100x150 Steel Gymnasium Building

This page is ordered around access, because on a 100-foot endwall the opening arrangement settles how a steel gymnasium at 100x150 is actually used.

The footprint holds 4 activity fields — 2 across by 2 deep — and the remaining 10 feet is marginal: there is no perimeter loop, so warm-up happens across the middle of whatever else is running.

Commitment first: 64% of the 15,000 square feet goes to activity fields at 2400 square feet each, and 4,000 square feet survives as edge strip. A footprint is worth its own decision when that split lands where the work does. What the building holds in its busiest week is the honest brief; the rest of the year is slack.

A 100 by 150 footprint is a clearly directional plan: 15,000 sq ft enclosed by 500 ft of wall, at a 1.5:1 length-to-width proportion. Along its 150 ft dimension it takes 2 runs of activity fields at 60 ft, leaving 30 ft over — the 30 ft is where the argument about this size actually happens. A fieldhouse only earns its volume if it does something a divided set of rooms could not: full-size activity, a perimeter loop, indoor events out of season. The planning risk is subdividing it into pieces that a cheaper building would have held. Timetable changeover, not session length, is what the entry and circulation routes are sized for.

At 100x150 the operating question is a specific one: what does this floor do that several smaller buildings could not, and is the plan protecting that? That is a different question from the one a steel gymnasium of another shape has to answer, and it is why this footprint is planned as a large multi-activity fieldhouse floor rather than as generic covered area.

One opening per position works on this gable: 2 across 100 feet, with 20 feet of wall to distribute as piers. Splitting that margin evenly is what keeps the elevation buildable. Depth is bought cheaply and width expensively, which is why this proportion tends to be argued about before anything else.

At least one opening large enough for vehicle or plant access changes what the building can host, because event equipment does not arrive through a personnel door.

Nominal bay division computes to 6 bays at about 25 feet, narrower than the 40-foot module — so frame lines land inside positions and the interior has to be set out from the columns. Utilities entering on the wrong elevation quietly rewrite the interior layout.

Depth here creates a hierarchy: 2 rows means front positions get used and rear positions get filled. Deciding which is which up front is what keeps 100x150 workable. Insulating later is possible; framing for insulation later is much harder.

A fieldhouse rarely extends; it is planned at its final size and grows by adding attached ancillary buildings. Leaving one elevation clear for that is the practical provision.

Configured as a large multi-activity fieldhouse floor, 100x150 is judged on whether the 4 activity fields it holds match the operation, and on whether the 20 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 150-foot length being bought for depth, or for the repeated bays — a long repeating bay sequence, so segment boundaries are set by bay lines rather than by walls?
• What clear height does the activity need, measured to the lowest obstruction?
• Are the run-off margins protected from storage and seating?

The activity pattern this floor could equally be planned around is an activity floor with a permanent spectator side: there is no concourse behind the seating, so spectators queue and stand at the floor edge. Dividing the 15,000 sq ft by the 40 by 60 ft activity field gives roughly 4 positions before circulation is deducted a second time for cross movement. Whether the plan keeps 4 or drops to 2 comes back to the question this footprint is really answering: what does this floor do that several smaller buildings could not, and is the plan protecting that?

Treating the last 10 feet as a room is the recurring planning error at 100x150: there is no perimeter loop, so warm-up happens across the middle of whatever else is running. Plan the exit as carefully as the entrance; buildings are emptied under more time pressure than they are filled.

The 20 feet of spare width runs the whole 150-foot length — 3,000 square feet of wall strip. It earns its keep as shelving, staging or a walking route, not as another activity field. Interior divisions are the last decision that should be fixed, because they are the first one that usually changes.

The longest internal travel on a 100 by 150 plan is about 180 ft corner to corner, and the shortest useful one is the 100 ft cross-run. For a a large multi-activity fieldhouse floor that matters where fieldhouse planning sits, because shortening the 100 ft run to serve it lengthens every trip along the 150 ft dimension. Egress and occupancy for a room holding a gathering are determined by the local authority for that building. That movement pattern, not the 15,000-square-foot total, is what decides whether the leftover 10 feet is useful here.

Across a 100-foot span the 4:12 pitch adds 16.7 feet between eave and ridge. The centreline measures 40.7 feet; anything parked or stacked near a wall lives with the 24-foot eave. Long spans buy flexibility that is only worth paying for if the operation actually changes shape.

A large floor raises the height question for activities that a smaller floor never hosts, and the height applies over the whole area. Requirements for specific activities are set by the governing bodies concerned.

Ventilation across 15,000 square feet at this height: an intensively occupied volume with high activity levels, where air handling is planned for the occupied peak.

The estimate at 100x150 moves with four computed quantities: 15,000 square feet of floor, 500 feet of perimeter, 12,000 square feet of wall and 15,811 square feet of roof. Everything else is site and specification. Height is the dimension people regret; it cannot be added later without rebuilding the frame line.

Proportion drives cost here as much as size does: 500 ft of wall around 15,000 sq ft is 0.033 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 a large multi-activity fieldhouse floor is the fit-out fieldhouse 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

• 60x100 holds the same 4 activity fields but changes the leftover depth by +16 feet, which is where the difference is actually felt.
• 50x120 moves the count from 4 to 6 activity fields (2 across by 3 deep), which is the reason to choose between them.
• 80x80 moves the count from 4 to 6 activity fields (3 across by 2 deep), which is the reason to choose between them.

Because this footprint is planned as a large multi-activity fieldhouse floor, the useful next reads are different from the ones a differently shaped steel gymnasium suggests: fieldhouse planning, perimeter loop layout, large clear volume planning.