Guide

What is EN 13830 curtain walling?

By Paul Fradley, Founder and Technical Lead · Updated June 2026

BS EN 13830 is the product standard for curtain walling: the non-loadbearing aluminium framing hung off a building's structure to form a continuous external envelope. It sets out how a stick or unitised curtain wall is classified and tested for air permeability, watertightness, wind resistance, impact and thermal performance, so a specifier can compare systems on a common basis. Our curtain walling is built to EN 13830 with units to 1.5 x 3.6m at 350kg, a 66mm sightline, glazing to 58mm and Ucw from 0.6. Tell us the elevation and loads and we will quote the right system. Get a quote.

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What is EN 13830 curtain walling?, aluminium by VitrineAlu

Built to EN 13830Classified for air, water and wind by test, not by claim

66mm sightlineSlim aluminium mullions and transoms, glazing to 58mm

Ucw from 0.6Thermally broken framing for low whole-wall heat loss, confirmed at quote

What does BS EN 13830 actually cover?

BS EN 13830 is the harmonised product standard for curtain walling, and it covers how the envelope is classified and tested rather than how it looks. It defines curtain walling as a non-loadbearing building envelope, usually aluminium-framed, that carries its own dead weight plus wind and impact loads back to the floor slabs or main structure, but takes no load from the building itself.

The standard sets the performance characteristics a curtain wall must declare and the test methods used to prove them. That is the framework that lets you compare one system against another on like-for-like classified figures rather than marketing numbers. For the systems we fabricate to it, see our product range.

Air permeability, watertightness and resistance to wind load
Impact resistance and reaction to fire where required
Thermal transmittance (Ucw) and, where specified, acoustic performance
Durability, dead-load capacity and accommodation of building movement
The basis for UKCA marking of the curtain wall as a construction product

Stick vs unitised: how is the system built?

The difference is where the wall is assembled: a stick curtain wall is built piece by piece on site, a unitised wall is built as finished frames in the factory. On a stick system, vertical mullions are fixed back to the structure first, horizontal transoms span between them to form a grid, then glazing and infill panels are installed into that grid. It suits a wide range of elevations and is the common route for low to mid-rise commercial work.

A unitised curtain wall is built as completed storey-height frames in the factory and craned into place. It speeds the site programme and tightens quality control, and tends to be specified on taller or repetitive facades. EN 13830 covers both, and the right choice depends on building height, access and programme.

Mullions: the vertical members carrying wind load back to the slabs
Transoms: the horizontal members spanning between mullions
Infill: glazed units, insulated spandrel panels or opening vents
Pressure plates and capping that clamp and weatherseal the glazing line

What thermal performance does curtain walling reach?

Curtain walling is rated by Ucw, the calculated whole-wall U-value that combines the framing, the glass and the spandrel panels across the elevation. It is not the same as a window Uw, because it accounts for the proportions of frame to glass over the full facade.

Our thermally broken curtain walling reaches Ucw from 0.6 where specified, using insulated framing and high-performance glazing. The achieved figure depends on the glass specification, the frame-to-glass ratio and the spandrel build-up, so we confirm the whole-wall Ucw on the engineered elevation at quote. For how U-values are calculated and compared, see our guide to aluminium U-values.

Ucw from 0.6 where specified, whole-wall basis
Thermally broken aluminium mullions and transoms
Glazing to 58mm to suit double or triple insulated units
Insulated spandrel zones for solid panel areas

What weather and wind classes does EN 13830 use?

Under EN 13830 a curtain wall is classified by test against air permeability, watertightness and wind resistance, and those classes are declared as tested figures rather than loose claims. They are the numbers that matter on an exposed elevation.

Our curtain walling is specified to air permeability Class AE, watertightness to RE1200 and wind load designed to EN 13116 at 2000Pa. Site exposure, building height and location set the required classes, so the design loads are confirmed against the specific elevation.

Air permeability tested and classified to Class AE
Watertightness classified to RE1200
Wind resistance designed to EN 13116 at 2000Pa
Classes selected against the building's exposure and height

What are the maximum unit sizes and sightlines?

Our curtain walling carries units to 1.5 x 3.6m at 350kg per unit on a 66mm sightline. Larger panes and slimmer framing mean more glass and a cleaner facade, but unit size is limited by glass weight, frame depth and wind load.

The 66mm sightline keeps the visible aluminium narrow while the frame depth carries the wind load over the span. Final mullion and transom depths are sized to the elevation height and exposure, so the structural design follows the building, not a fixed catalogue figure.

Maximum unit size to 1.5 x 3.6m
Unit weight to 350kg
Sightline 66mm
Glazing to 58mm to suit the insulated unit specified
Mullion and transom depth engineered to span and wind load

When is curtain walling specified instead of windows or doors?

Curtain walling is specified where you need a continuous glazed envelope spanning across and between floors, rather than openings punched into a wall. It carries only its own weight plus wind and impact load, so it can form full-height screens, atria and wrapped corners that individual windows cannot.

Punched openings, single large screens or domestic-scale glazing are usually better served by windows and doors, which are loadbearing within their own frame and rated by Uw. Where you want big spans of uninterrupted glass on a commercial facade, curtain walling to EN 13830 is the right route. For sliding and folding openings within or alongside that envelope, see our product range.

Continuous floor-to-floor and multi-storey glazed elevations
Atria, entrance screens and wrapped or stepped facades
Mixed glazed and insulated spandrel zones in one plane
Commercial envelopes where windows and doors set into infill would not span

Common questions

What is EN 13830 in simple terms?

EN 13830 is the product standard for curtain walling. It defines curtain walling as a non-loadbearing aluminium envelope hung off the building structure, and it sets out how that envelope is tested and classified for air permeability, watertightness, wind resistance, impact and thermal performance. It gives specifiers a common basis to compare systems.

Is curtain walling loadbearing?

No. Curtain walling is non-loadbearing. It carries its own dead weight plus wind and impact loads back to the floor slabs or main structure, but it takes no load from the building itself. That is what lets it form continuous glazed elevations across and between floors.

What U-value can EN 13830 curtain walling reach?

Curtain walling is rated by Ucw, the whole-wall U-value combining framing, glass and spandrel panels. Our thermally broken curtain walling reaches Ucw from 0.6 where specified. The achieved figure depends on the glass, the frame-to-glass ratio and the spandrel build-up, so we confirm the whole-wall Ucw on the engineered elevation at quote.

What is the difference between stick and unitised curtain walling?

A stick curtain wall is assembled member by member on site, with mullions fixed first, transoms spanning between them and glazing installed into the grid. A unitised curtain wall is built as completed storey-height frames in the factory and craned into place. Both are covered by EN 13830, and the choice depends on building height, site access and programme.

What is the largest unit EN 13830 curtain walling can take?

Our curtain walling carries units to 1.5 x 3.6m at up to 350kg per unit on a 66mm sightline, with glazing to 58mm. Mullion and transom depths are engineered to the elevation height and wind exposure, so final sizes are confirmed against the specific building at quote.

Completed North West new build with VitrineAlu anthracite aluminium bifold doors, windows and dormers — The frame disappears, the view does the talking.

Proof, not promises

Specified and made by people who have fitted it

Paul Fradley, Founder and Technical Lead, has worked almost every role in windows and doors across more than twenty years: surveyed, fabricated on the floor, fitted on site, then ran the technical and operations side. He leads the spec on every project, so what we quote is what we fabricate.

4.5 / 5 from 20 Google reviews. Council for Aluminium in Building member. Tested to BS EN 14351-1 and BS EN 13830 where specified.

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