Check Out Our New Podcast – Solar Roof Talk!

Quick Mount PV is proud to present Solar Roof Talk, a monthly podcast series for rooftop solar installers and others in the solar industry. Hosted by solar industry veterans, Jeff Spies, Senior Director of Policy & Susan Stark, NABCEP Certified PV Technical Sales Professional&Product Specialist.

In this first episode, Jeff and Sue discuss key takeaways from the recent NABCEP CE Conference 2017 in Dallas and recap the following sessions:

  • Residential Roof Racking Systems – Rail vs Rail-less and Building Integrated PV Panel
  • Wiley Burndy Solar Solutions for Grounding, Bonding & Wire Management
  • SEI PV with Energy Storage for Residential Applications
  • Rapid Shutdown Requirements and Solutions Panel
  • UL 2703 – PV System Bonding/ Grounding and Fire Classification Panel
  • Calculating Payback in a Post NEM Market Panel

Subscribe to our podcast on SoundCloud, iTunes, and follow it here on the blog!

Tools & Techniques: Attaching solar on
steep slope roofs

Roofs over 2:12 pitch are considered steep slope and instead of using a waterproofing membrane like a low slope roof, they typically use water shedding roof coverings that rely on gravity to keep the water out of the structure. The significant majority of steep slope roofs use asphalt shingles or tile. The other common steep slope roof options include wood shake, wood shingles, metal shingles, slate, standing seam metal roofs, or exposed fastener metal roofs. There are a variety of roof attachments and flashing methods available for each roof type, and careful selection is needed to insure you are able to deliver a structurally sound, waterproof, code compliant solar attachment system.

Waterproofing basics

Building codes require that roof penetrations be flashed per the roofing manufacturer installation instructions. A significant majority of asphalt shingle manufacturers follow the National Roofing Contractors Association guidelines for penetration flashing which mandate metal flashing for all penetrations and specify the upper edge of the flashing must reach up into the third course of shingles. The vast majority of tile roof manufacturers follow the Tile Roofing Institute’s installation guidelines that requires metal flashing to be installed at the underlayment level and sealed using bibbing or three coursing with roofing cement and reinforcing fabric.

Structural attachment method

Rafter attached systems have been the norm for solar installations as the tried and true attachment method. Building officials allow rafter attachment as long as the roof meets established criteria. An alternate attachment method secures the racking system directly to the roof sheathing. Using sheathing attached systems may be inadvisable since it can be difficult to verify whether the sheathing is reliably secured to the rafters. As a result sheathing attached systems are often not allowed on existing roofs in many jurisdictions. Sheathing attached systems can work well for new or re-roofs applications since the installer and building official can verify that the sheathing is attached to the rafters before the roof covering is installed. If a sheathing attached system is used on a new roof, it’s important that point loading on a single attachment does not get concentrated on a single fastener. This could initiate a structural problem if the fastener pulls out under dynamic uplift forces from windstorms.

This flashed roof attachment is rafter mounted and provides a reliable structural attachment for full code compliance
This flashed roof attachment is rafter mounted and provides a reliable structural attachment for full code compliance

Shingle roof attachment

Options for shingle roof attachments include standoff cone flashings, hooded flashings, and integrated seal flashings. Standoff cone flashing use a metal cone flashing that elevates the seal area above the roof plane. Hooded flashings are inexpensive, but have a major vulnerability as they have an opening on the downhill side of the attachment, which can allow wind driven rain to access the penetration. Integrated seal flashings use rubber seals and can be very effective. Seals located at the waterline will degrade more quickly than elevated seals particularly in cold climates where freezing water can wear out a rubber seal.

Metal cone flashing provides ample elevation of the seal above the waterline, assuring longer seal life

Metal cone flashing provides ample elevation of the seal above the waterline, assuring longer seal life

The patented QBlock waterproofing system elevates the seal of this integrated flashed attachment above the waterline.
The patented QBlock waterproofing system elevates the seal of this integrated flashed attachment 0.7” above the waterline. This approach positions the sealing area in a protective cavity shielding the seal from moisture and UV exposure.

