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AS35 Composite Cladding Panels are insulated steel cladding which consists of two coated steel profiles bonded to a core of PIR insulation; they may be used to form roofs, down to a 4 degree pitch, and walls. The external faces have clean, sharp lines and the panels are available in an extensive range of finishes and colours.

The system includes a comprehensive range of guttering, flashings, sealants and rooflights. The AS35 system offers rapid coverage and swift completion of a weatherproof building envelope to give a high performance building.


Steadmans’ composite roof and wall panels are ideal for use in the efficient completion of a wide range of building projects across many market sectors, including industrial, retail, office, health, education and leisure. Steadmans insulated panels are ideal for roofing and cladding steel framed buildings and can be fully integrated with both modern and traditional methods of construction.

Steadmans’ AS35 panels are manufactured in a quality process certified to ISO 9001:2015 using non-ozone depleting technology. This provides designers with an environmentally responsible product with excellent thermal performance and a predicted service life of 40 years. AS35/1000 insulated panels are available in 40mm, 60mm, 70mm, 80mm, 100mm, 110mm, 120mm and 130mm options.

AS35 panels are available in a wide range of colours and can be specified to achieve insulation U-values to aid compliance with the latest L2 regulations. The composite panels are also Loss Prevention Certification Board (LPCB) approved and fully compatible with all Steadmans’ other pre-engineered construction products such as gutters, flashings, rooflights and fixings.


AS35 roof and wall panels have been tested by the Loss Prevention Certification Board and comply with the requirements of LPS 1181:2005. Part 1 Issue 1.1: Series of Fire Growth Tests for LPCB Approval and Listing of Construction Product Systems – Part 1: “Requirements and Tests for Built-Up Cladding and Sandwich Panel Systems for Use as the External Envelope of Buildings”.

logo LPCBlogo LPCB

    • Approved Documents
      • A Structure
      • B Fire safety
      • C Site preparation and resistance to contaminants and moisture
      • L2A Conservation of fuel and power in new buildings other than dwellings
      • L2B Conservation of fuel and power in existing buildings other than dwellings
    • The Scottish Building Standards: Technical Handbook
      • Non-domestic
    • BS 476 Fire tests on building material and structures.
      • BS 476-3:2004 Classification and method of test for external fire exposure to roofs.
      • BS 476-7:1997 Method of test to determine the classification of the surface spread of flame of products.
    • BS 5250: 2011+A1:2016 Code of practice for control of condensation in buildings.
    • BS EN 1090-2:2008+A1:2011 Specification for materials, fabrication and erection. Rolled and welded sections.
    • BS 8206 Lighting for buildings.
      • BS 8206-2:2008 Code of practice for daylighting.
    • BS EN 10143:2006 Continuously hot-dip coated steel sheet and strip. Tolerances on dimensions and shape.
    • BS EN 10346:2015 Continuously hot-dip coated steel flat products. Technical delivery conditions.
    • BS EN 12056 Gravity drainage systems inside buildings.
      • BS EN 12056-3:2000 Roof drainage, layout and calculation.
    • BS EN ISO 10140 Acoustics. Laboratory measurement ofsound insulation of building elements.
      • BS EN ISO 10140-2:2010 Measurement of airborne sound insulation.
    • BS EN ISO 10211:2007 Thermal bridges in building construction. Heat flows and surface temperatures. Detailed calculations.
    • BS EN ISO 13788:2012 Hygrothermal performance of building components and building elements. Internal surface temperature to avoid critical surface humidity and interstitial condensation. Calculation methods.
    • LPS 1181:2005 Part 1 Issue 1.1: Series of Fire Growth Tests for LPCB Approval and Listing of Construction Product Systems – Part 1: Requirements and Tests for Built-Up Cladding and Sandwich Panel Systems for Use as the External Envelope of Buildings.
    • ECCS document 115:2001 European recommendations for the design of sandwich panels.
    • MRCMA Technical paper 14. Guidance for the design of metal roofing and cladding to comply with Approved Document L2: 2001.
    • TM 37: Design for improved solar shading. 2006

Performance data for the ‘AS35 Insulated Roof & Wall Panels’ covers tables for allowable unfactored roof loads for all colours of panels, the durability and the life to first painting of the plastisol coated panels. It also includes fire resistance results, thermal conductivity and the effects of biological attack.

AS35 panel performance data can be found in the ‘AS35 Insulated Roof & Wall Panels’ technical brochure.

