In brief
- A low wet area membrane bid often prices only the floor sheet and omits tanking height at walls, surface preparation, laps and testing.
- Ask each bidder for a measured quantity, the products and the test he will run; gaps in the written scope show up as water under the tile later.
- Confirm membrane thickness, lap widths and test durations against the project specification or the engineer before award, not from a supplier's verbal advice.
Contents
Wet area membrane bids in Borama come in low when the estimate prices only the sheet on the floor and skips the tanking height, surface preparation, laps and testing. A bathroom, kitchen or shower room fails later at the wall joint, the pipe collar or the door threshold, not in the middle of the floor. Ask each bidder to price the full wet area, not the visible floor alone.
A membrane laid on a dusty or cracked screed bonds poorly even when the material itself is sound. Preparation is part of the work and part of the cost: grinding, filling, priming and dust removal all take labour and materials. If the bid does not name preparation, the allowance is probably missing from the price.
What is usually missing from a low wet area membrane bid in Borama?
The most common omission is tanking height at the walls. The required tanking height and the build up are set by the project specification and the engineer. Ask what height is priced and why.
Other items that drop out of a cheap bid:
- Surface preparation: grinding, filling cracks, priming and dust removal.
- Reinforcement tape at internal corners and around pipe penetrations.
- Laps between sheets, which use more material than a plain area calculation.
- Upstands at thresholds and behind the door frame.
- A protection layer before screed or tiles go down.
- A flood test or water tightness test, including the time and water it uses.
Each of these is a real cost. A bid that leaves them out is not cheaper; it is incomplete. Check the written scope line by line against the specification before you compare totals.
How do unrealistic tender allowances affect the work?
When the allowance is too thin, the installer cuts the only things that are hard to see: coat thickness, lap width and test time. The sheet may look correct under the tile and still leak at the first heavy use.
Testing is often the first casualty. General practice is a flood test with the level marked and recorded, but the duration and method must be confirmed against the project specification or engineer. A bid that does not price the test has no reason to run it.
Material quality also slips. A thinner sheet, a cheaper primer or a skipped reinforcement tape saves money at the point of purchase and fails at the point of use. Ask for the product name, the batch and the manufacturer's data sheet, and keep a sample of what actually arrives on site.
Supervision matters here. Confirm on your own project who will inspect the substrate before the membrane goes down, who will check the laps after each sheet, and who will witness and sign the test before screed. Agree those names and the inspection points in writing before work starts.
How do you detect a low wet area membrane bid before award?
Compare scopes, not totals. Give every bidder the same measured drawing and the same specification, then check what each one has priced and what each one has left out.
Use these checks:
- Ask for a measured quantity of membrane, primer, tape and protection board, in square metres and linear metres, not a lump sum.
- Ask how many upstands, corners and pipe penetrations are included and at what height.
- Ask what test will be run, for how long, and who will witness and sign it.
- Ask which products and thicknesses are offered and request the data sheet.
- Walk a recent bathroom the bidder has completed. Ask the owner whether it has ever leaked and whether a test was done.
If a bidder cannot answer these without guessing, the price is built on assumptions. You can also ask the municipal engineer's office what it holds on record for the area or type of building, but the project specification and the engineer remain the reference.
What to do next
Before you award, send every bidder the same measured drawing and specification, then ask each one to resubmit with preparation, upstands, penetrations, laps, protection and testing priced as separate lines. Compare the resulting scopes, not the totals. Ask the design engineer to confirm the tanking height, membrane thickness and test duration for the specific wet area. Keep the approved scope and the test record with the contract documents.
Frequently asked questions
How long should a wet area flood test last in Borama?
The duration is set by the project specification and the engineer, not by the supplier. General practice is to hold water with the level marked before and after, but confirm the exact duration and method for your project against the specification or engineer, and record the reading with photographs and a signature.
Should the membrane go under the screed or on top of it?
The position depends on the system and the specification. Some systems bond the membrane to the substrate and protect it with screed; others use a different build up. Ask the design engineer to confirm the layer order and the protection detail before the screed is placed.
Can I compare wet area membrane bids on the total price alone?
No. A lower total often means missing lines, such as surface preparation, corner tape, threshold upstands or testing. Compare item by item against the same measured drawing and specification, and ask each bidder to explain anything that is absent.
Local reporting: this article is written for building work in Borama and Somaliland. Ground conditions, prices and rules differ between places; confirm the details for your own site.