How thick should a concrete garage floor slab be in Dieppe for supporting heavy equipment?

For a garage floor slab in Dieppe that will support heavy equipment — vehicle hoists, large compressors, heavy machinery, loaded tool chests, or heavy vehicles like trucks and RVs — you need a minimum slab thickness of 5 to 6 inches with reinforcement, compared to the standard 4-inch residential slab. For point loads from vehicle hoists or equipment with concentrated leg loads, you may also need thickened pads at the load points, potentially 8 to 12 inches thick with additional rebar.

The standard 4-inch residential garage slab is designed for light-duty use — parking passenger vehicles, storing household items, and supporting foot traffic. It is poured with 25 MPa concrete (standard residential mix) and reinforced with either 6x6 W2.9xW2.9 welded wire mesh or fibre reinforcement. This standard slab can safely support distributed loads of approximately 250 to 300 pounds per square foot, which is adequate for cars and light trucks but insufficient for concentrated loads from hoists, heavy equipment legs, or fully loaded industrial shelving.

For a heavy-duty garage slab in Dieppe, the specifications should include several upgrades over the standard residential pour. The concrete thickness should increase to 5 inches minimum across the entire slab, with 6 inches preferred for shops and equipment garages. The concrete mix should be upgraded to 30 to 35 MPa for higher compressive strength. The reinforcement should shift from wire mesh to 10M or 15M rebar on 12-inch centres both ways, placed on chairs to position the steel in the lower third of the slab where it is most effective at resisting flexural cracking. For a two-car garage (24x24), upgrading from a standard 4-inch slab to a 6-inch reinforced slab adds approximately 2 to 3 additional cubic metres of concrete, at a cost premium of roughly $1,500 to $3,000 for the extra concrete, rebar, and labour.

Vehicle hoists require special attention. A two-post vehicle hoist distributes its load through two base plates, each typically 12x12 inches, with each plate carrying approximately 4,000 to 5,000 pounds when lifting a vehicle. That is a concentrated load of roughly 280 to 350 psi on those two small areas — far more than a standard 4-inch slab can handle without cracking. Hoist manufacturers typically require a minimum 6-inch slab with rebar reinforcement at the anchor points, and many recommend thickened pads of 8 to 12 inches beneath each hoist column. These thickened pads should be designed into the slab before pouring — they are formed by excavating deeper at the hoist locations and filling with reinforced concrete. Retrofitting hoist pads into an existing slab requires saw-cutting, removing the existing concrete at those locations, excavating, and pouring new thickened sections — feasible but more expensive and less ideal than building them in from the start.

The sub-base preparation matters as much as the slab thickness for heavy-duty applications. In Dieppe, which shares the Greater Moncton area's typical clay and silt soil conditions, the sub-base should be 8 to 12 inches of compacted granular fill (3/4-inch crusher run or pit run gravel) compacted to 95 percent Standard Proctor density. This compacted base distributes the point loads from the slab over a wider area of subsoil, preventing differential settlement that would crack even a well-reinforced thick slab. A 6-mil polyethylene vapour barrier goes on top of the compacted stone, beneath the concrete, to prevent moisture migration.

Control joints in a heavy-duty slab should be cut or tooled at 8-to-10-foot intervals in both directions to control where cracking occurs as the concrete cures and undergoes thermal cycling through NB's seasons. Joints should be cut to a depth of one-quarter of the slab thickness — so 1.5 inches deep on a 6-inch slab. Place control joints strategically so they do not fall directly beneath hoist base plates or equipment legs, as cracks at joints can widen over time and compromise anchor bolt connections.

If you plan to apply a floor coating — epoxy or polyaspartic — to a heavy-duty slab, discuss this with your concrete contractor before the pour. A broom finish provides the best mechanical bond for coatings, while a hard-trowelled burnished finish (common in residential garages) actually repels coatings and makes adhesion difficult. For a workshop or equipment garage, a broom finish with a polyaspartic coating applied after 28 days of curing gives you the best combination of durability, chemical resistance, and easy cleaning. Total cost for a heavy-duty 6-inch slab with rebar reinforcement, proper sub-base, and a polyaspartic coating in a 24x24 garage in Dieppe runs approximately $8,000 to $14,000.

Designing a heavy-duty garage slab is a job for an experienced concrete contractor who understands load requirements and NB soil conditions. Browse garage and general contractors in the New Brunswick Construction Network directory at newbrunswickconstructionnetwork.com to find professionals in the Dieppe area.