Steel Grating: A technical guide to our most popular access product

Steel grating is used for many different applications and is part of our range of safe and sustainable access products. Grated access flooring can be made from other materials, such as GRP and aluminium, but steel remains the industry leading material choice, primarily due to its sustainability, durability, and versatility.

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We’ll explore in detail our most popular steel grating products, Safegrid and Safegrid Treads, their uses, and how they can improve safety and accessibility for your project. This guide explains everything you need to know about steel grating products so you can decide which is the right one for your project requirements. 

What Is Ball Proof Compliance?

Steel flooring for working walkways and platforms must comply with the British Standards (BS) for ball proofing. These regulations are mandatory for all overhead steel flooring in the EU and the UK. The standards state that: “Floorings of working platforms or walkways shall only have such maximum openings that a ball with a diameter of 35mm cannot fall through. Floorings above a place where people are working, as opposed to the occasional passage, shall have such maximum openings that a ball with a diameter of 20mm cannot fall through.”

Depending on where  the steel grating is being installed, including the height of the grating, whether it will be walked on, and more, all determine the the ball proof requirements it must meet in order to be compliant. The smaller the pitch of the flooring (the gaps between the bars in the steel grating), the less risk there is of objects falling through and causing injury to anyone passing underneath. 

The different sizes of ball proof grating are:

• 20mm (20BP) – used for overhead walkways when the risk of falling objects is high. This size is also required for all grating used as fire escape stairs.
• 35mm (35BP) – more suitable for walkways where people occasionally pass underneath.
• Utility Grating – for below-head or ground-level walkways where nobody can pass underneath. The risk of falling objects is negligible.

Safegrid Steel Grating

Our Safegrid products offer the most efficient and sustainable steel grating access solution on the market; Utility grating is produced using the least amount of steel of any comparable product where ball proofing is not required. We have been manufacturing products in our Safegrid range for over 100 years, and they are the established industry standard for UK manufactured, high quality steel grate flooring. In fact, in many industries – the oil & gas industry in particular – our grating is synonymous; known simply as ‘Kennedy grating’. 

Our Safegrid products are:

• Sustainable
• Compliant
• High performance-to-weight ratio
• Recyclable

Why Choose Safegrid?

Safegrid offers strength and durability with its high performance-to-weight ratio. Its grated structure makes it exceptionally good at bearing heavy loads with maximum safety. It spreads the weight evenly across the entire grating span, utilising its multiple reinforced points. The steel grids we manufacture here at Lionweld are built to last using quality materials. Our Safegrid products are also corrosion-resistant, making them less susceptible to damage and general wear and tear over time. All of our products comply with British and European safety standards (BS-0:+A1:), ensuring the products you choose have been designed to the highest levels of safety.

Safegrid Grating Options

We recommend 3 variants of Safegrid, each of which complies with the above ball proof sizings:

• 20mm ball proof Safegrid – to be used where; a walkway is in constant use; traffic may pass regularly beneath; or where people work below a walkway. Compliant to BS – 0: + A1: (British) and BS EN ISO – 1: (European) Standards. 20mm ball proof flooring should also be used on fire escape stairs.
• 35mm ball proof Safegrid – to be used for walkways with infrequent use, occasional traffic passing below or no people are working beneath. Compliant to BS – 0: + A1: (British) and BS EN ISO – 1: (European) Standards
• Utility Safegrid Grating – To be used for walkways below head height where people cannot pass underneath. This range is non-ball proof, has the widest pitch and is the most sustainable steel grating available on the market as it uses the least amount of steel. 

Safegrid Treads

Our Safegrid Treads products are our access products designed for stairways. They do exactly as their name implies; they provide a safe walking surface for stairs. The Safegrid Tread is manufactured with integral end plates with drilled holes so they can be bolted to stair stringers. Our drilled hole positions have been standardised across our tread range, but alternative drillings are available on request.

The nosing bar is then attached along the full width of the leading edge of the tread and this is selected to suit the requirements of your project, considering slip resistance, visibility and loading Our standard nosing options include Liongrip, Durbar and Hi-Vis. 

Our Safegrid Treads products are:

• Compliant and safe
• Available with three different standard nosing options
• Available in 35mm or 20mm ball proof configuration
• Able to be bolted to stair stringers

Why Choose Safegrid Treads?