Tile roof attachment

Options for tile roof attachment have expanded dramatically in the past several years and fall into three general categories: standoffs, tile hooks, and threaded bolts. Regardless of which method you choose, flashing at the deck level (underlayment level) is code required by the Tile Roofing Institute. Underlayment flashing can be challenging for certain tile attachments including the sliding track style base mount, but fortunately a growing number of code compliant tile roof attachments include preformed metal flashings to seal the penetrations at the underlayment level. This code compliant tile hook (pictured at top) is quicker to install and has no visible flashing. The standoff on the right is super strong and uses a malleable tile level flashing. Both roof attachments are sold with deck-level flashing that are sealed to the underlayment under the tile.

Tile standoffs

Tile standoffs are much stronger than hanger bolts as they have a larger diameter base and post, but both standoffs and hanger bolts require double flashing since the tile must be penetrated to allow for installation. The tile level flashing can be installed above or below the tile that is penetrated and the secondary flashing at the underlayment level would be sealed to the underlayment using bibbing or three coursing with roofing cement and reinforcing fabric. For curved tile, the TRI requires a malleable metal flashing molded to the tile.

Tile hooks

Tile hooks typically do not penetrate the top of the tile, instead they protrude between 2 rows of tiles. The tile lug will need to be trimmed using a tuck pointing diamond blade to allow for clearance of the hook and insure proper tile seating. Some metal strap style tile hooks allow the weight of the array to rest on top of the tile. This method of attachment is inadvisable, as the array will vibrate on the tile in a windstorm, increasing the likelihood of broken tile. The best tile hooks provide a strong mounting location that elevates the hook and racking system off the tile– preventing contact with the tile under full wind loading conditions.

Tile hook with underlayment bibbing

To be code compliant, tile hooks must have metal flashing installed using Tile Roofing Institute approved underlayment bibbing (shown on the left).Three coursing with roofing cement and reinforcing fabric (shown on right).

Less common roof types

Asphalt shingle roofs and tile roofs represent over 90% of all solar installations in the US, but many solar installers are confronted with less common roofs like wood shake/shingle, slate, or metal shingle. These roof types are often found on more expensive homes and are more challenging for the installer. The benefits of learning how to work on these upscale roof types are fewer competitors and better profit margins. Typically partnering with an experienced qualified roofer is advisable. Metal panel roofs are common in rural areas but exposed fastener roofs (corrugated or trapezoidal) may be less desirable than standing seam roofs as the fasteners often require periodic tightening and access to these fasteners is difficult after a solar installation. Standing seam roof rack systems typically attach to clamps on the standing seams. Standing seam panels are held on with clips, so the installer and building official should verify there are sufficient clips securing the roofing system, so it can withstand the uplift forces from the solar array when subject to strong winds.

This home with Decra metal shingles in Florida uses standoffs with flashing installed with a Decra

This home with Decra metal shingles in Florida uses standoffs with flashing installed with a Decra “Underpan” to channel any leakage safely to the top of the shingles below.

As flashed roof attachment options continue to expand, it’s important to verify your your attachment of choice will provide a reliable, long-term, structurally robust and waterproof system for the life of the roof and array. Your customers will thank you.

…….

This article was originally written for Solar Novus Today

The Next Generation Home

We’ve been working with nextgenhometv.com on their web series, First to the Future Home, featuring TV star and carpenter, Ty Pennington. The series covers the design, build and reveal of a truly next generation home, showcasing what it takes to make a house energy efficient, weather resistant, healthy and smart. As you might imagine, rooftop solar was an important aspect of this project.

