Where the margin goes
Most lost margin is not dramatic. It is a quantity that was light, an item that sat in somebody else's package, or an allowance that turned out to be a scope rather than a sum. None of that shows up until the work is on site.
By then the price is fixed and the only route back is a change, which has to be instructed by somebody who would rather not.
The quantities you are given
Where a bill or a schedule is provided, check whether it is a contract document or information only. The difference decides who carries an error in it, and it is often stated in a single line of the preliminaries.
Spot check the items that carry the most money rather than remeasuring everything. If the large items are sound, the small ones usually follow.
Exclusions and the gaps between packages
Read the exclusions in your own package against the exclusions in the ones either side of it. Work that everybody has left out does not disappear, it lands on whoever cannot prove they excluded it.
Interfaces, builders work, making good and temporary works are the usual places where that happens.
Provisional sums and what they hide
A provisional sum is an admission that the work is not defined. It will be instructed later, priced later and will carry whatever programme effect comes with it. Treat the sum as a placeholder, not as a price you have agreed.
Where a sum is large relative to the package, ask what it covers before you tender rather than after you win.
What this means for you
Half a day on the measure before a tender goes in is usually worth more than any amount of argument afterwards, because everything is still negotiable while nobody has committed.
Reltic checks measured quantities and subcontract packages for contractors before they price, and says plainly where the risk sits.
Send the package before you price it
We will tell you what the quantities support, what is missing and where the margin is exposed.