The gap between design and construction
On a commercial project, weeks or months can pass between the original site survey and the day the install crew arrives. During that time tenants move, roofers patch leaks, rooftop units get replaced, and parking lots get restriped. The engineer designed against the building as it was recorded. The crew builds on the building as it is. A pre-construction survey exists to close that gap.
This is not a repeat of the original survey. It is a targeted verification, organized around the question every EPC project manager asks before releasing materials: is there anything on this site that will stop us or cost us money that we do not already know about?
What the pre-construction visit confirms
The roof still matches the plan
- Rooftop equipment, penetrations and curbs are where the drawings show them, and nothing new has been added.
- Roof condition has not deteriorated, and no recent repairs, overlays or new membrane work changed the warranty situation.
- Drains, scuppers and parapets match the layout, and array rows will not block water.
- Any roof area that was set aside for future equipment is still free.
The structure is as recorded
If the original record included assumptions, such as framing hidden behind a ceiling, the pre-construction visit is the last cheap chance to resolve them. If a mechanical contractor has since opened a ceiling or added a unit, framing that was unreadable may now be visible. Note any modification near the array area and tell the engineer before materials arrive. The method for recording framing is described in our note on roof structural assessment for commercial solar.
The electrical room is ready
- The switchgear, meter and transformer match the nameplates in the design, with no change in ratings or arrangement.
- Space for inverters, combiners and disconnects is still free of storage, new equipment or tenant modifications.
- Conduit routes are clear and the proposed wall and roof penetrations are still acceptable.
- The outage window for the tie-in is agreed with the owner and, where required, the utility.
Logistics: where schedule is won or lost
Crane and lift planning deserves real attention at this stage. Confirm the pad location, reach, overhead lines, ground bearing, access for delivery trucks and the street or lot permits needed. Confirm where pallets of modules and racking will be staged, how they get to the roof, and who must be informed when deliveries arrive. Confirm hours, escorts, badge requirements, parking for the crew, restrooms and any site safety orientation.
Safety is part of logistics. Check anchor points, parapet heights, guardrails and skylight protection against the fall protection plan. Fall protection requirements depend on the type of work and the standard that applies, so the plan should be reviewed by the contractor's safety lead rather than assumed.
Permits, utility and paperwork
A pre-construction survey is a good moment to walk the paperwork against the building. Do the permit drawings match what is on site? Has the utility approved the interconnection path that the design uses? Is any required roofing contractor engaged to supervise or inspect penetrations? Our permitting and engineering page explains how stamped plan sets support this step, and the roof warranty note covers the contractor requirement.
Documenting the baseline
The visit also creates a dated baseline of the building before work starts. Photograph the roof surface, the parapets, the interior areas near conduit runs and the electrical room as they stand. If damage is alleged later, an organized baseline set protects the EPC and the owner. It also provides a reference for the closeout, when the crew documents the as-built condition.
Who should do it
Ideally someone who did not do the original survey, working from the engineer's design set rather than the survey photos. A fresh pair of eyes checking the design against the building catches different problems than the person who already believes the original record. The visit should be short and focused, and its output should be a go or no-go note with an itemized list of changes.
A simple go or no-go list
The output of a pre-construction survey should be decisive. A useful format is a short list that ends in a single call: go, go with changes, or hold. Each line on the list should name an item, its status and the person responsible for any follow-up.
- Roof area for the array is clear and matches the plan: yes or changes needed.
- Structure and electrical match the recorded data: confirmed or deviations listed.
- Crane, staging and access plan is workable: confirmed or open issues.
- Roofer requirements and inspections are arranged: confirmed or pending.
- Outage window for the tie-in is agreed: confirmed or pending.
- Safety plan reviewed against site conditions: confirmed or open issues.
A written list like this also gives the project manager something to share with the owner and the field supervisor. It turns a vague feeling that the site is probably fine into a record of what was actually checked, which matters when schedules slip and someone asks what was known when materials were released.
How Solar Survey AI supports EPCs
Solar Survey AI performs on-site commercial surveys nationwide, with a network of 500+ technicians, capturing the roof, structure and electrical room in one visit and delivering 48 hours after the survey. EPCs use the same network to verify a site before mobilizing, to re-survey after a long delay, or to add a missing zone, such as the electrical room, to an earlier record. See the commercial on-site survey and design and engineering pages for scope, and the requirements note for what a full record contains.
If the first record is complete and recent, a pre-construction visit may be brief. If it is old, incomplete or based on assumptions, treat the visit as insurance against the most expensive kind of surprise: the one discovered with a crane on site.