If you want a safe and compliant access solution that can consider have specific slip resistance, visibility, and loading capacity requirements then our Safegrid Treads products are the leading product. Available to comply with both 20mm and 35mm ball proofingwhich can change depending on where the stairs are located and the volume of traffic underneath. We manufacture all our Safegrid Treads to comply with the British and European standards (BS-0:+A1: and BS EN ISO – 1: respectively). 

Safegrid Treads Options

Made using our Safegrid steel flooring, each stair tread is built with integral end plates for bolting to stringers, alongside a nosing bar to the leading edge, our stair treads are supplied in standard widths, the flooring pitch will determine which is most suitable for a project. We are the only UK manufacturer of steel grating and steel stair treads, meaning that we have the capabilities in-house to produce custom Safegrid Treads for your project. View our Technical Data for more specifications.

Compliance with British Standards

These products are compliant with British Standard BS EN ISO -2: and BS-0 +A1 in relation to flooring and treads, but what does that actually mean and cover? The following covers the specific requirements of these standards for all steel grated flooring, and as such details how both Safegrid and Safegrid Treads should be used and the quality specifics they meet.

British Standards Considerations

When it comes to steel grated flooring, there are strict considerations that should be factored into any design to ensure the safety of those in the area at all times. 

Specifically, when it comes to walkways and platforms (the typical applications for steel grated flooring), how the space will be used needs to be taken into account, for example;

• Will tools, spare parts etc be carried across it?
• How quickly will people be passing across the space?
• The position of the walkway or platform?
• The likely load bearing requirements of the space?
•  How frequently and for how long will these structures be used for?
• The number of operators that will be using the space and tools they will require or be using?
• What (if any) obstacles may be in the space? Does this affect any of the above factors?
• Where does the walkway or platform lead to, is it a deadend?
• The condition of the surrounding walls (if any)
• The need for any unrestricted or restricted areas on the walkway or platform

British Standards: Access Gauges & Walkways

When it comes to specific measurements, the British standards access gauge for walkways sets out strict requirements for any space that requires a steel grated flooring walkway or platform. These standards are in place to ensure the safety of all involved or using the space at any time.

Walkway Head Height

The minimum head height for over working platforms and walkways is mm, unless exceptional circumstances are apparent. If there are any obstacles that are unavoidable, this may drop to a minimum of mm head height and should be fitted out with the relevant padding and warning signs required to warn all who use the space of the limited head height available.

Walkway Width

The minimum width of a walkway or platform should be no smaller than 800mm. This allows for safe passage through the area. Where a passageway or walkway is to be used by multiple operators simultaneously, this minimum width increases to mm to allow for the added usage. 

If there are extenuating circumstances such as a machine, or the walkway is only in use for a small number of hours for a limited number of days within a 30 day period, then the minimum width can be reduced to just 600mm.

Further reductions can be made, if the walkway or platform is over a shorter distance of less than mm, in this case, the minimum width can be dropped again to just 500mm wide. This minimum width also applies if, at floor level, there are obstructions such as pipes or electric works. Along with the reduced minimum width, in these circumstances, the maximum height can be reduced to just 200mm.

Walkway Stairs or Steps

Where the horizontal walkway is interrupted and the vertical height between two walkways or platforms cannot be closed by stairs, a single step can be installed as long as:

• the step is clearly visible through colour or guard railings to alert operators to its presence
• the height of the step is between 150mm and 300mm for safe usage avoiding trip hazards

British Standards: Hazards

When it comes to any flooring, there are strict requirements and safety measures to adhere to, to ensure all parties are safe at all times. 

There are an array of instances where a hazard could occur in relation to flooring, we will cover the most common here and specify the British Standards Regulations specific instructions for each one.

Trip Hazards

British Standards stipulate that the height difference between the 2 sections of flooring joined together should be no more than 4mm, or any gap between 2 sections should be no larger than 20mm.

Slip Hazards

Both enhanced slip resistance and ribbed walkways should be installed where needed, particularly on ramps with an angle pitch of between 10 & 20 degrees. The distances between these measures should be between 400 & 500mm. The height of any ribs in the flooring should be between 10 & 20mm.

Accumulation of liquids

All flooring should be designed in a way that ensures liquids that accumulate for any reason are able to safely drain away, preventing further hazards or injury from occurring. 

Falling objects

The British Standards Regulations state that where a risk assessment has identified a hazard  as a result of falling objects, is more significant than other hazards such as slipping, then the flooring should be a closed top flooring to eliminate this risk.