AS35 U-Values

Panel Thickness (mm) U-Value (W/m²K)
40 0.50
60 0.35
70 0.30
80 0.25
100 0.20
110 0.18
120 0.16
130 0.15



AS35 insulated panels consist of a core of polyisocyanurate (PIR) insulation sandwiched between a heavily profiled external weather sheet and an internal shallow profiled liner. The PIR insulation bonds to the steel sheets during the manufacturing process, together the insulation and steel form strong, rigid panels with good thermal performance.

On one side of the panel (the ‘female’ side) the weather sheet extends beyond the insulation to permit lapping and is sealed with factory applied anti-condensation tape. Panels can be supplied with the insulation cut back at one end to enable the formation of end laps on wide span roofs.

Steel profiles

The standard external weather sheet is 0.5mm thick and the internal liner 0.4mm thick: other thickness can be supplied for special orders. The steel is either hot-dip galvanised to BS EN 10346:2009 or Aluzinc coated, then finished with one of the coatings listed in Table 03 or one of an equivalent quality.

In order to maintain our high standards of customer service we may replace the steel listed here with that of similar quality from different suppliers.

PIR insulation

AS35 panels are formed with PIR insulation which is laid down between the weather sheet and liner on the production line.

The PIR expands to a high performance insulation core and bonds to the steel facings forming a strong rigid panel. The PIR is produced with a non-ozone depleting blowing agent.

PIR has a low thermal conductivity: for a given U-value panels with PIR cores will be thinner than those with mineral wool or EPS cores. PIR can withstand higher temperature than other foam insulants and when in contact with fire forms a surface char which limits fire spread.

Table01: AS35 Panel Dimensions

Cover 1m
Standard lengths 2m – 22m
Thickness 40, 60, 70, 80, 100, 110, 120 & 130mm
Cutback – roof panel lap 150mm
Cutback – boundary & valley gutters 100mm
Cutback – external trimline gutters 75mm

Table 02: AS35 Panel Manufacturing Tolerances

Cut to Length: L<3m +/- 5mm
Cut to Length: L>3m +/- 5mm
Cover width -2mm / +2mm
Thickness -2mm / +2mm
End square <3mm

Table 03: AS35 panel steel coatings

Coating Thickness Description Applications
Colorcoat HPS200 Ultra 200μm Colorcoat HPS200 Ultra pre-finished steel provides exceptional performance and corrosion resistance for building envelope applications. Guaranteed for up to 30 years it is backed up with even more extreme testing and real world global data to demonstrate the best combination of excellent colour stability, gloss retention and outstanding durability.  Designed to withstand even the most demanding and aggressive environments, Colorcoat HPS200 Ultra pre-finished steel provides super durability and corrosion resistance. Whatever your type of building, from warehouses to houses, retail outlets to processing plants, Colorcoat HPS200 Ultra demonstrates proven performance and reliability.
Colorcoat Prisma 50μm Colorcoat Prisma pre-finished steel provides exceptional performance and corrosion resistance for building envelope applications especially for vertical cladding. Guaranteed for up to 30 years it is backed with even more extreme testing and real world global data to demonstrate the best combination of excellent colour stability, gloss retention and outstanding durability.  Designed to withstand the rigours of the external environment, versatile, lightweight and strong, Colorcoat Prisma pre-finished steel is the ideal choice for your building envelope for contemporary, long lasting colour. Whatever your type of building from warehouses to offices, or schools to houses, Colorcoat Prisma offers you a range of attributes that enables you to create beautiful, modern and durable roofs and walls, Confidex guaranteed for up to 30 years.
Colorcoat LG 200μm Leathergrain plastisol product suitable for roof and wall cladding applications where good performance is required tat a competitive price. Coloroat LG comes with a performance guarantee up to 25 years including cut edge protection.  Leathergrain plastisol product suitable for roof and wall cladding applications where good performance is required at a competitive price.
 Leathergrain 200μm A polyvinyl chloride (PVC) Plastisol coating that uses the latest UV resistance technology to ensure it offers robust protection, even in the most adverse industrial environments. The weather face is finished with a leather-grain emboss.  The ideal choice for a wide range of internal and external structures: from wall and roof cladding to internal wall face.
 PVDF 27μm A polyvinylidene difluoride (PVDF) coating that offers high resistance to UV light, excellent colour stability, good corrosion resistance and a good surface chemical resistance.  The choice of building owners and architects for prestigious commercial buildings. Available with a high gloss finish.
 Polyester 25μm A smooth polyurethane (PU) coating with greater coating thickness and improved performance over standard polyester. A modern colour range which includes solids, metallic and matt shades.  A tough performer – excellent exterior durability, with superb colour retention and stain resistance make it a great choice for both commercial and industrial buildings.

