Kinetic Solar
Kinetic K-Flash™ Premium Roof Mount (KFLK-42S)
Kinetic K-Flash™ Premium Roof Mount (KFLK-42S)
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Kinetic K-Flash™ Truss-Mount Roof Attachment (KFLK-42S)
If you're investing in a rooftop solar array, the roof attachment is not the place to cut corners. The Kinetic K-Flash™ KFLK-42S is a premium flashed roof mount designed specifically for asphalt shingle solar installations, providing a strong structural attachment with excellent long-term leak protection.
Unlike basic roof mounts that depend heavily on sealants around exposed roof penetrations, the K-Flash uses a large integrated flashing that slides beneath the shingles and safely sheds water around the attachment point. It is one of the best waterproofing options available for shingled-roof solar installations.
The KFLK-42S is the structural-member version of the Kinetic K-Flash system. It includes two 5/16-inch × 4-inch self-drilling lag screws designed to fasten into a roof truss, rafter or other suitable structural member.
Two 4-inch structural lag screws provide a secure connection to the roof framing while distributing the attachment load across two fastening points. Both screws must properly engage a truss, rafter or other suitable structural member.
K-Flash combines a full flashing beneath the shingles with a raised sealant channel and a separate blind mounting stud. This design directs water around the attachment while avoiding an exposed L-bracket fastener through the top of the flashing.
Why You’ll Love It
- Structural-member attachment designed to fasten securely into a truss or rafter
- Two 5/16" × 4" lag screws provide strong dual-point structural support
- Premium flashed roof attachment designed specifically for asphalt shingle solar installations
- Excellent waterproofing protection with a large flashing footprint and raised sealant channel
- Separate blind mounting stud avoids placing the L-bracket fastener through the flashing
- Installer-friendly design supports a fast, clean and professional installation
- Professional black finish blends well with most asphalt shingle roofs
- Compatible with the deck-mount version when a required attachment falls between trusses
- 20-year Kinetic limited warranty when installed according to manufacturer requirements
The KFLK-42S must fasten into a truss, rafter or other suitable structural member. If one of your required mounting locations falls between trusses, use the KFLK-44S direct-to-deck version instead. Both mounts use the same K-Flash profile and can be mixed within the same rail system.
Pair the KFLK-42S with the KLB3-M L-Bracket Kit and Rapid-1 Rail system for a professional-grade rooftop solar mounting solution designed for long-term strength, clean installation and reliable service.
Technical Specifications
| Model | KFLK-42S |
| Roof Type | Asphalt Shingle |
| Mount Type | Fully Flashed Structural-Member Roof Attachment |
| Structural Attachment Points | 2 |
| Included Fasteners | Two 5/16" × 4" Self-Drilling Lag Screws |
| Fastener Material | Coated Steel |
| Required Attachment | Truss, Rafter or Other Suitable Structural Roof Member |
| Flashing Size | 9" × 12" |
| Flashing Material | Malleable Aluminum |
| Mounting Plate | Mill-Finish Aluminum |
| Finish | Textured Black Powder-Coated Flashing |
| Rail Compatibility | Rapid-1 System and Compatible L-Brackets |
| Certifications | UL 2703 / LTR AE-001-2012 as part of the K-Rack system |
| Application | Residential and Commercial Solar Installations |
| Warranty | 20-Year Kinetic Limited Product Warranty |
Applications
- Residential rooftop solar systems
- Installations requiring direct attachment to roof framing
- Off-grid cabins and cottages
- Garages, workshops and outbuildings
- Tiny homes and accessory buildings
- Agricultural buildings
- Commercial rooftop solar arrays
- Retrofit installations on existing asphalt shingle roofs
What's Included
- One Kinetic K-Flash flashing
- One aluminum mounting baseplate with blind attachment stud
- Two 5/16" × 4" self-drilling structural lag screws
- Serrated flange nut
- Manufacturer-supplied hardware package
The KFLK-42S is only as strong as the structure it is fastened into. Locate and confirm the centre of the truss or rafter before drilling. Roof sheathing alone is not the intended structural attachment for the two 4-inch lag screws.
