40x80 Livestock Barn

No price appears on this page. The quantities that scale an estimate at 40x80 are 3,200 square feet of slab, 49.4 cubic yards of nominal concrete, 3,840 square feet of wall cladding and 3,298 square feet of roof cladding. Doors and their approaches decide more about daily use here than the enclosed area does.

Proportion drives cost here as much as size does: 240 ft of wall around 3,200 sq ft is 0.075 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 barn organised around a central feed alley serving pens on both sides is the fit-out central feed alley implies, along with framed openings and the height chosen for the 40 ft span.

• ventilation provisions and sidewall openings
• interior pens, gates and durable linings
• the alley width the cleaning machine needs
• drainage and washdown provisions

This page is ordered around the alley, because the width the feeding equipment needs is taken out of the building before a single pen is drawn.

The footprint holds 4 feed-face pens — 2 across by 2 deep — and leaves 12 feet of depth for the alley width itself, sized for the feeding equipment rather than for people walking.

Efficiency is the useful number here: 800 square feet of enclosed floor per feed-face pen, against a 468-square-foot module. That is generous — the footprint is doing more than hold modules. Circulation width is the first thing surrendered under pressure and the first thing missed afterwards.

A 40 by 80 footprint is a clearly directional plan: 3,200 sq ft enclosed by 240 ft of wall, at a 2:1 length-to-width proportion. Along its 80 ft dimension it takes 3 runs of feed-face pens at 26 ft, leaving 2 ft over — the 2 ft is where the argument about this size actually happens. Taken purely as arithmetic, 40 by 80 gives 1 feed-face pens across the 40 ft dimension once 16 ft is reserved for movement, and 3 deep along the 80 ft dimension. Run as a a barn organised around a central feed alley serving pens on both sides, 6 ft across is below the 12 ft this use needs to be worth planning, so the alley is walk-width only, so feeding is done by hand or from outside rather than driven through A stock building is entered at night by somebody alone, and lighting and route legibility are part of the brief.

At 40x80 the operating question is a specific one: is the alley wide enough to drive and feed from, and does the width left either side still make a usable pen? That is a different question from the one a livestock barn of another shape has to answer, and it is why this footprint is planned as a barn organised around a central feed alley serving pens on both sides rather than as generic covered area.

One opening per position works on this gable: 2 across 40 feet, with 4 feet of wall to distribute as piers. Splitting that margin evenly is what keeps the elevation buildable. The span is the commitment; everything inside it is rearrangeable later, and the 40-foot dimension is not.

Openings at both ends of the alley turn feeding into a drive-through rather than a reverse, which is the single largest labour difference in this plan. Whether that is possible is a yard question.

Animals loaded through a handling route at one end; feed and bedding delivered to a different point entirely.

The housing pattern this barn could equally be planned around is a deep-bedded pack barn cleaned out in campaigns rather than daily: there is no clean-out approach, so the pack is emptied through the same opening used daily and the building is out of use while it happens. Alley down the centre, pens either side, feed face along both alley walls. Off-centre alleys create a deep side and a shallow side, which is occasionally deliberate and usually accidental.

The 12-foot leftover depth is 480 square feet across the full width — deep enough to plan deliberately, and at this footprint it goes to the alley width itself, sized for the feeding equipment rather than for people walking. Two feet of spare width reads as nothing on a plan and as a great deal when a machine is being turned.

Spare width is the more valuable of the two leftovers here: a continuous 4-foot strip beats the same area stranded at the end of the run, because it touches every position along the way. The plan is only as good as the route into it, which is a site question rather than a building one.

Compared with a 40 by 60 of the same width, the extra depth here adds run rather than reach: it buys about 3 feed-face pens in line, and every position past the second is retrieved by moving what stands in front of it. Spent as a square 57 by 57 instead, the same 3,200 sq ft would stand 2 feed-face pens across rather than 1, and would trade this plan's length for parallel access. That is the width-against-depth decision this footprint has already made. This is the scale at which informal habits start to fail: two people working at once need the routes named on the plan rather than agreed by memory. The longest internal travel on a 40 by 80 plan is about 89 ft corner to corner, and the shortest useful one is the 40 ft cross-run. For a a barn organised around a central feed alley serving pens on both sides that matters where central feed alley sits, because shortening the 40 ft run to serve it lengthens every trip along the 80 ft dimension. Lighting placement follows the observation routine rather than the structural grid. That movement pattern, not the 3,200-square-foot total, is what decides whether the leftover 12 feet is useful here.

At 20-foot nominal bays the structure works with the layout instead of against it: one feed-face pen per bay line, walls free of awkward half-positions. Whoever operates the building daily should read the plan before it is frozen, because they know where the pinch points are.

With 2 rows deep, the rear row is behind the front one. Without a route past it, those feed-face pens become storage positions rather than working ones — the real cost of depth at this width. Daylight placement changes how a floor is used far more than its cost suggests.

The building lengthens along the alley, which is the cheapest possible extension because the alley, the feed face and the routine all simply continue.

Configured as a barn organised around a central feed alley serving pens on both sides, 40x80 is judged on whether the 4 feed-face pens 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 three parked lanes, or two lanes and a moving lane wide enough for equipment to pass, or does it need a second lane that this 40-foot span cannot give?
• Is the 80-foot length being bought for depth, or for the repeated bays — six to eight repeated bays, and the bay line becomes the organising device for the whole plan?
• How does air move through the barn on a still day?
• Can the cleaning machine work the full alley without moving animals twice?

The stored configuration carries a 16-foot eave and computes to 21 feet at the ridge on a 3:12 pitch — a 5-foot rise across 40 feet. Height is therefore not uniform, and the sidewall is the constraint. Security and after-hours access are easier to design in the door layout than to bolt on later.

Alley height is set by the feeding equipment and the pen height by air movement. Both are specific to the equipment and to the building rather than to the type.

Ventilation across 3,200 square feet at this height: air quality above the animals is the defining requirement of the building, and it drives ridge, eave and sidewall decisions together.

• 32x40 holds the same 4 feed-face pens but changes the leftover depth by -12 feet, which is where the difference is actually felt.
• 36x40 moves the count from 4 to 6 feed-face pens (3 across by 2 deep), which is the reason to choose between them.
• 24x60 moves the count from 4 to 1 feed-face pens (1 across by 1 deep), which is the reason to choose between them.

Because this footprint is planned as a barn organised around a central feed alley serving pens on both sides, the useful next reads are different from the ones a differently shaped livestock barn suggests: central feed alley, feed face planning, drive through feeding.