We were honored to be included in the series and on the roof. Our QBase Composition Mount was installed on a sustainable and 100% recyclable Decra metal shingle roof during the SolarCity installation episode (episode 25). And just for fun, our first ever TV commercial is at the end of the latest episode (episode 28). Also, If you are interested in the Decra install, make your way to episode 18. The home will also include an AET solar thermal system, which they discuss in episode 24. Check it out, the episodes are short (less than 5 minutes) and it’s really amazing to see the latest innovations in smart, energy efficient home products, from foundation to rooftop. Enjoy!

Ty Pennington’s First to the Future Home

Ty Pennington’s First to the Future Home

Installing Solar On Metal Shingle Roofs

Over the past few years, our tech support staff has fielded a growing number of questions about metal shingle roofs. Metal shingle installations are more challenging than asphalt shingle roofs or even tile roof projects and require partnering with a qualified roofer. As a result, fewer solar installers bid these projects. However they can be more profitable than other projects as they are less subject to intense competitive pressures. Metal shingles are noticeably more expensive than asphalt shingle and tile roofs. Homes with metal shingle roofs are often in affluent areas with owners that are more likely to invest in solar. These homeowners tend to be less concerned about the modest savings common in grid tie competition and are usually more concerned with an attractive installation that preserves the aesthetic appeal of their pricey metal shingle roof.

To help make sense of this more challenging installation, we contacted the largest metal shingle manufacturers, and developed several methods for installing on metal shingle roofs. While there is a wide array of metal shingles, they typically fall into three basic mounting configurations:

Figure 1: Decra interlocking metal shingles with Quick Mount PV QBase mount installed over Decra underpan

Figure 1: Decra interlocking metal shingles with Quick Mount’s QBase Comp Mount installed over Decra underpan

Interlocking
Interlocking metal shingles most often resemble asphalt shingles or slate. They are directly nailed or screwed to the deck and have interlocking lips on the upper and lower edges, or sometimes on all four sides. These interlocking lips lock together for a lightweight, highly wind resistant roof. This style of metal shingles often requires complete removal of the roof from the ridge to the bottom of the array.

Figure 2: Batten mounted metal shingle

Figure 2: Batten mounted metal shingle


Batten Mount
Batten Mount metal shingles often resemble shake or tile. They typically mount to horizontal wood battens attached directly to the deck with screws inserted into the leading edge of the shingle. Batten mount metal shingles are relatively easy to install solar onto, because the individual shingles can be removed by taking off the screws at the top and bottom of the shingle and installing the mount. 
Figure 3: Counter batten roof

Figure 3: Counter batten roof

Counter Batten Mount
Counter Batten Mount metal shingles are installed onto a grid work of horizontal wood battens secured to vertical wood battens attached to the roof deck. This arrangement is best in a wet climate as it allows for rapid drainage of water that might leak past the metal shingles. An important caution is in order: before quoting any metal shingle project, always check for old shingle or shake roofs under the array. If you find an old shingle or shake roof under the metal shingles, the best strategy is the “strip and go” procedure outlined below. It is very challenging to effectively seal mounts on roofs of this configuration.

There are four methods for installing Quick Mount PV mounts on metal shingle roofs.

Figure 4: The light blue underpan extends under the mount and channels any rainwater harmlessly off the roof just below the mount. Note how the upper edge of the underpan is sealed to the underlayment.

Figure 4: The light blue underpan extends under the mount and channels any rainwater harmlessly off the roof just below the mount. Note how the upper edge of the underpan is sealed to the underlayment.


1) Underpan: Quick Mount PV has worked closely with Decra (the largest manufacturer of metal shingles) to develop a procedure for installing solar arrays on Decra metal shingles (aka stone coated metal panels). Decra is unique in offering a clever drainage pan configuration referred to as underpans. These underpans are positioned under the mount location with a flashing installed over the mount and the shingle installed over the flashing. Any water that hits the mount flows harmlessly down the underpan to the shingles lower down the roof. Since Decra stone coated metal panels are galvanized steel, any contact between the aluminum mount and the metal shingle is protected with a barrier material like a fully adhered underlayment.

