We have just launched a new brochure focusing on our RoofDek range of structural roof decking and trays.

The brochure is a component of “The Works”, our new design, specification and construction manual.

Well illustrated throughout, it highlights the UK’s most comprehensive selection of structural roof decking solutions.

There is a detailed overview, including diagrams and all key product data, of RoofDek shallow and deep deck profiles, liner trays and fully tested acoustic solutions.

Dedicated sections deal with sustainability issues, safety, technical information, structural, diaphragm and acoustic design considerations.

In-depth case studies show a diverse sample of major UK projects that have successfully deployed RoofDek systems. They include the UK’s largest curved green roof, two new university campuses and a combined cycle gas turbine power station.

RoofDek decks range from 32mm to 210mm, with a wide choice of structural trays. They support all types of insulated roof systems, including single ply membranes, standing seam systems, green roofs, slates and tiles, three ply felt and asphalt.

Our structural design service provides deck diaphragm design assistance and full support calculations for all profiles.

Get your copy of the RoofDek brochure now by clicking here.

Fasteners are a vital component to ensure the safe installation of structural decks or trays. The correct fixing, to be specified by the fastener manufacturer, to suit the application of fixing to cold rolled thin gauge purlins, hot rolled steel sections or timber supports. Self drilling / self tapping screws (commonly known as drill screws), must be a minimum 5.5 mm diameter, available in carbon steel or austenitic stainless steel, and must resist all pullout, pullover and shear forces.

The load acting on a screw can be calculated thus:-

Screw Load (kN) = Wind Load (kN/m2) x Support Centers (m) x Screw Centers (m) x Factor of Safety

Example:- To find the fastener load for D60 deck spanning 3000 mm with an applied wind load of 1.5 kN/m2
Screw Load = 1.5 x 3 x 0.2 x 2 = 1.8 kN

Fastener manufacturers can confirm:-
Pullout, pullover and shear values, to suit gauge of deck / tray, type and thickness of support structure, and provide information on the correct torque setting for screw guns, to ensure that the screw is not overdriven or underdriven.

For further information please do not hesitate to get in touch with our Technical Department at Tata Steel, E mail: roofdek@tatasteel.com

Where the profiled metal deck, or tray, is being used as a vapour check layer, the deck / tray must be reasonably airtight so that the air permeability does not exceed 5 M³/h/M² at an applied pressure of 50 pa in accordance with the Building Regulations 2000, Approved Document ADL2 2010. Under laboratory testing sealed decks / trays can achieve an air leakage as low as 0.5 m³/h/m². A reasonable practical expectation for a finished system would be 3 to 5 m³/h/m².

Decks
Sealant tape: Inside joint (suitable for side laps and end laps). High performance strip sealant placed between sheets, prior to fixing. Suitable sealant, 6 mm x 5 mm, Type A, continuous strip sealant.

Sealant tape: Over joint (suitable for side laps, butt joints and sealing on to penetrations). High performance barrier tape securely adhered over joint. Suitable sealant, 50 mm x 1 mm Polyband tape.

Position tape in straight, unbroken lines parallel to and slightly back from edge of sheet. Place into troughs. Do not allow to stretch or sag into position. Do not over-compress.

At roof perimeter provide fire resisting profiled filler blocks to close open flutes of decking, bed filler blocks top and bottom in continuous strip sealant.

Provide internal flashings to ensure continuity and effectiveness of seal, especially at corners of sheets such as at roof / wall junctions and at all penetrations of pipes, ducts, etc Deck must be installed with fasteners incorporating a sealing washer.

Trays
Sealant tape: Inside joint for side laps. High performance strip sealant placed between tray flanges, prior to fixing. Suitable sealant, 12 x 2 mm, Type A, continuous strip sealant.

Sealant tape: For sealing tray ends. High performance strip sealant laid on support structure. Bed tray down onto 6 mm x 5 mm, Type A, continuous strip sealant.

