Choosing the right shed size is one of the most important decisions you’ll make in your build. If you’re asking “what size shed do I need?” you’re already thinking the right way. Getting this decision right saves you money, avoids future regrets, and ensures your shed actually works for what you need it to do. This guide covers common sizes, what fits inside each, WA council rules, and the number one mistake shed owners make.
Common Shed Sizes and What They Fit
Before we dive into how to figure out what size shed you need, let’s look at the most popular shed sizes in Perth and what they’re typically used for.
Single Garage (6m x 3m)
This is the entry-level shed size. It will fit one standard car or ute, or serve as a compact storage shed. There’s minimal room for workbenches or extra storage alongside a vehicle. Suits small blocks or tight side setbacks.
Double Garage (6m x 6m)
The most popular shed size in Perth. A 6×6 fits two vehicles side by side, or one vehicle with generous workshop and storage space along the sides and rear wall. This is where most homeowners land when they work through what size shed they need. It’s versatile without being oversized.
Workshop (9m x 6m)
Step up to a 9×6 and you’ve got serious room. This size comfortably fits two vehicles plus a dedicated workshop area, or one vehicle with a full workshop setup including workbenches, tool storage, and room to actually move around. Popular with tradies and hobbyists.
Triple Garage (12m x 9m)
Now we’re into large-scale territory. A 12×9 will house three or four vehicles, a full workshop, a ride-on mower, and still have room left over. This is the sweet spot for rural properties, car enthusiasts, and anyone running a business from home. If you’re wondering what size shed you need for a serious workshop, this is usually the answer.
Farm Shed / Barn (18m x 9m)
Built for rural and semi-rural properties, an 18×9 shed can house farm machinery, hay storage, multiple vehicles, and a workshop all under one roof. These are common on lifestyle blocks throughout the Perth hills, Mundijong corridor, and wider WA regions.
Industrial / Commercial (20m x 12m+)
For commercial operations, warehousing, and large-scale storage, sheds in the 20x12m range and above are purpose-designed to meet your operational requirements. These always require custom engineering and detailed site assessment. Explore our full range of custom-designed sheds for commercial and industrial applications.
How to Measure What You Actually Need
Working out what size shed you need starts with a simple exercise. Grab a tape measure and a piece of paper, then follow these steps:
- List everything that will go in the shed: vehicles, tools, workbenches, bikes, kayaks, ride-on mower, storage shelving, etc.
- Measure the big items. A standard car is about 4.8m long and 1.8m wide. A dual-cab ute is 5.4m long. A workbench needs at least 600mm depth plus 1m of standing space in front of it.
- Add circulation space. You need room to open car doors (at least 700mm per side), walk between items, and access storage. Don’t forget about the roller door tracks, which eat into usable width.
- Sketch a rough floor plan. Draw your items to scale on paper and see how they fit. This is where most people realise they need to go one size up.
Our team at Dynaspan can help you work through this process. We use our online design tool to create a 3D model of your shed so you can see exactly what fits before you commit.
The #1 Regret: Building Too Small
After building thousands of sheds across WA, the single most common piece of feedback we hear is: “I wish I’d gone bigger.” It’s almost never the other way around.
Here’s why. When you’re deciding what size shed you need, you tend to think about what you own right now. But sheds last decades. Over the next 10–20 years, you’ll accumulate more tools, take on new hobbies, maybe buy a boat or a caravan. Your kids will need storage space. That workshop corner will grow into a workshop half.
The cost difference between, say, a 6×6 and a 9×6 shed is surprisingly small compared to the total project cost. But extending a shed later? That’s expensive and disruptive. Our advice: whatever size you think you need, go one size bracket up. You’ll thank yourself in five years.
Council Setback Requirements in WA
Your shed size isn’t just about what fits inside — it’s also constrained by where your council allows you to build. In Western Australia, the Residential Design Codes (R-Codes) set minimum setbacks from property boundaries:
- Rear boundary: Typically 1m minimum for sheds under 2.4m wall height, or standard setback (usually 1.5m–6m) for taller structures.
- Side boundary: Sheds can often be built to the boundary or with a 500mm–1m setback, depending on wall height and length on that boundary.
- Front setback: Sheds are generally not permitted forward of the building line. Check your local planning scheme.
- Total boundary wall length: Most councils limit how much of your boundary can be built on — typically no more than one-third of that boundary’s length.
These rules vary between councils, so it’s essential to check with your local authority or work with a builder like Dynaspan who manages the approval process for you. We know the rules for every council across the Perth metro area and greater WA.
Ceiling Height: Don’t Forget to Think Vertically
When thinking about what size shed you need, height matters just as much as floor area. Standard wall heights are 2.4m to 2.7m, but going to 3m or 3.6m walls opens up significant possibilities:
- Room for a car hoist
- Space to fit a caravan, boat, or motorhome
- Overhead storage on racking systems
- A more comfortable, open-feeling workspace
- Clearance for a mezzanine floor
Taller walls add modest cost to your shed build but can effectively double your usable space when combined with a mezzanine.
Mezzanine Floors: Double Your Space
A mezzanine floor is a partial or full upper level inside your shed. It’s one of the smartest ways to get more usable space without increasing the shed footprint — which matters when setback rules limit how big you can build. Mezzanines are ideal for storage, a home office, a gym, or even a studio space above a workshop.
All Dynaspan sheds are engineer-certified and can be designed to accommodate mezzanine floors. Our ShedSafe accreditation ensures the structural design accounts for the additional loads. With a 25-year structural warranty, you can build upward with confidence.
Still Not Sure What Size Shed You Need?
That’s completely normal — and it’s exactly what our team is here for. We’ve helped thousands of WA homeowners and businesses work out the right shed size for their block, their budget, and their plans. Every Dynaspan shed is custom-designed, engineer-certified, and built with genuine COLORBOND steel.
Download our free shed buying guide for a comprehensive overview, or jump straight to a conversation with our Perth-based team.
Get your free, no-obligation quote today and let’s work out the perfect shed size for your needs.