Dimensions Guide

Selecting the right dimensions for your steel carport or garage is essential to ensuring your vehicles, equipment, or workshop tools fit comfortably. Metal structures are highly customizable, but standard sizing conventions apply.

Here is the dimension design guide for steel buildings. Once you have a target footprint in mind, the sizing estimator can turn these rules of thumb into a recommended width, length, and leg height for your vehicles.

Choosing Your Building Width

1. Width Guidelines (Single, Double, and Triple Spans)

The width determines how many vehicles can park side-by-side:

• Single-Car (12 to 18 feet wide): A 12-foot wide structure fits a single compact car or truck. Upgrading to 18 feet wide provides comfortable door clearances and storage space.
• Double-Car (20 to 24 feet wide): A 20-foot wide garage accommodates two standard vehicles, but a 24-foot width is highly recommended for full-size trucks or SUVs.
• Triple-Car (26 to 30 feet wide): Accommodates three vehicles or provides space for a two-car bay plus a dedicated workshop area.

Widths beyond 30 feet move into clear-span engineering territory — see wide-span structures for the foundation and permitting differences at that scale.

2. Length Guidelines (Footprint vs. Roof)

The length determines how many vehicles or items can fit front-to-back:

• Standard Lengths: Standard lengths start at 20 feet and increase in 5-foot increments (e.g. 20’, 25’, 30’, etc.).
• Footprint Offset: In the steel building industry, length dimensions usually represent the outer frame length (from base rail corner to corner). The roof panels typically overhang an additional 6 inches on the front and rear gables.
• Recommendation: If you want a 20-foot long enclosed interior space, order a 25-foot long building to allow for structural columns, roll-up door recesses, and workspace.

3. Side Leg Height vs. Peak Height

Leg height is the most common point of confusion when ordering steel structures:

• Leg Height: Measured from the ground base rail to the top of the side walls (where the roof rafter joins the column).
• Peak Height: The highest center point of the roof, which rises above the leg height depending on the roof slope (typically 3 inches of rise per foot of width).
• Door Clearance: Roll-up doors require headroom. A 10-foot leg height is needed to install an 8-foot tall roll-up door.

Quick Reference: Width by Vehicle Count

Vehicles	Recommended Width	Typical Use
1	12’–18’	Compact car, truck, or single workshop bay
2	20’–24’	Two standard vehicles or one truck + storage
3	26’–30’	Three vehicles or two bays + workshop
30’+	Clear-span engineering	RV fleets, commercial, agricultural

Before ordering, confirm your final dimensions clear your property with an on-site measurement check and any local permit requirements for your footprint.