Airport Terminal Thermal Break Framing: SDS/2 Detailing Case Study

The package covered HSS 3½x3½x¼ frame assemblies with L2½x2½x¼ and L4x4x¼ members, supported off W12x26, W10x19, W14x22 and W12x19 framing. Structural thermal breaks sat at the frame-to-structure connections. The frames, connections, bills of material and field bolt lists were detailed in SDS/2 and issued as one coordinated package.

A thermal break puts a 1" pad between the frame and the supporting structure, so the connection stops behaving like a standard bolted joint on paper. Bolt grip grows by the pad plus washers and bushings, holes must align through the steel plies and the pad, and the shop has to finish welding before the pad goes in.

Bolt stack-up

Each thermal break connection was bolted through the pad with (4) 3/4" dia. A325N bolts, washers and bushings. Copying a bolt length from a standard connection would leave too little thread for the nut, so bolt length has to be worked out from the full stack of plies, pad, washers and bushings, then carried consistently onto the field bolt list.

Holes and alignment

Bolted connections used 13/16" holes for the 3/4" bolts. With a pad in the joint, the hole pattern in each steel ply and in the pad has to line up, and each has to be called out clearly enough that the shop drills the steel and the pad is prepared to match.

Loose parts and sequencing

Pads, bushings and field bolts do not ship welded to anything. They have to appear on the drawings and lists as items the field will install, and shop welding near the interface has to be complete before the pad is fitted.

The detailing considerations behind these points are covered in depth on the structural thermal break detailing page.

The package delivered framing plans, sections, frame detail sheets with bills of material and unit weights, and field bolt lists. Plans were issued on ARCH D 24x36 sheets and detail sheets on ANSI B 11x17 and ARCH C 18x24, using the sheet sizes US shops and field crews already work with.

Every deliverable came from the same SDS/2 model, so marks on the plans, details and lists matched. How drawings are checked before release is described on the quality control page.

The bills of material on the frame detail sheets carried ship marks, minor marks, quantities, lengths, grades and unit weights, with field bolts kept on a separate field bolt list. That split lets the shop buy and cut material from the detail sheets while the field crew gets exactly the fasteners it installs.

Consistent marks across the plans, details and bolt list are what make a package fabrication-ready rather than just complete. For the full anatomy of a package, see steel shop drawings.

The package was issued as Rev A for approval on September 3, 2026, and as Rev 0 for fabrication and field use on September 9, 2026: six days between the approval issue and the fabrication issue. The convention was letters for approval issues and numbers for fabrication issues, so cleared sheets were obvious.

The six days covered the whole cycle, including the reviewers' time, on a single package. It is a real data point from a real job, not a schedule promise for other work.

The project shows three things a fabricator can verify from the record: thermally broken bolted connections detailed through to the field bolt list, US drawing conventions used throughout, and a bill of material structured with ship marks, minor marks, grades and unit weights. The package reached Rev 0 for fabrication and field use six days after the approval issue.

Those are the claims the drawings support, and this page makes no others. For fabricators considering overflow capacity, the steel fabricators page covers how a first package is set up to your shop standards.

The project is anonymised because shop drawings are the fabricator's deliverable, and publishing a client's name, project name, location or drawings needs the client's written permission. Until that permission is confirmed, this page describes the work by its technical facts and regional location only, with no drawing images and no job numbers.

If drawing extracts are published later, the title block, company logos and address, project name, job number, detailer and checker initials, and software serial information will be removed entirely, not blurred. A third party's certification mark shown next to Vertex branding would misrepresent whose credential it is.