Choosing and collecting mould samples

Start with the distinct patches you want information about. Different materials, separate areas of growth or different wetting histories are useful reasons to consider separate samples. You can record several spots in one room; you do not have to sample every room.

Keep each chosen spot separate so the laboratory can report on it individually. The kit planner supports one to 100 samples, with a custom enquiry for larger quantities. The number is your choice, guided by the locations you want investigated and any recipient’s collection requirements.

Usually, where they are distinct patches or have different materials or moisture histories.

Consider a lower wall, skirting or plasterboard affected by a prolonged leak, and a ceiling where condensation has been reported. These are distinct materials or moisture histories, so separately labelled samples let you compare the findings without assuming one result describes both.

Different moisture conditions can support different moulds, but the same mould may occur in both places and several types may share a patch. Position and appearance cannot establish the type or confirm the moisture cause. BRANZ research describes associations between mould growth and different wetting conditions (opens in a new tab).

Record the property address once, then give each sample its own room and exact position. For example: “Laundry, skirting below the window” and “Laundry, ceiling above the tub”. The kit delivery address can be different from the sampled property.

• Surface material, approximate patch size and visible appearance.
• When you first noticed it and whether it has returned after cleaning.
• Known leaks, dampness, condensation, repairs or recent treatment.
• A wider location photograph and a close view, if you wish.

“Not sure” is fine. Photos are optional and help locate growth; they do not identify mould species. Keep private health or dispute details out of photographs and observations. Make your sample-location plan →

Use the sample lifters supplied with your kit and follow the included collection, labelling, packaging and return instructions. This guide helps you plan your samples; it does not replace those instructions.

Do not combine different spots into one sample. Match each sample number, using the kit reference followed by /1 or /2, to its location record and paperwork. Record the collection date and collector. Follow the kit instructions for where to place the label and how to package and return the sample.

If someone needs a particular sampling method or report, check that before collecting. You can tell us the requirement without explaining the underlying circumstances. See the documentation checklist →

Do not open walls, cut material or climb unsafely to collect a sample. If a spot is unsafe or difficult to reach, ask a local builder or suitably qualified tradesperson for assistance. Ask us about the collection method before sampling damaged timber or crumbling board.

A surface mould result does not establish the extent of timber decay or whether timber remains sound. Suspected rot or structural deterioration needs a separate building assessment. MBIE explains the investigation of damaged timber (opens in a new tab).

Our mould-testing service is a DIY postal kit for New Zealand addresses, including rural properties. You collect and label the samples using the instructions supplied for your confirmed kit.

A surface sample collects material from a chosen patch for laboratory examination. Air sampling collects airborne material using a different method and a sampling plan. The postal kit is for surface samples; it does not measure room air or locate concealed growth.

Identification may be to a mould group or genus rather than an exact species. A result describes the submitted sample, not the entire property, structural condition or someone’s health.

You can choose surface tests and enquire separately about a wider moisture investigation or professional air testing. Plan your DIY surface samples →