*Installing Mounts on an S-Tile Roof
Second in a series: Attachments for Tile Roofs
Last month, I shared the top takeaways from the evaluation process I managed when I was responsible for vetting and approving mounting equipment for one of the largest national solar integrators. In that article, I shared key features that make a big difference when selecting roof attachments for composition shingle roofs. In this article, I’ll share my recommendations for tile roof attachments.
Roof Attachments for Tile Roofs
There are three main categories of solar roof attachments for tile roofs—Standoffs, Tile Hooks and Tile Replacements. It’s important to understand each category in order to select the best attachment for your project.
Standoffs & Threaded Studs
Tile Standoffs are part of the early generation of tile roof mounts. The base is secured to the trusses or rafters with lag bolts. The post extends up from the base, through the tile where it is attached to the rail, typically with an L-foot. Standoffs deliver adequate strength and spans, but the install process is time-consuming and requires cutting or grinding large holes in tiles. This can break or crack tiles and creates clouds of concrete dust. Besides the mess that the dust makes, the high silica content poses a health risk. In fact, new OSHA regulations require dust abatement procedures. This reduces the risk, but further complicates the installation process. My recommendation is to limit the use of Tile Standoffs to unique applications that cannot be resolved with other types of roof mounts.
Threaded stud-based tile mounts don’t require messy grinding or cutting tiles, although they still require drilling a hole in the tile. In my experience, stud-based tile mounts are an inherently weak design. To that end, I do not recommend using this style of mount at all. Instead, opt for Tile Hooks or Replacement Tile Mounts.
Tile Hooks are the most common type of tile roof attachment. They are generally the most cost-effective tile mounting solution. They don’t have the strength of Tile Replacements, but, in lighter loading conditions, a quality Tile Hook can still allow for long spans. They are usually compatible only with rail-based racking (not compatible with rail-less). The base is secured to the rafters or trusses with lag bolts and the arm extends out from under the tile where it supports the mounting rail. The distance the arm runs from the base to the rail attachment point creates a cantilever that subjects the components to high stresses. Therefore, it’s important to install a quality, high-strength hook.
Some tile hooks are designed for one specific tile, while other “universal” hooks adjust to various tile profiles. Here’s what to look for when selecting a universal tile hook:
- First and foremost, the arm of the hook should be engineered to handle the load of the array with minimal deflection. If the arm deflects far enough, it will rest on and damage roof tiles. An easy rule of thumb is to look for arms that are not just flat, stamped steel.
- The base plate should have East-West adjustability, allowing it to span from the rafter to the location where the hook comes out of the tile.
- The arm should include vertical adjustability, to compensate for variation in tile thickness and batten or batten-free fastening.
- Installation should not require grinding or notching common profiles and of tiles. brands and profiles. Adjustability, thickness of the arm, overall size, and incorporating materials that can deliver the necessary strength with minimal thickness are all important factors here.
Tile Replacements are a higher-strength alternative to tile hooks. When tile hook spans are limited by loading conditions, Tile Replacements can reliably deliver a full 6’ span and are compatible with rail-less racking systems. Replacement tile mounts tend to cost more than tile hooks or standoffs, so keep this in mind when opting for a Tile Replacement for wider spans as it may not necessarily save money. Add up the labor and material costs for both approaches and compare.
The base is secured to the rafters or trusses with lag bolts. A rectangular-shaped extrusion known as a “riser” extends up from the base to the flashing, which is shaped and colored to match the tiles. The racking bolts through the flashing and into the base. These mounts can be more complex to install, so it is important to select one that will provide a simple installation experience.
Here’s what to look for when selecting a Tile Replacement:
During installation, the riser and flashing hole must be aligned. Generally, there are three different approaches informing products that are currently on the market:
- The first approach includes the riser in a fixed position on the base. This requires a tedious, manual process to select the correct lag-hole on the base that aligns the riser with the flashing hole.
- The second approach has a fixed-position base, but no hole in the flashing. To go with this approach, you position the flashing, find where the threaded stud in the base contacts the back of the flashing, then tap with a hammer to punch the stud through the flashing. This method is better than the first option, but it introduces the possibility of errors such as knocking a hole in the wrong spot or deforming the flashing. In addition, it still takes more time than the third option.
