NOTE This standard covers the protective cover assemblies, preformed fillers, and fire-barrier systems installed over or within a structural separation joint in a building. (1.1)

NOTE Building expansion joints are deliberate, continuous gaps left in the structure so that independent portions of a building can move relative to one another without cracking, racking, or shearing the finishes and the structure. (1.1.1)

NOTE The movement an expansion joint accommodates comes from several sources acting together: thermal expansion and contraction of long structural runs, wind sway at the upper floors of tall buildings, seismic drift between adjacent structural masses, and differential settlement of separately founded sections. The cover assembly must absorb all of these without losing closure, fire rating, or weathertightness. (1.1.2)

NOTE The location, quantity, and nominal width of every expansion joint are outputs of the structural engineer of record, not selections made in this section. (1.1.3)

NOTE The structural design gap, the building's Seismic Design Category, the calculated thermal movement, and the required fire-resistance rating of each penetrated assembly are inputs to this standard; the cover assembly, filler, and fire barrier are sized and selected to satisfy them. (1.1.4)

NOTE Cover assemblies and fillers shall be provided at every structural expansion and seismic separation joint indicated, in the installation plane shown, sized for the movement demands established by the structural design. (1.2)

NOTE Boundaries with adjacent standards. (1.3)

NOTE The backer rod and field-applied sealant placed within the reveal faces of a cover assembly, and any sealant-only closure of a non-structural control joint, are governed by Joint Sealants. (1.3.1)

NOTE Sheet-metal counterflashing, copings, and reglets where the expansion joint meets the building envelope are governed by Sheet Metal Flashing And Trim. (1.3.2)

NOTE Continuity of the roofing or waterproofing membrane across the structural separation is governed by Membrane Roofing; this section governs the cover assembly and its flashing flanges, and the lap sequence between the two is a coordination item. (1.3.3)

NOTE Structural pour strips, construction joints, and saw-cut control joints in the slab itself are part of Cast In Place Concrete; this section picks up at the cover assembly and filler installed over or within the pre-located structural gap. (1.3.4)

NOTE Pipe and duct expansion compensators, including rubber bellows on mechanical piping loops, are governed by the mechanical specifications and are not part of this section. (1.3.5)

NOTE A single building may carry several joint families at once - a heavy-duty floor cover in the loading dock, a flush flooring-insert cover in a lobby, a seismic three-axis cover at a structural separation, and fire-rated barriers wherever any of those joints crosses a rated wall or floor. Each location is scheduled independently against the plane, gap, movement, traffic, exposure, and rating that apply there. (1.3.6)

NOTE Action Submittals (3.1)

NOTE Informational Submittals (3.2)

NOTE Closeout Submittals (3.3)

NOTE Qualifications and source control. (4.1)

NOTE Fire-resistance listing. (4.2)

NOTE Each expansion joint system located in a fire-resistance-rated floor, wall, ceiling, or head-of-wall assembly shall be a complete system tested in accordance with UL 2079 or ASTM E1966 and listed for a rating equal to or greater than the rated assembly it penetrates. (4.2.1)

NOTE Mock-ups and field verification. (4.3)

NOTE Sizing the cover assembly to the structural design gap. (5.1)

NOTE The single most common failure in expansion joint specification is matching the cover assembly's travel range to the nominal structural gap alone, ignoring the thermal and seismic movement that opens and closes that gap in service. A 2 in. nominal joint that adds 0.5 in. of movement in each direction needs a cover rated for roughly 3 in. of total travel, not 2 in.; sized only to the nominal gap, the cover binds when the joint closes and disengages when it opens. (5.1.1)

NOTE Movement axes. (5.2)

NOTE A joint may be required to move in one, two, or three axes. A thermal-only joint moves primarily along a single horizontal axis. A seismic separation must accommodate drift in the two horizontal axes and vertical offset between adjacent structures - three-axis movement. A standard cover assembly cannot accommodate three-axis seismic drift; that demand requires a listed seismic system. (5.2.1)

NOTE Exposure and watertightness. (5.3)

NOTE A cover assembly is selected for the wettest exposure it sees. Interior-dry covers have no weather seal and will leak at an exterior facade, a roof, or a wet room. Exterior and wet-area covers carry a continuous EPDM or silicone seal; roof and below-grade covers must be fully waterproof and spliced into the adjacent membrane. (5.3.1)

NOTE Installation plane. (6.1)

NOTE Each installation plane imposes a distinct cover assembly family. Floor covers carry traffic and must sit flush; wall covers span vertically and must be paintable or finished to match; ceiling covers conceal the joint overhead; roof covers shed water and integrate with membrane; transitions where a joint turns a corner require purpose-built corner units. (6.1.1)

