Column-free means every pound of roof load has to travel to two footings per frame, and in Natrona County those footings sit below a 3 foot frost line. That is the whole design problem in one sentence. A clear-span rigid frame has tapered steel columns and rafters, no interior posts and a roof that pushes outward as well as down, so the foundation carries horizontal thrust that a column-and-beam building never sees. We design and build these buildings for owners who need open floor: aircraft, trucks, equipment, people.
The airport is the obvious Casper example. Casper-Natrona County International Airport covers 5,150 acres, logged 43,126 operations in 2022 with 71 percent general aviation, and has 131 based aircraft. A hangar or maintenance shop for that traffic needs an opening wide enough for a wingspan and a floor free of posts, and our rigid frame buildings give owners that without a truss roof. The same logic applies to oilfield equipment barns, truck repair bays and cross-dock terminals.
These buildings are a specialized form of pre-engineered metal building, and the manufacturer supplies the primary frames. We bring the foundation design, the erection and the coordination with the engineer of record, and we offer them under design-build delivery when the owner wants one contract for both.
Spans of 100 feet and more mean heavy frames, big cranes and careful pick planning. The frames are fabricated in sections, bolted at the splice and stood in order, and they are stable only after the bracing is in. We plan temporary bracing for wind during erection, because an open frame with no sheeting is a sail. The City of Casper lists a 115 mph 3-second gust at exposure C for dwellings, and a wide frame with no roof deck deserves the respect that number implies.
Snow is the other load that grows with the span. The City directs designers to 2024 IBC Table 1604.5 and the ASCE Hazard Tool for snow load instead of a fixed value, and the engineer must account for drifting where the roof meets an adjoining structure or a parapet. Where a clear-span building abuts a lower roof, the drift that builds on the lower roof becomes a design load, and we raise it early so it can be addressed on the drawings.
The foundation is where clear-span jobs go wrong. Horizontal thrust at the column base is resisted by tie rods in the slab, by buried grade beams or by wide footings, and each has a different effect on slab design and cost. The frame reactions come from the manufacturer, and the geotechnical report decides which option works. We insist on the geotechnical report before we price.
Deflection limits matter for door openings, and for crane or hoist loads where those are specified. Commercial permits in Casper often require engineered drawings, a life-safety plan and structural calculations, and an issued permit is good for 180 days. We time the permit so that foundations can start while frame fabrication is underway.
The door is the hardest element. A hangar door that spans the whole end wall carries its own weight, wind load and track loads, and it needs a header that can accept all three without deflecting. Truck terminals need a different set of openings, and arenas need roofs with long clear heights and acoustics. We ask the owner what has to go through the opening before we choose the frame layout.
We then check the clear height, eave height and slope against the use. A frame sized to the equipment, not to a catalog size, saves money in heating, lighting and insulation. When a building is long, we add expansion considerations and tell the owner where joints will fall.
Aircraft storage and maintenance are the clearest fits, and our aircraft hangar work uses the same frames. Truck repair shops, transload buildings and truck terminal and cross-dock facilities benefit from open floor. Oilfield service companies often want a building where a rig, a pump truck or a vacuum unit can be driven in and worked on.
Schools and colleges use rigid frames for gymnasiums, shops and training halls. Casper College lists more than 130 academic and technical programs on a campus of more than 200 acres, and technical programs in particular need big open floors for equipment. Education institutions and campuses such as Casper College are the audience for this kind of build.
The wider the span, the heavier the frame, and the price per square foot rises with it. Clear height, door size, insulation, snow load and foundation type all move the number. A 60 foot span is usually cheaper per square foot than a 150 foot span, and an owner who can split the use into two buildings sometimes ends up spending less overall.
We lay out the trade-offs in the proposal so the owner can see whether a column or two would save a meaningful amount without damaging the use. If an interior column in the back corner costs a shop nothing, we will say so, and we will also say when a column would get in the way of a forklift every day for the life of the building. Owners of oilfield equipment barns in particular tend to regret an interior post the first time a boom truck has to back around it in January.
Send us the largest thing that has to move through the door, the clear height you need and the site. We will return a frame concept, a foundation approach and a schedule built around delivery.
Practical spans for pre-engineered rigid frames run from about 60 feet to well over 150 feet, depending on loads and the manufacturer. Wider spans are possible but require heavier frames and often a different structural system. We ask for the use and the snow load first, then pick the frame.
Yes, but it must be designed in from the start. A mezzanine or bridge crane changes the loading on the columns and foundation, and retrofitting one is expensive. If you may want either in five years, tell us now.
Wind and stability. A partially erected frame has not yet got its bracing and roof deck, so it is vulnerable. We plan lifts, temporary bracing and weather limits in advance and stop when the wind requires it.
Yes. The foundation of a clear-span building carries large concentrated loads and horizontal thrust, and the soil decides the design. We recommend ordering the report before design, not after.
Casper lists a 3 foot frost line to the top of footing, so footings must reach below it or be protected. For a heated hangar the slab area is protected, but the perimeter and door thresholds still need frost detailing.