Steel checker plate (also called diamond plate, tread plate or floor plate) is steel plate rolled with a raised pattern on one face for grip, used for stair treads, landings, platforms, ramps and covers. In North America it is commonly supplied to ASTM A786, which covers floor plate up to 1 in (25 mm) thick. Typical sheets are 4 x 8 ft, 4 x 10 ft and 5 x 10 ft, in thicknesses commonly from about 1/8 in to 1/2 in. Price depends on thickness, sheet size and how much cutting, bending and welding the part needs, so this guide covers what to know before you order and how to get an accurate quote.
What checker plate is
Floor plate is hot-rolled with raised figures at regular intervals on one surface. The pattern gives a better footing than smooth plate and hides scuffs and wear. ASTM A786, "Standard Specification for Hot-Rolled Carbon, Low-Alloy, High-Strength Low-Alloy, and Alloy Steel Floor Plates", covers floor plate for flooring, stairways, transportation equipment and general structural purposes.
The names overlap:
- Checker plate is a common term in Canada.
- Diamond plate describes the most familiar pattern.
- Tread plate describes how it is used.
- Floor plate is the term used in steel specifications.
The same pattern is also made in aluminum and stainless steel. Aluminum tread plate is lighter and doesn't rust, which suits truck boxes and trailers, but it is a different material and much less stiff than steel, so it can't simply replace steel plate of the same thickness. This guide is about carbon steel checker plate for construction.
Sizes and thicknesses
Checker plate is sold by sheet or plate size and thickness. In Canada and the US it is generally stocked in imperial sizes.
Common sheet sizes:
| Sheet size (ft) | Metric equivalent (approx.) |
|---|---|
| 4 x 8 | 1,219 x 2,438 mm |
| 4 x 10 | 1,219 x 3,048 mm |
| 5 x 10 | 1,524 x 3,048 mm |
Larger sheets are available from some suppliers. One large North American distributor lists A786 floor plate in widths from 48 to 96 in and lengths from 96 to 240 in.
Common thicknesses run from about 1/8 in to 1/2 in, with thinner gauges for light-duty use and heavier plate up to 1 in for demanding floors and covers. Under ASTM A786, the maximum thickness is 1 in (25 mm).
| Nominal thickness (in) | Approximate metric equivalent |
|---|---|
| 1/8 | 3.2 mm |
| 3/16 | 4.8 mm |
| 1/4 | 6.4 mm |
| 5/16 | 7.9 mm |
| 3/8 | 9.5 mm |
| 1/2 | 12.7 mm |
About "10 mm checker plate." Metric drawings often call for 6 mm, 8 mm or 10 mm checker plate. Because plate is widely stocked in imperial thicknesses, 10 mm is often supplied as 3/8 in (9.5 mm), and 6 mm as 1/4 in (6.4 mm). The difference is small, but it is a design change, so the designer should accept the substitution, especially where the plate spans between supports.
When you compare quotes, confirm that both suppliers mean the same thing by thickness. The raised pattern adds height and weight above the plate itself, so ask how the supplier states it.
Where checker plate is used
- Stair treads and landings on utility, industrial and service stairs, often with a bent nosing
- Platforms and walkways around equipment and on mezzanines
- Trench, pit and sump covers, frequently with a lifting slot or handle
- Ramps for loading areas and equipment access
- Floor patches over openings in existing floors
- Truck decks, trailer floors and toolbox lids
- Kick plates and wall protection where carts and pallets bang into walls
On stairs, checker plate is common indoors. Outdoors it holds water, slush and ice, so steel bar grating is usually the better tread. See exterior steel stairs for outdoor tread choices.
Checker plate vs grating for floors
| Checker plate | Steel bar grating | |
|---|---|---|
| Surface | Closed; nothing falls through | Open; light, air, water and debris pass through |
| Grip | Good when dry; can be slippery wet, icy or oily | Good; serrated bars improve it |
| Small items and tools | Can't drop through | Small objects can fall through |
| Weight for the span | Heavier, and thin plate needs close support | Strong for its weight; spans further between supports |
| Cleaning | Easy to sweep and wash | Harder to clean |
| Best for | Indoor platforms, covers, treads where nothing should fall through | Outdoor stairs and platforms, plant floors, wet or dirty areas |
Some platforms use both: grating for most of the floor and checker plate where people work under the platform or where tools could fall.
