Getting the size wrong for a machinery shed is an expensive mistake. A shed that’s too narrow means equipment can’t enter safely. A shed that’s too low means a grain auger can’t clear the door. Neither problem is cheap to fix once the concrete is poured and the frames are up.
What follows are the actual dimensions you need: real equipment measurements, minimum clearance figures, and combined-storage scenarios that reflect how farms actually work. Spec your machinery shed against these numbers before you speak to any builder.
Key Takeaways
- A shed quoted as “12m wide” does not give you 12m of usable equipment width. The internal clear span is always less than the structural span, and the difference matters when you are storing wide machinery.
- Folded headers can reach 4.3m in height. Eave height must be at least 300mm greater than the tallest item passing through the door.
- Combined-equipment storage requires you to add each machine’s width plus inter-machine clearance plus wall clearance. Side-by-side storage of a large tractor and a folded header typically requires a minimum internal clear span of around 10m.
- In Victoria, shed size directly affects whether a planning permit is required. A building permit is almost always required regardless of size.
Why Getting the Size Wrong Costs More Than Getting It Right
An undersized shed does not just cause inconvenience. It creates real operational problems: equipment that cannot enter without scraping, doors that cannot open fully, and, in some cases, a structure that needs to be extended at high cost within a few years of being built.
A shed extension is never as simple as bolting on another bay. Footings, frames, and drainage all need to be revisited. Getting the dimensions right at the planning stage is almost always cheaper than fixing them later.
Understanding the Three Sizing Variables: Span, Clear Span, and Eave Height
Three terms, three different numbers, and mixing them up is the most common sizing mistake in machinery shed planning.
Structural span is the total width of the shed measured from the outside of the frame to the outside of the frame; it’s the number a builder typically quotes.
Internal clear span is the usable width between the inner faces of the columns, and it’s always less than the structural span. A shed with a 12m structural span may only deliver 11.2m to 11.4m of internal clear width, depending on column size, and that gap matters when you’re fitting a 9m header through the opening.
Eave height is the distance from the finished floor level to the underside of the eave, and it sets the maximum height of anything that can enter the shed. It isn’t the same as ridge height; always compare equipment height against eave height, not ridge height.
Common Farm Equipment Dimensions and Minimum Shed Requirements
The table below lists typical dimensions for common farm machinery and the minimum internal clear span and eave height required to store each one safely. Clearance figures assume a minimum of 600mm per side for safe manoeuvring and 300mm overhead clearance for door entry.
These are planning reference figures. Actual structural design requires an engineer.
| Equipment Type | Typical Width | Typical Height | Typical Length | Min. Internal Clear Span | Min. Eave Height |
| Mid-range tractor (100 to 200hp) | 2.5m, 3.0m | 3.0m, 3.5m | 4.5m, 5.5m | 4.2m | 3.8m |
| Large tractor (200hp+) | 3.5m, 4.5m | 3.5m, 4.2m | 5.5m, 7.0m | 5.7m | 4.5m |
| Rigid header (6m, 9m) | 6.0m, 9.0m | 3.8m, 4.2m | 7.0m, 9.5m | 10.2m | 4.5m |
| Folding header (folded) | 3.5m, 4.5m | 4.0m, 4.3m | 9.0m, 12.0m | 5.7m | 4.6m |
| Self-propelled sprayer (chassis) | 2.8m, 3.5m | 3.8m, 4.5m | 8.0m, 11.0m | 4.7m | 4.8m |
| Silage wagon | 2.8m, 3.2m | 3.5m, 4.0m | 8.0m, 10.0m | 4.4m | 4.3m |
| Grain auger (transport position) | 0.6m, 1.0m | 3.5m, 4.5m | 10.0m, 14.0m | 2.2m | 4.8m |
Boom width on a self-propelled sprayer is not a relevant shed-sizing dimension. The sprayer folds its booms for storage. Use chassis width and folded height as the design inputs.
Note: These figures represent typical ranges across common equipment classes in each category, not exact specifications for any single manufacturer or model. Machinery dimensions vary between brands and even between model years, so confirm the actual width, height, and length of your specific equipment before finalising shed dimensions, most manufacturers publish these figures in their equipment spec sheets.