- The third option is a variable-position riser. This configuration, which is unique to Unirac’s Tile Replacement greatly simplifies and speeds up alignment. First secure the base with lags, place the flashing over the riser bolt, then insert the flashing into the surrounding tiles. The riser will follow the flashing and slide into position.
The distance between the roof deck and the tile varies between tile profiles and the attachment method e.g. batten or batten-free. Most brands in this category are fixed-height, offering three different bases with permanently risers or one base with three different field-attached risers.
Many times, I have had to mix-and-match bases to get the right height for odd-ball tiles, such as using a W-tile base on an extra-thick flat-tile. Usually, the issue would not be discovered until we started the install, so we had to waste time running back to the warehouse to get a different base. A variable height mount would have allowed us to adjust and keep installing, saving time and frustration, but there weren’t any on the market at the time.
Having multiple fixed-height mounts meant three different bases, three flashing profiles (plus bolts and hardware). All of these components further complicated things from ordering to warehouse, loading the truck and install.
These Days, variable height risers are available. One adjustable base replaces 3 fixed-height bases. Be sure to select a Tile Replacement that has this feature.
If you’ve ever seen rubber pipe vent flashings that are a few years old, you know that exposed rubber doesn’t last long in a roof-top environment. Avoid mounts that rely on exposed rubber for roof-level waterproofing, such as those with the post extending through the flashing that is sealed with an exposed rubber collar.
Finally, look for a Tile Replacement with an integrated deck-level seal, such as mastic/ butyl patch around the lag holes. This limits the need to handle messy, sticky materials.
General Product Requirements
Whether you decide to go with Tile Hooks or Replacement Tile Mounts, be sure your mount meets the following criteria for the most seamless installation process possible.
- Deck-level flashings add an additional layer of protection and are required by some AHJ (AHJs). Any tile mount should have an optional deck-level flashing available.
- Optional tile replacement flashings. These are, of course, integrated into Tile Replacements by default. When selecting a tile hook, make sure you have the option to purchase a matching flashing as tiles will break as installers walk across the roof. Using replacement tile flashings on your mounts allows the tile at each mount to be used to replace broken tiles elsewhere on the roof. This is important because, sometimes, finding matching tiles can be impossible.
When I was an operations manager in Southern California, one of my installation crews was faced with a roof of tiles that were rather brittle. At the end of the job, we needed to replace a good number of those tiles. I soon discovered that the tile was made by a long-gone manufacturer. After spending hours unsuccessfully searching tile boneyards and working the phones, we found the only matching product was in Las Vegas, Nevada. It was only sold by the pallet, so I had to order much more than I needed, pay an exorbitant price, and have it shipped in. Tile replacement flashings can prevent scenarios like this.
Unirac’s Attachments for Tile Roofs
Pro Series Solarhooks are Unirac’s Tile Hook attachments. This product line meets the criteria I outlined above. The Unique “Power Arch” shape of the arm adds up to 60 percent more strength without using bulky materials that would require excessive grinding of tiles. Optional Tile Replacement and Deck Level Flashings are available. The All Tile hook has full East-West and vertical adjustability and works with any tile profile. The Pro Series also includes hooks for stone-coated steel roofs and non-adjustable options for West, Spanish and Flat.
Flashkit TR is Unirac’s Tile Replacement. This meets the requirements I laid out above for replacement tile mounts and features a unique and innovative adjustment and alignment system. The universal single base unit features adjustable height and can adjust East-West as well. If you need a taller base, just slide the riser off, rotate it, and slide it back onto the base. Once the base is fastened, the flashing drops over the stud in the base, automatically aligning the post with the flashing hole. The waterproofing seals are fully encapsulated and protected from UV degradation. At the deck level, the base comes with butyl patches pre-installed at the lag holes. Optional deck-level flashing is available.
If you read both articles in this series, you should now have a good grasp of the basics of selecting attachments for residential roofs. Thank you for following this series, and please reach out with any questions you might have pertaining to products and/or the installation process.