A recent Ask the Expert question and answer from TRI President and Technical Director, Rick Olson.
How long should underlayment last under a tile roof? I hear some people say 10-20 years, others say 25-30 years or even 20-35 years. Can you tell me which is true with a tile roof installation?
There is no one answer the fits all. There are a variety of underlayment types being used with tile roofing that include organic, synthetic and even self adhering.
Some builders/contractors install multiple layers of the underlayment, for instance 2 layers of a 30 lb organic, or a single layer of a 40 lbs as an upgrade to the tile roofing system. Self adhering underlayment is another upgrade that is used in some areas.
The key to understanding your underlayment longevity is to read the literature of the underlayment manufacturer. Many of the synthetic products do not have formal code issued product approvals and therefore it may be harder to know their service life. The amount of time the underlayment is exposed to Ultra Violet sunshine prior to having the roof tiles installed can also affect the long term performance.
Generally, the organic based and self adhering products will have a longer life than the synthetics.
Hopefully this helps provide some guidance.