Common roof, wall and rooflight details for the AS35 insulated panels. The details contained in the PDF’s are the coloured versions shown on pages 13 to 30 in the ‘AS35 Insulated Roof & Wall Panels’ technical brochure.

AS35 Composite Panel Brochure

These sheets are available for download in PDF format :

Design details – Roofs

Common details for Steadmans AS35 roof panels.

Design details – Walls

Common details for Steadmans AS35 wall panels.

Design details – Rooflights

Common details for fitting factory assembled, in-plane rooflights to Steadmans AS35 roof panels. These details show twin skin GRP rooflights, although triple skin GRP rooflights are available for projects where higher thermal performance is required.

Site Work

Handling and storage

AS35 panels are delivered to site in plastic wrapped packs with end and side protection. The panels are packed with weather faces together to reduce pack height. The height of a pack and the number of panels it contains depends upon the thickness of the panels (see table 13).

Table 13: AS35 panels

Panel core thickness 40mm 60mm 70mm 80mm 100mm 110mm 120mm 130mm
Weight (Kg/m)0.5/0.4 Steel 10.06 10.74  11.10 11.62 12.38 12.86 13.34 13.66
Panels per pack (max.) 17 11 11 9 7 7 7 7

The packs can be off-loaded directly to the roof, or to a storage area, which should be dry and kept well away from traffic. Packs may be stacked up to 2.5m high on pallets provided with delivery.

Handle AS35 panels carefully to avoid marking the weather sheet or liner. Lift panels from the pack – do not drag them. Carry panels by the male (filled) edge – do not lift panels by the female edge or just the top sheet. See table 13 for the weight of panels.

Observe site health and safety procedures and the results of manual handling and other assessments.


Before fixing any panels check the squareness and accuracy of the steelwork. Determine the direction of the prevailing wind. Check panels for damage before fixing and remove any excess insulation from side and end laps.

Supply and Delivery

AS35 panels are available directly from Steadmans. AS35 panels are supplied in plastic wrapped packs: fully timber crated packs are available for sea freight shipping at additional cost.

AS35 panels are usually delivered to site. Off loading is the responsibility of the customer. Delivery by self off-load vehicles can be arranged.


Design Guidance

Design guidance for the ‘AS35 Insulated Roof & Wall Panels’ includes information on the supporting structure, panel fixings, end and side laps, fire rating, thermal performance, control of condensation, drainage, and the incorporation of rooflights.

AS35 design guidance can be found in the ‘AS35 Insulated Roof & Wall Panels’ technical brochure.


Annual inspection

It is good practice to carry out annual inspection of the building exterior and to carry out any remedial work identified during the inspection.


Minor scuffing to the colour coating should not be treated. Deeper scratches which reach the substrate should be repaired with touch-up paint. The touch-up paint should only be applied to the original scratch using a fine paint brush. As touch-up paint will dry to a slightly different colour than the original coating the area to be touched up should be kept as small as possible.

Check for: Remedial action:
Blocked gutters, which may cause overflow into the building. Clean gutters and wash out any blockage.
Build-up of debris, which can retain water and cause corrosion. Remove debris.
Dirt retention on areas not washed by rainwater: that affects the appearance of the building and, if left untreated, could cause the coating to breakdown. Wash down with fresh water using a hose and soft bristle brush. Heavy deposits can be removed with a solution of water and household detergent or proprietary cleaner.
Mould growth, which is rare, but can affect the appearance of the building. Wash down, then apply a cleansing solution: consult Steadmans Technical Department for guidance.
Local damage – breakthrough of the panel coating could result in corrosion of the substrate. Assess the extent of the damage and either touch up (see opposite) or overpaint the affected area or replace damaged sheets.
Drilling swarf and fixing debris. Remove debris.
Condition of fixings – faulty fixings can cause leaks or rust staining on the surface of the panels. Replace faulty fixings and missing clips.
Corrosion of cut edges. Cut or abrade edges back to clean bright metal and repaint: consult Steadmans Technical Department for guidance.

Meta Slate Plus Roofing System

Meta-SlatePlus is a roofing sheet that has the appearance of natural slate but embodies the advantages of a modern lightweight but strong building material. Meta-SlatePlus is manufactured from 0.7mm galvanised coil with a slate blue matt polyester paint finish to the outer surface and a grey epoxy based primer to the inside. The sheet is specially embossed with a regular slate pattern and finished to appear like natural slate. Other external colours and finishes are available by special order subject to quantity and coil availability. Meta-SlatePlus is ideal for use in environmentally sensitive locations where box profile sheeting may not be acceptable to local authority planning departments. Meta-SlatePlus is extremely easy to fit and boasts a beautifully simple secret fix joint system. Meta-SlatePlus roofing sheets are available in lengths up to 6m.

