Where the unit sits is decided once, answers to three authorities, and is nearly free to get right and expensive to get wrong. The authorities: NFPA 37 — the national standard governing stationary engines — the manufacturer’s install manual, and whatever covenants your neighborhood signed. The governing numbers: NFPA 37 wants five feet from operable openings and vents; enclosure-tested units like Generac’s and Kohler’s may sit as close as 18 inches from a non-combustible wall, with roughly three feet of service space in front. Your unit’s install manual can be stricter, and local code has the last word — which is exactly why the full install sequence puts this check on paper at the site visit.
What do the placement rules actually govern?
Three kinds of distance, whatever their current values:
- From the structure. Combustion equipment near a wall is regulated — material, distance, and exhaust direction all participate.
- From openings. Windows, doors, soffit vents, crawlspace vents. This is the rule that exists because exhaust drifts, and it’s the one that most often vetoes the “obvious” spot beside the back door.
- For service. Clear space around the unit so a technician can actually open it. Forgotten at placement, cursed at every service visit after.
The manufacturer manual layers its own requirements on top, sometimes stricter than code. Inspectors check both at the permit inspection — which is exactly why placement gets settled at the site visit, on paper, before anything is poured.
Why is placement effectively permanent?
Because the pad, the gas run, and the electrical run all terminate at the unit. Move the generator three feet and you’ve re-bought some of each; move it across the house and you’ve re-bought most of the install. “We’ll adjust it later” is not a sentence that survives contact with trenching costs.
That permanence is also the argument for choosing the spot on total cost, not on first glance. The compliant spot closest to both meter and panel usually wins — and the ground itself gets a vote, since the pad has its own requirements about drainage and soil that a pretty corner of the yard may fail.
What’s the honest HOA advice?
Submit first, pour second. Alabama covenants typically let associations regulate visibility and screening more readily than they can prohibit equipment, and in practice most of these conversations end at screening shrubs and a sight-line compromise — cheap concessions at planning time, bitter ones after concrete.
Bring the HOA a drawing: unit location, screening plan, a note that placement follows NFPA 37 and manufacturer requirements. Boards approve documents faster than they approve arguments. And if your neighborhood has no HOA — much of the county doesn’t — your remaining authority is the neighbor who’ll hear the weekly self-test. Aim the exhaust accordingly; it costs nothing on drawing day.