Choosing the right size is one of the biggest decisions when buying a metal building. This guide covers width, length, height, and how to match size to use.
Size Matters More Than You Think
One of the most common regrets we hear from metal building owners is: "I wish I had gone bigger." It's natural to size a building for your current needs, but a little extra space costs surprisingly little compared to the convenience it provides. Whether you're buying a carport, garage, workshop, barn, or commercial building, getting the dimensions right from the start saves you the cost and hassle of upgrading later.
Width: How Wide Should Your Building Be?
Width is typically the first dimension to determine because it's based directly on what you plan to store or shelter. Here are the standard width recommendations:
- 12' — Single vehicle (compact to mid-size car)
- 14' — Single vehicle with extra clearance (truck or SUV)
- 18' — Two compact cars or one vehicle plus workspace
- 20' — Two mid-size vehicles side by side
- 22' — Two full-size vehicles with comfortable door-opening clearance
- 24' — Two large vehicles (trucks, SUVs) with generous room
- 30' — Three vehicles or two vehicles plus dedicated workspace
- 40' — Four vehicles, large workshop, or agricultural equipment
- 50'+ — Commercial applications, large equipment, or multi-use buildings
Length: How Long Should Your Building Be?
Length is determined by the number and size of items you plan to store, plus the buffer space needed for comfortable access. Standard lengths start at 21 feet and increase in 5-foot increments (21', 26', 31', 36', 41', etc.).
- 21' — Standard car parking (about 2 feet of buffer front and back)
- 26' — Car plus small workshop area or storage at the back
- 31' — Large truck, SUV, or car with significant workspace
- 36' — Most boats, small to mid-size RVs
- 41' — Large RVs and motorhomes (measure your RV + add 5')
- 50'+ — Multiple bays, commercial use, or equipment lines
Height: Don't Overlook Side Wall Height
Side height is measured at the wall, not at the peak. This is a critical distinction because the peak height will be several feet taller depending on your roof style and building width. Common side heights and their uses:
- 6' — Minimum for standard cars (tight fit, limited to basic carports)
- 7' — Standard single garage door height
- 8' — Standard double garage door height with clearance
- 9' to 10' — Trucks, SUVs, lifted vehicles, most enclosed garages
- 12' — Large RVs, box trucks, agricultural equipment
- 14'+ — Tall RVs, commercial vehicles, equipment with lift attachments
Sizing for Specific Uses
Here are our most popular size recommendations by building type:
- Single Carport: 12'W x 21'L x 7'H — Basic car protection
- Double Carport: 20'W x 21'L x 7'H — Two-car coverage
- Single Garage: 14'W x 26'L x 9'H — One car, enclosed with storage
- Double Garage: 22'W x 26'L x 9'H — Two cars, fully enclosed
- Workshop: 24'W x 31'L x 10'H — Vehicle plus work area
- RV Cover: 18'W x 36'L x 12'H — Standard RV or large boat
- Barndominium: 30'W x 40'L x 12'H — Open concept living/working space
- Farm Building: 40'W x 60'L x 14'H — Large equipment and livestock
- Commercial: 50'W x 100'L x 16'H — Warehouse, manufacturing, retail
The 'Go Bigger' Rule
Our number one piece of advice: if you're debating between two sizes, go with the larger option. The incremental cost of an extra 5 feet of length or 2 feet of width is minimal compared to the total building cost, but the extra space is invaluable. You'll find uses for it — whether it's a workbench, tool storage, a second vehicle you didn't plan on, or simply the comfort of not squeezing past your car to get to the door.
Get a Custom Quote
Every property and every need is different. Our Building Specialists can help you determine the exact dimensions that work best for your situation. Call (833) 722-7678 for a free consultation, or design your building in 3D at CarportX.sensei3d.com to visualize different size options before you buy.