Position tape in straight, unbroken lines parallel to and slightly back from edge of sheet. Provide internal flashings to ensure continuity and effectiveness of seal, especially at corners of sheets such as at roof / wall junctions and at all penetrations of pipes, ducts, etc.

Tray must be installed with fasteners incorporating a sealing washer.

Perforated decks and trays are not suitable to act as a vapour control layer, requiring a separate membrane layer, installed above acoustic insulation.
Note – Further insulation will be required above the vapour control membrane to meet U value requirements.

For further information please do not hesitate to get in touch with our Technical Department at Tata Steel, E mail: roofdek@tatasteel.com

The correct orientation for deck installation is for the narrow trough to be down onto the support structure. This ensures that the widest crown is uppermost, providing maximum support for insulation. Direction of lay can be left to right or right to left, ensuring that the correct engagement of side lap is maintained.

A running check should be taken during installation to ensure that the closing dimension ‘X’ is maintained. A tolerance build up due to discrepancies in steelwork and deck cover width manufacturing tolerance can occur.

To determine setting out dimension ‘X’ (Example based on D100 over 20000 mm roof width)

Where sheets are cut down to make up a finishing section, the unsupported edge requires to be supported by a zed spacer.

Alternatively the closing width can be adjusted by overlapping the deck by the profile pitch:-

Based on the previous example, if the number of sheets is increased to 29 with a single one pitch overlap at each end, the setting out dimension will be:-

To determine setting out dimension ‘X’ (Example based on 20000 mm roof width)

To produce a make up section, trays may be cut down their length, overlapped on the micro ribbed pan section, and stitched together at 450 mm centers. In this manner the standard 600 mm cover width can be adjusted to 429 mm or 257 mm, as indicated below.

For further information please do not hesitate to get in touch with our Technical Department at Tata Steel, E mail: roofdek@tatasteel.com

For circular buildings the lay of decking is dependant on the orientation of support beams. They can be installed radially or laterally. For either type installation on circular buildings, sheet ends require to be rake cut.

Rake cut ends will not overlap and will be butt jointed, requiring a minimum support flange of 150 mm, i.e. ensuring a minimum end bearing of 75 mm.

The selection of deck orientation could be decided for aesthetic reasons, however there are important structural issues which must be considered.

For circular segmented structure, it is not possible to manufacture tapered decks and rake cutting along the long parallel length is not recommended. Therefore decks must be laid as shown in the diagram below, in single span condition with rake cut ends.

Rake cut ends will not overlap, requiring butt joints with a minimum support flange of 150 mm, i.e. ensuring a minimum end bearing of 75 mm.

Decks can only be manufactured with square cut ends. The installation contractor must provide any requirement for rake cutting on site, allowing for subsequent costs.

Typical rake cut joint indicating correct installation

• Where decks are installed with rake cut end laps, these cannot be adequately sealed for air permeability. Therefore a separate vapour control membrane layer must be installed.
• Angled rake cuts will require special rake cut fillers, to close off the wider troughs, at the building perimeter to maintain air permeability requirements.
• Where decks have to accommodate an angled end lap joint, any attempt to install decks with an overlap, instead of rake cut ends, will result in the decks not nesting as indicated below.

Deck installed incorrectly by attempting to twist overlap without rake cutting.

For further information please do not hesitate to get in touch with our Technical Department at Tata Steel, E mail: roofdek@tatasteel.com

The increasing complexity of roof decking projects makes any new software aimed at easing the process very welcome indeed. Earlier this year Tata Steel introduced RoofDek Analysis Software, allowing structural engineers and specifiers to conduct full deck analysis to Eurocodes 3 and 9. The company has now launched a new online tool to further improve its service.

The Tata Steel RoofDek Quick Selector is a web based structural analysis tool. It allows a user to rapidly select the right structural roof deck for a project on a PC or tablet, including iPad.

“The program does two things simultaneously. It provides an optimised RoofDek specification, and it also allows the user to choose an alternative RoofDek profile,” explained Adrian Wallwork, Tata Steel’s Product Manager – Structural Decking Products.

