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Screws

A screw is a cylindrical fastener that often tapers to a point at one end and has a helical ridge or thread formed on it that wraps around the shaft. The head at the other end is shaped so it can be rotated by some means. In timber construction, the screw thread forms a thread in the timber as it is driven in. Timber screws often have a cutting tip that forms a hole in the timber, negating the need to pre-drill a hole.

Screws can be used for timber to timber fixings or for fixing a fastener to timber (typically steel to timber).

Screws are also used for fixing sheet materials to timber framing, such as plasterboard to wall framing and particleboard to floor joists.

The benefit of screws over nails is that not only shear loads can be transferred but the thread provides axial load transfer or a clamping action, and the screw can be easily removed later if necessary.

Development of self drilling screws, new screw heads and access to portable mechanical driving devices enable fast and efficient insertion of screws and has resulted in a resurgence in the use of screws in recent years.

 

Screw fixing to steel plate in architectural truss

Source: Courtesy MiTek

 

Availability

Screws are available throughout New Zealand from building supply stores.

See Vendors Database

 

Key points

  • Screws are threaded fasteners that can be used for fixing timber to timber or steel brackets or sheet materials to timber.
  • The threads in screws allow shear and axial loads to be transferred.
  • Self-drilling screws, new screw heads and access to portable drills/drivers have caused a resurgence in the use of screws.

Source: Courtesy MiTek