Steel and glass screens and doors

At a glance

Figures are from Steel Window Association (SWA) fact sheets (Aug 2024) and the Glass and Glazing Federation (GGF) guide (Issue 4, 2018), for the systems they describe; none is a design value for your screen.

What counts as a steel-framed screen, and which standard applies

The look is a thin grid of steel sections holding glass. Searchers often describe it with a manufacturer’s name used as shorthand. A brand name is not a specification and says nothing about the section, the glass or fire performance, so this sheet says steel-framed screens.

BS 6510 is an external standard. BSI Knowledge lists BS 6510:2010, Steel-framed windows and glazed doors. Specification, as current (published 30 November 2010, no amendments listed). Its scope is units factory-assembled from mild steel profiles, hot-rolled or cold-formed, and installed vertically in external building walls. It excludes any unit with a frame member longer than 3 m, patent glazing, curtain walls that span between floors, and kits supplied in bar form for assembly on site. The performance requirements common to external windows and doors sit in BS 6375. We read the scope on the listing, not the standard. An internal screen therefore falls outside it, so a drawing that says “to BS 6510” needs a sentence saying what is meant: usually the section family and the workmanship, with no external weathertightness class.

Section families. The Steel Window Association (SWA) describes W20 as the traditional system, 32 mm wide with 5 mm thick flanges, originally for commercial, public and industrial buildings and now used in homes. W30 evolved from it so that multi-light windows need no coupling bars. W40 was designed for larger sizes and thicker double or triple units. W50 TB is a thermally broken section built differently from the solid hot-rolled ones. For internal work SWA names fixed glazed screens, hinged single and double doors, sliding doors and pivot doors, in raw steel (with every weld and joint visible), galvanised steel or powder coat in colours mainly from the RAL range, including metallic and textured finishes.

Thermal break. SWA’s U-values are for external windows and doors: 2.0 W/m²K overall for W20 doors and screens, 1.5 for triple-glazed W40 doors and as low as 1.2 for W50 TB. Between two heated rooms the usual questions are sightline, glass and fire, not U-value (our reading), so a thermal break is mainly an exterior decision.

Glass: safety and manifestation apply to every screen

These rules apply to every glazed screen and door, fire-rated or not. Approved Document K (2013 edition, England) asks, in requirement K4, that glazing people are likely to contact either breaks safely, resists impact or is protected. Diagram 5.1 marks the critical locations: all glazing in doors up to 1500 mm above the floor, glazing in a side panel within 300 mm of a door edge up to 1500 mm, and any other glazing below 800 mm.

In a critical location paragraph 5.2 gives three routes: glass that breaks safely, glass that is robust or in small panes, or glass that is permanently protected by a screen (5.8). For safe breakage, 5.4 accepts Class 3 of BS EN 12600 or Class C of BS 6206, and Class 2 or B in a door or door side panel where the pane is wider than 900 mm.

Small panes. This is the route a glazing-bar screen can use. Paragraphs 5.6 and 5.7 define a small pane as an isolated pane or one of a number held in glazing bars: no more than 250 mm across, an area of no more than 0.5 m², and annealed glass at least 6 mm thick (Diagram 5.3). A screen with larger panes needs laminated or toughened glass of the right class instead, so the grid you draw decides the glass you need.

Manifestation. Section 7 treats large uninterrupted areas of glazing in non-domestic buildings as critical locations. Doors and screens need marking at two heights, 850 to 1000 mm and 1400 to 1600 mm, that contrasts with the background from both sides (7.4, Diagram 7.2), with a logo at least 150 mm high or a band or broken line at least 50 mm high. Diagram 7.1 lists glass that does not need it: panes less than 400 mm wide between frames, glass with rails at those two heights, and doors with a substantial frame or a large handle on each pane. A steel transom at the right height can therefore do the job, which is worth settling before the grid is fixed.

Our guarding and handrail sheet draws the same critical locations. The 2013 edition is still the guidance in force: the Building Safety Regulator opened a call for evidence on Part K on 19 October 2026 and says current requirements and guidance stay in place meanwhile. BS 6206 appears in the document alongside BS EN 12600; see the standards list for what we saw of its status.

Fire-resisting glazed steel: what the rating means

A rating belongs to a system, not a section. The GGF guide says plainly that metal frames must not be used for fire screens or doors unless suitable fire test evidence is available, and that an integrity frame must not be used where insulation is wanted (its Best Practice Rule 8). Approved Document B says the same from the regulator’s side: small differences in fixing method, joints or dimensions might significantly affect performance and should be tested or assessed (Appendix B, B2).