Frequently Asked
Does this mount need to land on a roof truss?
Yes. The KFLK-42S is the structural-member version of K-Flash. Its two 4-inch lag screws must fasten into a truss, rafter or other suitable structural roof member.
Roof sheathing alone is not the intended attachment for this model. If the required mounting position falls between trusses, use the KFLK-44S direct-to-deck version instead.
What's the difference between the KFLK-42S and KFLK-44S?
The difference is how they attach to the roof:
- KFLK-42S: Two 5/16-inch × 4-inch lag screws fasten into a truss, rafter or other structural roof member.
- KFLK-44S: Four 1/4-inch × 2-inch structural screws fasten directly to suitable roof decking.
Use the KFLK-42S when the mount lines up with structural framing. Use the KFLK-44S when the required mounting position falls between trusses.
Can I mix this with the deck-mounted version?
Yes. The KFLK-42S truss-mount and KFLK-44S deck-mount versions can be used together in the same solar array.
For example, use the KFLK-42S where a rail crosses a convenient truss and the KFLK-44S where the required attachment falls between trusses. Both models use the same K-Flash mounting profile, so the L-brackets and rail remain at the same height.
Keep every attachment within the maximum permitted rail spacing for your installation.
How do I find the roof trusses?
If the underside of the roof is accessible, locate the trusses or rafters from inside the attic and measure their spacing. Common spacing is 16 or 24 inches on centre, but you should confirm the actual framing rather than assume.
Mark the centre of each structural member carefully. Both lag screws must engage solid framing—not merely the shingles and roof sheathing.
Do I need to use both lag screws?
Yes. The KFLK-42S is supplied as a two-lag structural attachment. Use both lag screws in the designated baseplate holes and ensure both properly engage the structural member.
Can I space the mounts 48 inches apart?
Yes, provided the rail is permitted to span 48 inches for the snow and wind loads at your location.
On a roof with trusses spaced 24 inches on centre, mounts placed every 48 inches can land on every second truss. Mount spacing is measured along the rail and must remain within the allowable span for the rail system.
Can I space the mounts 36 inches apart on 24-inch trusses?
Not if every KFLK-42S mount must land on a truss. With 24-inch truss spacing, mounts positioned every 36 inches will alternate between landing on a truss and falling between trusses.
Use 48-inch spacing if permitted by the rail span requirements, reduce the spacing to match the framing, or use a KFLK-44S deck mount at the locations that fall between trusses.
Does it require roof sealant?
Yes, sealant is recommended as part of the K-Flash installation. Apply compatible roofing sealant beneath the flashing in the raised stamped channel surrounding the attachment area.
The flashing directs water around the mount, while the sealant provides a second layer of protection around the lag-screw penetrations. Follow Kinetic's current installation instructions when applying it.
Why is the flashing installed underneath the shingles?
Installing the flashing beneath the upper shingles allows rainwater to flow over the flashing and continue down the roof. Water is directed around the lag-screw penetrations instead of collecting against them.
This is more reliable than simply drilling through the shingles and covering exposed fasteners with caulking.
Can it be installed on an existing shingle roof?
Yes. Carefully lift the shingles above the mounting location, fasten the baseplate into the roof framing, and slide the flashing beneath the upper shingles.
Replace any cracked, brittle or damaged shingles before installing the mount. The flashing should sit flat and allow water to drain naturally down the roof.
Do I need an L-bracket?
Yes. The KFLK-42S attaches to the roof, but an L-bracket is required to connect the roof mount to the solar rail.
The KLB3-M L-Bracket Kit is the matching option we recommend for Rapid-1 rail.
Will it work with Rapid-1 rail?
Yes. Install the KLB3-M L-Bracket on the threaded stud above the flashing, then attach the Rapid-1 rail to the L-bracket using the included rail hardware.
Not sure how many roof mounts, L-brackets or rail lengths you need? Send us your panel dimensions, roof layout and truss spacing, and we can help you build a practical material list.
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