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® EzyBrace® or click here. 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.