What E, EW and EI mean. Approved Document B names resistance to fire penetration (integrity, E) and to the transfer of excessive heat (insulation, I) (B18). The GGF guide adds EW, integrity with limited radiated heat, which it describes as a feature of the tested element rather than of the glass, and which Approved Document B does not use. The time follows the letters: E 30 is thirty minutes of integrity, EI 30 thirty minutes of integrity and insulation.

Why the letters matter for design. If glazed elements in fire-resisting enclosures and doors can meet only integrity, their use is limited by Table B3. If both integrity and insulation are met, Approved Document B sets no restriction on the use or amount of glass (5.4). Insulating glass is much thicker than integrity-only glass: in SWA’s tested builds the monolithic integrity glasses are about 5 to 6 mm and the laminated intumescent types 13 to 15 mm, so an EI screen needs a deeper rebate and bead and is rarely as slender. SWA also reports a W20 door and screen build assessed for 60 minutes of integrity but only 14 minutes of insulation, a reminder that integrity does not stand in for insulation.

Table B3, in outline. Where an uninsulated glazed element is on an escape route, Table B3 caps the glazed area. The rows below are condensed from the 2019 edition with the 2026 amendments (printed pages 150 and 151); the 2029 amendment reprints the table with the same limits, and the fire engineer decides which row applies to a given screen.

Heights are from the floor (item 7 more-than-one-stair walls: from the landing floor or stair pitch line). The 100 mm limit is meant to reduce fire spread from a floor covering. Dwellinghouse rows and the full notes are in the table. The glass must be marked with the maker’s and the product’s name.

A glazed screen to a protected shaft. Paragraph 8.34 lets an uninsulated glazed screen separate a stair and a lobby or corridor entered from it if the stair needs no more than REI 60, the screen achieves at least E 30, Table B3 is met and the lobby or corridor is enclosed in construction of at least REI 30 (Diagram 8.4).

Doors in a screen. BSI lists BS EN 1364-1:2015 as the fire test for non-loadbearing walls including glazed walls (Annex A covers glazing) and says it excludes walls containing door assemblies, which fall under BS EN 1634-1. A screen with a door therefore needs evidence for the door as built into the screen. Our fire door specification guide covers doorsets, FD30S and E30 Sa.

The evidence chain. The GGF guide lists a test report from an accredited laboratory (applicable only to the system as tested, and confidential to the sponsor), an assessment report from a suitably qualified person, a classification report to BS EN 13501-2 with its field of application, a declaration of conformity and, recommended, a third-party certificate. Extended application of results for glazed partitions follows BS EN 15254-4. SWA says its full assessments are available to specifiers of named projects, in confidence. Ask for the one that matches your screen: its size, glass, bead, fixing centres, frame section and door furniture.

Details that decide the rating. A frame that is not symmetrical must be tested with both faces to the fire, or with its weaker face to the fire, and the installation instructions then say which face may meet it (GGF). Steel expands: the guide gives about 25 mm for a 3 m section at 700 °C, and a bow of roughly 150 mm if it is held, so the fixings and gaps follow the test. Fixings and shims must not be affected by heat: the guide says steel fixings and shims, and never brass screws or plastic shims. The surround must achieve at least the fire performance of the screen, and any gap behind the frame is packed with fire-resistant material (GGF, section 6).

Specifying and buying a steel screen

A steel-framed screen is a set of decisions the drawing has to state. Our metalwork brief checklist lists what any metalwork drawing must say; for a screen add the following.

• The system and the sightline. Name the section family, the tee-bar face width and the perimeter frame, and approve them on a shop drawing and a mock-up (shop drawing checklist, prototype and mock-up approval).
• Which standard, and which part. BS 6510 for the section family and workmanship only, if that is the intention, and no external weathertightness class.
• The finish system. SWA says hot-rolled sections to BS 6510 are hot-dip galvanised to BS EN ISO 1461 and then polyester powder coated to BS EN 13438, and quotes a life of at least 15 years; that is the trade body’s own statement. See powder coating metalwork, and for a raw look blackened, burnished and raw steel and visible welds.
• Glass, safety and manifestation. Type, class and marking for every critical location, and the manifestation heights.
• Perimeter and movement. SWA’s installation sheet, written for windows, calls for a perimeter design gap for thermal movement, size variance and opening tolerance, and says no load is to be applied to the head. Allow the same at the ceiling, and read thermal expansion of metals and tolerances for visible metalwork.
• Fixings in contact with steel. See galvanic corrosion before specifying stainless or brass fixings into galvanised steel.
• If it is fire-rated: the position and rating from the fire strategy, the evidence required before manufacture, face of exposure, and a rule that nothing is changed, cut or glazed on site unless the evidence allows.

