Fire-Rated Decking in the UK, London: What You Need to Know
Fire rated decking has become one of the most important considerations for balconies, roof terraces, communal terraces and raised decks in London.
Following changes to Building Regulations after Grenfell, combustible materials can no longer be used in certain external wall systems and balcony constructions on relevant buildings. This has changed how balconies and terraces are specified — particularly in London where high-rise residential buildings are common.
Decking is part of that external wall system and part of the balcony construction. On many projects it must therefore be non-combustible or limited combustibility.
This article explains what fire rated decking means in the UK, which fire classes matter, and which materials can be used on balconies and terraces in London.
What Is Fire Rated Decking?
Fire rated decking is decking that has been tested for reaction to fire and classified under the European classification system EN 13501-1.
Every material receives a Euroclass:
A1 — Non-combustible. Does not contribute to fire at any stage. Highest classification.
A2 — Limited combustibility. Very limited contribution to fire. Often shown as A2-s1,d0 or A2fl-s1.
B, C, D, E, F — Combustible. Contribution to fire increases as you move down the scale. Most timber and standard WPC composite decking falls here.
The suffixes matter: s1, s2, s3 relates to smoke production, d0, d1, d2 relates to flaming droplets. fl means classification for flooring. For decking you will often see A2fl-s1 — A2 classification tested as a floor finish, s1 = low smoke.
For many balcony and terrace projects in London, the requirement is A1 or A2-s1,d0 / A2fl-s1.
Standard timber decking and most wood-plastic composite (WPC) decking is typically Class C, D or E and does not meet non-combustible requirements for relevant buildings.
UK Building Regulations and Balconies in London
Building Regulations are devolved, but in England the key change came via The Building (Amendment) Regulations 2018 and subsequent updates — often referred to as the ban on combustible materials.
In England, Regulation 7(2) and guidance in Approved Document B restrict use of combustible materials in external walls of relevant buildings.
Relevant buildings include:
residential buildings containing flats
student accommodation, care homes, hospitals, dormitories
with a storey at least 11m above ground level (threshold lowered from 18m in 2022)
External wall is interpreted broadly — it includes balconies, terraces, and components attached to external wall. For balconies on relevant buildings, this means decking, frame, fascia, soffits, balustrades and other components should achieve European Class A1 or A2-s1,d0 or better, with limited exceptions.
London Fire Brigade has also issued strong guidance that combustible materials should not be used on balconies regardless of height due to risk of fire spread. Many London boroughs, housing associations and freeholders now require A1 or A2 rated balcony decking on all buildings, not only those above 11m.
This does not automatically mean every ground-level garden deck in London needs A-rated decking. Whether fire rating is required depends on building type, height, use, location and specification. For a low-level garden deck at a single-family house, standard composite or timber may still be appropriate. For a balcony, roof terrace or raised terrace attached to a flat, it very often needs to be fire rated.
Check building type early. Do not assume requirements that apply to a second-floor balcony on a block of flats also apply identically to a house garden.
Fire Classes Explained — What Should You Look For?
When you see fire rated decking advertised, ask for classification to BS EN 13501-1 and request the test certificate, not just marketing claim.
Look for:
Class A1 — Non-combustible decking. For example aluminium decking, porcelain pavers on A-rated pedestals, some stone systems.
Class A2-s1,d0 or A2fl-s1 — Limited combustibility. For example some high-performance aluminium systems and specially formulated mineral-based composite boards that achieve A2. The s1, d0 element is important — s1 = low smoke, d0 = no flaming droplets.
BROOF(t4) — External fire performance of roof. Often required for roof terraces. This is a different test (TS 1187) relating to fire spread across roof. Some terraces need both Euroclass and BROOF(t4). Do not confuse BROOF(t4) with A1/A2 reaction to fire — they are separate.
If supplier cannot provide classification to EN 13501-1 from accredited test, treat claim with caution.
Which Decking Materials Are Fire Rated?
1. Aluminium Decking — A1 or A2fl-s1
The most widely accepted non-combustible decking for balconies and terraces in London. Aluminium decking systems are typically A1 or A2fl-s1, do not contribute to fire, have no flaming droplets and maintain structural integrity. Powder-coated aluminium also offers long life and low maintenance. For relevant buildings above 11m, this is now the default specification for many developers and managing agents.