However, for grated flooring that is manufactured with gaps, other requirements apply:

• If the gaps are greater than 20mm then; either a toe plate at least 100mm in height should be installed OR the gap should be reduced
• If the gaps are greater than 20mm but less than 120mm, a toe plate of at least 100mm should be fitted. Where a 100mm high toe plate is not possible due to obstructions, this can be reduced to a minimum height of 50mm
• If the gap is greater than 120mm but less than 180mm, a toe plate and a handrail (or equivalent) structure with a height of between 900mm and mm should be installed.
• If the gap is greater than 180mm, whole body access is possible, in which case, a guard rail should be fitted to prevent access to the gap. 
• Where metal treads or landings are used for fire escapes, the gratings shall not allow passage of a 20mm diameter ball.

Falling through a floor

To avoid any falls through a floor, the British Standards clearly stipulate that any removable elements of the flooring should be secured with fastenings to prevent movement and it should be possible to inspect all fixings to detect any corrosion or hazardous loosening.

British Standards: Design & Construction

All walkway and platform products are designed in accordance with British Manufacturing standards. 

Calculating Load Bearing Weights

When looking specifically at the British Standards regulations for walkways and platforms, each of these should be designed with the load bearing requirements in mind. These regulations state that determining these requirements should take into account:

• the number of operators that will be working on each specific location
• the mass of any tools, spare parts and equipment needed at the location
• the strength of impact on the structure due to a drop of tools or machine parts 
• Any possible concentration of loads due to weight distribution of parts needed at the location
• Any weight due to environmental causes like water or snow, that can be deposited at the location

There are simple formulas used to calculate the load bearing weight requirements, these are:

• for evenly distributed loads across a structure, it would work out as 2kn/m2
• for concentrated loads applied to an unfavourable area, it would work out as 1.5kn per 200mm x 200mm space

When loaded with the design load, the deflection of the flooring shall not exceed 1/200th of the span.

When we work with a client, we take into account any deflection under the dynamic loading, any possible lateral movements of a platform, ensuring no loss of balance of the user of the platform or walkway. 

Where a platform or walkway has an area of load bearing space alongside an area of non-loaded space, any height differences should not exceed 4mm.

Safegrid & Safegrid Treads Compliance with British Standards

We detail all of the specifications on these products in our Data & Downloads section

Safegrid Technical Specifications

Safegrid Treads Technical Specifications

Sustainability

Lionweld Kennedy have recently obtained the world’s first Environmental Product Declaration (EPD) for steel grating!

As part of efforts to lead a better change within the industry and raise the standards as a leader, obtaining our EPD for our low-carbon, infinitely recyclable Safegrid products cements our commitment to our ESG plan and becoming a more sustainable business. Transparently displaying the environmental performance of our product throughout its entire lifespan allows customers to make a more sustainable choice when reviewing their supply chain. Securing an EPD for Safegrid allows Lionweld Kennedy to once again set the benchmark for steel manufacturing worldwide due to us being the first, and only, steel flooring manufacturer to receive an EPD!

If you would like to learn more about our EPD and the immense value it provides for our customers and the supply chain, click here.

Get Safegrid & Safegrid Treads Custom Made For Your Project

Metal Bar Grating is the workhorse of the industrial flooring market and has served industry for decades. Strong and durable with an exceptional strength-to-weight ratio, metal bar grating can be easily fabricated to nearly any configuration. The high percentage of open area makes bar grating nearly maintenance free and all products are fully recyclable.

Manufactured by assembling a series of equally spaced metal bars to connecting cross members, bar grating is available in three popular materials; mild carbon steel, series aluminum and 300 series stainless steels. Additionally, Interstate Gratings can produce gratings constructed with other specialty metal alloys. Get in touch with us to discuss your situation.

The load tables on the pages within this website provide load/deflection criteria for most common applications. These tables provide a concise reference allowing the specifying authority to select the appropriate bearing bar size and spacing for the intended application. Pedestrian loads are commonly analyzed with uniform and concentrated loads. For pedestrian comfort, deflection is typically limited to 1/4″. Heavy duty and vehicular load tables are presented for specific load conditions. Heavy duty load tables are presented with deflection limited to the lesser of 1/8″ or L/400. If your application is not addressed by the load tables found in this website, please contact Interstate Gratings. We will gladly discuss the merits of our diverse products and assist in selecting the product most appropriate for your application.

