The Design Process

Once detailing is completed, a set of assembly plans is printed showing how and where each component part is connected to make a completed frame. In addition, a second set of drawings is printed which will be used by carpenters to install on-site.

Finally, the files are sent to the manufacturing equipment which automatically rolls each individual element for all frames.  Each part is pre-numbered and cross-referenced to the assembly plan to ensure correct assembly into a wall panel or roof truss.   Common systems used in Australia to complete this work include:

• ENDUROFRAME® Building System
• FRAMECAD
• Scottsdale Construction Systems
• Supaloc Steel Building Systems
• Vertex CAD/CAM Systems and Howick
• Vertex CAD/CAM Systems and Stoddart

Factory staff use the assembly drawings to screw each element into the final frame.  

Frames are stacked at the factory until needed at the site.

Note that frame manufacturers must meet compliance requirements relating to the strength of screws used for assembling frames in the factory including minimum design capacities and pull out capacities.  Self-tapping screws (generally hex head or #3 phillips head or special star drive) are increasingly being used by frame manufacturers where holes are pre punched in the factory setting and therefore a higher level of accuracy can be achieved. 

NASH also provides guidance on coating classes for durability of screws.

It is worth noting that components can also be disassembled by simply unscrewing or drilling out the connection. This may be necessary if a component is:

• damaged on-site or during transport
• a design alteration is made after assembly
• a large service needs to be accommodated.

Replacing factory assembly fasteners should be done under guidance from the frame fabricators to ensure that the frame connection engineering is maintained.

Steel clearly identified by product designation marking, as required by AS1397, promotes efficient, error-free fabrication and can assist on-site verification that the supply meets the requirements of the NCC. This is the simplest and most reliable manufacturing path, minimising the risk of a non-compliant and potentially unsound structure.

AS 1397 is the standard relevant to metallic coated steel used in residential and low-rise construction, or as we have been referring to it: LGS framing. AS 1397 includes test procedures for all critical properties; markings on packaging of steel and markings on the steel itself.

Markings required on the steel coil itself include the following elements:

• the Australian Standard number i.e. AS 1397
• the base metal thickness (BMT)
• steel base designation (eg G550), and
• the coating class (eg AM150) and surface finish (where applicable)

Unmarked steel is a risk because:

• it may be made to another standard
• test certificates may not be sufficient or relevant

These will vary from supplier to supplier. Product markings on strapped packs and sometimes on individual items, identify the frame manufacturer and support verification of compliance of material with relevant design standard(s).

Typically, fabricated parts for LGS frames are coded with information to assist fabricators and erectors in the assembly and installation process. This matches the part information shown on the fabrication drawings and the frame number shown on the site assembly drawings.

As an example, the following information refers to parts produced in ENDUROFRAME® and are coded in the following order:

• Job Id
• Frame Number
• Part Number
• Part Usage

In the below example, the job id is “office_sample”, wall is "W005" and "107" is the part number. (Note the Stud-10933 relates to the component and the size, however not all fabricators provide this)

In the factory, the fabrication crew uses this information for wall frame and truss assembly. On the site, the frame erection crew can use the same information to identify what the assembly is (“Frame Number”) and where it is intended to be used in the structure.

Different frame suppliers may use slightly different marking systems, but they should all be able to relate the wall frames and roof trusses to the site erection plans supplied.

In the factory, the fabrication crew uses this information for wall frame and truss assembly. On the site, the frame erection crew can use the same information to identify what the assembly is (“Frame Number”) and where it is intended to be used in the structure.

Different frame suppliers may use slightly different marking systems, but they should all be able to relate the wall frames and roof trusses to the site erection plans supplied.