A common question for the home or building owner is “how long do roofs last?”. The two most common roofs are sloped roofs with composition shingles which generally last 30 years or flat roofs with some kind of white roll roofing which last around 20 years. There are several other different kinds of roofs which can have variable life expectancies depending upon how well they are constructed (leaving aside poor workmanship).
For example a concrete tile roof or a slate roof or a clay tile roof, if it is installed with excellent, high quality, thick rubber underlayments can easily last 50 years and in some cases well past that. But generally speaking a quality tile roof will last 40-50 years. In the past, they would last 25 – 35 years.
With a tile roof, always insist on a thick rubber membrane – particularly with old school Spanish tile which relies more heavily on the underlayment being a part of the waterproof system, whereas, for example, a one piece interlocking concrete tile system can (and this is proven) perform for decades without any underlayment at all (originally, they were installed this way).
With composition shingle roofs, there are thicker and longer lasting shingles which will last 40 to 50 years or so but my feeling on those is that while they may not leak after 30 years, since they share essentially the same granule surface as their 30 year shingles do, I don’t really see why the surface is going to look any better, so they won’t leak look, but they may look like garbage.
With flat roofs it’s generally more difficult to get them to last longer than 20 years without adding more membranes and significant cost. With a hot tar roof your typical system would involve 3 membranes and that would last about 20 years and if you added in another membrane with hot tar you can add another four to five years to it and so on – up to a point. There are certain aspects to how long a flat roof lasts such as drains and drip edge metal that have a tendency to fail after 25 years no matter how many membranes are involved. Probably the two most common flat roof membranes nowadays however are torchdown systems and single ply rubber systems.
With a touchdown system the only way you can make it last longer than 20 years generally speaking is by adding a second layer which will almost double your cost although there are pretty good white coatings that will add life to your roof, when done correctly these are not cheap at all but can be done by the homeowner. With a single ply rubber roof you would simply go with a thicker membrane and they are quite a bit more expensive.
How long do roofs last? Each type is different. But, remember, with shoddy workmanship and cheap labor or untrained, inexperienced roofers, any roof with last less than it should. Always choose a high quality roofer.
This article was contributed by Matt Glass, one of the family owners of J and J Roofing – servicing the Los Angeles area including Sherman Oaks, Studio City, Burbank, Encino, Pasadena, Woodland Hills and Porter Ranch.