Is it reasonable to ask all of these of a contractor quoting a small domestic job?

Yes, and it takes about ten minutes. The four diagnosis questions matter on any job of any size, because they determine whether the repair is aimed at the right thing. The method and scope questions matter wherever more than one quote is being compared. On a very small job some of the scope questions collapse into one — is that the whole price, and what is not in it — but nothing on the list is unreasonable to ask somebody who is about to drill into a building.

What if all three quotes fail these questions?

That is a common and informative outcome, and it usually means the diagnosis has not been done by anybody. The productive next step is to pay for the diagnosis separately rather than collecting a fourth quote. A diagnostic investigation with moisture readings, crack monitors installed and read, water testing and a written report sits in the range of $450 to $1,500 — cheap relative to a repair aimed at the wrong cause, and it converts three incomparable quotes into three prices for a defined scope.

A contractor says the cheapest quote must be cutting corners. Is that fair?

Sometimes, and it is testable rather than a matter of opinion. In this trade the cheapest quote is usually cheaper for three specific reasons in combination: surface ports glued to the face instead of drilled mechanical packers, one attendance instead of two (which means either the packers come out before 24 hours or there is no making good), and no verification documentation. Put those three questions to the cheapest tenderer directly. If the answers confirm it, the quote is not cheap — it is for a different job.

Should the contractor who diagnosed the problem be allowed to quote the repair?

There is a genuine tension there, and it is manageable rather than disqualifying. A contractor who investigates and then quotes the cure has an incentive to find a cure they sell. What controls it is that the diagnosis is written down and testable: which paths were found, how each was established, and what was ruled out. A report specific enough for another contractor to price from is a report that can be checked. Where the amounts are large or the building is in dispute, an independent consultant who does no rectification work removes the tension entirely.

How long should be allowed between issuing a scope and awarding?

Long enough for the tenderers to attend the site, which is the step that produces useful quotes. A quote produced without an attendance is priced off assumptions, and assumptions are what turn into variations. For a strata job there is a second constraint: the committee’s own spending limit and the type of resolution needed to approve works of a given value depend on the regulation module the scheme is registered under, so the approval path should be confirmed with the strata manager before the tender goes out rather than after the quotes arrive.

Is a longer warranty a good reason to choose one quote over another?

Rarely, on its own. Term length is the easiest thing in a quote to extend and the hardest to enforce, and two of the numbers commonly quoted are not the same promise — a product warranty from the resin manufacturer typically covers the material rather than its installation, and a workmanship warranty comes from the contractor. What is worth comparing is the document itself: what it covers, what it excludes, who is standing behind it, and whether the contractor is still likely to exist when it is called on. A contractor who can produce the document on request is telling you more than the number in it does.

Guide

Twelve questions to ask before accepting a waterproofing quote

Updated 25 August 2026

Three quotes for the same leaking wall routinely arrive with three different numbers, three different methods and three different scopes, and no obvious way to tell which is the outlier. The price spread is rarely the useful signal. What separates them is whether the contractor established the cause before pricing the cure.

The questions below are designed to surface that. Each is answerable in a sentence by somebody who has done the diagnosis, and each produces a recognisable kind of evasion from somebody who has not. They apply to any contractor quoting water ingress work, in any state.

Asking all twelve of every tenderer is not adversarial and it is not unusual. It is the only way to compare quotes that describe different work, and a contractor who is confident in their scope will answer them without friction.

Questions about the diagnosis

These four matter most, because everything downstream depends on the cause being right. A repair executed perfectly on the wrong diagnosis still fails.

Where is the water getting in, and how did you establish that?The crack that is visible is very often not the entry point — water tracks laterally between a membrane and the concrete, or between a slab and its topping, and exits at the weakest point, sometimes metres away. A good answer describes an observation: inspected after rain, dye traced, moisture mapped. A weak answer describes the symptom back to you.
What did you rule out, and how?Naming what was excluded is what turns an opinion into a diagnosis. Drainage, a leaking service that can be pressure-tested, condensation, membrane failure and structural movement should each have been considered. A contractor who ruled out nothing has not diagnosed anything.
Have you seen it during or shortly after rain?A wall inspected in a dry week can look almost dry and still be a genuine hydrostatic leak, because the mechanism runs days after the weather that caused it. Timing the inspection to the weather is worth more than any instrument, and it is the step most often skipped for scheduling reasons.
Is the drainage working, and did you check it?Blocked or absent subsoil drains, weep holes rendered over during a repaint, a driveway falling toward the building, a downpipe discharging at the footing. These are the actual cause behind a very large share of enquiries, and clearing them is sometimes the entire fix.

