Installing structural screws to help secure our solar racks
This video demonstrates how to install structural screws to secure solar racks, showing the steps to fasten racks to a building structure for a stable solar array. It covers measuring and locating structural members, fastening the racks with structural screws, and sealing the penetrations to ensure a long-lasting installation.
Build Sequence
1. Plan layout and gather materials
Review the racking layout, determine screw locations in advance, confirm required screw type and length for the rack and roof structure, and gather screws, rails, and tools.
2. Locate structural members
Locate rafters, purlins, or other structural members behind the roof surface where the racks will be fastened using measurements or a stud-finder. Mark the center of each structural member for screw placement.
3. Mark and lay out screw positions on rails
Position the mounting rails in place and transfer the marked screw locations to the rails and flashing/roofing surface. Verify spacing and alignment across the array.
4. (If required) Pre-drill pilot holes
If specified by the screw manufacturer or substrate, drill pilot holes through the rail and roof covering into the structural member to prevent splitting and ensure correct screw seating.
5. Install structural screws
Using an impact driver or drill with the correct bit, drive the structural screws through the rail into the structural member. Use washers or sealing washers as required and ensure screws are seated flush without over-torquing.
6. Apply flashing and sealant
Install any required flashing and apply appropriate roof sealant around penetrations to prevent water ingress, following manufacturer recommendations for materials and methods.
7. Inspect and torque-check
Visually inspect all fasteners, check alignment of rails, and torque-check screws if a specific torque spec is provided. Replace any improperly seated fasteners.
8. Final cleanup and safety check
Remove debris from the roof, ensure all tools and loose hardware are removed, verify sealant has been applied neatly, and confirm rooftop safety measures are restored.
Frequently Asked Questions
What type and size of structural screw should I use?
Use the screw size and type recommended by your racking manufacturer; screws must be long enough to penetrate the structural member properly and be rated for structural loads and the environment (often coated carbon steel or stainless steel). If unsure, consult the racking spec sheet or a structural engineer.
VIEW FULL ARTICLE →Can I install these screws myself or should I hire a pro?
A competent DIYer with roofing experience and proper safety equipment can install structural screws, but because of the risk of roof leaks and fall hazards — and structural/permit considerations — hiring a qualified installer or consulting an engineer is recommended for most installations.
VIEW FULL ARTICLE →How do I ensure I’m screwing into a structural member?
Locate rafters or purlins using measurements from the eave/birdsmouth, a stud finder designed for roofs, or by inspecting the underside in accessible attic spaces. Mark centers and verify alignment before driving screws.
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High‑strength fasteners used to attach solar rack rails to structural members. Size and coating depend on racking system and roof substrate.
The rail system being secured by the structural screws; specific model depends on the solar racking system in use.