Concrete Cutting
Cutting a new stair or elevator opening in a suspended slab.
By CoreCut Demolition · Published September 28, 2026
- suspended slabs
- structural openings
- temporary shoring
An opening for a stair or elevator is not a large version of a pipe hole. Removing part of a suspended floor changes the way the remaining slab carries load.
The sequence belongs on an engineer's drawings before a saw reaches the site. Temporary support, section handling and protection of the new edge all depend on that design.
Design the opening and support first
The engineer sets out the opening, reviews the slab and designs temporary shoring and any permanent structural changes. Shoring is installed and checked before cutting begins. The demolition team does not decide that a slab appears strong enough to hold itself while pieces are removed.
Drawings should identify what is removed, what remains and how the work proceeds. The owner coordinates the applicable City of Mississauga Building Division permit before structural cutting. Site measurements are compared with the documents so an offset does not become a structural surprise.
Scan the slab at the proposed lines
Scanning looks for reinforcement, tendons and embedded services that drawings may not locate precisely. The findings are compared with the engineer's plan before the cutting marks are finalised. Read what scanning can and cannot find to understand why a blank-looking scan is not a guarantee.
A post-tensioned floor requires particular care; an unidentified tendon is not treated as an ordinary bar. If findings conflict with the approved cut, the work stops for engineering review. Access below is checked for services, people and the route for lowering material.
Cut and remove controlled sections
A perimeter cut defines the opening and protects the slab that stays. The engineer-approved sequence determines how inner sections are divided, supported and lowered or lifted out. The crew plans rigging and the receiving area around the weight and access of each section, without treating a cut piece as free until it is secured.
Slab sawing may establish parts of the cut; other techniques may be required at edges or for handling. Water and slurry need containment, especially above occupied space. The removal path must not introduce new loads or damage into areas outside the work zone.
Protect the opening as soon as it exists
An exposed floor edge creates a fall hazard immediately, even while cutting continues nearby. Barriers, covers and controlled access are arranged before the first section is freed and maintained through handoff. People working below need protection from falling fragments and water as well as the planned lowering operation.
The finished edge may also need preparation for new framing or support. Structural demolition depends on a clear scope of what remains and which trade completes that edge. Leaving an open hole for a later contractor without assigning protection is not an acceptable handoff.
Coordinate the next contractor
The stair or elevator contractor needs the approved opening, clear tolerances and an installation sequence. The demolition crew confirms the location and removal plan with those drawings, while the engineer defines when temporary supports may change. If the installer needs embedded items or a different edge, that request goes back for review before the concrete is altered.
Access, deliveries and debris hauling can conflict in a busy building. A coordinated schedule keeps the opening secure and the receiving area available until the new work is ready to proceed.
When to bring in a professional
Bring in the structural engineer and the stair or elevator contractor at design stage, not after a sawcut reveals a problem. A qualified scanning specialist provides the concealed-condition information needed for review. CoreCut Demolition Mississauga performs planned wall sawing and floor cutting once approved support and handling are in place. Request a site review with the structural documents and intended installation sequence.
Frequently asked questions
Can shoring be installed after the first cuts?
No. The temporary support specified by the engineer must be in place and verified before the slab is cut according to that plan. Removing concrete changes the load path as soon as a section is released. The crew should not improvise the timing or substitute an unapproved support because an opening appears small.
Why not cut one large piece and lift it out?
The engineer-approved sequence and the available lifting route determine section sizes. A single piece may be difficult to secure, move or receive without affecting the remaining slab or occupied space below. Controlled sections let the team plan each support and lift, but the exact approach must follow the structural and site conditions.
Who protects the opening before the new stair arrives?
That responsibility should be assigned in the project sequence before demolition starts. Barriers, covers and controlled access are needed as soon as the first part of the hole opens and remain until a safe permanent condition exists. The owner and contractors should agree on inspection and handoff rather than assuming the next trade will arrive immediately.
Is scanning still needed when structural drawings exist?
Drawings establish the design intent but may not show every installed service or field change at the precise cut location. Scanning adds site-specific evidence for the engineer to review. Neither replaces the other: the cut plan should reflect both the approved structural design and what the team actually finds in the slab.
Primary planning references
Source links checked 6 October 2026. Confirm the requirements for your property and scope with the relevant authority and qualified professionals.