Substructure
Class A1 Rail Substructure System
Single beam substructure for non-combustible decking and tiling systems
Key Advantages
- Class A 1 rated (EN 13501-1:2018), fully compliant with BS 8579
- Full metal substructure, zero plastic and zero rubber “gaskets”
- Specially profiled bearer rails / joists click onto Metalpad & MetalPad EX pedestals
- Fast, easy, seamless connection
- Self-levelling option available
- Greater spans between pedestals possible
- Massive height range, multiple rail build up possible
- All fixings and connectors provided
- Weight bearing and extremely stable
- Spreader plate available for larger weight distribution
- No rotting, warping or rusting
- Environmentally friendly, manufactured from recycled aluminium and fully recyclable

Paving / Tiling Applications
- Integrated Class A1 for porcelain tiles and paving slabs
- Special paving lug headpiece fixed to rail with screw
- Headpiece can be fitted anywhere along the rail for perfect alignment of tiles
- Single beam bearer rails mechanically fixed to Metalpad EX pedestals
- Designed to give greater support to slabs and tiles and additional lateral strength across the deck
- Faster installation of suspended paving and tiling projects
- Weight bearing joists mean very large spans between pedestals possible
- Joist “ties together” pedestals, fitted together quickly and easily using clips and fixings
- Massive height range achievable, multiple joists can be fixed together
- Lugs on paving headpiece easily removed with pliers for junctions, stretcher bond etc.
- Starter / end clip fitted to rail to secure tiles at perimeter
- Ensures adequate drainage gap between tiles and wall

Decking Applications
- Fully integrated substructure system for installing Class A1 decking
- Single beam bearer rails mechanically fixed to Metalpad EX pedestals
- Fixings fitted to top of joist
- Designed to give greater support to decking and additional lateral strength across the deck
- Faster installation of suspended decking projects
- Weight bearing joists mean very large spans between pedestals possible
- Joist “ties together” pedestals, fitted together quickly and easily using clips and fixings
- Massive height range achievable, multiple joists can be fixed together
- Fast, safe, secure construction of substructure

The Rail / Joist
These rails are single beams with exceptional strength. They come in a number of different heights / sizes and multiple pieces can be connected to form strong platforms across the whole deck, which will support extremely heavy loads and pedestrian traffic in Class A paving or decking installations.
20mm Joist
Used where low buildup is required.
Where strength is required but height threshold spacing is critical, the 20mm joist can be installed at right angles to a larger rail to create a racking joist framework. This racking joist system allows for rapid installation and modification.
Not suitable for large unsupported spans.
30mm Joist
Also used for low buildup areas. Special underside box junction designed to hold bolt to fix directly to MetalPad EX pedestals.
70mm Joist
Used extensively for paving and decking areas supported by pedestals. Designed for unsupported spans of up to 1 metre.
Special right angled side cleats slide into the slots within the sides of the beam to connect perpendicular joists for construction of framework.
120mm Joist
Used extensively for paving and decking projects using support pedestals.
Huge unsupported spans of up to 1,700mm are possible. Extremely heavy duty beam with reduced deflection.
Ideal for ultra-high build-ups as rails can be cross fixed to increase height by 120mm per row; creating extremely high weight tolerance and lateral stability.

Self-Levelling Headpiece
Special Self-Levelling / slope corrector headpieces are available for MetalPad EX range which connects securely onto the headpiece and gives a slope correction up to 5° in all directions.
The lugged headpiece holds the tiles / slabs securely in place and finds its own natural position to create a flat upper surface.
If the headpiece is inverted the lugs can wrap around a number of the aluminium rails available from Wallbarn.
There are no non-metallic elements on this Slope Corrector so it complies with a Class A1 fire rating.

Spreader Plate
The standard baseplate for MetalPad EX is 100mm diameter which is sufficient for applications onto hard sub-surfaces such as concrete. However, if users need to mount pedestals directly onto softer surfaces such as insulation or waterproof membranes then an additional spreader plate can be used.
The pedestal will slide into the slots on the top side of the spreader plate and lock into place. The spreader plate is 175mm diameter with a smooth underside to diffuse and distribute the weight effectively.

