the inside. On the surface, it looks fine; but underneath, the insulation can be saturated. Workmen may drop tools, puncturing the membrane. Air conditioning repairmen are notorious because they remove sharp metal panels, which may drop and cause damage. When leaks are concealed or just ignored, what would have been a $250 repair becomes a $250,000 roof replacement.
“Standing water can be a building code issue,” cautions Shephard, “so keep that in mind in reviewing bids. If a contractor says a tapered roof is required for drainage, beware if another proposal comes in with a cheaper bid for a flat installation. If it ponds, the city building officials can deny a permit.
“Early on, some single-ply membranes failed as manufacturers were learning about the product, and several companies did go out of business. Now the products are predictable and consistent, and if properly installed and inspected, they will last their predicted lifetime and more. Their big draw is that they are less expensive to install. However, there is no redundancy. Premature failure in modified bitumen or TPO roofing will occur when they get a leak no one is aware of and it leaks for a year. The roof fails before the membrane does, from the inside out. It’s directly tied to lack of maintenance.”
Metal roofing, by nature the most expensive, has the highest windstorm resistance. “Metal roofing—whether standing seam, 5v crimp, or stone-coated steel tile—can last 25–30 years or more,” notes Shephard. “Sun does not damage the metal, though it can fade and coatings can chalk. However, it’s not hard to repaint. We have seen some premature failure on cut edge details because the cut edges can rust.”
The other primary concern with metal roofs is using the proper metal. “If you are near salt water, within a half mile, aluminum should be used instead of steel,” says Shephard. “Even aluminum won’t last as long in a saltwater environment. The lifespan of any metal component will be cut 25–30 percent off its normal lifespan if it is within a half mile of saltwater.” As with all roofs, regular inspections will catch small problems before they can expand.
“Maintenance is the best money you can spend on a roof,” stresses Shephard. “Fifteen or twenty years ago, it was not emphasized in the industry, but it is to the benefit of the property owners because it will really extend the life of a roof.” By doing its job, your roof is facing the sun and rain so you don’t have to. By doing your job of inspecting and repairing issues along the way, you can keep the same roof for its maximum useful life and minimum per-year cost.
Mike Shephard with Advanced Roofing and Sheet Metal contributed to this article. For more information on Advanced Roofing and Sheet Metal call (888) 386-4412 or visit www.advancedroofingandsheetmetal.com.