In brief
- A low damp proof membrane bid often omits surface preparation, lap sealing and protection, so the membrane is priced but the work around it is not.
- Ask for the membrane's subgrade, lap and protection details in writing, then compare them with the site and with the project specification.
- The client can close the gap by naming the membrane, jointing method, protection layer and testing in the tender before bids are opened.
Contents
A low damp proof membrane bid in Garowe usually means work has been left out, not that the membrane is cheap. The bid price may cover the sheet alone while surface preparation, lap sealing, protection and repairs sit outside it. Ground moisture ingress then shows up later as damp floors and rising salts, and the client pays for the fix through variations or rework.
Where do damp proof membranes underbidding risks in Garowe start?
The gap starts when the tender describes the membrane and stops there. A membrane only works if the ground beneath it is firm, even and free of sharp stones, and if the sheet is laid without gaps and sealed at every lap. Bidders who price only the roll leave out the sand blinding, the lap adhesive or heat welding, the protection layer above the membrane, and the labour to cut and fit around foundations and service entries.
The local check is the bill of quantities. Ask whether it lists preparation, jointing, protection and repairs as separate items or hides them in one rate. Ask the municipal engineer's office what drawing and specification the plot was approved under, and walk a recent site to see how the membrane there was laid and covered. If the bid rate covers everything in one line, ask for the breakdown in writing before you compare bids.
How do you spot omitted membrane work in low bids?
You spot it by comparing every bidder against the same written list, not against the lowest number. Build the list from the project's specification and engineer's instruction: subgrade preparation, sand blinding, membrane type and thickness, lap width and sealing, detailing at edges and penetrations, protection board or screed, and where the membrane turns up at walls.
Then ask each bidder to confirm, in writing, that the rate covers each item. Look for the items missing from a low bid. Protection is a frequent omission, because a membrane left exposed to site traffic is punctured and its laps lift. Service penetrations are another, since a sheet laid around a pipe without a sealed collar lets water past it. Then set the programme so the membrane is laid only when the trades that follow will cover it the same day or soon after. Confirm the lap widths and cover depths against the project's specification or engineer, as general practice varies with the membrane product and the ground conditions.
When should a client stop a bid and ask for the missing detail?
A client should stop when a bid cannot show the method, the materials or the labour for any listed item. That is a question about scope, not a judgement on the bidder. Ask for the material data sheet, the jointing method and the name of the person who will supervise the laying. If the ground is soft or wet, ask what the bidder will do before laying and whether the section needs to be raised, drained or re-compacted.
Check the contract for what it allows. It may have a clarification period, a requirement for method statements, or a process for accepting an alternative membrane. Payment terms may also release money only against inspected stages. Ask the municipal engineer's office whether it holds borehole logs or previous site records for the plot. Test records or a site visit can show whether groundwater or salts are present, which decides how much preparation and protection the job really needs.
What to do next
Write a one-page membrane scope statement before bids are opened: membrane type and thickness, preparation, lap and jointing method, detailing at walls and pipes, protection layer, and who inspects before covering. Send it to every bidder, ask for written confirmation that each item is priced, and compare the confirmed bids against that single list.
Frequently asked questions
Does a low damp proof membrane bid in Garowe mean the contractor will do poor work?
Not necessarily. It means the bid covers less work than the specification asks for. Ask for a written breakdown of preparation, jointing, detailing, protection and repairs before you compare it with the others.
What should a client ask for before covering a damp proof membrane?
A signed inspection of the laid membrane, photographs of laps and wall or pipe junctions, and confirmation that the protection layer is in place. Check the contract to see how the works are inspected and paid for.
Local reporting: this article is written for building work in Garowe and Puntland. Ground conditions, prices and rules differ between places; confirm the details for your own site.