All Plumbers, Electricians and Builders
Too often, Building Inspectors are finding that people, most often plumbers and electricians, are drilling or notching floor joists, rafters, purlins, etc, in a manner that is contrary to that permitted in the NZ Building Code.
Clause 7.1.7 of NZS 3604:1999 “Code of Practice for Light Timber Framed Buildings” sets out the approved manner in which floor joists may be drilled or notched. NZS 3604 is an acceptable solution for building methods under the NZ Building Code.
7.1.7 Holes and Notches in Floor Joists
7.1.7.1 Holes drilled in floor joists other than cantilevered joists shall:
- Be within the middle third of the depth of the joist; and
- Be not more than three times the depth of the joist from the face of a support.
5.1.7.2 Notches in floor joists other than cantilevered joists shall not be more than 450mm from the face of a support;
Provided that notches that do not reduce the effective depth of a joist to less than the minimum depth required by Table 7.1 for the joist span concerned shall be permitted in any position (see 7.8.).
7.1.7.3 Holes and notches shall be:
- Not more in diameter or depth than one-fifth the depth of the joist or 32mm, whichever is the lesser;
- Be at minimum spacing measured along the joist between the edges of the holes or notches of not less than the depth of the joist”.
The same criteria are to be used for rafters and purlins.
Would you therefore ensure that you and/or your staff are fully conversant with the above.
Remember: The builder and/or owner could charge you with any costs involved in rectifying problems arising from faulty drilling or notching.
Fig 5.8- Holes & Notches in Floor Joists other than Canterilevered Joists
For further information:
Telephone: (07) 885 0772 or Fax: (07) 885 0799
Or see below for more contact details.
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