Path-Q Solar

How should roof loading from ballast be evaluated before using a non-penetrating solar mount?

Answer

Evaluate the complete load path and the roof's capacity for both concentrated and distributed ballast loads, including the weight of panels, racking, ballast, snow or water where relevant, and wind-related forces. A non-penetrating mount still requires structural review and a roof-protection plan.

Key points

  • Review load distribution at support points, not only the average load per roof area.
  • Assess wind uplift, sliding, overturning, edge effects, and the building's roof framing.
  • Confirm that pads or protection layers will not damage the membrane or block drainage.

What it depends on

  • Roof framing and allowable loads
  • Mount design, ballast quantity, and support-point spacing
  • Roof slope, membrane, drainage, and condition
  • Wind exposure and other environmental loads
  • Panel layout and building edge distances

Risks and trade-offs

  • More ballast can improve stability but increase structural demand and roof pressure.
  • Reducing ballast without engineering justification can increase movement or uplift risk.
  • A system that avoids penetrations may still affect roof warranties, drainage, and future maintenance.

Information you may need

  • Mounting system calculations and equipment weights
  • Roof plans, framing information, and inspection findings
  • Roof membrane and drainage details
  • Site exposure and proposed array geometry

Your next step

What to do next

Have a qualified structural professional review the mount supplier's load and wind calculations against the actual roof before approval.

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SQ02641