Steel grating is usually provided with bare steel (no finish), painted with one coat of IG ECOCOAT™ or other special paint finishes, or hot dip galvanized in accordance with ASTM A-123. Aluminum products are commonly supplied mill finish but they are also available with optional chemically cleaned or anodized finishes. Due to discoloration that occurs during welding and fabrication, Stainless Steel grating products typically require secondary cleaning.

IG ECOCLEAN™, abrasive blasting, and passivation provide a uniform and clean surface. All grating products can be provided with specialty finishes including enamel, epoxy paints or powder coating. When considering specialty finishes, consultation with the coating manufacturer is essential.

As manufactured, grating panels are provided with open ends. Optional trim banding, a metal flat bar welded to the open ends of the panel, provides additional transverse stiffness and a finished architectural appearance. Banding should be specified for all removable grating panels, the closed end of a banded panel providing additional worker safety during the removal and replacement process.

Gratings subject to vehicular loads should always be specified as banded. In these applications, the band bar helps reduce impact stresses by transferring loads to adjacent bearing bars and further resists deformation caused by repetitive traffic patterns on open end gratings.

Trench banding, where the band bar is elevated above the bottom of the bearing bars, is appropriate for drainage applications. The elevated band bar allows for efficient drainage and will not trap liquids between the band bar and the grating support.

Load banding, where each bearing bar is welded to the band bar, helps distribute load throughout the grating panel. See Banding Weld Standards for specific welding practices.

Aluminum Bar Grating is lightweight, corrosion resistant, non-sparking and has an unmatched strength-to-weight ratio. Manufactured from ASTM B221, or alloy, aluminum grating is available in four distinct products, type “ADT” Dovetail Pressure Locked , type “SG” Swaged Rectangular Bar, type “SGI” Swaged “I” Bar, and type “SGF” Swaged Flush-Top and. All four products are available with bearing bar spacing ranging from 19/16″ (1-3/16″) to 7/16″ on center and with cross bars at either 4″ or 2″ on center. Rectangular bar products are manufactured with standard plain or optional serrated walking surfaces and “I” bar products are manufactured with a standard skid-resistant striated walking surface. Aluminum products are typically shipped “mill finish” with no additional treatment. For architectural applications or highly corrosive environments, supplemental anodizing, chemical cleaning or powder coat finishes are available.

Type “ADT” Aluminum Dovetail Pressure Locked Grating

Type “ADT” aluminum gratings have deep rectangular cross bars and are manufactured by inserting pre-punched bearing bars and cross bars into an interlocking configuration and deforming the cross bars under intense hydraulic pressure. The deep cross bars on type “ADT” gratings make them popular for architectural applications such as sun shades and infill panels with the deeper cross bar serving as a distinct architectural accent. Click Here* for detailed product specification information.

Type “SG” Swaged Rectangular Aluminum Grating

Type “SG” rectangular bar provides clean, crisp lines and the cross bar is fully locked within the bearing bar, slightly below the top surface. Type 19-SG-4 aluminum grating is the industry recognized standard for industrial applications with nearly 80% open area. Type “SG” gratings are available in close mesh ADA conforming spacings 11-SG-4 and 7-SG-4 which are commonly used in public areas. When specifying type 11-SG-4 for ADA applications, 3/16″ thick bearing bars must be specified.

Type “SGI” Swaged “I-Bar” Aluminum Grating

Manufactured with highly efficient “I” shaped extruded bearing bars, type “SGI” aluminum grating carries the same load as 3/16” thick rectangular bar type “SG” aluminum grating, but weighs slightly less per square foot. Additionally, the striated top and bottom flanges of the “I” bar provide enhanced skid resistance without the cost of serration.

Type “SGF” Swaged Flush-Top Aluminum Grating

Manufactured with a unique, extruded cross bar that is flush with the top surface of the bearing bars after swaging, type “SGF” aluminum grating provides an enhanced walking surface for areas subject to continuous pedestrian traffic. Available in rectangular bar with plain or serrated surfaces, type “SGF” aluminum grating is also available in ADA conforming spacings for applications located in the public way.

Stainless Steel Bar Grating is manufactured from alloy types 304, 304L, 316 and 316L and available in grating types “WS” (welded stainless grating), “DTS” (dovetail stainless pressure locked) and “SLS” (swage locked stainless). Popular for highly corrosive environments and long-lasting architectural applications, stainless steel bar gratings are available with bearing bar spacing ranging from 19/16″ (1-3/16″) to 7/16″ on center and with cross bars at 4″ or 2″ on center. Each product is available with standard plain or optional serrated surface and finish options are diverse and should be closely considered.

