Solar Roof Talk Episode 3! Rail-based vs Rail-free – Part 2

Quick Mount PV is proud to present Solar Roof Talk, a 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 episode, Jeff and Sue continue their discussion of the GTM Research report: U.S. PV Racking 2017: Landscape, Pricing and Forecasts and a comparison of rail-based vs rail-less pv mounting. Topics include:

  • Comparison of rail-based vs rail-less pv systems
  • Module-level electronic attachments
  • Residential and commercial racking and mounting markets
  • Surprise conclusions from the report

Listen to Part 1 here.

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

Solar Roof Talk Episode 2! Rail-based vs Rail-free – Part 1

Quick Mount PV is proud to present Solar Roof Talk, a 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 episode, Jeff and Sue discuss the GTM Research report: U.S. PV Racking 2017: Landscape, Pricing and Forecasts and a comparison of rail-based vs rail-less pv mounting. Topics include:

  • Comparison of rail-based vs rail-less pv systems
  • Module-level electronic attachments
  • Residential and commercial racking and mounting markets
  • Surprise conclusions from the report

Subscribe to our podcast on SoundCloud or 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

Stop by our booth at SPI and check out our exciting new products!

spi-qmpv200
We are getting excited for Solar Power International next week and wanted to share with you what we have in store! So stop by our booth (#1412) and say hello. What are you looking forward to checking out at the show? See you in Vegas!

 

Quick Rack™

Introducing Quick Rack, an innovative rail-free QR-Johan-275
mounting system that significantly increases speed and ease of solar installations. Quick Rack will be featured at our booth with live product presentations so stop by and learn more.

Quick Rack, featuring QRack™ technology, is an integrated roof mount and racking system, engineered to be robust and structurally sound. Quick Rack is fast and easy to install, with only a few components and minimal tools required. Quick Rack features integrated flashing and grounding, requiring only one ground lug for up to 300 contiguous modules.

Eliminating long rails significantly reduces material handling, installation time, and labor costs. The Quick Rack system also features our patented Elevated Water Seal. This ensures long-term water seal integrity and waterproofing for the life of the roof and solar array. Quick Rack also comes with design software, ensuring every solar array is accurately designed and code-compliant.

 

Quick Hook® Series

To better meet your needs in the tile market, we’re updating our Quick Hook product line to work with a broader range of tiles and mounting options. Quick Hook, featuring QHook® technology, is now designed for use with side-mounted or bottom-mounted rails. Multiple height options allow for use with a variety of tiles. Includes preformed flashing for code compliance. Updated hooks will be available in late November but we will have a special sneak peek at our booth at SPI. Current Quick Hooks products will continue to be available until then.

Quick Hook® SS/LS – For Side Mount RailsQH-SideMount
Standard height & low height hooks for side-mounted rails. Preformed flashing and adjustable hook with 6″ base for simple, clean installation.
Available finishes: aluminum mill (A)

Quick Hook® SB/LB – For Bottom Mount RailsQH-BottomMount
Standard height & low height hooks for bottom-mounted rails. Preformed flashing and adjustable hook with 6″ base for simple, clean installation.
Available finishes: aluminum mill (A)

Download our tile product brochure for more information. (PDF 514KB)

 

Classic Composition & E-Mount Series

The Classic Comp Mount andE-Mount Lag E-Mount, featuring our patented QBlock® Elevated Water Seal technology, are now available with three attachment options: standard 6″ hanger bolt, extended 6.5″ hanger bolt, or lag screw.

 

Extended Warranty

We have doubled warranty coverage for our QBlock®, QBase® and QHook® line of solar roof mounts to 20 years. Effective Sept. 1, all solar mounts featuring the patented technologies QBlock, QBase and QHook, will be covered with a 20-year limited product warranty. Our engineering, ISO 9001:2008 certified manufacturing, and years of field experience means we can stand behind our products for decades.

If you have any questions, please leave a comment below. We look forward to seeing you next week in Las Vegas!

10 Tips for Installing Solar Roof Mounts

Our training and tech team spends much of their day answering technical questions on solar mounts for comp shingles, tile, shake, metal shingles and other roof types. We advocate quality installation practices that improve reliability and longevity of rooftop solar systems. Most PV arrays are capable of producing power for 20-30+ years. If the roof and waterproof mounts last the life of the solar system, the homeowner reduces their monthly energy cost and insures clean, emissions free power for years to come.

We’ve compiled our top ten tips for installing solar on shingle and tile roofs. By following these guidelines you will ensure better long-term system quality and lower the cost of power for your customers.

1. Locating rafters
Rafter-finding techniques include attic rafter mapping, rubber mallet roof tapping, drilling two to three holes through the sheathing to locate the edge of the rafter or using sophisticated stud finders like the Bosch D-tect 150.

