Why waterproofing quotes are worth comparing carefully
Waterproofing is one of those jobs that can look straightforward on paper but become expensive very quickly if it is not specified properly. A shower, bathroom, deck, balcony or retaining wall may all need different products, preparation and workmanship standards. If you compare quotes only on price, you can end up paying twice: once for the original job, and again to fix leaks, failed membranes or poor detailing.
In New Zealand, waterproofing also sits alongside other rules and trade responsibilities. Some jobs may involve building consent, especially when part of a larger alteration or new build. If the work affects plumbing, drainage or electrical components, those parts must be handled by appropriately authorised tradespeople. A good waterproofing quote should make clear what is included, what is excluded, and who is responsible for each part of the job.
Start by describing the job clearly
The quality of the quotes you receive depends heavily on the information you give. Before you contact anyone, write down a simple job brief that includes:
- The location: bathroom, shower, laundry, deck, roof, planter box, basement, retaining wall or other area - The approximate size in square metres or linear metres - Whether it is a new build, renovation, repair or leak investigation - The surface type: concrete slab, fibre-cement, plywood, plasterboard, existing tiles, timber framing or masonry - Whether old finishes need to be removed first - Whether there is known damage, movement, mould or water ingress - Whether the area will need to remain usable during the work - Any council, body corporate or insurance requirements
If possible, include photos, a rough sketch and measurements. For bathroom or shower work, a few clear photos of the substrate, corners, waste, hob, junctions and any damaged areas can help the waterproofer quote more accurately. For outdoor jobs, mention the site exposure, access, drainage and whether the work will be affected by weather.
What to ask for when requesting quotes
A professional quote request should make it easy for the trade to price the same scope of work each time. Ask for a written quote that covers:
- The exact areas to be waterproofed - The preparation required before membrane application - The waterproofing system or product to be used - How many coats or layers are included - The warranty offered and any conditions - Whether labour, materials, travel and GST are included - Whether they will remove and replace tiles, flooring, fixtures or finishes - Who will handle any associated plumbing, drainage, building or tiling work - An estimated start date and programme - Any assumptions, exclusions or provisional items
It is usually best to request at least three written quotes from people who regularly do waterproofing work in the same type of setting as yours. A bathroom membrane specialist is not automatically the best fit for a large deck, and someone who mainly does exterior membranes may not be the right choice for a small tiled shower.
What a good waterproofer quote should include
A proper quote should read like a scope of work, not just a number. The more detail it contains, the easier it is to compare fairly.
| Item | What to look for | Why it matters | |---|---|---| | Scope | Exact rooms or surfaces, with measurements | Prevents disputes over what is included | | Preparation | Substrate repairs, sanding, cleaning, priming, removal of old membrane | Preparation often makes or breaks a waterproofing job | | System | Brand or type of membrane, primer, reinforcement tape, sealants | Different systems suit different substrates and exposure | | Method | Number of coats, detailing at corners, junctions and penetrations | Weak detailing is a common cause of leaks | | Labour and materials | Clear breakdown or at least confirmation they are included | Helps you compare like-for-like pricing | | Exclusions | Tiles, plumbing, joinery, painting, rubbish removal, scaffolding | Avoids surprise extras later | | Timeframe | Start date, duration, drying/curing time | Waterproofing often needs cure times before finishing work | | Compliance | Consent requirements, producer statements, warranties if relevant | Important for larger or more complex projects | | GST | Whether the price is plus GST or GST-inclusive | Prevents nasty surprises when comparing totals |
A strong quote will also identify the substrate condition. If the contractor has inspected the site and noticed movement, rot, cracking, poor falls or moisture damage, they should say so. Waterproofing over an unstable or wet substrate is a false economy.
Fixed price vs charge-up: which is better?
Waterproofing quotes in New Zealand are usually offered in one of two ways: fixed price or charge-up.
Fixed price
A fixed-price quote gives you a set total for a clearly defined job. This is often the safest option for homeowners because it makes budgeting easier.
Best for:
- Standard bathroom or shower waterproofing - Clearly scoped deck or balcony membrane work - Jobs where access and substrate condition are known
Watch for:
- Vague wording like “subject to site conditions” without detail - Too many exclusions that shift the real cost back onto you - Missing allowances for prep, waste removal or follow-on work
Charge-up
Charge-up means you pay for actual labour and materials used, usually at an hourly rate plus materials. This can suit repair work where the problem is hidden and the scope is uncertain.
