50x100 Pole Barn

This page is ordered around the bay, because at this size the post frame is not a background system — it is the plan, and it decides where walls, openings and divisions can go.

The footprint holds 20 open bays — 4 across by 5 deep — and the remaining 4 feet is marginal: there is no closed bay, so nothing in this building is secure and everything in it is exposed to whatever blows in.

What distinguishes 50x100 is depth behaviour: 5 rows along 100 feet after 6 feet of circulation, with 4 feet unaccounted for at the end of the run. The corner nobody plans for is the one that fills first, which is an argument for planning it.

A 50 by 100 footprint is a clearly directional plan: 5,000 sq ft enclosed by 300 ft of wall, at a 2:1 length-to-width proportion. Along its 100 ft dimension it takes 5 runs of open bays at 18 ft, leaving 10 ft over — the 10 ft is where the argument about this size actually happens. An open-front post-frame building is a roof and a windbreak rather than an enclosure, and its usefulness is set almost entirely by orientation. The open side facing prevailing weather turns shelter into a wind tunnel; facing away, the same building works all year. Gutters and where the roof discharges decide the condition of the ground people walk on.

This footprint is planned as a partly open building offering shelter rather than enclosure. Compared with a 50 by 80 of the same width, the extra depth here adds run rather than reach: it buys about 5 open bays in line, and every position past the second is retrieved by moving what stands in front of it. Spent as a square 71 by 71 instead, the same 5,000 sq ft would stand 5 open bays across rather than 3, and would trade this plan's length for parallel access. That is the width-against-depth decision this footprint has already made. At this size the building becomes a shared resource, and shared resources need a written rule for who parks where and which door is kept clear. The building is used without ever being entered through a door, which is the point. Anything requiring a door belongs in the closed bay. Ventilation follows what the building holds — equipment, animals and stored crop each want a different pattern.

Read this page as a construction-form page, not a use page. Pole barn is a construction-form category on this platform: it describes the post-frame approach, where posts carry the roof and the walls enclose between them, and the uses it serves — agricultural, garage, workshop, storage — are applications of that form rather than definitions of it. The question it answers is how a 50x100 footprint behaves when it is built this way.

The use this post-frame shell could equally be bought for is a post-frame building built specifically around working rather than storing: there is no bench depth between posts, so benches stand proud of the wall and the working floor shrinks by their depth. Dividing the 5,000 sq ft by the 12 by 18 ft open bay gives roughly 15 positions before circulation is deducted a second time for cross movement. Whether the plan keeps 15 or drops to 10 comes back to the question this footprint is really answering: which way does the open side face, and what does that decide about how the building can be used in winter?

There is no end zone at this footprint. 4 feet is circulation slack, not floor area with a purpose, and there is no closed bay, so nothing in this building is secure and everything in it is exposed to whatever blows in. What the building holds in its busiest week is the honest brief; the rest of the year is slack.

Width is fully committed at 50x100. With 2 feet spare, wall storage and passing room compete with the open bays directly. Plan the exit as carefully as the entrance; buildings are emptied under more time pressure than they are filled.

Compared with a 50 by 80 of the same width, the extra depth here adds run rather than reach: it buys about 5 open bays in line, and every position past the second is retrieved by moving what stands in front of it. Spent as a square 71 by 71 instead, the same 5,000 sq ft would stand 5 open bays across rather than 3, and would trade this plan's length for parallel access. That is the width-against-depth decision this footprint has already made. At this size the building becomes a shared resource, and shared resources need a written rule for who parks where and which door is kept clear. The building is used without ever being entered through a door, which is the point. Anything requiring a door belongs in the closed bay. Ventilation follows what the building holds — equipment, animals and stored crop each want a different pattern. That movement pattern, not the 5,000-square-foot total, is what decides whether the leftover 4 feet is useful here.

50 ft across takes 4 open bays and leaves 2 ft. Over 100 ft of run that slack becomes a continuous side aisle rather than 5 separate gaps.

100 ft divides exactly into 10 bays at 10 ft. Over 5,000 sq ft a single 10-ft grid is the difference between a plan and an accumulation.

100 ft is deep enough for 5 ranks and a zone behind them. 5,000 sq ft needs a stated route through it; without one the middle silts up.

16 ft carries a genuine second level: 15 ft deep across the 50-ft width is 750 sq ft more floor. Framing for it now is a drawing change; adding it to a finished frame is a structural one.

The 50-ft gable clears about 42 ft after corner framing — 2 module-width openings abreast. At 5 ranks deep the useful pattern is end in, side out, using the 100-ft wall's 6 possible positions.

This shape buys frontage with skin: 300 ft of perimeter for 5,000 sq ft, 60 ft per 1,000 sq ft, 6% above a square of the same area. At 2 to 1 that is the trade, not an error.

At 50 feet the gable will not comfortably take one opening per open bay: 4 positions with 2 feet spare leaves too little wall for piers. A single wider opening, or a sidewall opening, is the workable route. Long spans buy flexibility that is only worth paying for if the operation actually changes shape.

The open face is the opening. Its width and orientation are the two decisions that define the building, and neither can be changed afterwards without new walls.

Loading happens bay by bay: what can be brought in at one opening and set down in that bay is the practical unit, not the length of the wall.

At 25-foot nominal bays the structure works with the layout instead of against it: one open bay per bay line, walls free of awkward half-positions. Interior divisions are the last decision that should be fixed, because they are the first one that usually changes.

With 5 rows deep, the rear row is behind the front one. Without a route past it, those open bays become storage positions rather than working ones — the real cost of depth at this width. Utilities entering on the wrong elevation quietly rewrite the interior layout.

Extension is cheapest along the 100 ft dimension, where each added bay repeats work already framed; widening past 50 ft is a different frame rather than a longer one. Growing to 50 by 118 adds a 6th run of open bays — useful if the constraint is open bays rather than the 10 ft already spare at the far end.

Configured as a partly open building offering shelter rather than enclosure, 50x100 is judged on whether the 20 open bays it holds match the operation, and on whether the 2 feet of spare width leaves the route this mode depends on.

• Does the work need three lanes and a working lane, or two lanes with an interior work hall between them, or does it need a second lane that this 50-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?
• Does the intended layout tolerate interior posts, or does it genuinely need a clear span?
• Where do the openings fall relative to the post lines, and does any opening have to bridge one?

The stored configuration carries a 16-foot eave and computes to 22.3 feet at the ridge on a 3:12 pitch — a 6.3-foot rise across 50 feet. Height is therefore not uniform, and the sidewall is the constraint. Insulating later is possible; framing for insulation later is much harder.

Height on a 50 ft span is a separate decision from the 100 ft length, and it is the span that sets the frame's behavior. Raising the eave over 5,000 sq ft affects every bay along the 100 ft dimension, so the test is whether open front pole barn genuinely needs the extra clear height or only the floor area.

Ventilation across 5,000 square feet at this height: post-frame buildings are frequently left partly open or lightly enclosed, so natural cross and ridge airflow does much of the work and enclosure level is the variable to settle first.

• 40x50 moves the count from 20 to 6 open bays (3 across by 2 deep), which is the reason to choose between them.
• 30x70 moves the count from 20 to 6 open bays (2 across by 3 deep), which is the reason to choose between them.
• 36x60 moves the count from 20 to 4 open bays (2 across by 2 deep), which is the reason to choose between them.

Because this footprint is planned as a partly open building offering shelter rather than enclosure, the useful next reads are different from the ones a differently shaped pole barn suggests: open front pole barn, orientation and prevailing weather, closed end bay.