In brief
- A low waterproofing bid often excludes surface preparation, joint treatment, curing time and a watertightness test rather than doing the same work for less.
- Ask for a written method statement that names the product, the number of coats and the test, then compare bids on that scope, not on the total alone.
- Hold retention against a passing water test, and check what the contract allows before releasing any payment.
Contents
Tank waterproofing underbidding risks in Qardho start at the pricing stage. A bid can look low because it leaves out surface preparation, corner and joint treatment, curing time or a watertightness test, not because the applicator works faster. Two bids for the same tank can cover different work, so comparing totals alone tells you little about what will be built.
What gets left out of a low waterproofing bid?
Omitted costs usually sit in the preparation and proving stages, not in the coating itself. A realistic allowance covers mechanical preparation of the substrate, filling of honeycomb and blowholes, a fillet at the wall-to-floor junction, treatment of pipe penetrations and construction joints, the specified number of coats, and controlled curing between coats. General practice is to keep the substrate damp or primed as the product data sheet requires, and to protect fresh coats from direct sun and wind until they cure; confirm the intervals and limits against the project specification and the manufacturer's data sheet. A bid that quotes one coat over a dusty, unbonded surface, or that schedules no time between coats, has moved cost out of the line item rather than reduced it.
How does underbidding show up in stored water leakage?
Stored water leakage follows the details the low bid skipped: the floor-to-wall fillet, the joint around the inlet and outlet pipes, the manhole surround and the first coat over a weak, dusty render. Water finds these paths under head, so a tank can pass a quick visual check and still weep at a penetration a week later. The mechanism is simple: coating bonds only where the substrate is sound, clean and prepared, and any gap in coverage becomes the leak path. Ask for the applicator's test records from a recent tank, and walk that tank with the owner to see how it performs. Ask the relevant municipal office what records, if any, it holds that could help confirm local practice.
How do you compare bids without guessing?
Compare bids on a written scope, not on the headline figure. Request a method statement that names the product and manufacturer, states the number of coats and the dry film thickness or coverage rate, describes surface preparation, gives curing intervals, and specifies a watertightness test with its duration and acceptance criteria. Confirm those limits against the project specification and the product data sheet, because they vary between cementitious, epoxy and membrane systems. Then price the missing items yourself, or ask two suppliers for written quotes for the same product and quantity, so the gap between bids becomes visible. A bid that omits the test is not cheaper; it is unpriced risk held by the client.
What to do next
Before awarding the tank waterproofing package in Qardho, issue a one-page scope template and require every bidder to price each line: preparation, fillet and penetration treatment, coats, curing, protection and water test. Confirm the required test duration in the project specification, and check your contract for what it says about retention and payment against a passing test. Award on the completed scope, not the lowest total.
Frequently asked questions
Can a low waterproofing bid still pass a water test?
It can pass a short test and still leak later at a penetration or an unbonded patch. Insist on the specified test duration and inspect the joints and pipe entries before the tank is covered or rendered.
What should a waterproofing method statement include?
The product name, surface preparation, number of coats, curing intervals, joint and penetration details, and the watertightness test with its acceptance criteria. Confirm each item against the project specification and the manufacturer's data sheet.
How do you price the omitted waterproofing items?
List the missing items, then ask two suppliers for written quotes for the same product, quantity and coverage. That gives a comparison figure to set against each bid, rather than an estimate.
Local reporting: this article is written for building work in Qardho and Puntland. Ground conditions, prices and rules differ between places; confirm the details for your own site.