“The Selector page opens with pre-populated span and load figures as an example. Users can then modify these to their own requirements to find the right decking profile for a given project.

“A suitable decking profile for both single and double span applications is then displayed.

“The pre-filled information is suitable for a general roof deck application, but of course may not be suitable for any particular project.

“The user can therefore edit all the input data to suits the project; a steel or aluminium deck, perforated or not perforated and the support type. Deflection limits under imposed and wind load can be set separately.

“Loads can then be input. Unfactored loads are required, as the program applies load factors to them. Separate provision is made for live load, imposed dead, wind suction, wind pressure, general snow, snow drift and construction line load.

“Each time new information is added, it is evaluated and the deck selection may change accordingly. The user can also try different decks from the dropdowns at any point if required.

“The whole exercise is carried out on one screen and the page may be printed out as record of the design. Calculations are carried in accordance with Eurocode 3.”

The RoofDek Quick Selector augments Tata Steel’s suite of roof decking software, which includes RoofDek Analysis Software.

Please click here to find out more about RoofDek Quick Selector.

The new Tata Steel RoofDek Quick Selector complements the RoofDek Tedds Analysis package released earlier this year.

The Quick Selector is a web based fast structural analysis tool, requiring no extra software. It allows a user to design a structural roof deck with a few inputs and selections from drop down lists. The Selector instantly provides an optimised deck solution, but the user may also try any alternative Tata Steel deck for the application.

The RoofDek Tedds Analysis program, on the other hand, is fully downloaded into the user’s PC, using the CSC Tedds Lite platform; it requires no other software beyond a Windows platform, to run. This program, aimed primarily at Structural Engineers, allows full structural analysis of any Tata Steel RoofDek application.

Product Comparison Table

Both Tata Steel RoofDek design tools are freely available, on completion of a simple registration process.

Register to use the web-based quick selector here

Download the RoofDek Analysis Software here

Fasteners are a vital component to ensure the safe installation of decks. The correct fixing as specified by the fastener manufacturer, to suit the application of fixing to cold rolled thin gauge purlins, hot rolled steel sections or timber supports.

Self drilling / self tapping screws (commonly known as drill screws), must be a minimum 5.5 mm diameter, available in carbon steel or austenitic stainless steel, and must resist all pullout, pullover and shear forces.

For compliance with non fragility requirements, fasteners should be positioned 50 mm minimum in from the deck sheet end.

Alternatively:-

• Shot fired pins may be installed into hot rolled steel sections, subject to minimum flange requirements, as specified by fastener manufacturer.
• Side lap stitching screws may be replaced with rivets, as specified by fastener manufacturer.

Decks are fixed to the support structure from above the deck. The table below indicates generic recommendations, which must be checked against specific project requirementsm especially for high wind suction loads, which may require more than one screw per trough, and reduced side lap centres when the deck acts in diaphragm.

(*) Fixing centres for side laps may be required to be reduced, subject to diaphragm design.
(**) D210 requires alignment cleats to prevent profile spread.

Where the deck is required to provide a vapour barrier, screws must be supplied with a sealing washer. If a separate vapour control membrane is installed above the deck, screws can be installed without washers.

Self drilling screws are primarily used, suitable up to specific support flange thickness specified by fastener manufacturers. Where flange thickness is greater, self tapping screws are required, installed into a pre drilled pilot hole.

Aluminium decking
for aluminium roof deckingm, the fastener frequency is the same as for steel decks. However to prevent bi-metallic corrosion, austenitic stainless steel screws must be installed. A simple site test to determine the grade of screw is to check with a magnet, as stainless steel screws are non magnetic.

Tubular support structure
Decks can be installed above tubular structure, however this requires special consideration.

• The bearing support will be minimal, thus increasing the bending and reaction moment over the support.
• Location of screws is more difficult, any deviation from the apex position could cause the screw to twist out of alignment.
• The sheet end will be visible, any deviation in panel length tolerance may indicate staggered sheet ends. Manufacturing tolerances on length allow + 10 mm / – 5 mm up to 3000 mm, and + 20 mm / – 5 mm for lengths over 3000 mm.

