40 ft clear span
Forty feet sits inside every manufacturer's standard frame line and outside the tier this section is about. The span is not what makes a 40 ft building cost what it costs, and a rigid frame is not automatically the cheapest way to cover it.
Priced as a 40 × 100 ft building at a 16 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
2.04 – 2.97 lb/sf
Primary and secondary, 4 – 6 tons total
Building package
$13.45 – $16.33/sf
$54K – $65K over 4,000 sf
Installed
$20.84 – $31.02/sf
$83K – $124K, before interior buildout
Modular would save
nothing
No saving at this width
Outside the usual range. This width prices outside the $14–22/sf band commonly quoted for metal building packages. That band describes ordinary spans; a 40 ft clear span legitimately leaves it, and clamping the figure to look tidy would make it useless exactly where it is most needed. How these figures were derived.
At this span: Light frames. Span is rarely the cost driver at this width - eave height and snow load matter more.
The short answer
Buy this building on eave height, snow load, and who is quoting it — not on span. And have a post-frame builder price the same footprint, because at 40 ft they are still in the game.
Planning-stage estimate calibrated to published industry ranges. Not a substitute for a stamped design by a licensed engineer.
This is below the tier this section covers. Under 60 ft wide you are narrower than most dealers chasing commercial rigid frame work will price keenly. The main quote form reaches the dealers who build this size every day and will get you more responses than the section's own.
Geometry that follows from the width alone, at this page's 16 ft eave. These are planning rules, stated so they can be argued with — the derivations are on the methodology page.
| Dimension | At 40 ft | Why it matters |
|---|---|---|
| Frame depth at the haunch | 19–24 in | Span/25 to span/20. The deepest point of the frame, at the knee, where the moment peaks. |
| Clear height at the sidewall | 14–14.4 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 | 20 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 | 2 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. |
The rafter in a 40 ft frame is a light member and primary framing is a small share of the package. Eave height and ground snow move the price further than width does: a few feet of eave changes the frame weight more than several feet of span, because the eave lengthens the column and raises the moment at the knee while the span is still short enough not to punish you for it.
That is why two 40 ft buildings on the same footprint get quoted a long way apart. The difference is almost never the width. It is the eave, the snow load the dealer designed to, and what the package includes.
The modular saving at this width is 0%, and that is not a rounding artefact — it is the honest answer. Below the crossover, splitting the span adds a footing, a column, a base plate and a connection in exchange for relief on a rafter that was never expensive. There is no version of a 40 ft building where a column line pays for itself.
So the decision people agonise over on wide buildings does not exist on this one. Clear span is simply what you get, and it costs nothing extra.
Post-frame construction, open-web bar joist on masonry or tilt-up, and light tube-frame suppliers all reach 40 ft comfortably. As buildings get wider these drop out one at a time; at 40 ft every one of them is live and any of them can win on price for a particular use.
A rigid frame's advantages here are real but they are advantages, not a foregone conclusion: a genuinely clear floor, a code-compliant envelope, engineer-stamped drawings for your jurisdiction, and a maintenance profile measured in decades. If none of those is worth much to you, price the alternatives properly before assuming steel wins.
The uses whose typical width covers 40 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 |
|---|---|---|---|
| Self-Storage | 30–60 ft | 9–12 ft | Unit module and drive-aisle width. Single slope drains away from the doors. Usually single slope. |
| 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 40 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 Clear Span frame with straight columns. Under 60 ft the weight penalty for constant-depth columns is small, and they simplify sidewall framing.
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.