Installing Solar on Tile Roofs – Don’t Forget the Base Flashing

One of the most common code violations we see in tile roof PV system installations is the failure to install a base flashing. However, flashing at the underlayment level is highly recommended as it is required by the Tile Roofing Institute (TRI). While tile routes most the rainwater off the roof, water routinely blows up between tiles and the underlayment serves as the ultimate waterproofing of the deck. Standoffs, tile hooks, tile tracks, or hanger bolts without base flashing are vulnerable to leaks, and are a fundamental code violation. Violating this important code requirement puts your customers and your business at risk since the installer is legally responsible for any resulting leak damage.

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Above tile mounts are missing base flashing and are therefore violating the TRI guidelines and the building code.

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Code compliant base flashing being installed using the TRI approved underlayment bibbing method.

The alternate method of sealing base flashing is the TRI approved 3-coursing method shown above on Quick Mount PV's, Quick Hook product.

The alternate method of sealing base flashing is the TRI approved 3-coursing method shown above on Quick Mount PV’s, Quick Hook product.


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Above photo shows evidence of water running down the underlayment. This is why the TRI requires base flashing.

The TRI guidelines specify the flashing requirements for penetration flashing, and the TRI Technical Brief for Solar Systems (#2008-01) specifically states Deck mounted or other systems that penetrate the tile or roof deck shall have both primary roof tile flashing and secondary deck flashing. Since tile hooks do not penetrate the tile, you only need a base flashing, but you MUST have a base flashing. Base flashing must be installed using either underlayment bibbing or 3-course sealing to the base level.

Since the IBC and IRC codes require installing flashings per the roofing manufacturer guidelines, the TRI guidelines become the code requirements for all member companies. You can find a full list here. To add further validity to the TRI guidelines, they have been certified with the International Code Council using the ICC Evaluation Service Report system. – ICC-ESR-2015P and some TRI member companies including the two largest tile manufacturers (Boral/Monier and Eagle) even specify the TRI flashing guidelines in their ICC Evaluation Service Reports:

So always remember to install base flashing. Your customers will thank you, and you will protect your contracting business from the legal liability of avoidable roof leaks.

Quick Mount PV offers both live trainings and free webinars on installing flashed solar mounts on tile roofs. For more information, visit our website.

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