12x20 Shed Kit

This page is ordered around access, because on a 12-foot endwall the opening arrangement settles how a metal shed at 12x20 is actually used.

The footprint holds 2 machine positions — 2 across by 1 deep — and leaves 7 feet of depth for a margin beside the machine for fuel, attachments and the room needed to walk around it.

Read this footprint through its span. 12 feet across is the fixed constraint; 20 feet of length is the negotiable one, and at 1.67 to 1 the building is long for its width, so movement runs front to back. Height is the dimension people regret; it cannot be added later without rebuilding the frame line.

A 12 by 20 footprint is a clearly directional plan: 240 sq ft enclosed by 64 ft of wall, at a 1.7:1 length-to-width proportion. Along its 20 ft dimension it takes 2 runs of machine positions at 9 ft, leaving 2 ft over — the 2 ft is where the argument about this size actually happens. Once a shed holds something with wheels, the plan is set by getting that thing in and out rather than by how much fits. Door width, approach and the clear line to it matter more than the floor area behind them. Anything stored on the floor of a small building is stored in the only circulation it has.

At 12x20 the operating question is a specific one: can the machine be got out without moving anything else, on the worst day of the year? That is a different question from the one a metal shed of another shape has to answer, and it is why this footprint is planned as a shelter for wheeled equipment, where the door and the turning line decide the plan rather than as generic covered area.

At 12 feet the gable will not comfortably take one opening per machine position: 2 positions with 2 feet spare leaves too little wall for piers. A single wider opening, or a sidewall opening, is the workable route. Noise from this floor reaches the office, the neighbours and the yard, and separation is a plan decision.

Door width is the governing dimension, and the apron outside it is part of the plan whether or not it is drawn.

The gable clears roughly 4 ft after corner framing: 0 openings at most. The 20-ft sidewall takes up to 1 openings with piers between, which is where a second entry belongs.

20 ft divides exactly into 2 bays at 10 ft. Openings and lighting set out on that one grid.

One more 10-ft bay makes it 360 sq ft — 50% more floor for one more frame line. Widening past 12 ft changes every frame instead, which is why length is decided late and width early.

2 machine positions fit the 12-ft span with 2 ft to spare. With 1 ranks behind each other the width sets retrieval order: what goes in first comes out last.

7 ft survives at the end of the run — 84 sq ft across the full width. That is a zone to name before the frame is ordered, not a leftover to discover after it.

At 20-foot nominal bays the structure works with the layout instead of against it: one machine position per bay line, walls free of awkward half-positions. Every foot of width added multiplies through the roof and the frame; every foot of length mostly adds skin.

One row deep keeps the layout honest — no aisle to protect, no rear zone to serve, and the full 20-foot length available along the wall. Cleaning, maintenance and inspection all need reach, and reach is planned in the gaps rather than in the modules.

A second position needs width, not length, which makes widening the more expensive but more useful direction here.

Configured as a shelter for wheeled equipment, where the door and the turning line decide the plan, 12x20 is judged on whether the 2 machine positions 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 room for one car or one small tractor and almost nothing beside it, or does it need a second lane that this 12-foot span cannot give?
• Is the 20-foot length being bought for depth, or for the repeated bays — one or two frame bays, so there is no repeating rhythm to plan against?
• What is the largest item that has to go through the door?
• Is the base and path suitable for wheeling things in wet weather?

The storage pattern this small footprint could equally be used for is a store with a genuine standing aisle, so items behind the front row stay reachable: there is no aisle depth, so the back of the building can only be reached by moving what is in front of it. Dividing the 240 sq ft by the 5 by 9 ft machine position gives roughly 2 positions before circulation is deducted a second time for cross movement. Whether the plan keeps 2 or drops to 1 comes back to the question this footprint is really answering: can the machine be got out without moving anything else, on the worst day of the year?

Depth arithmetic leaves a working end zone here. 84 square feet sits past the last row, which is why 12x20 tends to be planned with a margin beside the machine for fuel, attachments and the room needed to walk around it designed in rather than added later. A wider bay is a structural decision and a longer bay is a layout decision; the two are often confused.

Only 2 feet of width is spare, so there is no wall strip: anything set along a sidewall comes out of a machine position's clearance. Service routes are cheap to plan now and expensive to retrofit through a finished shell.

Spent as a square 15 by 15 instead, the same 240 sq ft would stand 2 machine positions 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. Compared with a 12 by 20 of the same width, the extra depth here adds run rather than reach: it buys about 2 machine positions in line, and every position past the second is retrieved by moving what stands in front of it. At this scale the building is usually operated by one or two people who know where everything is, so the plan can be loose and the doors matter more than the divisions. The longest internal travel on a 12 by 20 plan is about 23 ft corner to corner, and the shortest useful one is the 12 ft cross-run. For a a shelter for wheeled equipment, where the door and the turning line decide the plan that matters where equipment shelter sits, because shortening the 12 ft run to serve it lengthens every trip along the 20 ft dimension. Daylight through a single door leaves the back wall dark, which is where things get lost. That movement pattern, not the 240-square-foot total, is what decides whether the leftover 7 feet is useful here.

Across a 12-foot span the 3:12 pitch adds 1.5 feet between eave and ridge. The centreline measures 15.5 feet; anything parked or stacked near a wall lives with the 14-foot eave. A building that cannot be reversed out of is a building that gets used in one direction only.

Clearance for the tallest thing entering — a raised deck, a cab, a loader arm — is the height decision, not standing room.

• 10x10 moves the count from 2 to 3 machine positions (3 across by 1 deep), which is the reason to choose between them.
• 10x12 moves the count from 2 to 3 machine positions (3 across by 1 deep), which is the reason to choose between them.
• 12x16 holds the same 2 machine positions but changes the leftover depth by -2 feet, which is where the difference is actually felt.

Because this footprint is planned as a shelter for wheeled equipment, where the door and the turning line decide the plan, the useful next reads are different from the ones a differently shaped metal shed suggests: equipment shelter, door width, clear run to the door.