40x120 Hay Barn

This page is ordered around zoning across the 40-foot span, because that is the dimension a hay barn cannot change later.

The footprint holds 8 handling lanes — 2 across by 4 deep — and leaves 18 feet of depth for a passing widening at the midpoint so a loaded machine and an empty one can meet without one backing out.

Commitment first: 59% of the 4,800 square feet goes to handling lanes at 352 square feet each, and 1,680 square feet survives as edge strip. A footprint is worth its own decision when that split lands where the work does. Circulation width is the first thing surrendered under pressure and the first thing missed afterwards.

A 40 by 120 footprint is a long corridor of a plan: 4,800 sq ft enclosed by 320 ft of wall, at a 3:1 length-to-width proportion. Along its 120 ft dimension it takes 5 runs of handling lanes at 22 ft, leaving 10 ft over — the 10 ft is where the argument about this size actually happens. A through-lane converts the building from a store into a handling route. The lane costs stack area permanently and repays it in movement, so the plan is only right for operations where forage is trucked in and out rather than made and kept. What is stored changes across the year, and a building sized for one material behaves differently when the next one arrives.

This footprint is planned as a drive-through store worked from both ends without reversing. Traffic is one-way, which removes the reversing that dominates every other arrangement. That single change is usually what justifies the lane in operations handling trailers rather than loader buckets. Ventilation openings that are useful in summer are the same ones that drive rain in during winter, which is an orientation decision.

The storage arrangement this floor tends toward in a heavy season is a large-volume seasonal store filled in a burst and drawn down over months: unloading has to happen outside, which is the constraint that decides whether filling continues in poor weather. Dividing the 4,800 sq ft by the 16 by 22 ft handling lane gives roughly 5 positions before circulation is deducted a second time for cross movement. Whether the plan keeps 5 or drops to 1 comes back to the question this footprint is really answering: does the operation move enough material for a through-lane to be worth the stack space it consumes?

The 18-foot leftover depth is 720 square feet across the full width — deep enough to plan deliberately, and at this footprint it goes to a passing widening at the midpoint so a loaded machine and an empty one can meet without one backing out. 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 8-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.

Traffic is one-way, which removes the reversing that dominates every other arrangement. That single change is usually what justifies the lane in operations handling trailers rather than loader buckets. Ventilation openings that are useful in summer are the same ones that drive rain in during winter, which is an orientation decision. That movement pattern, not the 4,800-square-foot total, is what decides whether the leftover 18 feet is useful here.

One opening per position works on this gable: 2 across 40 feet, with 8 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.

The 40 ft ends and the 120 ft sides offer very different opening budgets: 40 ft of end wall has room for one wide opening or two modest ones, while 120 ft of side wall can carry several without the openings competing. On this plan the deciding factor is whether drive-through forage handling or lane width planning should be the first thing reached from the door.

Loader-handled from the open side, with the working face moving as the stack grows and shrinks.

Nominal bay division computes to 5 bays at about 24 feet, wider than the 16-foot module — so a position can sit inside a bay without a frame line splitting it. Whoever operates the building daily should read the plan before it is frozen, because they know where the pinch points are.

With 4 rows deep, the rear row is behind the front one. Without a route past it, those handling lanes 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.

Through stores extend sideways, adding flanking stack without touching the lane. Lengthening the lane rarely improves anything except capacity behind the same face.

Configured as a drive-through store worked from both ends without reversing, 40x120 is judged on whether the 8 handling lanes it holds match the operation, and on whether the 8 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 120-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 stack height do you plan, and can the loader place a bale above it inside the building?
• Which sides stay open for airflow, and which face the weather?

No price appears on this page. The quantities that scale an estimate at 40x120 are 4,800 square feet of slab, 59.3 cubic yards of nominal concrete, 4,480 square feet of wall cladding and 4,948 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: 320 ft of wall around 4,800 sq ft is 0.067 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 drive-through store worked from both ends without reversing is the fit-out drive-through forage handling implies, along with framed openings and the height chosen for the 40 ft span.

• eave height set by handling clearance above the stack
• how many sides remain open
• the apron the loader and trailers use
• roof drainage over an open working face

Across a 40-foot span the 3:12 pitch adds 5 feet between eave and ridge. The centreline measures 19 feet; anything parked or stacked near a wall lives with the 14-foot eave. Security and after-hours access are easier to design in the door layout than to bolt on later.

Clear height along the lane is set by loaded vehicles rather than by the stack, and it applies for the whole length rather than at one point. That is a different height brief from a stacked store.

Ventilation across 4,800 square feet at this height: airflow through a stack is the reason many hay barns stay open-sided; enclosing them changes how the stored crop behaves.

• 40x50 moves the count from 8 to 9 handling lanes (3 across by 3 deep), which is the reason to choose between them.
• 30x70 holds the same 8 handling lanes but changes the leftover depth by -12 feet, which is where the difference is actually felt.
• 36x60 moves the count from 8 to 9 handling lanes (3 across by 3 deep), which is the reason to choose between them.

Because this footprint is planned as a drive-through store worked from both ends without reversing, the useful next reads are different from the ones a differently shaped hay barn suggests: drive-through forage handling, lane width planning, two-ended access.