Planning for Combined Equipment Storage
A working farming operation rarely stores one machine per building, and planning for combined storage reflects how most farms actually use their sheds.
Scenario one: large tractor plus folded header stored side by side
A large tractor at 4.5m wide and a folded header at 4.2m wide together span 8.7m. Add 600mm clearance at each wall and 600mm between the machines, and the total usable width required is 10.5m. That requires an internal clear span of at least 10.5m, which typically means a structural span of around 11.2m or more.
Scenario two: self-propelled sprayer plus silage wagon in the same bay
A self-propelled sprayer at 3.5m and a silage wagon at 3.2m together span 6.7m. With standard clearances, the required internal clear span is approximately 8.5m. The controlling height dimension here is the sprayer’s folded height, not the wagon’s, so the eave height must accommodate the sprayer’s 4.5m folded height plus 300mm clearance.
For headers and sprayers specifically, a drive-through bay is worth considering. It removes the need to reverse large equipment and reduces the risk of frame and wall damage during manoeuvring. Drive-through configurations require open bays at both ends and add to the overall building size, but the operational benefit on a busy farm is real.
Eave Height for Headers, Augers, and Tall Equipment
Two figures matter here, not one:
- A folded header can reach 4.3m.
- A grain auger in operating position may reach 10m or more, but the design-relevant figure for shed sizing is its transport height, typically 3.5m to 4.5m for large augers.
Size the door opening to whichever of these is tallest, plus the 300mm clearance margin.
Standard eave heights for farm machinery storage in Victoria typically range from 4.5m to 6m for large equipment. That’s a planning reference, not a guaranteed figure; your specific equipment determines the correct number.
For wider spans, Universal Beams (UB) or Open Web Trusses (OWT) are often required rather than Rectangular Hollow Section (RHS) frames. This affects the structural design but doesn’t reduce the internal clear height.
Framing Choice and What It Means for Your Shed Size
The frame type of a machinery shed directly affects the gap between the structural span and the internal clear span, not just the quote.
C-section frames are lighter and cheaper and suit narrower spans and lighter storage loads. For a working machinery shed storing large tractors, harvesters, or hay, they’re generally not the right choice:
- Less stiff under heavy wind loads on large open-fronted bays
- Don’t carry the same long-term structural performance as RHS frames
RHS structural steel is stronger and longer-lasting. Trusteel Fabrications builds machinery sheds using RHS frames as standard because the loads in a working shed, point loads from heavy tyres, wind loads on open bays, and the structural demands of wide clear spans, require it. For very wide spans, UB or OWT framing may be required.
The column size in each system differs slightly, which is why the gap between structural span and internal clear span varies depending on the framing choice. A builder who can’t tell you the internal clear span for a given structural span isn’t giving you the information you need.
| Frame Type | Used When | Why |
| C-section | Narrower spans, lighter storage loads | Lighter and cheaper, but not suited to heavy wind loads on large open-fronted bays |
| RHS (Rectangular Hollow Section) | Standard for working machinery sheds | Handles point loads, wind loads, and wide clear spans over the shed’s working life |
| Universal Beams (UB) or Open Web Trusses (OWT) | Very wide spans, beyond what RHS alone can carry efficiently | Engineered for that specific span and load combination |
Victorian Permit Requirements and How Shed Size Affects Them
Shed size in Victoria isn’t just a design decision; it’s a regulatory one too, and it’s rarely explained clearly. Whether a rural machinery shed needs a planning permit comes down to the property’s zone:
- Common rural zones include the Farming Zone, Rural Activity Zone, and Green Wedge Zone.
- Farm buildings associated with an established agricultural use may qualify for a planning permit exemption under the relevant zone provisions.
- These exemptions have conditions that vary by zone and aren’t automatic.
Check your property’s zone using VicPlan before finalising dimensions, and contact your local council to confirm whether an exemption applies. If your machinery shed sits alongside other farm buildings, our farm sheds guide covers the same permit and zoning questions for the wider property.