Type “WS” Welded Stainless Steel Grating

Our strongest and most economical stainless product, type “WS” gratings are manufactured by forge welding rectangular bearing bars and drawn cross bars. This welding process provides a positive fused intersection providing years of service under the most demanding conditions.
Type “WS” stainless gratings are available in “19 space” (1-3/16″), “15 space” (15/16″) and “11 space” (11/16″) bearing bar centers. Standard cross bar spacing is 4″ on center and the optional 2″ cross  bar spacing is also available.  

Click Here* for detailed product specification information.

Anchor

 – A device by which grating is attached to its supports

Band

 – A flat bar welded to the end of a grating panel, or along the side of a cutout, and extending neither above nor below the bearing bars.

Load Carrying Band

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 – A band used to transfer load between bearing bars.

Trim Band

 – A band which carries no load, used primarily for appearance and closing open ends.

Bearing Bars

 – Load-carrying main elements made from steel, aluminum or stainless steel, extending in the direction of the grating span

Bearing Bar Centers

 – The distance center-to-center of the bearing bars.

Carriers

 – Flats or angles which are welded to the grating panel and nosing of a stair tread and are bolted to a stair stringer to support the tread.

Clear Opening

 – The distance between faces of bearing bars in rectangular gratings, or between a bent connecting bar and a bearing bar in a riveted grating.

Cross Bars

 – The connecting bars which extend across the bearing bars, usually perpendicular to them. The may be bent into a corrugated or sinuous pattern and, where they intersect the bearing bars, are welded, forged or mechanically locked to them.

Pressure-Locked Grating

-Pressure-locked means bearing bars are locked in position by cross bar deformation instead of riveting or welding. Several proven methods include:
•   Expansion of an extruded or drawn tubular   cross bar;
•   Extruded cross bar deformed or swaged between bearing bars;
•   Press assembly of rectangular cross bars into slotted bearing bars.

Radially Cut Grating

 – Rectangular grating which is cut into panels shaped as annular segments, for use in circular or annular areas.

Reticuline Bar

 – A sinuously bent connecting bar extending between two adjacent bearing bars, alternately contacting and being riveted to each.

Rivet Centers

 – The distance center-to-center of rivets along one bearing bar.

Riveted Grating

 – Grating composed of straight bearing bars and bent connecting bars, which are joined at their contact points, by riveting.

Serrated Grating

 – Grating which has the top surfaces of the bearing bars or cross bars, or both, notched.

Cross Bar Centers

 – The distance center-to-center of the cross bars.

Curved Cut

 – A cutout following a curved pattern.

Cutout

 – An area of grating removed to clear an obstruction or to permit pipes, ducts, columns, etc. to pass through the grating.

Electro-Forged

 – A process of combining hydraulic pressure and heat fusion to forge bearing bars and cross bars into a panel grid.

Finish

 – The coating, usually paint or galvanizing, which is applied to the grating.

Flush-Top Grating

 – A type of pressure-locked grating in which the cross bars and bearing bars are in the same plane relative to the top surface of the grating.

Grating

 – An open grid assembly of metal bars, in which the bearing bars, running in one direction, are spaced by rigid attachment to cross bars running perpendicular to them or by bent connecting bars extending between them.

Hinged Panel

 – Grating panels which are hinged to their supports or to other grating parts.

I-Bar

 – An extruded aluminum bearing bar having a cross section shape of the letter “I”.

Length

 – Refer to Span of Grating

Nosing

 – A special “L” section member serving as the front or leading edge of a stair tread, or of grating at the head of a stair.

Span of Grating

 – The distance between points of grating support, or the dimension of the bearing bars in this direction.

Straight Cut

 – That portion of the cut edge or cutout of a grating which follows a straight line.

Swaging

 – A method of altering the cross-section shape of a metal bar by pressure applied through dies.

Toe Plate

 – A flat bar attached against the outer edge of a grating or rear edge of a tread, and projecting above the top surface of the grating or tread to form a lip or curb.

Tread

 – A panel of grating having carriers and a nosing attached by welding, and designed specifically to serve as a stair tread.

Welded Grating

 – Grating in which the bearing bars and cross bars are joined at their intersections by either electro-forging or conventional hand welding.

Width

 – The overall dimension of a grating panel, measured perpendicular to the bearing bars, and in the same direction as the cross bars.

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