The AS35 insulated panel consists of two coated steel profiles bonded to a core of PIR insulation. The metal sheets are made from either Z275 galvanised steel or AZ150 aluminium-zinc coated steel to BS EN 10346:2009. The top profile is 0.5mm thick, and the internal liner 0.4mm thick, and are both covered by a choice of one of several organic coatings. Panels are available in lengths of 1.8m to 22m and in thicknesses of 40, 60, 70, 80, 100, 110, 120 and 130mm.

Meta-SlatePlus is designed to provide a strong, rigid slate effect roof with good thermal performance down to a 10° pitch. The system includes a comprehensive range of clips, jointing pieces, flashings, end closures, sealants and coated steel or plastic gutters and downpipes.

The Meta-SlatePlus system offers rapid coverage and swift completion of a weatherproof building envelope to give a high performance building. To download a pdf of the Meta-SlatePlus overview brochure, click here.

Performance, design & sitework

Performance data, design guidance, and sitework instructions for the Meta-SlatePlus slate effect roofing sheet is contained in the ‘Meta-Slate Roofing Systems’ technical brochure. To download a pdf of the Meta-Slate brochure, click here. An instructional fitting CD is also available from our sales department.

Performance data, design guidance, design details and sitework instructions for the AS35 panel is contained in the ‘AS35 Insulated Roof & Wall Panels’ technical brochure Common details for Steadmans AS35 wall panels.

Fixing Meta-Slate roofing sheet over an AS35 insulated roofing panel

Once the AS35 has been securely fixed to the roof substructure in accordance with the Certificate holder’s instructions, the Meta-Slate roof sheets can be fixed in place.

The installation of the Meta-Slate roof sheets over the AS35 panels is very similar to the installation over rafter/purlins. The roof sheets are fixed every third raised section of the AS35 panel using 5.5mm by 25mm self-drilling screws. The screws are fixed through the overlap between panels so that the screw is driven through two thicknesses of the metal top sheet (fixed at a maximum of one per metre of panel length). The frequency of fixing can be increased around the edges of the installation or where special detailing is required.

Note: the projects shown here are examples of roofs fitted with the Meta-Slate roofing sheet.


Steadmans offer a range of factory assembled in-plane rooflights to match the dimensions of AS35 panels (see table 10). Energysaver triple skin rooflights give a U-value of 1.9W/m²K* and consist of two skins of GRP with a central membrane, hardpak spacers and foam end pieces. Double skin rooflights are available if a lower thermal performance is acceptable. Each rooflight has a metal underlap strip built into the crown of the male edge which enables the rooflights to be stitched with standard screws.

Rooflights can be supplied to meet project requirements for light transmission, durability, non-fragility rating, fire resistance and thermal performance: contact Steadmans’ sales office for details.

Table 10: Rooflights

Minimum slope ° 6
Maximum length m 7
Width (centre-centre) mm 1000
Thickness mm 40, 60, 70, 80, 100, 110, 120 & 130
U-value (Standard) W/m2K 3.0*
U-value (Energysaver) W/m2K 1.9*
Low U-value energysaver W/m2K 1.0 – 1.9*

*Figures supplied by Brett Martin Daylight Systems Ltd. Other manufacturer’s figures may vary


Steadmans manufacture and supply a range of gutters to match AS35 panels. Gutters are produced from a variety of materials including pre-galvanised steel (to BS EN 10143:2006) and pre-coated steel, either painted or PVC-coated on one or both sides: aluminium can be supplied to special order. Complete gutter systems and accessories can be manufactured to specification, up to 10m long and 3mm thick: contact Steadmans’ sales office for details of sizing.


Steadmans manufacture a range of flashings to match AS35 panels in plastisol leathergrain, polyester, Nova, Scintilla, galvanised, or PVDF finishes. Flashings can be supplied in lengths up to 6m in traditional profiles, or can be shaped to meet special customer requirements.


Steadmans supply a range of NFRC Class A butyl sealants, profile foam fillers and expanding foams to enable AS35 panels to be sealed to each other and to other building components, so avoiding thermal bridging and air leakage.

NBS Plus

NBS Plus is a library of technical product information written in NBS format, linked to NBS clauses and clause guidance. The links within the specification software allow you to specify products quickly and accurately by a click of a button then drop the product information directly into a specification.

NBS is the industry standard specification system used by more than 45,000 registered users to download relevant building clauses. Available online and on CD-ROM, as well as hard copy, it is a library of pre-written technical specification clauses and preliminaries for producing building specifications.