Every A&A project contains work that nobody can see at tender. A wall comes down and there is a beam in it. A ceiling opens and the services run nowhere near where the drawings show. The question is never whether this will happen. It is whether you found out in week two with a plan, or in month three with a stopped programme and an argument about who pays.
Why as-built drawings are so often wrong
The drawings usually describe what was designed, not what was constructed. Site changes during the original build were not always drawn up. Later tenants altered things without records. Services were re-routed by whoever was available at the time. On an older building, the paperwork may have passed through several owners and managing agents.
Treating as-built drawings as a starting hypothesis rather than as fact is the single most useful habit in A&A work.
What is most commonly discovered
The conditions that turn up again and again:
- Structure that is not where the drawings show it, or is larger than drawn
- Live services concealed in walls and slabs with no record — power, data, sprinkler, drainage
- Previous alterations done without approval or without records
- Waterproofing that has failed, and the substrate damage underneath it
- Floor levels that vary far more than assumed once the finish is lifted
- Fire stopping missing at penetrations formed by earlier works
- Materials from an earlier era requiring specialist handling and disposal
Reducing the surprise before it becomes a variation
Some of it can be found before the programme is committed. An opening-up survey — a small number of controlled openings at the highest-risk locations — converts guesses into facts for a fraction of the cost of discovering them later. Scanning before coring is the same principle applied to a single operation, and it is what stops a core drill from finding a live cable or a post-tension tendon.
Non-destructive scanning is routine and cheap relative to the consequences. Skipping it to save a day is a poor trade in any building, and a serious one in a building that is occupied.
Price the unknown honestly rather than hide it
There are three ways to deal with scope that cannot be defined at tender: exclude it and argue later, inflate the price to cover it, or identify it openly and price it as provisional with agreed rates for the work if it arises.
Only the third gives a comparable tender and a programme that survives contact with the building. A quotation that names its unknowns is not a weaker quotation; it is the one that has looked.
The variation process matters more than the variation
What makes discovered scope expensive is usually not the work. It is the standstill while it is being decided. A process agreed before works begin — who is notified, how fast a decision is expected, what rates apply, what happens to the programme — keeps a discovered condition to its own cost rather than letting it stop everything around it.
- Record the condition with photographs and a location reference the same day it is found.
- Notify the consultant and the client immediately, not at the next site meeting.
- State the programme consequence separately from the cost consequence.
- Price against rates agreed at the start of the contract wherever possible.
- Re-sequence the work around the affected area while the decision is being made.
- Update the as-built record so the next project does not rediscover the same thing.
Keeping the rest of the job moving
A discovered condition should slow down one area, not the project. That depends on a programme with enough independent work fronts to absorb it, and on being able to change a component without restarting a supply chain. When the joinery, stone and metalwork are produced in our own facility, a piece that no longer fits the discovered condition is re-made here in days rather than re-ordered in months.
What the client can do to reduce exposure
Release the building for an opening-up survey before the design is frozen. Share every drawing and record that exists, including the ones from previous tenants. Be clear about which areas absolutely cannot be disturbed. And allow a contingency that reflects the building’s age and history rather than a standard percentage applied out of habit.
How Rongda Pacific handles discovered conditions
On A&A projects in occupied buildings we plan for discovery rather than hope against it: risk locations identified before mobilisation, scanning before any coring, same-day notification with the programme impact stated separately, and in-house production so that a changed component does not become a changed programme.
Frequently Asked Questions
Can discovered scope be avoided entirely?
No, but most of the expensive surprises can be converted into known facts before the programme is fixed, by an opening-up survey at the highest-risk locations and by scanning before any cutting or coring.
Who pays for work that could not have been seen at tender?
That is set by the contract, which is exactly why the variation route and the applicable rates should be agreed before works start rather than negotiated under programme pressure.
What is an opening-up survey?
A small number of controlled openings at locations where the risk is highest — a wall that may contain structure, a slab that may carry services — made and reinstated before the design is frozen, so the findings can be designed around.
Does scanning before coring really make a difference?
Yes. Non-destructive scanning is inexpensive relative to a severed cable, a cut tendon or a drained sprinkler main, and in an occupied building the consequence of any of those extends well beyond your own works area.
