Roof Framing Plans: Structural Members, Connections, and Detailing

The S1-7H roof framing plan represents the highest structural level of the building. Unlike the floor plans below it, this sheet also picks up all of the areas that had no structure underneath them, most notably the large open-to-below spaces such as the gymnasium in the bottom right corner of the plan.

The plan uses the same cast of structural members seen on previous sheets, including K-series joists, wide flange beams, and concrete perimeter walls, but it also introduces some new member types and connection details worth understanding before construction begins.

Sloping Beams and Reading Top-of-Steel Elevations

One of the first things to notice on this plan is the presence of arrows on certain beams, indicating that those members slope in a specific direction. These are not level beams; they pitch from one column line to another to achieve the roof drainage geometry the architect and civil engineer require.

The plan makes this explicit by pairing the arrows with top-of-beam elevations at each column grid line. For example, a beam might read 29'-11" at column line H and 29'-8" at column line J. That three-inch drop over an eleven-foot bay tells the steel fabricator and the ironworker exactly how much pitch needs to be built into that member. All of the slope information lives right on the plan next to the member.

Key Takeaway: When you see an arrow on a beam label, locate the top-of-steel dimensions at each end of that beam. The difference between those two numbers is the total slope across that bay.

Long Span Joists: the LH Series

The roof framing plan introduces a joist type not found on lower-level plans: the LH, or long span, series. These are open-web steel joists engineered for spans that exceed the practical range of the standard K-series joists seen elsewhere on the project.

Breaking Down the Designation

The designation 32LH10SP1 can be read piece by piece:

• 32—Depth of the joist in inches, measured from top chord to bottom chord
• LH—Long span series designation; used for longer spans than the K-series
• 10—The joist number within the LH series, which indicates load-carrying capacity
• SP1—Special profile; indicates a non-standard geometry tailored to project requirements

The Gymnasium Joists

The gymnasium area uses even deeper joists: 40LH12 members with SP3 and SP4 special profile designations. The 40-inch depth reflects the much longer spans required in a two-story open volume. The special profiles make particular sense in this context. Gymnasium ceilings commonly route mechanical ductwork through the joist space rather than below it, so the structural profiles of the joists are shaped to accommodate those penetrations while maintaining the necessary load path.

This is worth noting during coordination meetings: if HVAC duct runs are planned through these LH joists, the joist supplier and the mechanical engineer need to agree on penetration locations before fabrication begins.

Perimeter Details: Where the Roof Structure Meets the Wall

Two perimeter bearing conditions show up on this plan, referenced as details D and K on the detail sheets. Understanding both helps clarify how the roof structure transitions to the building envelope.

Detail D: Standard Bearing Condition

At locations where there is no opening in the exterior wall below, the joists bear on a bearing plate that is set into the wall. Metal decking laps over the joist, and a steel angle is used to connect the assembly. This is the most straightforward condition and will appear repeatedly around the building perimeter.

Detail K: Bearing at Wall Openings

Where a door or window opening exists in the insulated concrete form wall below, the bearing condition includes a lintel. A steel bearing plate or embed is cast into the wall as the concrete is poured. Once the wall cures, a steel angle lintel is welded to that embed, providing a continuous shelf for the exterior masonry above the opening to bear on. The detail also shows additional rebar in the wall header to account for the increased loads at that condition.

The Curtain Wall Condition: Detail G

One section cut on the roof framing plan, labeled detail G, shows a portion of the building where the perimeter is curtain wall rather than an insulated concrete form wall. Here the joist does not bear on concrete; instead, cold formed metal framing is connected back to the structural steel via an angle attached to the beam. The curtain wall itself is laterally braced back to the structure by a connector supplied and designed by the curtain wall contractor.

Cold Formed Metal Framing: Reading the Callouts

Within detail G, vertical and horizontal framing members are called out with a designation like 600S68 @ 16" O.C.. This is the standard notation for cold formed metal studs:

• 600—Stud depth in hundredths of an inch (600 = 6-inch deep stud)
• S—Stud shape, as opposed to a track or other cold formed profile
• 68—Material thickness in mils, equivalent to 16-gauge structural steel
• 16" O.C.—Spacing of studs at 16 inches on center

This notation differs from rolled steel member designations and from steel decking callouts. When you see a number-letter combination in this format on a structural detail, it signals cold formed metal framing rather than any other structural member type.

Understanding Weld Symbols

Structural details throughout this plan set use standard AWS weld symbols. These symbols appear as a flag with a leader line and one or more triangles attached, and they carry specific meaning about weld type, location, and size.

Fillet Welds

The most common weld shown on these details is the fillet weld, represented by a triangle on the weld symbol. The position of the triangle relative to the reference line tells the welder which side of the joint receives the weld:

• A triangle below the reference line means the weld goes on the near (arrow) side of the joint.
• A triangle above the reference line means the weld goes on the far side.
• Triangles on both sides indicate a weld is required on both faces of the joint.

The dimension shown alongside the triangle such as 3/16", is the leg size of the fillet weld. This is the measurement used by the welder and the inspector to verify that the weld meets the specified strength requirement.

Bolted Connections

Not all connections on these plans are welded. Bolted connections appear at beam-to-beam and beam-to-column locations. When a bolted connection is used, the detail includes a note describing the bolt diameter, quantity, and specification. A typical note might read "four 3/4-inch diameter bolts, " giving the fabricator everything needed to prepare the connection plates and drill the appropriate holes.

Stiffener plates at bolted connections may also be called out separately. These are short plates welded inside the web of a beam at a point of concentrated load to prevent web buckling.

Note: This plan set does not include a symbols and abbreviations page. If weld symbols or member designations are unclear in the field, reference AWS A2.4 for weld symbols and the Steel Joist Institute standard specifications for joist designations.

Roof Openings: Framing Requirements

Openings in the roof deck for mechanical equipment, skylights, roof drains, and similar penetrations are shown graphically on the framing plan but are not always individually dimensioned there. The plan relies on general notes to govern how all openings are to be handled:

• Any roof opening larger than one foot by one foot requires a continuous angle frame on all four sides. The specified angle is a 4x3x5/16 steel angle.
• Exact opening locations and sizes must be coordinated with the architectural and mechanical drawings before framing begins.
• Angle framing is also required at all roof drains, regardless of size.

How the Framing Works at an Opening

Detail C shows both a plan view and a section through a typical roof opening. In plan, two parallel joists or beams run on either side of the opening. Perpendicular to those, the angle frames span between the joists to pick up the cut decking and transfer load back to the adjacent framing. The section confirms that the angles sit on top of the structural members and run continuously around the perimeter of the opening.

Channel Members: the C-Shape Section

In one area of the roof plan, a C8x11.5 designation appears. This is a structural channel, also known as a C-shape, and it differs from wide flange beams in its cross section. Where a wide flange has flanges on both sides of the web, a channel has flanges on only one side, giving it a C-shaped profile when viewed from the end.

The 8 is the nominal depth of the channel in inches, and the 11.5 is the weight per linear foot in pounds, the same convention used for wide flange members. Channels are commonly used as edge members, bridging elements, or secondary framing where the asymmetric profile is advantageous for connecting to other elements.

Elevation Benchmarks and the Datum

Throughout the details on this plan, circular markers with partially filled quadrants appear at key locations. These are elevation benchmarks referenced back to the project datum, typically established at finished floor elevation zero. When a detail shows a top-of-steel dimension of 32'-11", it means that particular assembly must reach exactly 32 feet and 11 inches above the project datum. These benchmarks coordinate the structural elevations with the architectural finish elevations and mechanical clearance requirements, so they carry real consequences for coordination in the field.