Substructure
Class A2-s1,d0 Rail System
Substructure for non-combustible decking and tiling systems
> See our Knightsbridge case study hereKey Advantages
- Full Metal Substructure, made from galvanised steel
- Class A2-s1,d0 non-combustible material (EN 13501-1:2018)
- Complies to BS EN ISO 1716:2018
- Physically tested in accordance with procedure specified in BS EN 13823:2020
- Profiled Aluminium Joist clicks securely onto MetalPad
- Secure connection without mechanical fixings
- Suitable decking and paving solutions
- Very high weight tolerance
- Zero corrosion
- Creates lateral stability across deck by reducing movement
- Adjustable height with maximum flexibility
- Fully compliant with draft BS 8579

Paving / Tiling Applications
Specially profiled aluminium rails 20mm, 25mm or 50mm click onto headpiece without need for screws, drills or mechanical fixings for secure connection.
Powder coated headpiece prevents any reaction between steel and aluminium.
- Integrated Class A2-s1,d0 Rail system for installing porcelain tiles and ceramic planks
- Specially profiled bearer rails / joists click onto headpiece of Metalpad
- Designed to give greater support to slabs and tiles and additional lateral strength across the deck
- Faster installation of suspended paving and tiling projects
- Secure connection into spring loaded headpiece fittings; no screws, no drilling on site
- Large baseplates distribute weight efficiently reducing point loading
- Greater spans between pedestals possible
- Joist helps “tie together” pedestals, giving more lateral strength across the decking surface
- Large height range using three different sized joists
- Powder coated headpiece prevents reaction between steel and aluminium joist
- Additional headpiece clicks onto joist to hold slab / tile in place
- Clip head has four lugs for full support and uniform spacing of tile
- Clip head slides along Rail for accurate measurement and total support
- Fast, safe, secure construction of substructure

Decking Applications
- Fully integrated substructure system for installing Class A2-s1,d0 decking
- Specially profiled bearer rails / joists click onto headpiece of Metalpad
- Secure connection into spring loaded headpiece fittings; no screws, no drilling on site
- Large height range using three different sized joists
- Greater spans between pedestals possible
- Large baseplates distribute weight efficiently reducing point loading
- Powder coated headpiece prevents reaction between steel and aluminium joist
- Joist helps “tie together” pedestals, giving more lateral strength across the decking surface
- Class A2-s1,d0 decking surface fixed to joist
- Fast, safe, secure construction of substructure

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.

Double Box Rail
Wallbarn’s Box Rail is made from premium-grade 6063 T6 extruded aluminium. These rails were designed by Wallbarn and manufactured right here in the United Kingdom.
They seamlessly cater to both paving and decking applications, creating the perfect Class A non-combustible substructure system.
They are particularly useful for retro-fit projects for the common rip-and-replace schemes currently being undertaken to remove combustible materials from occupied flats.
A variety of connections and fixings are available to create sturdy grid frameworks.
They are designed with a ledged profile to slide between lugs on the MetalPad D or MetalPad EX adjustable height pedestals.
With years of successful implementation on numerous large-scale commercial and residential projects across the UK, the Box Rail has proven its reliability and strength.
It has now become a standard choice for Class A decking and raft systems due to its lightweight and easy installation properties.
Key Highlights:
- Crafted and engineered in the UK.
- Class A – non-combustible bearer.
- Ideal for both decking and paving projects.
- Provides robust support for decking or paving, especially at low height thresholds, and enhances lateral strength across the deck.
- Customised ledge profile ensures seamless connection to MetalPad D pedestals.
The three designs / heights were developed to adapt to low height threshold projects or larger height areas where larger spans between pedestals is possible.
When employed for paving systems, our substructure can attain a minimal height of 49mm (Paving Rail System).
For decking applications, we achieve a starting point of just 46mm for the substructure.
If you have any questions, get in touch.

I-Plus Beam
Wallbarn’s I-Plus Beam is an advanced aluminium rail/joist that establishes a new benchmark in substructure systems.
With exceptional strength enabling the handling of long spans, it is particularly well-suited for retro-fit projects which require Class A non-combustible substructures.
Post Grenfell rip-and-replace schemes require Class A materials throughout and I-Plus Beams help create strong, compliant and easy to fit solutions.
They are designed with a ledged profile on the underside to slide between lugs on the MetalPad D adjustable height pedestals, creating a seamless, integrated and comprehensive substructure system.
The I-Plus Beam is available in three heights: 50mm, 75mm and 100mm.
This means the often unknown height thresholds which appear only after the original deck has been lifted can be accommodated easily by matching the right beam to the right pedestal in any given area.
Designed and proudly crafted in the UK, the I-Plus Beam is an ideal solution for both decking and paving projects.
For scenarios necessitating end-to-end connections or perpendicular layouts, we provide tailor-made brackets and fixings. See our Connections page.
I-Plus Beams offer added flexibility and adaptability in your substructure design. With Wallbarn’s I- Plus Beam, you can confidently rely on a resilient, dependable, and top-tier solution for your construction requirements.
If you have any questions, get in touch.

Connections
There are two choices available for connecting I-Plus beams, offering installation convenience. The first approach involves utilizing self-tapping screws for robust mechanical fixing. Both straight and right-angle fixing brackets are equipped with two counter-sunk holes, allowing for easy attachment using the self-tapping screw.
The alternative fixing method involves employing a wing nut and an M8 bolt for manual securing. For this method, the bolt head is inserted into the side or bottom profile of the I-Plus beam, and the wing nut is placed around the bracket manually. This method’s advantage lies in its initial loose framework securing, allowing for flexible realignment to achieve precise positioning. Once the desired alignment is achieved, tightening the wing nuts ensures a secure substructure. This method guarantees a solid and well- aligned construction.
If you have any questions, get in touch.
NBS Source
- Class A Substructure for Non-Combustible Decking Systems
- Class A Substructure for Non-Combustible Paving Systems
- Class A1 Fire Rated Pedestal
- Class A2 Fire Rated Decking Pedestal
BIM Library
CAD Drawings
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25mm Ledged Rail
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50mm Ledged Rail
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Class A2-s1, d0 Pedestal for Decking 25-32mm
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Class A2-s1, d0 Pedestal for Decking 32-39mm
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Class A2-s1, d0 Pedestal for Decking 39-46mm
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Class A2-s1, d0 Pedestal for Decking 46-53mm
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Class A2-s1, d0 Pedestal for Decking 53-70mm
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Class A2-s1, d0 Pedestal for Decking 70-100mm
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Class A2-s1, d0 Pedestal for Decking 100-140mm
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Class A2-s1, d0 Pedestal for Decking 140-220mm
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Class A2-s1, d0 Pedestal for Decking 220-300mm
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 | 50cm | 60cm | 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 |