What holds up the new floor section once the opening is framed in?

New beams or angle framing are welded or bolted to the existing structure at the header and trimmer members, sized by an engineer for the loads the closed-in floor area will carry, then decked with plate or metal deck and concrete.

Do you need engineered drawings before starting?

Yes, or we coordinate with your engineer to get them. Closing a structural opening changes how load moves through the floor, so we work from a stamped design and produce our own shop drawings before any steel is cut.

Does the closure need fireproofing after installation?

If the floor assembly carries a fire rating, yes - the new steel and deck are brought up to the same rating with spray fireproofing or fire-rated board, coordinated with your fireproofing contractor or done by ours.

Product

Structural Steel Floor & Stair Opening Closures

Name: Steel Masters NYC
Address: 135 Liberty Ave, Brooklyn, NY, 11212, US
Telephone: (888) 577-8335
Price range: $$

When a stair is removed or a floor opening is no longer needed, the hole has to be framed and decked back into the structure. Steel Masters cuts in the new beams, welds the framing to the existing steel, and closes the opening so the floor carries load again.

We work from an engineer's design, or coordinate with yours, and produce shop drawings in house before fabrication.

Structural steel floor and stair opening closures turn a hole in the structure back into usable floor area, but only if the new framing is sized and connected correctly. Steel Masters has been framing in stair, shaft and floor openings for NYC buildings since 1972, working from engineered plans and welding new steel directly into sound existing structure rather than patching over the opening.

Why NYC Owners and Managers Choose Steel Masters

Engineered framing, not a patch - new header, trimmer and infill beams sized to the load the closed-in area will actually carry, per your engineer's design.
Welded or bolted to existing steel - connections land on sound existing members, not on the old trimmer edges left over from the opening.
Plate or metal deck infill - steel plate for a flush industrial finish, or metal deck and concrete when the floor needs a standard slab finish above.
Shored before anything is cut - temporary shoring keeps the floor supported through demolition and framing so the structure never loses its load path mid-job.
Sequenced around occupancy - staged cutting and welding lets us close an opening in an occupied building without a full floor shutdown in most cases.
Fireproofing coordination - new steel and deck brought up to the fire rating of the surrounding floor assembly where the building requires it.
Shop drawings before fabrication - connection and framing details drawn in house so the field crew, the engineer and the inspector are all working from the same plan.

What the Work Involves

New beams and angle framing are welded or bolted into the existing header and trimmer members that used to frame the opening, so the closed section ties into the floor's original load path instead of floating on its own. Steel plate or metal deck infill is sized to the load and welded or shot to the new framing, and shoring supports the floor through every stage of the cut, weld and deck sequence.

Where the closure sits in a rated floor assembly, we coordinate fireproofing on the new steel and deck to match the rating of the surrounding structure before the finish floor goes back down.

Where It Comes Up

Removing an old stair between floors, closing an elevator or dumbwaiter shaft opening, filling a former mechanical or duct chase, combining tenant spaces across a floor, and closing floor openings left after equipment or a hoistway is decommissioned. Any of these leaves a structural hole that needs engineered framing, not just a deck plate dropped in place.

Working in Occupied Buildings

Most of this work happens while the building stays in use above and below. We plan access, shoring and the cutting sequence before steel arrives on site, keep a path of egress open wherever the fire safety plan allows it, and schedule the noisiest welding and cutting for off-hours when the job requires it.

Every job is measured in the field and built to that opening - we fabricate in our own Brooklyn shop and install with our own crew, the same way we have since 1972.

- Steel Masters NYC, Brooklyn shop, 135 Liberty Ave

Related Steel Masters Product Lines

Structural Steel Alterations - the hub page covering all six alteration scopes we handle
Structural Steel Fabrication - the broader structural alteration work this closure work falls under
Steel Floor Reinforcing - adding capacity to a floor that already carries its full opening
Steel Plate Installations - the plate infill used to finish many opening closures
Structural Steel Modifications & Repairs - repairs to the surrounding structure when the opening closure is part of a larger job

Serving All Five Boroughs, Long Island & Westchester

Steel Masters fabricates in Brooklyn at 135 Liberty Ave and installs with our own crews across Brooklyn, Manhattan, Queens, the Bronx, Staten Island, Long Island and Westchester. Call (888) 577-8335, send us your plans through shop drawings and plans, or contact us online for a quote on structural steel floor & stair opening closures.

Frequently Asked Questions

Usually yes. We shore the opening, cut and weld the new framing in stages, and keep at least one path of egress open unless the building's fire safety plan calls for a full shutdown of that stair run.