2. Porcelain Pavers on A-Rated Pedestal System — A1
Porcelain pavers themselves are A1. When installed on A1-rated adjustable pedestals and A-rated supports, overall terrace can achieve A1. Consider weight, pedestal heights, wind uplift and drainage. Porcelain can be slippery when wet — check slip rating (R value or PTV).
3. A2 Rated Mineral Composite Boards
Newer generation of mineral-based composite boards formulated to achieve A2-s1,d0 or A2fl-s1. Unlike standard WPC, these contain high mineral content. Check classification carefully — most standard WPC composite sold for gardens does NOT achieve A2.
4. What Is NOT Fire Rated?
Most traditional timber decking (even when described as fire-treated), standard WPC composite decking, and PVC decking are typically Class C, D or E and are not suitable for balconies on relevant buildings where A1/A2 is required. Fire-retardant treatment can improve timber performance but rarely brings garden-grade timber up to A1/A2-s1,d0.
Fire Rated Subframe Is Just As Important As Boards
This is one of biggest mistakes on balcony projects — specifying A-rated boards on a combustible frame.
On relevant buildings, supporting structure should also be A1 or A2-s1,d0. This includes joists, beams, pedestals, fixings and fascia supports.
Timber joists, aluminium with plastic packers that are not A-rated, and standard WPC joists will not meet requirements for relevant buildings.
We therefore specify A1-rated aluminium subframes and A1-rated pedestal systems for fire rated terraces and balconies in London. This ensures boards, frame and pedestals work as compliant system rather than mixing classifications.
Hidden cavities, drainage and ventilation still matter. Fire rated does not mean maintenance-free. Water should be able to move away, not become trapped around supports and thresholds. Access to drainage and services should be considered.
What About Ground-Level Gardens in London?
For a typical single-family house with low-level garden deck not attached to a block of flats, there is generally no Building Regulation requirement for A1/A2 decking. You can still choose aluminium or porcelain for longevity and low maintenance, but standard Millboard, composite or hardwood remains acceptable.
For mixed-use buildings, flats above shops, maisonettes and buildings converted to flats, get clarification — threshold and building classification can change requirements.
How Much Does Fire Rated Decking Cost in London?
Fire rated systems generally cost more than standard garden composite — not because boards alone are expensive, but because entire system is engineered: A-rated pedestals, aluminium frame, non-combustible fixings, fire breaks, drainage detailing and access.
Like raised decking, comparing price per square metre without understanding structure is misleading. 30m² garden deck and 30m² balcony terrace at 5th floor with A1 aluminium system, crane lift, access restrictions and building management requirements are not equivalent projects.
Common Mistakes With Fire Rated Decking in London
Specifying A-rated boards on combustible timber joists and assuming compliance.
Accepting verbal claim of "fire rated" or "fireproof" without EN 13501-1 certificate showing A1 or A2-s1,d0 / A2fl-s1.
Confusing BROOF(t4) with A1/A2 — roof terraces may need both.
Forgetting subframe, pedestals, fascia and edgings — all need to meet required class on relevant buildings.
Assuming garden-grade WPC composite is fire rated because it contains word "composite". Most is Class C/D.
Is Fire Rated Decking Worth It?
For balconies, roof terraces and terraces on relevant buildings in London — it is not a choice, it is a requirement. For other properties, it can still be worthwhile: A1 aluminium and porcelain systems offer exceptional longevity, virtually no rot or decay, low maintenance and peace of mind.
Bespoke Fire Rated Decking Installation in London
At Decking Gurus, we install fire rated balconies and terraces across London, Essex and the Home Counties.
We specify:
A1 and A2fl-s1 aluminium decking systems for balconies and terraces requiring non-combustible finishes
A1-rated aluminium subframes and A1-rated adjustable pedestal systems
Porcelain paver terraces on A-rated supports where client prefers stone finish
Fully non-combustible build-up — boards, frame, pedestals and fixings — not just boards
As Approved Millboard Installers, we also install Millboard and composite for low-level gardens where fire rating is not triggered, ensuring right material is used for right application.
Fire rated decking should look like premium decking when finished. Achieving compliance means putting most thought into parts you eventually won't see — frame, pedestals and fixings.
Useful Guides
To understand structure behind fire rated systems, see Timber vs Steel Decking Frames: Which Is Best?.
For design details that also apply to balconies, see Which Balustrade Is Best for Your Decking? and Glass Balustrades for Decking: Pros, Cons & Costs.
