Most people shopping for an arch steel building know the classic Quonset shape. But Duro Span builds several series, and two of them solve problems the classic arch doesn’t: the compact M-Series and the peaked-roof A-Series. If you’ve already read our [Q-Series vs. S-Series vs. G-Series comparison], this covers the rest of the lineup.
The M-Series: compact, secure covered space
The M-Series is Duro Span’s smallest building — a single-radius clear span arch with straight sides, built for projects where you need tough, secure cover without going oversized.
• Width: 10’ to 20’
• Length: virtually unlimited, built in 18” increments
• Best for: equipment storage, small garages, repair space, tool and supply storage, general-purpose use
The M-Series also has an industrial side. Its design originated as a tamper-resistant security shelter for remote sites — covering well-head valves, oilfield equipment and remote storage. That’s why it shows up on energy and ranch properties in places like Texas, New Mexico and Kansas, where equipment sits far from the nearest building and needs protection from weather and theft.
If you need a backyard equipment building, a single-vehicle garage, or a locked enclosure at a remote site, the M-Series is usually the most cost-effective starting point.
The A-Series: steel strength with a traditional roofline
The A-Series trades the curved arch for a peaked, cathedral-style roof with a 4:12 pitch, on straight side panels angled at the base. From the road it reads like a conventional building; underneath, it’s still clear-span steel.
• Width: 20’ to 50’
• Roof: straight roof with a uniform slope (4:12 pitch)
• Best for: garages, workshops, storage and larger buildings on residential, agricultural and commercial properties
The main reason buyers choose the A-Series is appearance. If your building will sit next to a house, along a main road, or on a property where a rounded Quonset would look out of place, the peaked roof blends in more naturally. The added interior height near the peak also improves usable space for shelving, lifts and taller equipment.
Before you buy any building for a residential lot, check local zoning and any HOA rules — a traditional roofline can help, but approval is always local.
Where they fit in the Duro Span lineup
Every series is clear span — no interior columns or trusses — and every Duro Span building is engineered to the code for the location it’s delivered to.
Which one should you choose?
• Choose the M-Series if your footprint is 20’ wide or less and function matters more than looks.
• Choose the A-Series if appearance matters, you want a peaked roof, or you need a building between 20’ and 50’ wide that looks like a traditional garage or barn.
• Look at Q, S or G if you need the widest spans or the most steel-efficient arch.
Not sure which series fits? Call 888-848-2011 or request a free quote and a Duro Span specialist will match your project to the right building.