In brief
- A low prop removal bid can mean the tender left out temporary propping, monitoring or the wait for concrete to reach its specified strength.
- Ask for a method statement that names who gives the written instruction to strike each prop and how deflection is watched afterwards.
- Price the work from your own schedule, then compare the contractor's rate against each item in it.
Contents
Prop removal underbidding risks in Qardho start with scope, not price. A bid can come in low when the tenderer prices only the labour of taking props out, and leaves out temporary re-propping, deflection monitoring and the time spent waiting for concrete to gain strength. Treat every low bid as a scope question first.
What does a low prop removal bid leave out?
A low bid can omit the work that happens around the strike, not the strike itself. Ask each tenderer to price the same list and the gap appears. Typical omissions include:
- Temporary props or back-props left in place after the main props come down, and the extra handling that needs.
- The wait for concrete to reach the strength the specification or the engineer requires before any prop is released.
- Deflection readings, crack checks and the person who records them.
- Re-propping if a slab or beam moves more than the engineer allows.
- Access, lifting and the cost of keeping a section closed while props stay in.
The specification or the engineer sets both the strength at which a prop may be struck and the test method used to confirm it. Confirm both against the project specification before you compare bids. If a bidder quotes no waiting time and no test records, the number is not comparable with the others. Ask each tenderer to price the same scope, then compare against your own tender returns.
Why does premature striking happen?
Premature striking happens when props come out before the concrete has gained enough strength to carry the load. The mechanism is simple. Fresh concrete gains strength with time and curing, so a prop released early puts load on a member that is not ready, and the member deflects or cracks. On a suspended slab, the load may be its own weight, stored materials, blockwork stacked on it, or the next floor being built. Ask the project's structural engineer what records are relevant to this structure.
The risk rises where several trades share one programme. A mason wants the slab cleared to build walls, a steel fixer wants the area for the next pour, and the pressure to free the props moves the date forward. A tender that assumes one clean strike date with no holds has priced an ideal site, not a working one. Identifying scope gaps is the first step in checking any prop removal bid.
How do you check a prop removal bid in Qardho?
Check the bid against your own priced schedule, item by item, before you compare totals. Write the list, then mark what each bidder has covered. Look for these in the submission:
- A method statement that names the sequence of strikes and any back-propping.
- The strength at which the engineer allows each strike, and who confirms it.
- Who records deflection, how often, and what reading triggers re-propping.
- What the contractor does if a member moves or cracks.
- Test records for the concrete in the members being struck, not for other pours.
Ask the contractor to show strike records and test results from a comparable previous job. Ask two contractors for written quotes on the same scope, and ask a laboratory for its rate for the strength tests you need. Compare the figures against the priced schedule, not against each other.
What to do next
Write your own priced schedule for prop removal, covering temporary props, waiting time, testing, monitoring and re-propping, then send it to every bidder as the scope to quote. Add a line requiring written engineer approval before each strike.
Frequently asked questions
Who decides when props can be removed?
The structural engineer for the project, in writing, based on the concrete strength the specification requires. The contractor proposes the sequence and the test evidence, but the release decision is the engineer's.
What records should a client keep after prop removal?
Concrete strength test results for the members struck, the signed strike approvals, and the deflection readings taken during and after removal. These show whether the structure behaved as designed.
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.