Choosing the right size for your metal building is one of the most important decisions you’ll make. Too small, and you’ll wish you’d gone bigger. Too large, and you’ve spent more than necessary. Here’s how to get it right.
The Golden Rule: Go Bigger Than You Think
After helping thousands of customers, we can tell you with certainty: almost everyone wishes they’d gone a little bigger. Your needs will grow over time. When in doubt, add at least 20% more space than your minimum calculation.
Sizing by Building Type
Carports
| Vehicles | Recommended Width | Minimum Length |
|---|---|---|
| 1 car | 12’ | 21’ |
| 1 truck/SUV | 14’-18’ | 21’ |
| 2 vehicles | 18’-20’ | 21’ |
| 3 vehicles | 24’-26’ | 21’ |
Tip: If you have trucks or SUVs, go wider. Standard car widths are about 6’, but trucks with mirrors can be 7’+.
Garages
| Use | Recommended Size |
|---|---|
| 1-car garage | 12x21 or 14x21 |
| 2-car garage | 20x21 or 22x26 |
| 2-car + workshop | 24x31 or 24x36 |
| 3-car garage | 30x31 |
Tip: For workshops, add at least 10’ of length beyond vehicle parking for workbench space.
Barns
| Use | Recommended Starting Size |
|---|---|
| Small storage barn | 24x26 |
| Equipment barn | 30x41 |
| Livestock barn | 36x41+ |
| Multi-purpose farm barn | 40x61+ |
Tip: If you plan to add lean-tos later, choose a building width that accommodates them.
RV Covers
| RV Type | Minimum Width | Minimum Height |
|---|---|---|
| Travel trailer | 14’ | 12’ |
| Fifth wheel | 14’ | 13’ |
| Class A motorhome | 14’-18’ | 14’ |
| Class A + tow vehicle | 14’-18’ | 14’ |
Tip: Measure your RV with all accessories deployed (A/C units, antennas) for accurate height requirements.
Key Measurements to Consider
1. Width
Your building width determines how much side-to-side space you have. Consider:
- Vehicle widths plus door-opening clearance
- Walking paths between vehicles and walls
- Workbench or storage space along walls
2. Length
Length determines depth. Consider:
- Vehicle length (including hitches, bumpers)
- Workbench space beyond parking
- Storage space at the back
- Walk-around space
3. Height (Leg Height)
Standard leg heights are 6’-8’ for carports and garages. Consider going taller if:
- You have lifted trucks or tall vehicles
- You want overhead storage
- You plan to install a car lift
- You need clearance for an RV or boat
Property Considerations
Before finalizing your size:
- Check setback requirements — Most counties require 5’-15’ from property lines
- Measure your site — Walk the area and stake out the footprint
- Consider drainage — Water runoff from a larger roof needs somewhere to go
- Plan for access — Leave room for driving in and out comfortably
- Think future — Will you add vehicles, equipment, or hobbies?
Our Free Design Tool
The best way to visualize your building is our 3D configurator. You can adjust dimensions in real-time and see exactly how your building will look. Or contact us — we’ll help you figure out the perfect size for your needs.
