EcoFasten Solar wants to make sure installers are armed with as much information as possible before mounting a PV array on any residential roof. With that being said, it’s important to consider the following information prior to installation.
Make sure you inspect the roof before the PV array design, paying close attention to the following aspects:
- Structural evaluation of the building
- Structural evaluation of the roof
- Age of the roofing materials
- Type of roofing materials (especially important to determine the correct steps are taken in order to maintain the integrity of the roof)
- Dirt build up
- Pest damage
- Condition of underlayment (as the primary source of waterproofing the roof, this step is absolutely essential)
- Damage from past work (repair any damage BEFORE installing PV)
- Roof drainage
- Roof traffic
- Roof access and safety
Another important thing to consider on any installation is the need to pre-drill (and backfill). If you skip this step, you run the risk of cracking or splitting rafters, which will cause leaking and will ultimately be your fault. If it’s done the right way to begin with, there will be no headaches later on.
What to account for when mounting solar on:
- Nails – make sure to notch your flashing to fit around nails – this will ensure code compliance by allowing the flashing to extend up and under the third course of shingles
- Position flashing between vertical joints of shingles for additional waterproofing measures
(Images on right from RGS Energy)
- Try to keep your time on the roof to a minimum. Even the strongest tiles can be brittle and can break easily
- Be especially careful not to drop tools while on a tile roof
- Replace and cracked or damaged tiles prior to installing – think of it this way: the last person on the roof will usually be the one who is blamed for any recent damage
- Mission (clay) tile is fragile, and is not ideal to install over due to excessive risk of breakage. The “strip & go” method is often used, where the tiles are removed from the section of the roof that the array will be installed on, and replaced with asphalt shingles
- Make sure the flashing meets UL 441 standards as well as ICC-ES AC 286 4.1
- The process/tips for installing on a slate roof are very similar to that of a composition shingle installation, but the slate tiles will need to be removed prior to installing – DO NOT drill through slate
- For code compliance and waterproofing properties to remain intact on slate roofs, make sure the top edge of the flashing extends up and under the 3rd course of slate
- For installs on metal standing seam roofing, make sure to choose roof mounts that employ clamp-to-seam technology, which will never penetrate the roofing materials due to the use of set screws
- Make sure the mounts you use will not void roofing manufacturer’s warranties
- When installing on corrugated metal, it’s important to use a mount that either attaches to the ribs of the panel (as opposed to in the channel, where water flows and moisture accumulates), or to use mounts the employ waterproofing technologies such as EPDM rubber bushings that will form a compression-fit once the fastener is attached
- One of the advantages of installing a solar PV array to a metal roof is that metal is one of the longest lasting materials on the roofing market (it’s also recyclable), so your chances of needing to re-roof prior to installation are slim
Low-Slope / Membrane
- The roof must remain watertight!
- In most low-slope roofing, this is achieved through flashing the attachment points
- Different low-slope roof coverings will have different flashing requirements
- Choose a mounting system that has a lightweight, durable construction that will enhance uplift and seismic values without adding additional weight
- Opt for a system with a large base plate, allowing multiple attachments points to distribute compressive loads over standard insulation
What else should I be aware of?
- There are 3 zones for wind resistance analysis (Wind uplift could move or rip off and ruin the roof surface if the system is not engineered for the correct wind resistance):
- Field Zone- interior- lowest wind loads
- Perimeter Zone- ends- middle wind loads
- Corner Zones- highest wind loads
- Wind uplift could move or rip off and ruin the roof surface if the system is not engineered for the correct wind resistance
- Roof Systems are classified for the level of fire resistance
- Class A – highest rated (max spread of flames = 6 ft.)
- Class B – max spread of flames = 8 ft.
- Class C – max spread of flames = 13 ft.
- The PV system must be engineered with materials to match the fire classification of the roof
- The fire rating for PV components is governed by UL testing
- Limited Manufacturer warranties may be void if design/install/maintenance procedures are not followed
- Flashing must match the roofing manufacturers install instructions
- Rooftop PV cannot interfere with roof maintenance
- Work with roofing manufacturer and the roofing contractor
What about installing on different slopes?
- Installing any roofing material on a roof with less than 3:12 pitch does not make it low-slope roofing
- The minimum slope asphalt shingles should be installed on is typically 2:12 pitch
- Low-slope roofs can be used on commercial roofing as well as residential
- Low-slope roofs have a minimum ¼” rise over a 12” run (follow roofing manufacturer’s instructions)
- All low-slope roofs must allow water to drain
- Large commercial structures will have drainage paths
- All low-slope roofs must have the ability to dry within 24 hours (humidity is an exception)
- If the roof does not drain properly, bacteria and organic growth will appear on the surface of the roof
- This organic growth will break down the roofing materials prematurely
- Roof inspections increase the life of the roof, and should be done a minimum of twice per year
- Low-slope roofs are often patched during roof inspections
- Roofers look for signs of wear and patch the roof prior to any problems
How do EcoFasten Solar products help accomplish these things?
The EcoFasten Solar line of patented, watertight solar roof mounts is comprised of a series of product systems characterized by roof type application. Each system can be paired with a wide variety of brackets, allowing installers to attach EcoFasten roof mounts to any racking option. All EcoFasten compression brackets are designed with a countersink milled into their base. Depending on roof type, a cone shaped base plate, flashing and/or EPDM bushing will fit into the bracket’s countersink. When installed and fastened to the roof, a compression-fit, watertight seal is created. Fast, easy, hassle-free designs that were precision engineered with the installer in mind.
Feel free to email us with any questions you might have about mounting solar on any roof – that’s what we’re here for!
See you all at Intersolar booth #9733!
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