Yes, a reputable waterproofer should always provide a written scope of work before starting — and you should insist on one. This document sets out exactly what will be done, what products will be used, and what the job will cost, protecting both parties if any disagreement arises later. In New Zealand, where weather-tightness failures have caused significant damage to homes over the decades, getting waterproofing right — and documented — is especially important.
What Is a Scope of Work?
A scope of work (sometimes called a works specification or job specification) is a written document prepared by the waterproofer before any work begins. It is separate from — but often attached to — the quote or contract. A good scope of work removes ambiguity and gives you a clear record of what was agreed.
What Should a Waterproofing Scope of Work Include?
A thorough scope of work for a waterproofing job should cover:
- Location and area — exactly which surfaces are being waterproofed (e.g. shower floor and walls to 1800 mm, balcony deck, wet area floor)
- Surface preparation — how the substrate will be cleaned, primed, or repaired before membrane application
- Membrane system — the specific product name, brand, and number of coats (e.g. a liquid-applied membrane from a recognised supplier)
- Upstands and flashings — how the membrane will be turned up at walls, around drains, and at penetrations
- Compliance standard — reference to the relevant NZ Building Code clause (commonly E3 Internal Moisture for wet areas, or E2 External Moisture for decks and balconies)
- Thickness or coverage rates — the dry film thickness or spread rate specified by the manufacturer
- Cure times — how long before tiling or other trades can follow on
- Warranty — what product and workmanship warranty applies, and for how long
- Price and payment terms — a fixed price or clear schedule of rates
- Consent requirements — whether a building consent is needed (wet area waterproofing in a new build or significant alteration often requires one; always confirm with your local council)
Why a Written Scope Matters in New Zealand
New Zealand has had well-documented issues with leaky buildings, and waterproofing is one of the most critical elements in preventing moisture damage. The MBIE Building Performance guidance makes clear that wet area and external waterproofing must meet the NZ Building Code. Without a written scope, there is no way to verify after the fact that the correct system was installed to the correct standard.
A written scope also helps you:
- Compare quotes fairly — you can see whether two waterproofers are quoting the same system or cutting corners
- Confirm code compliance — the scope should reference the applicable Building Code clause and any relevant NZ Standard
- Protect your warranty — most membrane manufacturers require correct installation for their product warranty to be valid; a scope records that the right product was specified
- Resolve disputes — if something goes wrong, you have a written record of what was agreed
BRANZ publishes guidance on wet area construction and waterproofing best practice that both homeowners and tradespeople can reference.
What Products Might Be Specified?
The scope should name the actual membrane system — not just a generic description. Well-known waterproofing systems used in NZ include products from Ardex, Mapei, and Sika, among others. Each manufacturer publishes a technical data sheet specifying coverage rates, number of coats, and cure times — a good waterproofer will follow these and reference them in the scope.
Red Flags to Watch For
Be cautious if a waterproofer:
- Provides only a verbal quote with no written detail
- Cannot name the specific membrane product they will use
- Does not mention upstands, flashings, or drain details
- Skips any mention of surface preparation
- Offers no workmanship warranty
- Pressures you to start immediately without paperwork
Building Consent and Licensed Building Practitioners
Some waterproofing work requires a building consent — particularly in new builds, significant alterations, or where the work affects the weathertightness of the building envelope. Schedule 1 of the Building Act lists certain exemptions, but these have limits; always check with your local council before assuming consent is not needed.
Where a building consent is required, the work may need to be carried out or supervised by a Licensed Building Practitioner (LBP). Ask your waterproofer whether they hold an LBP licence and in which category — this is a reasonable and important question.
When to Call a Professional
Waterproofing is not a DIY-friendly trade. Membrane systems must be applied correctly to achieve the required film thickness and continuity, particularly at corners, penetrations, and junctions — the spots most likely to fail. A poorly waterproofed shower or balcony can cause hidden structural damage that costs far more to fix than the original job.
Always hire a qualified, experienced waterproofer for any wet area or external deck waterproofing. You can find local waterproofing professionals on tradedirectory.co.nz. Ask to see examples of previous work, check whether they hold an LBP licence if relevant, and always request a written scope of work before signing anything.
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SiteWise
Licensed Building Practitioner (LBP)