Therefore for tubular structure it is recommended that a flat plate is added, to provide a normal 100 mm minimum flat bearing support.

Timber support structure
Screw installation into timber taken from BS 5268:Part 2: 2000
Timber may be treated with preservatives that could have an adverse effect on carbon steel screws; therefore it is recommended that austenitic stainless steel screws are specified for installation into timber, ensuring a minimum embedment and minimum edge distances as indicated below.

The screw diameter may be taken as the screw root diameter.

Concrete support structure
It is not recommended to drill directly into concrete purlins, unless agreed satisfactory by a structural engineer. Straps can be added to connect a top hat section for the support and attachment of decking.

Masonary wall support structure
The level of masonary wall can not be guaranteed, therefore a steel section should be added to
support decking. This allows the deck to be fixed with standard Tec fasteners, or shot fired pins to a
suitable flange thickness.

For further information please do not hesitate to get in touch with our Technical Department at Tata Steel, E mail: roofdek@tatasteel.com

Projects featuring  RoofDek structural roof decking from Tata Steel have been recognised in category wins in The Roofing Awards 2012 – the National Federation of Roofing Contractors’ prestigious annual competition, recognising outstanding standards of workmanship and safety within the roofing industry.

Winning the Sustainable Roofs – Green Roofs category, Peacehaven Wastewater Treatment Works features approximately 18,000m2 of RoofDek D100 in Olive Green double-sided 0.9mm Colorcoat HPS200 Ultra®, as part of the green roof construction. Serving the Brighton and Hove catchment area, the £300 million state-of-the-art facility has the UK’s largest green roof of its kind and covers an area of almost two and a half football pitches.

Installed by Prater, the green roof is designed to absorb the plant into the rolling hills of the surrounding countryside and minimise impact on biodiversity through sustainable design.  The green roof provided an elegant solution to a decade of delays due to planning restrictions.

Peacehaven Wastewater Treatment Works also features the Tata Steel C19 Profile on the walls, also in Olive Green double-sided 0.9mm Colorcoat HPS200 Ultra®.

Please click here to view/download our comprehensive case study of the project.

Taking the spoils in the Flat Roofing – Reinforced Bituminous Membrane category, D.S. Smith Packaging’s Yorkshire facility features RoofDek D46 with a Brilliant White soffit finish, as part of a 9.900m2 refurbishment of an operational food packaging plant, suffering from a failed roofing system and a fragile original roof deck.
Work had to be undertaken while the factory was in full production and within a tight 14-week timescale, to be ready in time for incoming new equipment, worth millions of pounds.

Tata Steel RoofDek D100 structural roof decking was installed as part of an exciting and innovative green convex and concave curved roof construction at the new Maplefields School in Corby, built by Graham Construction for Northamptonshire County Council.

Designed by GSS Architecture, the new £15 million environmentally-friendly special school caters for pupils with learning and behavioural challenges. It comprises two buildings – the main school building and a sports hall, in addition to external play areas and a full synthetic pitch.

Maplefields has been built on the former Beanfields Secondary School site. It includes a primary and secondary school and a post-16 and diploma centre, providing vocational and sports facilities. The school can accommodate 65 staff and 110 pupils, aged 5-18.

The school’s roofs feature rainwater harvesting, high levels of thermal insulation, natural ventilation, green sedum roofs and solar thermal panels. A biofuel boiler supports an underfloor heating system. The project has also benefitted from extensive hard and soft landscaping and a habitat area.

The architecturally eye-catching curved roofs at Maplefields School presented a number of challenges.

The project is best described as three interlaced extensive sedum roofs, approximately 6000m2 in total, featuring broad curved sections, convex and concave, interspersed with aluminium standing seam roofs.

Approximately 3000m of curved fascias follow the waveform rooflines. A single-ply system, with tapered insulation and elliptical upstands, is installed on two atriums.

The school’s buildings comprise a main building with a central plant room, plus a sports hall.

The extensive curved sedum roofs and four of the standing seam roofs are located on the main building.