Best for:
- Leak investigations - Remedial work where the extent of damage is not yet known - Jobs involving unknown substrate issues or concealed defects
Watch for:
- No cap or estimate range - Poor communication about hours, materials and progress - “Open-ended” jobs that can drift well beyond your budget
If a contractor proposes charge-up, ask for an estimate range, a trigger point for review and written approval before any extra work outside the original scope. For most homeowners, a fixed price with well-defined inclusions is easier to compare and manage.
How to compare quotes fairly
The cheapest quote is not necessarily the best value, especially for waterproofing where failure can cause hidden damage for years. To compare fairly, line each quote up against the same checklist.
Look at:
- Scope: Are they quoting the same rooms, areas and prep work? - Materials: Is the membrane system comparable in quality and suitability? - Experience: Have they quoted similar jobs before? - Included work: Are tiling removal, substrate repairs or sealing included? - Warranty: Is it in writing, and what does it actually cover? - Timing: Can they start when you need them to, especially in wetter months? - Communication: Did they inspect the site properly and answer your questions clearly?
A quote that is $1,000 cheaper may simply be missing important items such as primer, reinforcement at joints, or enough labour for proper prep and cure time. It may also assume a perfect substrate when your actual job needs repairs first.
Spotting a quote that is too cheap
An unusually low quote can be a warning sign, not a bargain. In waterproofing, being underpriced often means something has been left out.
Common red flags include:
- A price that is far below the others with no clear explanation - No site visit before quoting, even for a complex job - No mention of substrate preparation or repairs - No product details or vague wording like “standard membrane” - No GST stated - No warranty or a warranty with lots of exclusions - Pressure to pay a large deposit before materials are ordered - A contractor who is reluctant to put the scope in writing - A quote that says “waterproofing only” but ignores corners, penetrations, upstands or junctions
A too-cheap quote may also reflect unrealistic allowances for drying time. In New Zealand’s cooler, wetter months, membranes and substrates can take longer to dry and cure. Rushing this stage can compromise adhesion and long-term performance.
Check credentials before you commit
For waterproofing, the right qualification depends on the wider job. It is sensible to check:
- Business details and references from recent local jobs - Public liability insurance - Whether the person has experience with the specific system being proposed - Whether any related plumbing, drainage or electrical work will be done by appropriately licensed people where required - Whether the work may need building consent or sign-off from your local council
Not all waterproofing itself is a licensed trade in New Zealand, but the surrounding work can be regulated. Plumbing, gasfitting and drainlaying are restricted work under the Plumbers, Gasfitters and Drainlayers Board, and electrical work is regulated by the Electrical Workers Registration Board. If your job includes moving a shower waste, altering plumbing, or working near electrical fittings, those parts must be handled correctly.
For larger projects, ask how the contractor documents the job. Good records can help if you later need to prove what products were used, what the substrate condition was, or what warranty applies.
Ask about councils, consents and downstream trades
A quote should not be isolated from the rest of the project. If waterproofing is part of a renovation, new bathroom or deck, the contractor should explain any coordination needed with:
- Builders or tilers - Plumbers and drainlayers - Electricians - The local council or building consent process
Some bathroom renovations may need consent depending on the scope of structural changes, plumbing alterations or wet-area design. Exterior waterproofing on decks, balconies or other building work may also need consent or engineering input. If the contractor cannot explain this at all, you may need to seek advice from your council or a licensed building practitioner involved in the project.
Questions to ask before you accept a quote
Before you sign, ask these practical questions:
- What exactly will you remove, prepare, waterproof and finish? - Which membrane system will you use, and why is it suitable here? - What substrate repairs are assumed, and what happens if more damage is found? - How long will the job take, including curing or drying time? - What does the warranty cover, and what voids it? - Will you give me photos during the job for records? - Are you quoting GST-inclusive? - What counts as a variation, and how will extra work be approved?
If the contractor answers clearly and in writing, that is usually a good sign. If the answers are vague, it is reasonable to keep looking.
The best quote is the one you can understand
For homeowners, a good waterproofing quote is not just competitive — it is specific, transparent and realistic. It should tell you what is being waterproofed, how the job will be done, what is included, what might cost extra, and who is responsible for the related trades.
Compare at least three written quotes, check the fine print, and be cautious of prices that look too low for the amount of preparation and detail the job really needs. Waterproofing done properly is rarely the cheapest quote on the page, but it is often the cheapest outcome in the long run.