Fixings & Connectors
It is possible to install different rail heights together on the same project; and to support both paving and decking surfaces on the same substructure frame.
The special Class A MetalPad – EX Starter Fixing Clip is used to fix rails quickly and easily to both the pedestals and to themselves, where multiple levels of rail / perpendicular frameworks are required.
CONNECTING BRACKETS
A number of straight, right angled and 45° angled brackets and connectors are available for easy and fast fitting to all rails where cross brace frameworks are required.
Straight brackets in three different sizes are used to connect both rail designs together on long runs to increase strength and stability. Long sections of rail can be created with full structural integrity.
The right angled brackets are screwed into joists set out in a cross bracing formation. Noggins (short lengths) perpendicular to the main joist create a solid framework. These brackets are particularly useful for ultra-low height thresholds.
The 45° angled brackets connect the 70mm and 120mm single beams to cross joists or concrete floors securely and easily. The significantly speed up framework construction.
FIXINGS FOR PAVING
PAVING LUG HEADPIECE
The paving lug headpiece is screw fixed into the slotted groove on rail to hold the tile in place. The lugs create uniform spacing between tiles on the plate and are undercut to ensure a tight fit. This is a loose laid system; the weight of the tiles or slabs brings stability.
PAVING STARTER / END PLATE
The starter / end plate is ideal for end of runs and to ensure consistent gaps around the perimeter. It is secured onto the rail via a screw fixing. The optional peg acts as a lug / pacer where 2 tiles are laid onto the plate.
FIXINGS FOR DECKING
The 4 Hooks hidden clips provide a full Class A non-combustible fixing system for decking. Secured with screws to the rail they are shaped to hold a decking board with the standard side milling profile.
The burnished steel option means no glaring silvery colours appear from beneath between the deckboards.
A new hidden fixing is currently in development to hold a variety of deckboards with a single screw fixing.

Fire Regulations
Our Class A2-s1, d0 rail system meets fire testing standard BS EN ISO 1716:2018
Certified Class A2-s1, d0 (Warrington Fire) – Powder Coating | Steel
They are classified in Class A (‘No contribution to fire’) in
Decision 94/611 /EC
This product has been developed to ensure compliance with:
- Draft BS 8579
- Amendment to Approved Document B May 2020
- Approved Document B 2019
- Advice Note on Balconies in Residential Buildings published by Department of Housing, Communities & Local Government (MHCLG) issued on 24 June 2019
- Regulation 38 of the Fire Safety Building Regulations published by the Government
For further information or to discuss a project, speak to a member of our technical team. Call us on 020 8916 2222 or send us a message here.
NBS Source
- Class A Substructure for Non-Combustible Decking Systems
- Class A Substructure for Non-Combustible Paving Systems
- Class A1 Fire Rated Pedestal
BIM Library
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Class A Rail Substructure System for Non-Combustible Decking Systems
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Class A Rail Substructure for Non-combustible Paving Systems
CAD Drawings
Material | Aluminium 6063T6 | EN 755-9 | ||
To Use With Pedestal | Click Head Pedestal Range | |||
Fixing Detail | Click function - zero mechanical fixings | |||
Fire Classification | Class A2-s1,d0 | BS EN 13501-1 2018 | ||
European Commission Decision 96-603-EC | ||||
B ROOF T4 | ||||
Approved Document B, Regulation 7 (2) | ||||
Balcony construction suitability | > 11m | BS 8579 | ||
Weight tolerance per m² | 600kg | |||
Height of rail / bearer | 20mm | 25mm | 50mm | |
Maximum span between pedestals | 60 x 60cm | 60 x 60cm | 60 x 120cm | based on 600kg per m2 weight |
Weight per lin mtr | 0.988kg | 1.998kg | ||
Exterior circumference | 184.96mm | 234.97mm | ||
Interior circumference | 175.30mm | 261.32mm | ||
Thickness of walls / floor | 2mm | 2mm | 3mm | |
Outer height | 20mm | 25mm | 50mm | |
Inner height | 16mm | 21mm | 46mm | |
Outer width | 60mm | 60mm | 60mm |