How To Select The Correct Fastener Type & Length

 

 

 

How To Select The Correct Fastener Type & Length

 

  1. Determine whether the fasteners are going to be used for crest fixing or concealed fixing.

v  For concealed fixing use a wafer head self drilling screw on Brownbuilt and Kliplock. (Make allowances for insulation material)

v  For KingKlip; Saflock; and Kraftlock wafer head or hex head self drilling screws can be used. (Make allowances for insulation material)

 

Concealed Fixing View

  1. When crest fixing determine the profile height of the sheeting to be fixed.

v  2.1     I.B.R. Profile = 38mm

v  2.2     Corrugated iron profile = 19mm

 

Crest and Valley Fixing

Crest vs Valley Fixing

  1. Add the compressed thickness of any insulation material to the profile height.
  1. Establish whether the sheeting is to be fixed onto timber or steel.
  1. If fixed to timber add a minimum of 30mm to the figure obtained in 3. above, to calculate the required fastener length.
  2. Use a Type 17 self-drilling screw (preferred) or a self-tapping roofing screw (not preferred).
  3. If fixed to steel purlins, determine the thickness of the purlins.
  4. For cold rolled purlins up to 4mm thick use:

v  A self-drilling screw with a no. 3 drill point

v  A self-tapping roofing screw in a pre-drilled hole (5.5mm Dia.)

  1. For hot rolled purlins from 4mm up to 12.5mm use:

v  A self drilling screw with a no. 5 drill point (Super Teks Series 500)

v  A self-tapping roofing screw in a pre-drilled hole (5.8mm Dia.)

  1. The minimum screw length for a self-drilling screw is calculated by adding the figure obtained in 2. above, the purlin thickness, the length of the drill point and 6mm for penetration through the purlin.
  2. The minimum screw length for a self-tapping screw is calculated by adding the figure obtained in 2. above, the purlin thickness and 15mm for penetration through the purlin.