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*ARCHIVE* - E3 internal moisture - comment sought - 29 Aug 2002

Proposed changes to New Zealand Building Code Clause E3 "Internal moisture" and its associated Approved Document have been released for public comment. Comments close on Friday 11 October 2002.

The three key proposed changes to the code clause are:

1 Protection of other property

The current code clause is written in such a way that only household units within the same building are protected. There is now a trend with inner city developments to convert office or retail space into household units. A common scenario is to have retail and/or office accommodation on the lower levels of a building with household units on the upper levels. The current code does not offer any protection to the occupancies that are not household units.

For example water damage to electronic equipment can be significant, therefore, it is felt that a need exists to amend the code in such a way that will offer protection to occupancies within the same building other than household units.

2 Inclusion of sanitary appliances

The current code clause refers to sanitary fixtures or laundering facilities. Dish washing facilities are deemed excluded by way of definition. Dishwashers can overflow and do fail resulting in the presence of free water in much the same way that sanitary fixtures and laundering facilities may overflow or fail. With these appliances frequently in the same space there is no good reason why any one should be excluded.

Introducing the defined term "sanitary appliances" overcomes this issue.

3 Introduction of heat

The essence of E3 "Internal moisture" is to avoid fungal growth (mould) in buildings. The current code only talks about an adequate combination of thermal resistance and ventilation to avoid mould growth. Space temperature or heat also plays an important role in controlling mould growth. (Currently only old people's homes and early childhood centres have any code requirements regarding heating.) The introduction of heat will provide for greater effectiveness in avoiding mould growth as well as providing heat to household units.

Currently there is no Verification Method for E3 "Internal Moisture". A Verification Method has been developed from a recent report commissioned by the Authority.

The proposed Verification Method will provide designers with a tool to calculate, using nomograms, the ventilation rate required, given the heating level and thermal resistance of the building, to avoid mould growth. The level of heating can also be obtained using the Verification Method.

The Acceptable Solution contains some proposed changes, which are:

  • Paragraph 1.0 is amended to better describe the intention of the Acceptable Solution.
  • Paragraph 2.0 is amended to talk about free water as opposed to water present only by accident.
  • A new paragraph has been added to cover the moisture transfer and heat build up caused by recessed luminaires (down lights).
  • Figures 3 and 4 contain minor amendments to reflect current practice.

Draft for comment approved document, E3 Internal Moisture [Word, 1.05Mb, 41 pages]

Figure 3: Baths, basins, tubs and sinks, joints against wall linings [PDF, 48Kb, 1 page]

Figure 4: Shower trays and Figure 5: Wall and floor coverings to unenclosed showers [PDF, 329Kb, 1 page]