A building permit is a separate requirement and almost always applies to a machinery shed regardless of floor area or zone. The Victorian Building Authority administers building permit requirements in Victoria, and Trusteel, as a registered VBA builder, manages that process directly, so there’s no separate registered builder to engage or council process to coordinate yourself.
Concrete Slab Considerations for Heavy Machinery
Most of the sizing conversation is about width and height, but what’s underneath the equipment matters just as much.
Heavy tractors, harvesters, and loaded wagons impose point loads that a standard domestic slab isn’t designed to handle. A few things follow from that:
- Typical machinery shed slabs are 150mm thick, with reinforcement specified for the equipment load.
- The exact specification depends on an engineer’s assessment of the heaviest axle loads involved.
- The apron outside the shed entry needs to be part of the slab design too; it’s where equipment manoeuvres and where concentrated tyre loads are highest.
A larger shed means a larger slab and a higher concreting cost. Factor this into your overall budget from the start, not as an afterthought once the structural quote comes in. Trusteel manages concreting as part of its full-build service, removing the need to coordinate a separate contractor.
How Trusteel Fabrications Handles Machinery Shed Sizing
Getting the size right starts with the equipment, not a shed catalogue, and everything else in this process follows from that.
Starting from Your Equipment, Not a Standard Size
What we see consistently on rural properties is that buyers start with a standard shed size and try to fit their equipment into it. The process works better when run in reverse: list the equipment, establish the real dimensions including clearances, then work out the structural span and eave height that actually deliver the internal space you need.
Trusteel works through equipment dimensions with you before anything is drawn up, and that conversation is what determines whether RHS frames are sufficient for the span involved or whether UB or OWT framing is required.
What You End Up With
Trusteel manages design, permits, fabrication, construction, and concreting as a single service, so there’s no separate engineer, concreting contractor, or registered builder to coordinate. The building permit is handled as part of the same process.
The result is a shed sized to your actual machinery, built to a structural specification that carries the loads a working farm puts on it, with permits sorted and a concrete slab designed for the equipment weight involved.
If you’re planning a machinery shed and want to work through the dimensions properly, work through your equipment list with Trusteel’s design team before anything is drawn up.
Frequently Asked Questions
What is the minimum shed width for a folding header?
A folded header typically measures 3.5m to 4.5m wide, and adding 600mm clearance on each side gives a minimum internal clear span of approximately 4.7m to 5.7m. If it’s stored alongside other machinery, add those widths and the inter-machine clearances to calculate the total bay requirement. Check the folded width of your specific header model before finalising shed dimensions.
Do I need a planning permit for a machinery shed in Victoria?
Whether a machinery shed needs a planning permit in Victoria depends on the property’s zone and whether the shed is associated with an established agricultural use. Farm buildings in rural zones may qualify for a planning permit exemption, but this isn’t automatic, and conditions vary by zone.
Check your zone using VicPlan and confirm with your local council. Either way, budget for the separate building permit sign-off, since that applies to virtually every machinery shed regardless of the planning permit outcome.
What eave height do I need for a grain auger?
The relevant figure for shed design is the auger’s transport height, not its operating height. Large grain augers in transport position typically measure 3.5m to 4.5m in height, and the door opening must be at least 300mm greater than that. For large augers, a minimum eave height of 4.8m is a reasonable planning starting point.
How much clearance should I allow between equipment and shed walls?
Allow a minimum of 600mm between each machine and the adjacent wall, and the same minimum, 600mm, between two machines stored side by side. Overhead clearance at the door should be at least 300mm above the tallest item entering the shed. These are planning references; tighter clearances are possible but create practical handling problems.
What is the difference between RHS frames and C-section frames for a machinery shed?
Rectangular Hollow Section (RHS) frames are stronger and stiffer, better suited to the loads in a working machinery shed: heavy equipment, wide open-fronted bays, and wind loads on large structures. C-section frames are lighter and cheaper but generally suited to narrower spans and lighter storage use. For very wide spans, Universal Beams or Open Web Trusses may be required in addition to or instead of RHS frames. The column size in each system also affects the internal clear span available for a given structural span.