Questions about the method

Mechanical packers, or ports glued to the surface?A mechanical packer locks into a drilled hole and seals inside the body of the element, so resin travels through the crack rather than onto it. Surface ports rely on a paste seal adhering to the face, which will not hold on a wall that is actively leaking. This single answer explains a large share of price differences between quotes.
Which resin family, and why that one for this element?The answer should turn on whether the element ever dries out permanently, not on brand preference — the choice between hydrophilic and hydrophobic is the decision that most determines whether the repair survives five years. Get the family and the product name in writing on the quote.
What packer spacing, and what pressure band?Spacing should never exceed the thickness of the element, and typical spacing runs 150 to 400 mm. Mechanical-packer polyurethane work commonly runs 35 to 140 bar, starting low. Wider spacing means fewer holes and a cheaper-looking quote, and resin that cannot travel far enough to seal between them.
If the resin volume was estimated, what expansion figure was that based on?Confined expansion inside a real crack is roughly 3 to 8 times. Free-rise figures on data sheets commonly read 8 to 30 times. A volume calculated off free-rise can be wrong by a factor of three or more, which shows up as either a shortfall on the day or a variation afterwards.

Questions about what is and is not included

Is the price per linear metre, per crack, or per job?Three quotes cannot be compared until they are on the same basis. A price per crack sounds cheaper right up until the crack turns out to be four metres long. Ask for the quantity counted and stated, not assumed.
Is making good included, and to what finish?Cutting the packers back, plugging the recesses and grinding flush is normally included. Re-rendering, painting, re-screeding or reinstating line marking usually is not, and it belongs on the quote as its own line rather than being discovered at the end.
What have you excluded that I should expect to see as a variation?The most useful question on the list, and the one contractors answer most differently. A considered scope has known unknowns — a void behind the element, render that turns out to need removal, a slab whose post-tensioning cannot be confirmed — and a good contractor names them up front with what each would cost.

Questions about proof and what happens afterwards

That last one is worth more than it sounds, and it is worth insisting on regardless of job size. When water reappears — and on a dry-side repair it sometimes does, somewhere else — the record is the only thing that establishes within minutes whether it is the sealed path or a new one. Without it the conversation is two people asserting things at each other.

Two related items belong in the same conversation. Ask for the warranty document itself rather than a line on the quote, and read what it excludes — what warranties on this work actually cover sets out why a leak reappearing elsewhere is usually not a warranty claim. And on any negative-side scope, ask for the redirection risk in writing before the work, because in Queensland that documented prior advice is worth considerably more to both parties than an exclusion clause, which is void anyway.

How will you demonstrate the repair worked, and what do I receive?The minimum worth accepting is observation for 24 to 48 hours and, where the season allows, through an actual rain event; moisture readings at marked points before and after; and photographs from fixed positions with a written description of what was found and what was done. A repair signed off the same afternoon has been finished, not verified.

The three checks that are not questions

Three things can be verified without asking the contractor anything, and all three are worth doing on every tenderer rather than on the one that seems suspicious.

The licence. In Queensland, trade work valued over $3,300 including labour, materials and GST requires the appropriate QBCC contractor licence, and the register is public — the class, the status and any conditions can be checked directly rather than taken from a logo on a vehicle. Across the border, NSW Fair Trading licensing applies instead, and a Queensland licence does not automatically carry.
The insurances. Certificates of currency for public liability and workers compensation, dated, before work starts. On common property a body corporate inherits the risk of an unlicensed or uninsured contractor, not the contractor.
The safety data sheets. Uncured polyurethane contains isocyanates, which are respiratory sensitisers, and drilling concrete releases respirable crystalline silica. Asking for the SDS for every product to be used on site is routine, not obstructive, and in a strata or commercial building the manager should be asking as a matter of course.

