Putting solar on a roof changes what that roof has to carry. The array adds permanent weight, maintenance loads and wind forces, including uplift, to a building that was designed for something else.

Whether the building can take it depends on how it was designed, what condition it is in today and how the array will be fixed to it. A roof that looks fine from the ground tells you very little about any of those.

Look at the building, not just the roof surface

RCC slabs, steel sheds with sheeting and older load-bearing buildings behave very differently, so start by identifying the roof type and collecting whatever drawings exist. Note cracks, corrosion, water ingress, past alterations and damaged connections. Photographs and a walk-over help define the question, but they cannot establish capacity on their own.

Then trace the load path: module, rail, mounting member, roof deck or slab, supporting beams and columns, and down to the foundation where relevant. How far the review goes depends on the building system and the records available.

  • Collect structural and architectural drawings and any alteration records.
  • Record visible deterioration, leakage and previous repairs.
  • Confirm the module layout and mounting details being proposed.

Fixings, edges and waterproofing

The fixing is often as critical as the main structure. Anchor type, edge distances, local bearing on the slab, purlin spacing in sheeted roofs and waterproofing penetrations need to be reviewed together. A detail that carries the load but breaks the roof's waterproofing has only swapped one problem for another. Roof edges and corners also see higher wind effects, so layout and fixings there deserve a closer look.

If the review finds a shortfall, raise it before procurement. A change in layout or support arrangement is cheap at this stage. Strengthening, if needed, should be designed for the actual building and approved by the responsible engineer, not picked from a generic detail.

  • Review anchor locations, edge distances and local bearing together.
  • Check roof-envelope details wherever the structure is penetrated.
  • List any extra survey or testing needed to close the assessment.
  • Hold installation until the project-specific checks are accepted.