2. Centering attachment point
Take care to center your lag bolt in the middle-third of the rafter. This ensures the fastener has the structural capacities listed by the American Wood Council charts.

3. Piloting holes
Drilling pilot holes is critically important when using 5/16- or 3/8-in. lag bolts in a 2x rafter. This is true even with the newer generation of self-drilling fasteners (like those from GRK). While these specialty fasteners can be installed in wider lumber without pilot holes, failure to drill pilot holes in the outer chord of 2×4 or 2×6 rafters will likely result in split rafters.

4. Remove shingle nails
Always remove the nails on composite shingles to allow the upper edge of flashing to be 1/2-in. Failure to remove nails is the most frequent mistake when installing flashing. Removing nails allows the flashing to extend up under the third course of shingles for code-compliant, reliable waterproofing.above the butt edge of the third course shingles. Failure to remove nails will prevent the flashing from being positioned up under the butt edge of the third course of shingles and thus become a leak risk, especially when the flashing is positioned under a butt joint between two adjacent sections of shingles.

5. Acceptable working temperature
Shingle temperatures should be between 45° and 85° F to avoid damaging the shingles. When installing on asphalt shingles above 85° F, care must be taken to avoid compression deflection of the flashing from over-torquing the lag bolt. Special roofing shoes or protective mats can be used to minimize the risk of bruising on warm or cold days.

This diagram shows the acceptable position for flashed roof-mounts. Most mounts will require at least one nail be removed.
This diagram shows the acceptable position for flashed roof-mounts. Most mounts will require at least one nail be removed.
6. Flashing width
Asphalt shingle flashings should be at least 9 in. wide to comply with roofing industry best practices. This assures at least 4 in. of coverage from the edge of the hole to the edge of the flashing. More width provides additional protection from wind-driven rain making 12-in. wide flashing very popular. Tile flashings typically are 18 in. or wider to meet Tile Roofing Institute (TRI) guidelines.

This flashed Quick Hook uses a three-course sealing system that is approved by the TRI guidelines. Mastic applied to fiber mesh provides long-term waterproofing of the top and sides of the base flashing to the rolled roof underlayment.

7. Flashing material
Flashings should be made from an NRCA-compliant metal (aluminum, stainless steel, lead or galvanized steel). This flashed Quick Hook uses a three-course sealing system that is approved by the TRI guidelines. Mastic applied to fiber mesh provides long-term waterproofing of the top and sides of the base flashing to the rolled roof underlayment.The TRI requires curved tile flashing be made from malleable metal. SMACNA (Sheet Metal and Air Conditioning Contractors’ National Association) considers galvanized steel to be suitable only for 15 years of service life, and any breach of the zinc coating will cause corrosion and rust staining. For this reason, galvanized is inadvisable in coastal and industrial environments as well as any installation with more than 15 years of expected life.

8. Seal design matters
Select flashed mounts with a robust seal. Seals that are elevated above the waterline will provide longer life than seals at the waterline, especially in freezing climates. Please note that sealant is a helpful addition to a properly installed flashing; however, when used alone, sealant is not an alternative to metal flashing required by building codes.

The Tile Roofing Institute guidelines require a base flashing be used at the underlayment level. The TRI guidelines are code-required for most tile roofs. Underlayment bibbing is one of two accepted methods for waterproofing the base flashing.

9. Install base flashing on all tile roof mounts
This frequently disregarded code requirement will cause premature leaks on tile roof installations within five to 10 years. The Tile Roofing Institute guidelines require a base flashing be used at the underlayment level. The TRI guidelines are code-required for most tile roofs. Underlayment bibbing is one of two accepted methods for waterproofing the base flashing.All major tile manufacturers abide by TRI’s guidelines which mandate flashing at both tile and underlayment levels. All tile standoffs need a “base flashing” that is bibbed or three-coursed to the underlayment. Then the “tile-level flashing” is installed either on top or just below the tile. Tile hooks also require base flashing, but tile-level flashing is not required since the tile is not penetrated.

10. The benefits of re-roofing under the array before solar installation
Most arrays are installed on roofs with less than 10 years of remaining life. It is strongly advised that the installer replace the shingles or tile underlayment under the field of the array before installing solar. Replacing the roof under an average-sized array prior to PV installation will add $1,000 to $1,500 to the initial installation cost. Homeowners who ignore this advice will pay an additional $3,000 to $5,000 to remove and reinstall an average-sized system for the inevitable roof replacement. Simply stated, unless your roof is relatively new, re-roofing prior to PV installation is the most effective strategy to getting the best financial performance from a solar investment.

Written by Jeff Spies. Original article appeared in Solar Builder’s May/June issue.