Know Your Tile Roof

It is advisable to perform a thorough roof evaluation prior to your project installation. At this time you should develop an array layout confirming everything on the drawing will fit as intended. Any irregularities should be noted, so you can deal with them on install day. The type and condition of the underlayment should be determined, so that any repairs or replacement can happen before or in conjunction with the installation. Often it is advisable to install new underlayment before installing a solar system. Remove a tile and see what is underneath. It is important to determine the following: The type of tile (concrete or clay, flat or curved, batten or direct attach, etc..) the manufacturer of the tile, the size of the tile, underlayment type (organic or synthetic, weight or thickness) type of sheathing (plywood or oriented strand board [OSB]) rafter size and spacing, age of roof structure, who roofed it, who built it, etc.

Photos should be taken of all of the roof variables and kept with the job file for future reference. Typically the tile roof manufacturer puts a stamp of some sort on the back of each tile. This stamp can be defined by the roofing yard, or by a little web research. The manufacturer’s instructions will spell out exactly what does and does not void the warranty of their roofing product. Officially, the roofing manufacturer’s instructions supersede our instructions, as our product is weaving into theirs. It is also important to have their instructions in the job file for any future reference.

Product Selection

The QBase Universal Tile Mount is intended to fit within most curved tile roof systems, as well as most flat tile systems. The QBase Standard Flat Tile Mount is intended for direct attach or batten attach flat concrete tiles. These mounts are sized to fit a standard 12-inch wide x 17-inch tall concrete tile roof system whether they be standard or light weight varieties. Height extensions are not intended for use with these products. Custom lengths can be ordered.

Waterproofing

Waterproofing on a tile roof it is ultimately achieved by the underlayment below the tiles. The tiles shed the majority of the water, but the underlayment prevents any wind driven rain from getting to the sheathing. The tiles help minimize thermal absorption and protect the underlayment from UV exposure and minimize the amount of water that gets to the underlayment. The aluminum underlayment level flashing is positioned over the QBase with the longer side of the flashing upslope, above the mount. The flashing would be integrated into the underlayment using bibbing methods shown in our training videos. If the tile roof uses battens, it will likely be necessary to remove battens to insert the bib up under the course of underlayment uphill of the mount. If the AHJ allows three course sealing, you should use an underlayment compatible roofing cement and reinforcing fabric to seal the aluminum flashing to the underlayment.

How Many Mounts Per Module?

To determine if the roof can handle the weight of the solar system and the uplift forces from strong winds, it is advisable to consult with a qualified solar installer. Many states and building departments have standard practices to ascertain if a roof has the structural capacity to handle these additional loads. If there are any questions as to whether the roof has the structural capacity to support a solar system, it is necessary to consult a licensed structural engineer to make this determination. Many racking manufacturers have web-based tools to calculate the spacing and number of mounts required. Many variables must be considered including strength of rail, distance between parallel rails, cantilever of modules over rails, pullout strength of mount, shear strength of mount, roof slope, height of roof, wind zone, array location on the roof, roof type, structural integrity of roof framing, wind speed requirements for the local area, etc. Quick Mount PV provides pullout and shear capacity as well as engineering test reports for all of our mounts on our website. We recommend reviewing our Wheel of Accountability, which is a summary of all the entities that govern waterproofing, electrical, fire, and structural requirements to comply with industry codes, standards, and installation best practices. A description of each entity and links to their websites can be found at quickmountpv.com/waterproof/code-compliant.html.

Sealants

It is important to put a roofing compatible sealant into any and all holes drilled into a roof. Most roofing manufactures list a suggested, approved sealant in their specifications. In freeze-thaw zones, it is important to follow the manufacturer’s rules for freeze-thaw conditions. Use the properly rated sealant for each specific application and condition. Some that may be more appropriate for asphalt/composition roofs include Geocell 3500 and ChemLink M-1 but be sure to do your own research to confirm a compatible and appropriate sealant with the roofing materials you are using.

Mounting Hardware

Each box includes all necessary mounting hardware, mounts with flashing, and written installation instructions.