NOTE Traffic loading at floor joints. (6.2)

NOTE Floor cover assemblies are rated to the heaviest wheel they carry. A pedestrian cover will deflect and unseat under a loaded fork lift; vehicular and forklift traffic require reinforced aluminum or steel extrusions engineered for concentrated wheel loads. The load class is therefore a primary selection, not a finish detail. (6.2.1)

NOTE Cover plate material and finish. (6.3)

NOTE The cover plate material is chosen for durability and to coordinate with the adjacent finish. Mill or anodized aluminum is the default for most interior and exterior covers; stainless steel and bronze serve corrosive or architectural exposures; heavy steel serves high-load floor covers. (6.3.1)

NOTE Floor cover mounting and flooring integration. (6.4)

NOTE A floor cover either sits proud on the finished floor (surface mount) or recesses into a frame so a flooring insert finishes flush with the surrounding floor. Where carpet, tile, or resilient flooring crosses the joint, the cover plate top must be set so the finished surfaces are level; ignoring finish thickness leaves the plate standing proud, which is a trip hazard and an ADA non-compliance. (6.4.1)

NOTE Spring-loaded center plate retention. (6.5)

NOTE Floor cover plates are commonly held by a spring or centering mechanism that keeps the plate centered over the moving gap and lets it slide rather than buckle as the joint opens and closes. The retention method affects how the plate behaves under traffic and movement and should be confirmed against the traffic class. (6.5.1)

NOTE Large seismic separation joints are a distinct product class. (7.1)

NOTE Standard cover assemblies serve nominal gaps up to roughly 3 to 4 in. Seismic separation joints can be far wider - up to 24 to 72 in. - and demand three-axis movement. These are custom engineered systems, often incorporating slide plates and flexing elements, with their own lead times, costs, and engineering engagement. Treating a large seismic joint as a catalog product is a scheduling and code failure waiting to happen. (7.1.1)

NOTE Where the joint penetrates a rated assembly, a listed fire barrier is required. (8.1)

NOTE When an expansion joint occurs in a fire-resistance-rated floor, wall, or ceiling, the joint is an opening in that rated assembly and must be protected to maintain the rating. IBC requires the joint system to equal or exceed the rating of the surrounding construction. An unlisted cover dropped into a 2-hour wall is an unprotected opening and a code violation that inspection will catch. (8.1.1)

NOTE Fire-barrier method. (8.2)

NOTE Different fire-barrier methods suit different joint sizes and movement classes. A draped or compressed ceramic fiber blanket handles larger gaps and high movement; mineral wool compressed with a surface sealant suits smaller, limited-movement joints; proprietary intumescent or gypsum composite systems serve a defined band of sizes. Each method is qualified only over the joint sizes and movements in its UL 2079 test; the wrong method for the actual gap fails the test condition even if the rating number is right. (8.2.1)

NOTE Fire barrier and cover assembly coordination. (8.3)

NOTE The fire barrier and the cover assembly are a paired system: the barrier maintains the rating while the cover provides the finished, trafficked, or weather surface above it. They shall be furnished as a coordinated assembly so that the barrier's movement capacity and the cover's travel range agree. (8.3.1)

NOTE Preformed filler is the resilient backup placed in the joint cavity. (9.1)

NOTE Preformed joint filler is a resilient board set in the structural gap, typically before the cover or sealant is installed. It limits intrusion of fresh concrete into the gap during the pour, provides a resilient backing that compresses and recovers as the joint moves, and establishes the depth for any sealant placed over it. Filler material is chosen from the recognized ASTM types. (9.1.1)

NOTE Sealant infill at reveal faces. (9.2)

NOTE Where a field-applied sealant closes the cover assembly reveal faces or transitions to the adjacent substrate, the sealant, backer rod, and joint preparation are governed by Joint Sealants and shall follow the guidance of ASTM C1193. (9.2.1)

NOTE General. (10.1)

NOTE Anchorage. (10.2)

NOTE Anchorage must suit the actual substrate. A floor cover anchored into cured concrete uses different fasteners and embedment than one fastened to steel deck or to a topping slab; the wrong anchorage lets the cover lift under foot traffic or seismic movement. (10.2.1)

NOTE Roof and exterior integration. (10.3)

NOTE The roof joint is the most vulnerable point on the roof plane, and the cover flange-to-membrane lap is where leaks start. The cover assembly flange must integrate with the membrane termination in a defined sequence so water always sheds over, never under, the lap. (10.3.1)

NOTE Fire-barrier installation. (10.4)