The drawings for an older building describe an intention. They describe what someone meant to build, decades ago, before the field changes, the undocumented renovations, the abandoned systems left in place, and the modifications made by people who did not update the record.
Renovation projects overrun on existing conditions more than on any other single cause, and the reason is structural: the budget is set using information that is known to be incomplete, and the gap is discovered after the contract is signed.
The Standard Practice Is the Problem
Conventional sequence is to survey what is accessible, design around it, bid the work, and handle what is discovered through change orders. This is normal, and it is also the most expensive way to manage the risk.
By the time a condition is discovered, the owner has no leverage. The contractor is mobilized, the schedule is running, the work is stopped, and the price for resolving it is negotiated under time pressure with a single bidder. Everything about that position favors the contractor, and it is entirely the product of when the discovery happened rather than what was discovered.
Investigate Before You Bid
The alternative is to spend a modest amount early to reduce what is unknown. On most institutional renovations that means some combination of:
- Selective demolition in representative locations to see actual construction, above ceilings, behind walls, and below floors
- Hazardous materials survey for asbestos, lead, PCBs, and mercury, sampled properly rather than assumed from building age
- Structural investigation where loads will change or openings are planned, including verification of actual member sizes and connections
- Systems investigation to establish what is actually connected to what, since abandoned and re-routed systems are common
- Utility locating before any site work, including private utilities that public locating services do not mark
- Measured survey of critical dimensions, because older buildings are frequently out of square and out of level in ways that matter
This costs money and it takes calendar time, both of which create pressure to skip it. The counter-argument is arithmetic: an unknown condition is priced twice — once by every bidder as contingency, and again as a change order when it materializes.
Investigation Improves Bids, Not Just Certainty
A frequently missed benefit is bid quality. Bidders price uncertainty. When a set of documents leaves significant unknowns, careful contractors add contingency and aggressive ones do not — which means the low bid may simply be the bidder who understood the risk least.
That is a bad outcome for the owner in both directions: either overpaying for contingency that never gets used, or awarding to someone who will discover the problem later and pursue it as a change. Better information produces bids that are both lower and more comparable.
Allocate the Residual Risk Deliberately
Investigation reduces unknowns; it does not eliminate them. What remains should be allocated on purpose in the contract rather than left to the differing-site-conditions clause and hope.
Options include an owner-controlled contingency for existing conditions with a defined draw process, unit prices for anticipated categories of remediation, allowances for scope that is known in kind but not in quantity, and explicit language on what constitutes a differing condition. Each is preferable to discovering the allocation during a dispute.
The contract structure decision here is as consequential as the investigation itself.
Historic Buildings Compound Everything
In historic structures, the problems multiply. Original construction methods may not be documented anywhere. Materials may not be commercially available. Repairs may require specialist trades with limited availability and long lead times.
And the response to a discovered condition is constrained: the obvious modern fix may not be acceptable to the reviewing authority, which means resolving an unforeseen condition can require a design change, a new approval, and a schedule extension rather than a simple field decision. Preservation review turns what would be a two-day problem in a modern building into a two-month one.
Document What You Find
Investigation findings should be recorded and issued to bidders, not held internally. An owner who investigates and then does not share the results has paid for information and given away its main benefit, while arguably increasing exposure by knowing something the bidders do not.
The record also has value long after the project: the next renovation of the same building starts from better information, which is a compounding return on the original investigation.
