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FRP Grating Fixing Methods for Access Structures
Overview
This Tech Talk Tuesday session focuses on FRP grating fixing methods, with a practical comparison between two common approaches: direct fixing and clamp-based fixing. The webinar explains where each method is suitable, what designers need to consider during the design phase, and how fixing selection can affect installation, coating protection, removal access, dissimilar metals, stair tread safety and long term performance.
The session is framed around FRP grating, but many of the principles also apply to decking products and walking surfaces more broadly. Direct fixing uses screws or bolts to secure the grating directly to the support structure, while clamp-based fixing uses a top clip and underside component to clamp the grating to the structure without drilling into the support member.
Treadwell’s broader FRP grating range includes GratEX moulded FRP grating with bi directional strength and GridEX pultruded FRP grating with uni directional strength and higher point loading capability, so selecting the right fixing method is part of ensuring the complete access system performs as intended.
Key Benefits
Clear distinction between fixing methods
The webinar separates grating fixings into two practical categories: direct fix and clamp-based fix. This gives designers and installers a simple framework for deciding whether to screw or bolt through the support structure, or clamp to the support without drilling.
Lower cost option with direct fixing
Direct fixing generally uses fewer components, making it a lower cost method compared with clamp-based arrangements. It is often suitable where drilling into the support structure is acceptable, such as timber, FRP, aluminium, plastic profiles or selected light gauge steel structures.
Good compatibility with timber, FRP and non metallic supports
Direct fixing is commonly used where the support structure is timber, FRP, HDPE, wood plastic composite or similar non metallic material. In these cases, drilling or screwing into the structure is usually not a major concern.
Coating protection with clamp-based fixing
Clamp-based fixing is useful where drilling into a galvanised or coated steel structure would damage the protective coating. This can help preserve corrosion protection and avoid the need for coating repair after installation.
Better option for heavy gauge steel structures
Where the support structure is heavy gauge steel, direct drilling or self drilling screws may not be practical. Clamp-based fixing allows grating to be secured to open steel sections such as PFCs, UBs, UCs and angles without penetrating the member.
Improved removal access in selected situations
Some clamp-based fixings can be loosened from above, which can make future grating removal easier where underside access would require scaffolding, elevated work platforms, boats or other access measures.
Dissimilar metal isolation options
The webinar explains that stainless fixings are often preferred for durability and appearance, but they can create galvanic concerns when used with mild steel or galvanised structures. Treadwell’s J clip and H clip options can be supplied with custom nylon or poly insulators to isolate stainless components from the support structure.
Wide fixing accessory range
Treadwell’s fixing range includes top clips such as M clips, C clips, L clips, D clips, W clips, S clips and O clips, along with underside accessories such as J clips, H clips, G clips, U clips, B clips and T clips. This gives project teams multiple ways to match the fixing to the grating type, support structure and access requirement.
Design support through TreadSpec and resources
The session notes that fixing selections can be made through TreadSpec calculators and that accessory information is available through Treadwell’s resource centre. Treadwell also promotes its products as FRP solutions supported by practical calculations and data for the application.
Applications
FRP grating fixed to timber supports
Direct fixing is generally suitable where FRP grating is being installed on timber support structures. Screws are typically used, and there is usually no need for a clamp arrangement because drilling into timber is acceptable.
FRP grating fixed to FRP structures
Where the support structure is also FRP, grating can typically be screwed or bolted into place depending on the structural detail, vibration requirements and whether access below is available.
Light gauge steel and aluminium structures
Direct fixing may be suitable for light gauge steel using self drilling or self tapping screws, and for aluminium structures where screwing or bolting is acceptable for the project.
Galvanised or coated steel structures
Clamp-based fixings are recommended where drilling into the support would damage galvanising or protective coatings. This is especially relevant for access structures where long term corrosion protection must be maintained.
Open steel support sections
Clamp-based fixing is most suited to open sections such as PFCs, UBs, UCs and equal angles, where the underside clip can engage with a flange or leg of the support member. Designers should consider this early so the support structure gives the clamp somewhere to engage.
Closed sections requiring fixing preparation
Where RHS or SHS support structures are used, clamp-based fixing is more difficult unless provision is made during design. Options include welded tabs or cleats, or openings in the web that allow the clamp to pass through and engage with the underside of the top flange.