Figure 5: The flashing shingle sandwich installation method requires a flashing installed between 2 metal shingles. Note that the lower metal shingle does not need to match color of the upper visible metal shingle.

Figure 5: The flashing shingle sandwich installation method requires a flashing installed between 2 metal shingles. Note that the lower metal shingle does not need to match color of the upper visible metal shingle.


2) Flashing sandwich: For batten mounted metal shingles that do not use underpans (like Gerard), you may be able to use the flashing sandwiching method. This requires purchasing enough of the exact same shingle as is currently on the roof. Color is not important, as these new shingles will be installed under the original shingle with a flashing sandwiched in between. The mount is bolted to the roof deck. Next, cut a 4” diameter hole into the new shingle and install over the QBase Comp Mount. Trim the top edge of the flashing as needed to fully cover the shingle. Finish by installing the original shingle over the top of the flashing. Cut small 1″ wide drainage slots in the butt edge of the top shingle to allow any water that gets onto flashing to easily drain. If the shingles are galvanized steel, use a self adhered underlayment on the top and bottom of the flashing to protect against galvanic corrosion caused by aluminum to galvanized steel contact. Finish by applying sealant around flashing cone to minimize water getting past flashing cone and sprinkle color matching granules into wet sealant to produce an attractive color matched mount. In this configuration, the bottom shingle serves the same function as the underpan in the method above.

 
3) Adhered flashed mount: Metal shingles that are fully interlocked on all four sides require a different approach. There are two possible approaches for “Aluminum Lock Roofing” shingles. The first method involves trimming the top edge of the Classic Comp Mount or E-Mount so the bottom edge of the flashing is just above the butt edge when the top edge is wedged all the way up in the interlock area above the penetration. The flashing is then coated with a sufficient amount of sealant, and the lag bolt is carefully torqued to the proper setting (when the QBlock stops pivoting). When installed properly, the gasket seal is tightly compressed between the flashing above and shingle below providing a reliable long term seal. The second option for interlocking shingles requires cutting a slit in the interlock just above the penetration and slipping the upper edge of the flashing under the second course of shingles until the block is positioned in the proper location. Sealant is applied to the cut area and under the flashing.

Figure 6: This metal shingle roof is installed over an old asphalt shingle roof. The best solar mounting option for this configuration is "strip and go".

Figure 6: This metal shingle roof is installed over an old asphalt shingle roof. The best solar mounting option for this configuration is “strip and go”.


4) Strip and go: If there is an old shingle or shake roof under the metal shingles, the easiest approach would be what is commonly referred to as, “strip and go”. First, a qualified metal shingle roofer would “strip” off the metal shingles from under the field of the array. Then the roofer would “go” by installing a new asphalt shingle roof under the field of the array. This installation method is a compelling option since the customer gets a new roof that lasts the life of the array, and the roofer can warranty the roof and flashed mounts. The long term cost benefits of a new roof under the array are dramatic- saving thousands in repair costs during the life of the solar system. When done properly, “strip and go” has the attractive appearance of Building Integrated PV Systems (BIPV), particularly when installed on batten mounted metal shingles shaped like curved tile or shake. There are six basic steps in the “strip and go” process.

  • Step 1: Roofer removes existing metal shingles under and around field of array.
  • Step 2: Solar installer secures QBase Comp Mounts over new underlayment into rafters using lag screws.
  • Step 3: Roofer installs shingles AND flashings over mounts.
  • Step 4: Solar installer assembles array.
  • Step 5: Roofer installs flashing around perimeter of shingles.
  • Step 6: Roofer installs metal shingles around perimeter of array.

While metal shingles require a bit more research, learning how to install on this high-end roofing system can boost your bottom line and bring solar to homeowners that often struggle to find a willing and able solar installer.

To learn more, register for our next metal shingle webinar on February 12. Or visit our website to download the presentation slides or view a previously recorded webinar.