Start with the building, not the brochure
An existing building may have little spare capacity for permanent equipment. Dead load is the weight of the building and installed materials that remain in place. A roof’s available reserve depends on its structure, current roof layers and other loads considered in the design. A light solar product can broaden the options, but cannot establish that reserve on its own.
A licensed structural engineer must confirm the roof before a solar layout is accepted. The engineer may need original drawings, information about alterations, roof layers and a site inspection. If records are missing, further investigation may be needed. An average roof-load figure is only one input to that assessment, not permission to place equipment anywhere on the roof.
Why ballast and penetrations matter
Ballast is weight used to restrain equipment without fastening through the roof. In a conventional ballasted array, that weight can add substantially to the permanent roof load. Its amount and distribution depend on the layout, wind conditions and equipment. Do not compare only panel weight while leaving ballast and mounting hardware out of the calculation.
Penetrating attachments can reduce reliance on ballast but introduce interfaces through the roof covering. Building owners often worry about those interfaces on a membrane under warranty. Properly designed attachments are possible, but the roof manufacturer’s requirements and warranty terms must be checked. A non-penetrating system avoids those holes, not every possible roof or structural concern.
Distributed load and point load
Over Easy Solar has a roof load of about 12.2 kg/m2, or about 2.5 lb/sq ft, including support feet. That describes the distributed load for the stated arrangement. It should not be read as the pressure beneath each individual foot. The system rests on discrete supports, so the roof receives localized loads as well as the overall added weight.
The point load is about 12.2 to 12.4 kg per support foot. An engineer also needs the support contact area and position to understand how that load passes through the membrane, insulation, deck and structure. Insulation compression and local deck behavior may matter even where the total additional weight looks modest. Confirm the exact support data and layout for the proposed roof.
Wind load is specific to the project
Wind uplift can act on the rooftop equipment and its supports. The building’s location, height, roof geometry, parapets and nearby obstacles influence the calculation. Over Easy wind load is calculated per project, including to ASCE 7-22 where applicable. The locally adopted rules and the engineer’s design govern the final requirements.
Units have no fasteners or roof penetrations, and most projects need no ballast. That is not a blanket statement that ballast is never needed. Project-specific wind calculations confirm the arrangement and whether additional ballast is required. Added ballast changes the structural assessment, so any such requirement needs to be included before the roof is approved.
What to gather for a review
Provide a roof plan or aerial image with one known dimension, the project location, roof obstacles and their heights, parapet height and membrane type. Add the available structural drawings and roof build-up information. Explain where maintenance access must remain and whether equipment or roof replacement is planned. These details help the designer produce a layout the engineer can actually review.
ArcEdge supplies and supports Over Easy Solar, rather than installing it. A roofer or solar installer places the units to the accepted plan, and a licensed electrician performs the electrical connection. A licensed structural engineer must confirm the roof. On an open flat roof without weight limits, conventional tilted solar usually costs less and fits more capacity in the same area; Over Easy is for flat roofs with a slope of 5 degrees or less.
Frequently asked questions
Is 2.5 lb/sq ft enough to approve a roof?
No. A licensed structural engineer must review distributed load, localized support loads, wind and the existing roof.
Is ballast always unnecessary?
No. The project-specific wind calculation determines whether ballast is needed.