100 ft clear span
A hundred feet is the width at which the haunch gets deep enough to matter to the people using the building. The eave on the drawing and the height you can actually work under at the sidewall are now different numbers, and the gap only grows from here.
Priced as a 100 × 200 ft building at a 28 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
5.26 – 7.32 lb/sf
Primary and secondary, 53 – 73 tons total
Building package
$18.35 – $22.66/sf
$367K – $453K over 20,000 sf
Installed
$28.44 – $43.06/sf
$569K – $861K, before interior buildout
Modular would save
5%
About $21K on the package
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 100 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: Haunch depth begins to govern interior clearance. Check usable height, not just the eave.
The short answer
Specify the clear height you need under the haunch, not the eave height you want. Every foot you find out about late is a foot of wall panel you pay for and cannot use.
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 28 ft eave. These are planning rules, stated so they can be argued with — the derivations are on the methodology page.
| Dimension | At 100 ft | Why it matters |
|---|---|---|
| Frame depth at the haunch | 48–60 in | Span/25 to span/20. The deepest point of the frame, at the knee, where the moment peaks. |
| Clear height at the sidewall | 23–24 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 | 50 ft | Haunch to ridge. What has to get on a truck. |
| Shipping pieces per half | 2 | Past ordinary haul length, so the half arrives in bolted segments and each splice is a connection to make up in the field. |
| Deflection allowance, L/240 | 5 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. |
At 100 ft the frame is about 48–60 in deep at the knee. Subtract that from a 28 ft eave and the clear height against the sidewall is 23–24 ft — several feet less than the number on the elevation. Clearance climbs as you move toward the ridge, so the middle of the building is fine. It is the first bay in from each wall that catches people.
Here is where it bites: a rack height, a mast-up forklift, a door head, a crane hook, or a mezzanine soffit set against the eave that then has to live under the haunch. Racking against the sidewall is the usual casualty, because the tallest thing in the building gets put where the building is shortest.
The fix is free if you catch it early — ask for the eave that gives you the clear height you need and let the manufacturer tell you what that eave is. It is expensive only when it surfaces after the anchor bolts are set.
Modular framing now saves around 5% on the package, which is no longer noise. That is the first real money on the table, and it means clear span at 100 ft has become a purchase rather than a default: you should be able to say what the clear floor is for.
Good answers exist in quantity at this width. A 100 ft column-free floor is the narrowest an aircraft hangar or a distribution building shows up at, and both need the width uninterrupted for reasons no saving touches.
Rafter halves are 50 ft each. That is right at the boundary of what moves on a standard flatbed without an oversize permit, so a 100 ft building is where freight starts being a line worth asking about rather than an assumption. Manufacturers handle it either way — a permitted load or a bolted field splice — but the two have different costs and different erection days, and the quote may not say which one you are getting.
The uses whose typical width covers 100 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 |
|---|---|---|---|
| Aircraft Hangar | 100–300 ft | 24–60 ft | Door opening and tail height, not floor area. The clear span is set by the widest aircraft plus wingtip clearance. Usually clear span. |
| 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. |
| Warehouse / Distribution | 100–400 ft | 28–40 ft | Rack grid and dock count. A column is free if it lands on a rack line, so modular almost always wins. Usually modular. |
| 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. |
A modular frame at this width comes in around 5% lower on the building package — roughly $21K on the 20,000 sf building priced above. That is real money rather than noise, so clear span at this width should be a decision rather than a default.
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.