Fabricating checker plate parts
Checker plate is cut, bent, drilled and welded like other plate, with a few differences:
- Cutting. Shearing, plasma, laser or torch cutting all work. Small, accurate parts with holes are best on plasma or laser. Our guide to steel plate cut to size in Ontario compares cutting methods.
- Bending. Treads and nosings are bent on a press brake. The drawing should show which face the pattern is on, because that sets the bend direction.
- Stiffeners. Thin plate deflects and drums underfoot. Covers and platforms often have angle or flat bar stiffeners welded underneath, or a frame around the edge.
- Drainage. Outdoor plate needs drain holes or a slope so water doesn't pool.
- Pattern direction. On visible work, the pattern direction is usually kept consistent across adjacent pieces.
- Finish. Steel checker plate rusts if left bare. Prime and paint for interior use, and hot-dip galvanize for exterior and wet locations.
Safety and code points
Checker plate is often chosen for grip, but the codes ask for a slip-resistant result, not a particular product:
- The 2024 Ontario Building Code requires treads, landings and ramps to have a wear-resistant, slip-resistant finish that is smooth, even and free of open defects. Outside dwelling units, stair treads and landings must have a slip-resistant finish or slip-resistant strips.
- Many stairs outside dwelling units also need a colour contrast or distinctive pattern at the leading edge of treads and landings, which bare checker plate doesn't provide on its own. A painted or contrasting nosing solves it.
- In workplaces, Ontario's Industrial Establishments regulation (Reg. 851) requires floors and other surfaces used by workers to be kept free of hazards and accumulations of snow or ice, and a cover on an opening in a floor, roof or other surface must be secured in place and built to meet the Building Code's structural requirements for floor and roof loads.
That last point matters: a checker plate cover is a structural element. Its thickness, stiffeners and supports should be designed for the loads it will see, including carts and forklifts where they can drive over it. Have your engineer or designer size it.
What drives the cost of checker plate
Plate is priced largely by weight, and checker plate also depends on how much work goes into each piece. The main drivers:
- Thickness and sheet size, which set the weight of steel
- Grade and specification, if the drawings call for something specific
- Nesting and drops: how efficiently your parts fit on standard sheets
- Cutting, bending and holes for each part
- Stiffeners, frames and handles welded on
- Finish: primer, paint or galvanizing
- Quantity, and whether parts repeat
- Delivery
Steel prices also move with the market, so quotes are usually valid for a limited time. For more on how plate quotes are put together, read steel plate prices in Canada.
What to send for a checker plate quote
- A drawing or sketch of each part with dimensions, thickness and pattern face
- Quantity of each part
- Holes, slots, bends and any stiffeners
- What the plate is for (tread, cover, platform) and what loads it carries
- Finish
- Delivery address
Checker plate parts from Procut
We cut, drill and fabricate steel plate parts to your details, and we build stairs, platforms and other miscellaneous steel in our shop in Erin, with CWB certified welding and shop drawings prepared in house. We deliver across the GTA and Ontario. Ask us about checker plate supply and fabrication for your job, whether it is treads for a stair, covers for a trench or decking for a platform.
Send your drawings or part list for a quote, or see our steel products.
Frequently asked questions
Is checker plate the same as diamond plate?
Yes. Checker plate, diamond plate, tread plate and floor plate are names for the same product: steel plate or sheet rolled with a raised pattern on one face for grip. In North America, steel floor plate is commonly supplied to ASTM A786.
What sizes does steel checker plate come in?
Common sheet sizes are 4 x 8 ft, 4 x 10 ft and 5 x 10 ft, and common thicknesses run from about 1/8 in to 1/2 in. Larger sheets and thicker plate are available from some suppliers, and ASTM A786 covers floor plate up to 1 in (25 mm) thick.
Can I get 10 mm checker plate in Canada?
Steel plate is widely sold in imperial thicknesses, so a drawing calling for 10 mm checker plate is often supplied as 3/8 in (9.5 mm) plate. That is a small change, but it is still a change to the design, so have the designer accept it.
Is checker plate slippery when wet?
The raised pattern helps, but smooth steel between the lugs can still be slippery with water, ice, oil or mud. For exterior and wet locations, open grating, abrasive coatings or slip-resistant strips are often a better choice.
