100x100 Steel Gymnasium Building

This page is ordered around height and clearance, because at 100x100 the 22-foot eave limits a steel gymnasium sooner than the plan does.

The footprint holds 3 viewing sides — 3 across by 1 deep — and leaves 40 feet of depth for a concourse strip behind the seating, so arriving and leaving spectators never stand in the clearance zone.

What distinguishes 100x100 is depth behaviour: 1 row along 100 feet after 18 feet of circulation, with 40 feet unaccounted for at the end of the run. The span is the commitment; everything inside it is rearrangeable later, and the 100-foot dimension is not.

A 100 by 100 footprint is a near-square plan: 10,000 sq ft enclosed by 400 ft of wall, at a 1:1 length-to-width proportion. Along its 100 ft dimension it takes 2 runs of viewing sides at 42 ft, leaving 16 ft over — the 16 ft is where the argument about this size actually happens. Adding spectators converts the building from one space into two that share a wall. The spectator side needs depth, a route and somewhere to accumulate, and taking all three from the activity clearance is how an event building becomes unworkable. Glare and fitting protection matter as much as light level over an activity floor.

This footprint is planned as an activity floor with a permanent spectator side. The longest internal travel on a 100 by 100 plan is about 141 ft corner to corner, and the shortest useful one is the 100 ft cross-run. For a an activity floor with a permanent spectator side that matters where spectator side planning sits, because shortening the 100 ft run to serve it lengthens every trip along the 100 ft dimension. Acoustics in a hard-surfaced hall affect whether instruction can be heard, which is a usability question rather than a comfort one.

The stored configuration carries a 22-foot eave and computes to 38.7 feet at the ridge on a 4:12 pitch — a 16.7-foot rise across 100 feet. Height is therefore not uniform, and the sidewall is the constraint. An empty building looks generous and a working one rarely does; plan against the working state.

Sightlines add a vertical dimension the plan alone does not show, and raked seating raises the height needed at the back of the viewing side beyond what the floor requires.

Ventilation across 10,000 square feet at this height: an intensively occupied volume with high activity levels, where air handling is planned for the occupied peak.

The activity pattern this floor could equally be planned around is a practice floor kept clear for training rather than for fixtures: there is no perimeter strip, so bags and equipment sit on the playing surface and the usable floor shrinks by more than the strip would have cost. One long side is given to viewing and everything that supports it; the activity floor keeps the rest. Splitting the seating across two sides doubles the routes required and halves the usefulness of each.

The 40-foot leftover depth is 4,000 square feet across the full width — deep enough to plan deliberately, and at this footprint it goes to a concourse strip behind the seating, so arriving and leaving spectators never stand in the clearance zone. Doors and their approaches decide more about daily use here than the enclosed area does.

The 4 feet of spare width runs the whole 100-foot length — 400 square feet of wall strip. It earns its keep as shelving, staging or a walking route, not as another viewing side. The building is fixed for decades while the operation inside it changes every few years, and the plan has to survive that.

The longest internal travel on a 100 by 100 plan is about 141 ft corner to corner, and the shortest useful one is the 100 ft cross-run. For a an activity floor with a permanent spectator side that matters where spectator side planning sits, because shortening the 100 ft run to serve it lengthens every trip along the 100 ft dimension. Acoustics in a hard-surfaced hall affect whether instruction can be heard, which is a usability question rather than a comfort one. That movement pattern, not the 10,000-square-foot total, is what decides whether the leftover 40 feet is useful here.

The 100-foot gable can carry 3 openings, one per viewing side, with 4 feet of wall left for piers between and beside them — the arrangement that keeps each position independently reachable. Ground conditions and drainage decide the floor before the frame does.

Separate entrances for the two populations are worth more than a larger single one. Egress provision for an occupied spectator area is determined for the specific building by the local authority.

Nominal bay division computes to 4 bays at about 25 feet, narrower than the 32-foot module — so frame lines land inside positions and the interior has to be set out from the columns. The floor treatment is a use decision that outlasts most of the equipment standing on it.

A single row means nothing is trapped: every position faces the opening directly, which is this footprint's advantage over a deeper building of the same width. Two operations of the same size can want opposite plans, so the arithmetic below is a starting point rather than a recommendation.

Extension is cheapest along the 100 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 142 adds a 3th run of viewing sides — useful if the constraint is viewing sides rather than the 16 ft already spare at the far end.

Configured as an activity floor with a permanent spectator side, 100x100 is judged on whether the 3 viewing sides it holds match the operation, and on whether the 4 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 100-foot length being bought for depth, or for the repeated bays — eight to ten repeated bays, which makes the layout a scheduling problem as much as a spatial one?
• What clear height does the activity need, measured to the lowest obstruction?
• Are the run-off margins protected from storage and seating?

• 50x80 moves the count from 3 to 2 viewing sides (1 across by 2 deep), which is the reason to choose between them.
• 40x100 moves the count from 3 to 2 viewing sides (1 across by 2 deep), which is the reason to choose between them.
• 60x80 moves the count from 3 to 4 viewing sides (2 across by 2 deep), which is the reason to choose between them.

Because this footprint is planned as an activity floor with a permanent spectator side, the useful next reads are different from the ones a differently shaped steel gymnasium suggests: spectator side planning, concourse layout, separated entry routes.

Quantities, not prices, are publishable here: roof cladding runs 10,541 square feet — 5% above the 10,000-square-foot floor at a 4:12 pitch — with 185.2 cubic yards of nominal slab beneath it. Neighbouring buildings, setbacks and the approach road often decide the orientation before the plan does.

Proportion drives cost here as much as size does: 400 ft of wall around 10,000 sq ft is 0.04 ft of wall per enclosed square foot, and a squarer plan of the same area would carry less. What moves the figure further on a an activity floor with a permanent spectator side is the fit-out spectator side planning implies, along with framed openings and the height chosen for the 100 ft span.

• clear height above the playing surface
• the clear span across the court and its run-off
• the support wing with changing rooms
• impact-resistant lighting and interior surfaces