Reading the answers

The pattern matters more than any single response. Three patterns come up repeatedly and each means something specific.

If the answer is	It usually means
A change of subject to the warranty or the guarantee	The diagnosis was not done. A warranty is being offered in place of a cause
A resin named by brand with no reason attached to this element	Whatever is already in the truck. Not automatically wrong, but not a decision either
A lump sum with no quantity stated	The quantity was not counted, so the risk of it being wrong sits with somebody — and it is worth establishing who before signing
A vague offer to investigate once work is under way	Sometimes entirely honest on a concealed element, and sometimes an unpriced scope. Ask what the investigation costs as its own line
An immediate, specific answer with a number in it	The job was assessed. This is the response the questions exist to find

What an evasion usually indicates.

If this is common property

For a body corporate the questions above still apply, and one thing has to happen before them: all tenderers need to be pricing the same document. Three injection quotes almost never describe the same work — one prices per crack, one per linear metre, one as a lump sum, and only one may include cutting the packers back and patching the holes.

Issuing a single scope of works with the quantities already counted, and asking every contractor to price that document rather than their own interpretation of the problem, is what makes the comparison real. How to scope and tender a water ingress repair has an editable template, a worked reconciliation of three quotes that looked incomparable, and the AGM paper structure that goes with them.

Common questions

Is it reasonable to ask all of these of a contractor quoting a small domestic job?: Yes, and it takes about ten minutes. The four diagnosis questions matter on any job of any size, because they determine whether the repair is aimed at the right thing. The method and scope questions matter wherever more than one quote is being compared. On a very small job some of the scope questions collapse into one — is that the whole price, and what is not in it — but nothing on the list is unreasonable to ask somebody who is about to drill into a building.
What if all three quotes fail these questions?: That is a common and informative outcome, and it usually means the diagnosis has not been done by anybody. The productive next step is to pay for the diagnosis separately rather than collecting a fourth quote. A diagnostic investigation with moisture readings, crack monitors installed and read, water testing and a written report sits in the range of $450 to $1,500 — cheap relative to a repair aimed at the wrong cause, and it converts three incomparable quotes into three prices for a defined scope.
A contractor says the cheapest quote must be cutting corners. Is that fair?: Sometimes, and it is testable rather than a matter of opinion. In this trade the cheapest quote is usually cheaper for three specific reasons in combination: surface ports glued to the face instead of drilled mechanical packers, one attendance instead of two (which means either the packers come out before 24 hours or there is no making good), and no verification documentation. Put those three questions to the cheapest tenderer directly. If the answers confirm it, the quote is not cheap — it is for a different job.
Should the contractor who diagnosed the problem be allowed to quote the repair?: There is a genuine tension there, and it is manageable rather than disqualifying. A contractor who investigates and then quotes the cure has an incentive to find a cure they sell. What controls it is that the diagnosis is written down and testable: which paths were found, how each was established, and what was ruled out. A report specific enough for another contractor to price from is a report that can be checked. Where the amounts are large or the building is in dispute, an independent consultant who does no rectification work removes the tension entirely.
How long should be allowed between issuing a scope and awarding?: Long enough for the tenderers to attend the site, which is the step that produces useful quotes. A quote produced without an attendance is priced off assumptions, and assumptions are what turn into variations. For a strata job there is a second constraint: the committee’s own spending limit and the type of resolution needed to approve works of a given value depend on the regulation module the scheme is registered under, so the approval path should be confirmed with the strata manager before the tender goes out rather than after the quotes arrive.
Is a longer warranty a good reason to choose one quote over another?: Rarely, on its own. Term length is the easiest thing in a quote to extend and the hardest to enforce, and two of the numbers commonly quoted are not the same promise — a product warranty from the resin manufacturer typically covers the material rather than its installation, and a workmanship warranty comes from the contractor. What is worth comparing is the document itself: what it covers, what it excludes, who is standing behind it, and whether the contractor is still likely to exist when it is called on. A contractor who can produce the document on request is telling you more than the number in it does.