Basement Chemical Injection Tenders in Abu Dhabi: What to Put in the RFQ

When a tower's basement walls and slabs start to seep, the owner or its facilities provider usually puts the repair out to tender. The quality of the RFQ decides whether the bids can be compared, and whether the leaks are still there next winter. These are the sections a basement chemical injection RFQ needs, based on the tenders we price.

1. A numbered leak schedule

The schedule is the core of the RFQ. Every bidder prices the same list, and the same list becomes the completion checklist. For each location it should give:

• A number, the level (B1, B2) and the element: retaining wall, floor slab or the slab above.
• The defect type: construction joint, shrinkage crack, cold joint, tie-hole or pipe sleeve.
• The flow condition at the time of the survey: dry stain, damp, dripping or flowing.
• A photograph and a mark on the basement layout.

If the schedule was made in summer, say so. Groundwater and rain change the flow condition, so bidders need to know whether "damp" was recorded in August or after a storm.

2. Define what one "location" is

Injection is usually priced per location, with walls and floor locations priced separately because floor repairs include concrete reinstatement. Disputes start when "one location" is not defined. State the maximum length of crack or joint a wall location covers, and the minimum area of a floor location. Also say whether the rate covers flowing water, or whether high-flow locations are a variation. A good bid states that its rates already cover the flow conditions recorded in the schedule.

3. The method you will accept

Set the method in the RFQ rather than leaving each bidder to choose one. The essentials for basement injection:

1. Surface preparation and a surface seal along the crack line, so the resin stays in the crack.
2. Holes drilled at an angle to cross the crack at about mid-depth of the wall, at a spacing set by the wall thickness and the manufacturer (commonly 150–300 mm), with mechanical packers.
3. Where water is flowing, a water-reactive polyurethane foam injected first to stop it. This is a temporary stage.
4. The permanent seal with a flexible polyurethane resin whose data sheet states its EN 1504-5 class, injected from the lowest packer upward at the pressure on the data sheet, until resin appears at the next packer.
5. Packer removal, holes filled with non-shrink repair mortar, and the wall repainted. Say whether a whole parking-bay wall or only the patch is repainted, because it changes the price.

For leaks through the floor slab or the slab above, add the reinstatement. After injection and the cure check, the area is saw-cut and broken out to a stated minimum depth, the reinforcement is checked, and the area is primed and reinstated with a non-shrink cementitious grout. Specify the minimum 28-day compressive strength the grout must reach, and how long the area stays closed to traffic while it cures.

More detail on what reviewers check is in what consultants check in an injection method statement.

4. A completion criterion you can measure

"Leak stopped" is not a criterion. Write one that can be checked at each location:

• Verified dry after cure. No visible seepage at the treated location at the inspection after the resin has cured.
• Re-injection included. Any location that is still seeping, or seeps again, is re-injected and re-inspected at no extra cost until it passes.
• A before-and-after record. Ask bidders how they verify. Photographs of each numbered location at the survey and again at the post-cure inspection, taken from the same position, show the result location by location.
• An as-built injection map marking every treated location. It becomes the reference for any warranty claim.

5. Settle the exclusions before award

Most claims on basement injection jobs come from the same few items. Decide them in the RFQ, not on site:

• Access. Who clears ducts, cable trays, panels, stored items and parked cars from each work zone, and by when.
• MEP services. Who isolates, moves and reinstates services that block a location.
• Dewatering. Local water-stop injection is part of the method. Pumping out a flooded basement is not, unless priced separately.
• Structural repair. Strengthening or replacing reinforcement is outside an injection scope and should be a variation.
• Flood or watertightness testing by a third party, if the engineer may ask for it.
• Site facilities. Power, water and a small lockable storage area near the basement.
• Bay closures. Who agrees closures and notices with tenants. The car park can stay open if bays are handed back in sequence. See car park leak repair without closure.

6. Commercial terms that match the work

• Measurement. Pay against locations completed and inspected, with walls and floors measured separately.
• Variations. Locations added after award are priced at the tendered unit rates.
• Defects liability. Twelve months is usual, secured by a retention that is released when the period ends.
• Programme. Ask for working days from mobilisation to completion certificate, excluding approval and permit time. A two-level tower basement is typically a matter of weeks, not months.

Comparing the bids

With the schedule, method and criterion fixed, the bids differ in what matters: the EN 1504-5 class of the permanent resin, the applicator's current certificate from the manufacturer, whether re-injection is included, how completion is verified, and the rate per location. A low rate that excludes flowing water or re-injection usually costs more by the end of the defects period.

We price basement injection against the client's own leak schedule and RFQ methodology. See leak repair for managed buildings.