Synthetic Tile Underlayment
Synthetic tile underlayments have been increasing in popularity in Arizona. However, in our opinion, they are not the best for material to use. In fact, we will recommend homeowners not to choose synthetic concrete tile underlayments. Let’s talk about why we don’t recommend synthetic concrete tile underlayments.
Some synthetic underlayments are more expensive than the felt type of concrete tile underlayments while other synthetics are cheaper. In fact, the material price can be double than of a felt type of underlayment. It would be cheaper to do two layers of felt than a single layer of synthetic.
Synthetic is the king of waterproofing capabilities and is 100% waterproof. How ever synthetics don’t self-seal around fasteners well (nails, staples, etc). This is the biggest issue when it comes to installing synthetic underlayment under concrete tile roofs. A concrete tile roof is comprised of
The underlayment is rolled out to cover the decks surface (keeping it waterproof) and nailed in place.
Batten strips (4 ft sections of 1×2 wood strip) are then nailed or stapled on top of the underlayment. They provide rows for the roof tile cleats to rest on and prevent them from sliding down the roof.
Then the roof tiles themselves.
Example of what is underneath a concrete tile roof
Installing a tile roof requires both the batten strips and underlayment to be fastened to the deck. So, with a synthetic underlayment that doesn’t automatically seal around the fastener’s penetrations, your roof is vulnerable.
The number one reason your concrete tile roof leaks is from water getting under the batten strips and going through the fasteners penetrations. Rubber modified felt papers will automatically seal these penetrations while synthetics will not.
So even though synthetics have a 50 years product warranty they are not the best tile underlayment for sealing the around the roof fasteners.
As far as durability, synthetic roof material is quite durable. However, when synthetic tears it tends to tear in big sections. Synthetic concrete tile underlayments have a durable surface for foot traffic and have an excellent non-slip surface
Synthetic underlayment has very strong UV resistant qualities. When exposed to the direct sun, the underlayment can maintain a UV resistance from 6 to 12 months