BUILDING WITH STEEL

General

General

general

Ready to build your next project with steel?

Submit your building plan and details (floor layout, elevations, and room dimensions) to your local NASH frame supplier. From the plan, your supplier will be able to quote and supply all the necessary components like brackets and fasteners.

For supply of light steel framing for commercial projects, or for dwellings with unusual requirements, it is advisable to discuss the complete building specifications with the frame supplier. Light steel framing manufacturers have developed their own unique systems, each with its particular features.  Because steel framing is an engineered product it is important to adhere strictly to the supplier’s instructions .

To find your local NASH member, click here.

 

Structure

Structure

Steel framing structure

Floor Construction

Steel sub-flooring systems are generally supplied with their own specific installation instructions. Instructions should be followed in every detail.

Steel framing can be installed on other types of flooring systems including concrete and timber.

Steel Wall Framing – Installation

Prefabricated steel wall framing is generally installed using the same techniques and sequence as timber framing.

The general procedure is:

  • The wall layout is marked on the floor using straight lines.
  • Squareness is checked by accurately measuring diagonals in large areas of the house first, then individual rooms.
  • Internal wall frames are stacked inside the room areas and external walls around the perimeter with their bottom plates adjacent to their final positions foundations.
  • Starting at any convenient external corner stand and plumb a wall frame panel in its exact position.
  • Stand and plumb an adjoining frame at right angles to make a self-supporting corner.
  • Clamp the frames together and check again that both frames are in their exact locations and standing vertical.
  • Connect the frames using the manufacturers recommended method – nails, screws, brackets, bolts or rivets.
  • Proceed with the installation of the frames around the house, standing internal and external frames as they occur.
  • The line of top plates in a run of walling should be checked with a string and temporary propping installed to keep them straight. Any misalignment must be corrected before loads are placed on the wall framing.
  • In most cases, props provide adequate temporary bracing during wall frame installation, and should be left in place until the permanent bracing is installed.

Check with your manufacturer and refer to the manufacturer’s installation guide.

Steel Wall Framing – Anchoring

Steel framing is fastened to the floor structure through the channel bottom plate after all panels have been aligned and plumbed.

Exact recommendations for the type, number and location of anchors should be supplied by the frame supplier or noted in the engineering specifications.

Concrete Floors

For concrete floor slabs the frame is fixed in place by using masonry anchors, generally hammer-driven concrete nails, expanding shell anchors or chemical anchors.

Steel Floors

With steel floor framing the bottom plate of the wall frames can be screwed to the joists with self-drilling screws.

Timber Floors

Wall frames are fixed to traditional timber floor framing at the ends of each frame and adjacent to the bracing with self-drilling screws which can drill through the steel bottom plate.

Bracing Systems

For advice and a design spreadsheet for Bracing Systems that have been developed by NASH and Winstone Wallboards visit www.gib.co.nz and search for GIB® EzyBraceTM FP-NASH. This is a wall bracing design spreadsheet intended for use with steel framed housing constructed within the design scope of NZS 3604.

Roof Framing

Prefabricated steel roof framing is suitable for spans up to approximately 16 metres.

For long spans using raked ceilings, lightweight high-tensile steel purlin sections are suitable.

Depending on the supplier’s recommendations, roof framing systems can be fixed directly to the wall frame.

Truss spacing can range from 600mm to 1200mm centres.

Roof Battens

Lightweight steel roof battens remain straight indefinitely. This is particularly important when some of the almost flat shingle-type tiles are used, as these tend to emphasise incorrect alignment.

Roof battens can be lapped rather than butt-joined at a rafter.

Steel battens are suitable for use with all types of roof framing.

Tiled Roofing

For tiled roofing, tile battens are usually fixed to the trusses over reflective foil laminate with self-drilling screws. Roof tiles are secured to steel battens in accordance with manufacturers’ instructions.

Longrun Roofing

For longrun roofing, the battens are normally fixed directly to the trusses or rafters and insulation blanket placed over the battens before installation of roof sheeting

Stainless Steel Fasteners

Please refer to the NASH Handbook and Standard Residential and Low-rise Steel Framing, Part 1 Design Criteria for advice on fasteners for light steel framing. More information about fasteners can be found here.

Building Wraps and Steel Frames

Please refer to the NASH Handbook and Standard Residential and Low-rise Steel Framing, Part 1 Design Criteria for advice on building wraps for light steel framing.

Enclosure

Enclosure

Steel framing - enclosure

External Wall Cladding

External wall claddings should attached in accordance with manufacturers specification.

Brickties are normally screwed to the face of each stud at spacings specified in the building code. Depending on the wall frame system used, wire brick ties which clip on to steel stud flanges may be available for brick veneer construction.

For lightweight cladding, the building code requires a thermal break such as a 12mm expanded polystyrene strip (EPS) be fixed to the outer stud face to reduce heat transfer across the wall system. See NASH publication N11.

Interior

Interior

Steel framing - interior

Ceilings

Ceiling battens are fixed to the underside of the bottom chord of roof trusses, rafters or intermediate floor joists.

Plasterboard ceiling lining is fixed to the steel battens or furring channels.

Internal Wall Lining

Plasterboard wall linings are fixed with bugle head self-drilling screws and standard stud adhesive.

Plasterboard screws can be tightened to finish slightly below the surface of the plasterboard without damaging the paper facing.

In wet areas, water resistant plasterboard or fibre cement sheet is fixed with self-embedding head screws. Flashing and tiling are done in the usual manner.

Prefinished wall linings may be glued to steel studs with a wallboard adhesive and braced in place until bonded.

Architraves, Skirtings and Mouldings

Timber trim that may need to be fixed through the linings into a steel frame can be secured with countersunk head extended point self-drilling screws, 50mm long for timber up to 23 mm thick and 65mm long for timber 23 to 30mm thick.

Manufacturers’ recommendations should be followed at all times.

Services

Services

Steel framing - Services

For more information about services, see video tips.

Plumbing

All light steel framing systems have pre-punched service holes provided in the wall studs.  All manufactures should fit grommets in service holes to protect services. Grommets are snapped into the service holes before piping is installed to support pipework and to prevent unwanted frame contact. All service holes  must be positioned close to the centreline of each stud.

Copper piping must be completely isolated from the steel frame.

In brick veneer construction, piping may be run in the cavity and fixed to the studs.

Wiring

All holes for services must be protected by grommets.

Steel frames must be permanently earthed in accordance with local electrical requirements. A temporary earth should be established until a permanent earth is installed.

External Door and Window Frames

The same door and window frames used in timber-framed construction are also used in steel-framed construction.

Aluminium window frames fitted into timber can be installed by fastening through the jamb studs into the back of the reveal after positioning.

If it is not possible to secret-fix the frame, as may be the case with a window or door head, countersunk head self-drilling screws can be driven through the frame and packing into the steel framing. The same type of screws may also be used to fasten aluminium window frames direct to steel frame openings.

Internal Door Frames

Timber door frames in internal walls can be secret-fixed through the back of jamb studs with screws.

Alternatively, the frame may be fastened through the jamb into the studs with countersunk head self-drilling screws.