How do you check low bid explanations in Qardho?

A low bid in Qardho is a claim that the bidder can buy, haul, place and cure the same work for less. The written low bid explanations matter more than the total, because they show which quantities, output rates and delivery assumptions the bidder used. Read that document line by line before you rank anyone.

What should a low bidder explain in Qardho?

A low bidder should explain the method, the quantities, the output rates and the delivery assumptions behind every major line.

Take the explanation and match it against the priced bill. For each large item, ask for the quantity the bidder measured, the labour and plant rate used, and the source of the material. A bidder who writes "local supply" without a named supplier, a quantity and a haul distance has not explained the line. A bidder who writes "curing by others" has moved a cost into someone else's budget.

In Qardho, water for mixing and curing and the haul of aggregate both sit inside the low lines. Ask the bidder to state where the water comes from, how it reaches the site and what happens if that source fails during a dry spell. Ask the same for cement, rebar and any imported finish. The bidder who cannot name the supplier has priced an assumption, not a delivery.

How do unverified delivery assumptions turn into cost?

An unverified delivery assumption turns into cost the moment the material does not arrive at the rate the bid assumed.

The mechanism is simple. A low bidder cuts the haul, the waiting time or the breakage allowance, then wins on the total. On site, the material arrives late, the crew stands idle, and the client meets the gap as a variation, a delay or a thinner layer of work. Omitted costs do not disappear; they move to the client or to the finished element.

Check the assumption in three places. Walk a recent site the bidder finished and ask how the material actually arrived. Ask the municipal engineer's office whether it holds records for the plot or the route. Request the supplier's written confirmation of quantity and delivery window, not a verbal promise. Where the explanation is silent, treat the line as open and price the risk yourself before award.

How do you test the rates behind the explanation?

Test the rates by rebuilding two or three of the largest lines from first principles and comparing them with the bid.

Pick the items that carry the money: excavation, concrete, blockwork, roofing, or whatever dominates the bill. For each, write down the quantity, the crew size, the daily output the bidder claims and the number of days that gives. General practice is to hold a contingency inside the rate for weather, breakdown and rework; confirm the figure the project's engineer expects against the specification. If the bidder's output needs more days than the programme allows, the rate is not low, it is incomplete.

Ask the bidder to explain any line that is far below the others. Ask what the bidder will do if the rate proves wrong. A clear answer names the allowance and the trigger; a vague answer names nothing. Keep the written answers with the tender file so the comparison survives staff changes.

What to do next

Take the lowest bid and its explanation, mark every line with no named supplier, no stated rate and no contingency, and send those questions back in writing with a deadline. Ask the municipal engineer's office which records it holds for the plot. Award only when the answers close the gaps, or carry the open lines as a priced risk in the contract.