How should transitions be detailed between Solar Roof on ≥2:12 slopes and adjacent low-slope membranes to avoid chronic…

Trade Talk
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How should transitions be detailed between Solar Roof on ≥2:12 slopes and adjacent low-slope membranes to avoid chronic leaks at saddles/valleys—what do long-term inspections show?

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Okay, so when you’re putting a Tesla Solar Roof on a roof that’s pretty flat, that spot where they come together can be a place where water might sneak in. Here’s how to dodge those problems:

Really lay on the waterproof membrane,

Put in some open valley flashing where the roof angles meet,

Give the mounting stuff a little lift,

And don’t just depend on caulk to keep water out.

If you set it up the right way and give those spots a once-over every year, you can skip those leaks at the saddle horror stories you might hear about.

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Long-term inspections show most chronic leaks come from insufficient overlap, trapped debris, or movement at the interface. So maintain clear drainage paths and re-seal exposed joints during routine roof checks.

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To detail transitions between Solar Roof on ≥2:12 slopes and adjacent low-slope membranes, follow these best practices to minimize the risk of chronic leaks at saddles/valleys

  • Waterproofing Membrane: Install a self-sealing bituminous membrane or equivalent at the transition points, such as valleys and roof deck penetrations. This layer provides additional protection against water intrusion.
  • Flashing: Use metal or plastic flashing along with the membrane at wall intersections and around penetrations. Ensure the flashing is properly integrated with the roofing materials.
  • Installation:
    • Center the membrane along the valley to ensure maximum protection.
    • Overlap membrane sections by 6 inches in a shingle fashion to allow water to flow unobstructed.
    • Secure the material in place with a heavy roller.
    • Ensure the membrane lays flat with no gaps, creases, or folds.
  • Design Considerations:
    • Use open valleys for low-slope roofs (≤3:12 pitch) to prevent debris accumulation.
    • Consider using laminated shingles with open valleys for better water drainage and reduced risk of ice dams.
  • Long-term Inspections: Regularly inspect the transitions and valleys for signs of wear, damage, or degradation. Check for proper water flow and ensure the membrane and flashing remain securely in place.