The sports hall has two standing seam roofs; a gentle concave/convex profile (S-shape on elevation) forms the main roof and the second roof is a convex profile. Designed by GSS Architecture, the decking on all buildings was specified as Tata Steel RoofDek D100 structural decking, in 1.2mm plain galvanised steel and in lengths from 8m to 15m.

Designed to accommodate the additional loadings imposed by green roof construction, RoofDek D100 features a 700mm cover width and a 233.3mm pitch. This provides a very strong deck and offers excellent insulation support. Its lightweight construction also minimises the load on the building structure.

A glass reinforced polyester solution was selected, to match the architect’s requirement for smooth fascias on the rooflines, where these were curved in elevation.

Proprietary GRP design and fabrication could achieve this without faceting, or shortened fascias, creating a radiused profile.

The roof build-up initially comprised two forms of RoofDek D100, ‘tek’-screwed to the primary steelwork, installed by Walter Watson.

Tata Steel RoofDek D100 perforated decking was installed where an acoustic performance was required on the sports hall and plant room roofs. This product includes perforated strips and is overlaid with an acoustic batt. Sound is absorbed when it passes through the perforations and is dissipated in the tissue-faced insulation batt.

Standard RoofDek D100 1.2mm galvanised deck was installed on all other roofs. This product lends itself to the requirements of a design curved in elevation.

The trapezoidal detail allows a degree of flexibility and is uncomplicated in its installation.

Where green roofs were installed, the build-up comprised of Tata Steel RoofDek D100, a vapour control layer, followed by 160mm PU insulation, then Bauder membranes, overlaid with an extensive green roof.

An upstand detail for the windcatchers and circular roof lights was also installed. The project’s six standing seam roofs were built up from the RoofDek D100, overlaid with a vapour control layer, over which halters were installed. Insulation is packed around these and the aluminium standing seam roof is then fixed to the halters.

The GRP rooflines (‘wave-form’ in elevation) were manufactured in two ‘arches’, concave and convex. These accommodated eight different radii. Jointing was effected utilising a specially developed lap jointing system.

The resulting construction achieved a lower cost than a metal alternative and offered superior detailing. There were only two small straight bullnose runs on the roofs in total, also manufactured in GRP.

Tata Steel has just released an upgrade to its popular free-of-charge roof decking software package that enables structural engineers and designers to carry out full deck analysis to achieve optimum design and cost efficiencies.

RoofDek Analysis Software is a partnership project with leading international developer CSC, best known for the very widely-adopted Fastrak, S-Frame and Tedds structural design software. It extends and enhances Tata Steel’s structural decking design software suite, which also includes ComFlor® Analysis Software for floor decking applications.

The latest software version contains a number of revisions and improvements. Key changes include the availability of enhanced deck illustrations, showing perforated and plain roof decks. Summary output has also been polished.

Support shear check results now include reduction factor and fastener specification and the user interface now allows up to two fixings per web on extended end laps. RoofDek D210 deep deck has been included for the first time, following successful testing to EC3.

RoofDek Analysis Software has been developed to assist structural engineers and other construction professionals involved in the design and specification of structural roof decking.

It brings software for deck design into the 21^st Century. Whereas earlier roof decking software has focused on a simple equation-based approach, RoofDek Analysis Software allows the user to carry out a full analysis and to fine tune decks in the same way as they can do with other components. It also completely satisfies the need to comply with Eurocode 3 Design of Steel Structures and Eurocode 9 – Design of Aluminium Structures, soon to be mandatory in the UK and useful throughout Europe and the rest of the World.

Users are able to input up to four spans, two of which can be cantilevers. Extended end laps can be included at internal supports. Thickness of deck can be varied each side of extended end laps. Default loads and load combinations are provided, however the user may input virtually any combination. Bending moment, shear, deflection diagrams plus full calculations to comply with Eurocodes 3 and 9 can all be output.

All input parameters and the extent of output are fully editable. The updated version of RoofDek Analysis Software can obtained here. Existing users will receive an auto-update.