100x200 Clear-Span Steel Building

This page is ordered around demise, because that is the decision this footprint settles first and every later choice follows from it.

5 lift bays fit across the 100-foot width with only 0 feet left over, which is a tight fit: the width is fully committed and nothing can be widened later without moving a wall.

Efficiency is the useful number here: 667 square feet of enclosed floor per lift bay, against a 600-square-foot module. That is a tight, efficient allocation with little slack. A leftover strip earns its place only when something is deliberately put in it; otherwise it is circulation with a nicer name.

A 100 by 200 footprint is a clearly directional plan: 20,000 sq ft enclosed by 600 ft of wall, at a 2:1 length-to-width proportion. Along its 200 ft dimension it takes 6 runs of lift bays at 30 ft, leaving 20 ft over — the 20 ft is where the argument about this size actually happens. Here the clear span exists to keep columns out of a lifting path, so the building is planned from the crane down rather than from the floor up. The runway's reach, not the floor's area, is what determines whether a heavy or awkward load can be moved from receiving to its final position without an intermediate handling step. A load-out lane, turning apron or service margin that is planned as permanent floor, not leftover space, is what keeps a wide floor usable years after it is filled.

This footprint is planned as a clear-span volume shaped by an overhead lifting path rather than by floor area. Compared with a 100 by 150 of the same width, the extra depth here adds run rather than reach: it buys about 6 lift bays in line, and every position past the second is retrieved by moving what stands in front of it. Spent as a square 141 by 141 instead, the same 20,000 sq ft would stand 6 lift bays across rather than 4, and would trade this plan's length for parallel access. That is the width-against-depth decision this footprint has already made. At this scale the building is infrastructure rather than a shed; scheduling, traffic direction and separation of activities matter more than any single dimension. Work follows the lift: a load is picked up near receiving, moved along the runway, and set down at a work or storage position, and the whole sequence has to happen without repositioning the crane's end trucks more than once per move. Door width and placement usually govern a clear-span building's usefulness more than its floor area does, because the door decides what can enter in the first place.

Nominal bay division computes to 8 bays at about 25 feet, wider than the 20-foot module — so a position can sit inside a bay without a frame line splitting it. Plan the exit as carefully as the entrance; buildings are emptied under more time pressure than they are filled.

Depth here creates a hierarchy: 6 rows means front positions get used and rear positions get filled. Deciding which is which up front is what keeps 100x200 workable. Interior divisions are the last decision that should be fixed, because they are the first one that usually changes.

Extension is cheapest along the 200 ft dimension, where each added bay repeats work already framed; widening past 100 ft is a different frame rather than a longer one. Growing to 100 by 230 adds a 7th run of lift bays — useful if the constraint is lift bays rather than the 20 ft already spare at the far end.

Configured as a clear-span volume shaped by an overhead lifting path rather than by floor area, 100x200 is judged on whether the 30 lift bays it holds match the operation, and on whether the 0 feet of spare width leaves the route this mode depends on.

• Does the work need an interior street with independent zones on both sides and turning room at each end, or does it need a second lane that this 100-foot span cannot give?
• Is the 200-foot length being bought for depth, or for the repeated bays — a long uninterrupted bay sequence that suits repetitive layouts and continuous processes?
• What dimension genuinely has to be crossed without a column?
• Is the clear height measured under the frame, or at the eave?

At 100 feet the gable will not comfortably take one opening per lift bay: 5 positions with 0 feet spare leaves too little wall for piers. A single wider opening, or a sidewall opening, is the workable route. Insulating later is possible; framing for insulation later is much harder.

The 100 ft ends and the 200 ft sides offer very different opening budgets: 100 ft of end wall has room for one wide opening or two modest ones, while 200 ft of side wall can carry several without the openings competing. On this plan the deciding factor is whether overhead crane building layout or runway reach planning should be the first thing reached from the door.

Across a 100-foot span the 4:12 pitch adds 16.7 feet between eave and ridge. The centreline measures 42.7 feet; anything parked or stacked near a wall lives with the 26-foot eave. Utilities entering on the wrong elevation quietly rewrite the interior layout.

Under-hook clearance, not eave height, is the number that governs the building, and it has to account for the lifted load's height plus rigging, not just the empty hook.

The use this column-free floor could equally be bought for is a column-free floor sized around turning and parking wheeled equipment, not fixed workstations: there is no turning apron, so every reposition becomes a multi-point manoeuvre around parked equipment. Dividing the 20,000 sq ft by the 20 by 30 ft lift bay gives roughly 24 positions before circulation is deducted a second time for cross movement. Whether the plan keeps 24 or drops to 18 comes back to the question this footprint is really answering: does the crane's runway actually reach every position a load needs to be set down, or only the middle of the floor?

The 8-foot leftover depth falls under the 12 feet this platform treats as usable for a clear-span steel building, so there is no staging strip under the runway, so every load has to be carried to its final position in a single lift. The corner nobody plans for is the one that fills first, which is an argument for planning it.

Width is fully committed at 100x200. With 0 feet spare, wall storage and passing room compete with the lift bays directly. What the building holds in its busiest week is the honest brief; the rest of the year is slack.

Compared with a 100 by 150 of the same width, the extra depth here adds run rather than reach: it buys about 6 lift bays in line, and every position past the second is retrieved by moving what stands in front of it. Spent as a square 141 by 141 instead, the same 20,000 sq ft would stand 6 lift bays across rather than 4, and would trade this plan's length for parallel access. That is the width-against-depth decision this footprint has already made. At this scale the building is infrastructure rather than a shed; scheduling, traffic direction and separation of activities matter more than any single dimension. Work follows the lift: a load is picked up near receiving, moved along the runway, and set down at a work or storage position, and the whole sequence has to happen without repositioning the crane's end trucks more than once per move. Door width and placement usually govern a clear-span building's usefulness more than its floor area does, because the door decides what can enter in the first place. That movement pattern, not the 20,000-square-foot total, is what decides whether the leftover 8 feet is useful here.

• 80x100 moves the count from 30 to 9 lift bays (3 across by 3 deep), which is the reason to choose between them.
• 60x150 moves the count from 30 to 6 lift bays (2 across by 3 deep), which is the reason to choose between them.
• 80x120 moves the count from 30 to 4 lift bays (2 across by 2 deep), which is the reason to choose between them.

Because this footprint is planned as a clear-span volume shaped by an overhead lifting path rather than by floor area, the useful next reads are different from the ones a differently shaped clear-span steel building suggests: overhead crane building layout, runway reach planning, under-hook clearance.

Quantities, not prices, are publishable here: roof cladding runs 21,082 square feet — 5% above the 20,000-square-foot floor at a 4:12 pitch — with 370.4 cubic yards of nominal slab beneath it. Long spans buy flexibility that is only worth paying for if the operation actually changes shape.

Runway support and the crane system itself dominate the budget conversation far more than wall or door finishes, since the building's entire value proposition is the lifting envelope.

• the span itself, which sets the primary frame
• clear height maintained under a deeper frame
• bracing strategy in the walls and roof
• opening positions the span makes possible