The studio coordinates manufacture through its partner workshops and does not claim that it or a partner supplies tested fire-resisting glazing. Where a project needs it, the question for any supplier is which tested or assessed system, from whom, with which evidence.

Fixed glazed screen and door(s) at [ref] in [hot-rolled steel sections, W20 family], welded mitred corners, tee bars [riveted and face-welded], to shop drawing [ref]. BS 6510:2010 is an external standard: [only the section family and workmanship apply; no weathertightness class]. Finish [galvanised to BS EN ISO 1461 then polyester powder to BS EN 13438, RAL [ ]] [or raw steel as sample [ref]]. Tee-bar face not over [ ] mm. Perimeter movement gap [ ] mm, sealed [ ]; no load on the head.

Glass [type and thickness to suit the rebate, confirmed by the glazier]. Critical locations (Approved Document K Diagram 5.1): BS EN 12600 class [3], permanently marked; small-pane annealed glass only within [250 mm width, 0.5 m2, 6 mm minimum] and agreed in writing. Manifestation [logo or band] at [850 to 1000] and [1400 to 1600] mm above finished floor, or steel rails at those heights.

Fire-resisting screen at [position ref, fire strategy drawing [ ]] to achieve [E 30 / EI 30 / EI 60] to BS EN 13501-2, as a complete system (frame, glass, seals, beads, fixings and fire stopping as tested or assessed), exposed from [face A / both faces]. Before manufacture submit the classification or assessment report with its field of application, installation instructions and [third-party certificate]. Glass marked with maker and product. No change, cutting or site glazing unless the evidence allows. Doors in the screen: evidence for the door as built in [BS EN 1634-1]. Handover: evidence, glass marking and fire-stopping records.

Standards and sources

• Approved Document B volume 2 (2019 edition, 2020 to 2026 amendments; 2029 amendments): 5.4, 5.5, 8.34, Appendix B, Table B3; read 6 Nov 2026.
• Approved Document K (2013 edition, England): Sections 5 and 7; call for evidence open from 19 Oct 2026.
• BS 6510:2010: BSI Knowledge: current. External windows and glazed doors; scope read, standard not read.
• BS EN 12600:2002, BS 6206:1981, BS 6262-4:2018, BS EN 1364-1:2015, BS EN 15254-4:2018, BS EN 13501-2:2023: statuses in the notes; none read.
• Steel Window Association fact sheets (Aug 2024); Glass and Glazing Federation guide (Issue 4, 2018): trade bodies; not design values for your screen.

Questions we are asked

Is a steel screen the same as a fire door?

No. A screen is a non-loadbearing wall that contains glass, tested to BS EN 1364-1, while a doorset is tested to BS EN 1634-1. BSI says the wall test excludes walls containing door assemblies, so a screen with a door needs evidence for the door as built into it. See our fire door specification guide for FD30S and E30 Sa.

Does BS 6510 apply to an internal steel screen?

Not by its scope. BSI Knowledge describes it as covering steel-framed windows and glazed doors installed in external walls, so an internal screen has to say which parts the partner is to follow, usually the section family and workmanship, with no external weathertightness class. The standard itself was not read for this sheet.

Can a slim steel screen be fire-rated?

Yes, as a tested or assessed system. The Steel Window Association and the Glass and Glazing Federation both describe steel systems rated for 30 or 60 minutes of integrity and, with insulating glass and special frames, for insulation. The look follows the evidence: insulating glass is thicker, so the rebate, beads and sightline change, and no standard screen becomes fire-rated by changing its glass.

What glass does a screen with a door need?

In Approved Document K critical locations, glass that breaks safely (Class 3 of BS EN 12600 for most positions), robust glass or small panes, or glass protected by a permanent screen. Critical locations include all door glass below 1500 mm, side panels within 300 mm of a door edge and other glass below 800 mm. A glazier confirms type and thickness for the frame.

Do thin steel screens need manifestation?

Large uninterrupted glazing in non-domestic buildings does, at two heights, 850 to 1000 mm and 1400 to 1600 mm, unless it is less than 400 mm wide between frames, has rails at those heights or has a substantial frame or large handles (Approved Document K, Section 7). A steel transom at the right height is the simplest answer.

Is thermally broken steel needed inside a building?

Usually not. SWA's thermal figures are for external windows and doors, and between two heated rooms the deciding factors are normally sightline, glass and fire performance (our reading). A thermal break matters for external walls and where there is a large temperature difference.

How big can a steel screen be?

It depends on the system and its tests. BS 6510 does not cover units with a frame member longer than 3 m. SWA's summary of its tested fire builds gives limits such as a 1.5 m mullion spacing and a 2.6 m height for the 60 minute build, but those belong to those constructions, so ask the partner for the limits of the system proposed.