Suspended Concrete Slabs & Elevated Decks

Elevated structural slabs, built to the drawings

A suspended slab is a floor that spans — it carries its own weight and everything on it between columns, walls or beams, with nothing underneath but the shoring that holds it until the concrete reaches strength. That makes it the most unforgiving concrete on a commercial job: the formwork sets the soffit elevation and the camber, the shoring carries the wet load and the construction load, and the reinforcement does the work the moment the props come out. There is no cover-up afterward.

Twin Peaks approaches elevated decks the way the structural drawings and the engineer of record intend them to be built — slab thickness and drop panels where they are called, top and bottom steel with the specified cover, embeds and sleeves located before the pour, and a pour and stripping sequence that respects how the structure is designed to gain load. We are a cast-in-place concrete and structural contractor first; elevated slabs sit alongside our architectural concrete and poured concrete foundation work, so the deck is a continuation of the same structure, not a separate trade bolted on.

Formwork and shoring: the temporary structure that makes the permanent one

Before a suspended slab is concrete, it is a temporary structure made of forms, stringers, joists and shoring — and that temporary structure has to be engineered for the loads it will actually see. We build and set formwork to hold the specified soffit elevation, slab thickness and camber, with form faces and joints detailed for the finish the slab needs.

Shoring carries three things we plan for separately: the dead weight of the wet concrete, the construction live load on the deck during the pour, and the time the slab needs before it can carry itself. Key considerations on every elevated deck:

• Shore loads and the deck below — the floor a shoring tower bears on has to be able to take the load coming down through it, which is why shoring and the structure it lands on are coordinated with the engineer, not assumed.
• Reshoring and backshoring — on multi-level structures the lower slabs are still gaining strength, so props are pulled and reset in a planned sequence that shares load across several floors rather than dropping it all on one green slab.
• Stripping strength, not stripping date — forms and shores come off when the concrete has reached the strength the drawings and the schedule call for, confirmed rather than guessed.
• Deflection and camber — long spans are formed with the camber the designer specifies so the slab lands flat under load instead of sagging to its final shape.

Getting the temporary structure right is most of what keeps a suspended slab on elevation, on tolerance and safe to work under.

Rebar, post-tensioning and embed coordination

An elevated slab is only as good as the steel inside it and the items cast into it. We coordinate reinforcement placement to the structural drawings and the rebar shop drawings — bar size, spacing, laps, top and bottom mats, and the concrete cover that protects the steel and gives the slab its designed capacity. On decks exposed to traffic or weather, cover and detailing matter even more, because they are what keep the reinforcement durable over the life of the structure.

Suspended slabs carry a lot of other trades' work, and most of it has to be in place before the pour: column and wall dowels, beam cages, slab edge forms and blockouts, drains and sleeves, electrical and mechanical penetrations, and anchor embeds and plates. We sequence this so inspection happens on a clean, complete deck. Where a slab is post-tensioned, we build to the PT designer's tendon layout and stressing sequence and coordinate the placing and stressing trade — the forming, shoring and reshoring plan has to account for stressing before the deck can be loaded or stripped. When an elevated deck is part of a larger structural scope, it ties into our wider structural and multi-family structural work.

Placing and finishing elevated slabs

Placing concrete on a suspended deck is a controlled, continuous operation. We plan the pour around access — pump reach and line routing, placement rate, and the construction load the fresh and curing slab can take while the pour moves across it — so the deck is never overloaded during the one operation it is weakest. Consolidation, screeding and the finish follow the spec: a hard-trowel finish for interior commercial floors, a broom or tined texture for parkade and ramp decks where traction matters.

Two things decide how an elevated slab performs long after the pour: flatness and curing. We finish to the flatness the use requires — tighter where floor coverings or equipment demand it — and control joints and pour strips go where the engineer locates them so shrinkage and movement happen where they are meant to. Curing is protected so the slab reaches strength without plastic or surface cracking, which matters most on thin, heavily reinforced decks. Where a slab finish is meant to be seen, it carries over into our exposed concrete finishes work.

Parkades, podiums and commercial floors

Most of the suspended-slab work on the North Shore and across Metro Vancouver falls into a few types, and each has its own demands:

• Parkade and parking-structure decks — suspended slabs and ramps over occupied or below-grade space, formed to drain, textured for traction, and detailed with the cover and crack control a trafficked deck needs. Where a deck receives a traffic-bearing membrane or waterproofing, that is installed by the appropriate waterproofing trade; our scope is the structural concrete it sits on — the forming, reinforcement placement, placing and finishing, and any structural concrete repair.
• Podium slabs — the transfer deck between a concrete base and the structure above, often thick and heavily reinforced or post-tensioned, where shoring and reshoring loads are at their highest.
• Suspended commercial floors — elevated floors in commercial and mixed-use buildings, finished flat and hard for their intended loading and use.

We serve this work on the North Vancouver and West Vancouver North Shore and out across the Lower Mainland, where commercial concrete naturally serves the wider region.

Schedule, safety and working to the engineer

On a commercial job the structure sets the critical path — the trades above cannot start until the deck is poured, cured and stripped — so an elevated-slab contractor is judged on holding the pour dates and keeping the cycle predictable from floor to floor. We plan forming, reinforcement, pour and stripping as a repeatable cycle and keep the shoring and reshoring plan moving with it.

Safety on suspended work is not separate from quality: the shoring that keeps a crew safe under a green deck is the same shoring that keeps the slab on elevation. We build and inspect falsework and shoring to carry the real loads, maintain edge protection and penetration covers, and strip only when the concrete has the strength to stand on its own. Throughout, we build to the engineer of record's drawings and defer the structural calls — mix design, reinforcement, stripping strength, shoring loads — to the people who stamp them. If you want to understand how we think about a structure before a drawing exists, our structural check is a starting point; for a defined scope, bring us the drawings and we will build to them.

Frequently asked questions

Do you build the formwork and shoring, or just place the concrete?

We self-perform the cast-in-place scope — building and setting the formwork, erecting the shoring and reshoring, coordinating and placing the reinforcement and embeds, and placing and finishing the slab. The formwork and shoring are engineered for the actual loads, and we build to the structural drawings and any falsework or shoring design provided for the project.

How do you handle reshoring on a multi-level structure?

On a multi-storey pour the slabs below are still gaining strength, so we don't simply strip and move up. Props are removed and reset in a planned reshoring or backshoring sequence that shares the construction load across several floors until the lower slabs can carry themselves. The sequence is coordinated with the engineer so no green slab is overloaded.

Can you work to post-tensioned slab designs?

Yes. On a post-tensioned deck we build to the PT designer's tendon layout and coordinate the placing and stressing trade, and we plan the forming, shoring and reshoring around the stressing sequence — the deck isn't fully loaded or stripped until stressing is complete. The PT engineer's design governs; we build the structure that carries it.

Do you install the waterproofing or traffic membrane on a parkade deck?

No — that is installed by the appropriate waterproofing trade, and we coordinate our schedule with it. Twin Peaks' scope is the structural concrete: forming the deck to drain, placing the reinforcement and embeds, placing and finishing the slab to the right texture and flatness, and any structural concrete repair. We keep our work to concrete and structure.

What size of projects and what areas do you take on?

We take on commercial and structural cast-in-place work — parkade and podium decks, suspended commercial floors, foundations, walls and columns — across the North Shore (North and West Vancouver) and the wider Metro Vancouver and Lower Mainland region. The best way to scope a suspended-slab project is to send us the structural drawings. Call (778) 882-8001 to talk it through.