High vibration or uplift areas
The session notes that not all clips are suitable for high uplift or vibration conditions, such as wave action or grating installed on vibrating equipment like mills or rotating plant. Clip strength must be appropriate for the application.
Structures where underside access is limited
If bolts and nuts are used for direct fixing, access underneath is required for both installation and removal. Clamp-based arrangements may be more practical where future removal is expected and underside access would be difficult or costly.
Stair tread fixing with additional restraint
The webinar advises that clamp-based fixings are not generally recommended for stair treads unless the stair tread is mechanically restrained against longitudinal movement. Tabs, angles, inside channel arrangements or FRP ledger angle kits can be used to prevent a tread from sliding off if fixings loosen.
FRP stair tread kits with ledger angles
Treadwell can supply a full FRP tread kit, including FRP grating and FRP ledger angle with pre drilled holes. This allows the stair tread to be bolted to the stringer using fixings suitable for the stringer material, then screwed or bolted to the FRP ledger angle without creating corrosion issues in the ledger.
Dissimilar metal sensitive installations
Where stainless steel fixings are preferred but the support structure is mild steel or galvanised steel, isolated clamp systems help reduce galvanic corrosion risk. This is particularly useful where durability and appearance are priorities.
FRP grating replacement and maintenance access
Fixing selection also matters where grating may need to be removed for inspections, plant maintenance or access below the deck. The webinar highlights that designers should consider removal access, not just initial installation.
Key Moments
- 00:18 👋 Welcome to Tech Talk Tuesday on FRP grating fixings; final 2025 session with Q&A available.
- 01:09 📌 Today's focus: two main grating fixing methods—direct fix (bolt/screw) and clamp-based (clip)—plus suitability, pros/cons, and design tips.
- 02:04 🔧 Direct fix secures grating straight to supports via screws/bolts; cheaper with fewer parts but requires drilling and possible underside access for bolts.
- 03:54 🪵 Direct fix suits timber, FRP, steel, aluminum, and composites; use lock nuts or anti-vibration measures like rubber sheets/nylon washers for screws.
- 06:15 🛡️ Clamp fix uses top clips and underside clamps for no-drill installation; ideal for coated/galvanized steel to avoid damage but needs appropriate clip strength for vibration/uplift.
- 07:22 🚫 Clamp fixings not generally recommended for stair treads due to potential sliding if loosened; design tweaks like tabs or FRP ledger angles can enable safe use.
- 08:48 📏 Minimum 40mm bearing area (or product thickness) required for proper support with clamp fixings on open sections like channels or I-beams.
- 10:33 ⚙️ Clamp fixings suit heavy/coated steel structures; direct fix common for non-metallics; both may need underside access depending on type.
- 12:11 🔩 Dissimilar metals issues (e.g., stainless clamps on mild steel) resolved with nylon/poly insulators to prevent corrosion while maintaining durability and aesthetics.
- 14:03 📋 Various top clips (C, L, D, W, S, O) and underside clamps (J, H, G, U, B, T) available; some allow top-only installation for easier removal.
Why Treadwell?
Treadwell’s strength is that it treats FRP grating as a complete access system, not just a panel product. This session shows how fixing method, support structure type, coating protection, bearing area, underside access, dissimilar metals, vibration, uplift and stair tread restraint all affect the final installation.
The company offers both FRP grating systems and the accessory knowledge needed to install them correctly. Its FRP grating range includes GratEX moulded grating and GridEX pultruded grating, while its broader FRP product range is positioned for corrosion resistance, lightweight construction, anti slip safety and low maintenance performance across demanding industrial applications.
Treadwell also provides practical fixing options for real site conditions. Whether the project requires direct fixing into timber or FRP, clamp-based fixing to coated steel, insulated clips for dissimilar metal isolation, top inserted T clips, heavier duty H clips, or FRP stair tread kits with ledger angles, Treadwell can help match the fixing system to the structure and application.
For designers, contractors and asset owners, the value is in reducing avoidable installation issues before they occur. By reviewing the support structure, fixing access, future removal needs, bearing area and corrosion concerns during design, Treadwell helps ensure FRP grating systems are safer, more durable and easier to maintain over the life of the asset.
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*Disclaimer
The information on this page is derived from webinar content and AI-assisted transcription and summarisation. While every effort has been made to ensure accuracy, minor inaccuracies may occur. We recommend viewing the original webinar recording for context.
