80 ft clear span
Eighty feet is the width the whole clear-span-versus-modular question turns on. Below it a column line saves nothing; above it the two curves separate and keep separating. At 80 they sit on top of each other, which makes this the one width where the decision is genuinely close.
Priced as a 80 × 150 ft building at a 24 ft eave, 25 ft bays, 20 psf ground snow on the ASCE 7-16 basis, 115 mph wind, no crane — a case that matches what actually gets built at this width. Change any of it in the calculator.
Framing steel
4.07 – 5.57 lb/sf
Primary and secondary, 24 – 33 tons total
Building package
$16.63 – $20.79/sf
$200K – $250K over 12,000 sf
Installed
$25.78 – $39.50/sf
$309K – $474K, before interior buildout
Modular would save
nothing
No saving at this width
At this span: The crossover band. Clear span and modular start to diverge in cost here - price both.
The short answer
Price both. At exactly this width clear span and modular should come back within a percent or two of each other, which means the layout — not the structure — should decide it.
Planning-stage estimate calibrated to published industry ranges. Not a substitute for a stamped design by a licensed engineer.
Geometry that follows from the width alone, at this page's 24 ft eave. These are planning rules, stated so they can be argued with — the derivations are on the methodology page.
| Dimension | At 80 ft | Why it matters |
|---|---|---|
| Frame depth at the haunch | 38–48 in | Span/25 to span/20. The deepest point of the frame, at the knee, where the moment peaks. |
| Clear height at the sidewall | 20–20.8 ft | Eave height minus the haunch. The height you can actually use in the first bay in from the wall; clearance rises toward the ridge. |
| Rafter half length | 40 ft | Haunch to ridge. What has to get on a truck. |
| Shipping pieces per half | 1 | One piece. Standard flatbed, no permit, no field splice. |
| Deflection allowance, L/240 | 4 in | Allowable midspan movement with a non-plaster ceiling, per IBC Table 1604.3. The weight model behind this page checks none of it. |
| Engineering | Standard | Inside the 150 ft ceiling for a standard single-span rigid frame. Expect a quick, comparable quote from several bidders. |
It is not a threshold the steel notices. It is the point where two cost curves cross: the clear span frame gets heavier with every foot of width, while the modular frame pays a fixed price for a column line and then amortises it over a wider and wider building. At 80 ft those two effects cancel — the model puts the saving at 0%.
A percent or two is inside the noise of a real quote. Which manufacturer is hungry that month will move the number further than the frame configuration will, so treat it as a tie and break it on something else.
Ask where the column would land. If it falls on a rack line, a demising wall, or a bay division you were going to build anyway, take the modular frame — you get a marginally cheaper building and lose nothing. If it lands in a drive aisle, a turning circle, or anywhere a forklift has to swing, take the clear span and stop thinking about it. At this width you are not paying a premium for the clear floor; you are getting it at par.
The one thing not to do is take the modular saving and design around the column afterwards. A single column in the wrong place costs more in daily operation than 0% of package price is worth, and at this width that saving is small enough for one bad placement to erase it entirely.
Framing runs about 4.07 – 5.57 lb/sf, up roughly a quarter from 60 ft for a third more width — the curve is starting to bend but has not turned steep. The haunch is 38–48 in deep, so at a 24 ft eave you still have 20–20.8 ft clear at the sidewall and clearance is not yet a design issue.
Rafter halves are 40 ft each, inside legal haul length, so the building ships and erects the way a 60 ft one does. Nothing about the logistics of an 80 ft building is unusual. That stops being true about 20 ft further on.
The uses whose typical width covers 80 ft, and what drives the geometry in each. A use that does not appear here is not impossible at this width — it is just not where it usually lands.
| Use | Typical width | Typical eave | What sets the geometry |
|---|---|---|---|
| Crane Bay / Manufacturing | 60–150 ft | 24–45 ft | Hook height drives the eave, and the crane runway loads the frame in a way roof snow never will. Usually clear span. |
| Riding Arena | 60–150 ft | 14–20 ft | A regulation arena floor cannot have columns in it. Width is set by the discipline, not the budget. Usually clear span. |
| Church / Worship | 60–120 ft | 16–28 ft | Unobstructed sightlines to the chancel. Clear span is the whole point of the building. Usually clear span. |
| Agricultural | 40–100 ft | 14–20 ft | Equipment turning radius and the angle of repose of whatever is stored in bulk. Usually clear span. |
| Retail / Office | 40–80 ft | 12–20 ft | Street presentation and parapet detailing. Frame cost is a minor line next to the facade. Usually single slope. |
Neither, in the sense that it does not matter. At 80 ft a modular frame saves nothing measurable: the column, its footing and its connections cost about what the span relief is worth. Take the clear floor, because it is free.
The frame selector's own recommendation for this case, with interior columns permitted, is a Modular frame with tapered columns. Web-tapered members follow the moment diagram and are the lightest way to carry this span.
Next step
A dealer quoting your actual geometry and load case beats any estimator, including this one. Three of them, each carrying engineer-stamped drawings for your state, cost you nothing to ask.