How to estimate antenna mounting height without a structural survey
When a candidate rooftop comes across your desk, the structural survey is the expensive part of the answer. It's also the part you shouldn't be paying for on every long-shot in a six-candidate ring search. Before an A&E firm ever gets dispatched, somebody on the acquisition side needs a working number for antenna centerline height, just to decide whether the building is tall enough to clear the RF line-of-sight and worth carrying into lease negotiation.
That's the gap this post is about: getting a usable rooftop height estimate before the site visit, not instead of one.
Why you need a height number before the survey, not after
A structural engineer's report tells you what the roof can hold and where the mounts go. It does not tell you, in week one of candidate screening, whether a building even clears the obstruction study. By the time you've scheduled a PE to climb onto a parapet, you've already spent site acquisition budget on a candidate that a rough height check could have ruled out.
Most teams solve this with whatever's on hand: county assessor records, a Google Earth ruler pull, or a call to the building manager who "thinks it's about twelve floors." Assessor data is frequently years out of date and doesn't track rooftop additions, mechanical penthouses, or the parapet height that actually drives your centerline math. Google Earth's measuring tool depends on you eyeballing a shadow or a 3D mesh that wasn't built for engineering use, and it varies candidate to candidate depending on imagery age and capture angle. None of these are wrong to use. They're just not consistent enough to screen a full ring of candidates the same way.
Desktop methods, and what each one actually gives you
- Assessor and permit records. Free, fast, and often stale. Good for a sanity check, not a decision.
- Shadow-length estimates from aerial or satellite imagery. Usable when the imagery and sun angle cooperate, but it's a manual measurement done per building, which doesn't scale across a candidate list.
- Stereo-derived height models from very-high-resolution imagery. This is the method that produces a per-building height value you can actually tabulate, because it's computed from the imagery geometry rather than measured by hand on each screenshot.
- LIDAR point clouds. Accurate where available, but coverage is patchy, and sourcing a one-off dataset for a single ring search rarely pencils out against the schedule.
No desktop method replaces the structural survey. What it can do: tell you, before you spend survey budget, which candidates in your ring clear the height threshold and which ones you can drop from the list without a site visit.
From building height to storey count, and what to do with it
Once you have a height figure for a candidate rooftop, converting it to an estimated storey count gives your RF team and your zoning application a number they can work with without needing a rooftop measurement crew first. That's useful in jurisdictions where permitting language references storey count or where your RF Data Sheet needs an antenna centerline estimate before the lease is even signed. It's a screening number, something to carry into the candidate comparison matrix, flag for the structural survey to confirm, and move on.
If you're running candidate screening across a market and don't want to pull assessor records and squint at shadows for every rooftop on the list, Storey Estimation turns stereo- or shadow-derived building height into a per-building storey estimate you can drop straight into your candidate spreadsheet, refreshed annually from VHR imagery, no site visit required to get the first number.
Run your next ring search against it before you book the structural engineer.