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Warning

Punching additional holes 

Whilst your steel frame comes with ample pre-punched holes, at times you may need to add additional holes.  There are various tools available and today we'll look at hand punches.

Before making additional holes consult the NASH design handbook to ensure correct spacing and size of holes.

A grommet should then be used to protect the cabling from the unflared edge.

Punching a New Hole

There are ample service holes in Light Gauge Steel (LGS) frames, however, if additional service holes are required in wall studs, they should be:

  • no larger than existing holes or as per NASH Part 2 Table 3.1
  • no more closely spaced than shown in the figure below
  • placed as close as possible to the centreline of the stud or less than D/10 centre offset
  • if a larger service hole is needed seek approval from the frame fabricator
NASH recommendation for location of new service holes

A grommet should be inserted in the hole to protect future services from the sharp edges. Common hole sizes for grommets are 28mm,32mm and 34mm. Other sizes are used, but please check with the frame manufacturer before commencing work.

Prepunched service hole in LGS with grommet

NASH recommends that hole sizes comply with the following diagrams. Always check with the frame fabricator prior to making service holes in beams.

shows suggested floor beam penetration details, and placement of service holes in LGS C section joists showing hole position and diameter relative to section depth, while meeting design standards.

There are three main ways of creating additional holes:

Using a hole saw or carbide-tipped saw 

TIP: If using a saw, pre-drill the hole (the same size used in the hole saw) as this prolongs the tool life and allows you to use a lower speed when you contact the steel frame with the hole saw.

Tools to cut holes in LGS

Using a hydraulic or hand hole punch

Hole Punch

Or using a stepped drill bit

step drill bit

NASH recommends the following hole layout for specific services.

recommended maximum density of holes, without reference to the manufacturer.