Contingency and hidden risks for a ₩334.1m Seoul flat renovation

[lookTheRiver]

Getting the contingency wrong could leave a 200 m² flat half-finished while access or structural questions are resolved. The preliminary Seoul budget is ₩334,100,000 for a new-build unit, covering the main rooms, surfaces, electrical review and some energy work. An extension is not part of the plan.

My assumption is that a new building should reduce hidden-condition risk, but concealed plumbing without usable access would be an obvious counterexample. The same applies if fixing a service route requires opening work that was priced as purely decorative.

Before choosing a percentage, which drawings, surveys and contractor exclusions should be checked? I would also like to separate genuine contingency from optional upgrades and establish whether any structural work could be triggered by the proposed layout.

 

[knitsAndAtlas]

At preliminary stage, I would hold roughly 12–15% outside the trade budgets, then reduce it only after the drawings, access conditions and exclusions are settled. Keep owner-requested upgrades separate from genuine contingency. The first contractor question should be: “What have you assumed is already present, accessible and compliant?” That answer often reveals more than the headline price.

 

[theo_cedar]

Is the flat being handed over as a finished unit or closer to a bare shell? “New-build” can conceal a major scope difference. Obtain the handover drawings and ask building management what work hours, lift use, deliveries, noisy-work periods and common-area protection apply. Those constraints can change both sequencing and contractor pricing.

 

[KindHarbor]

I would tighten the phrase “electrical checks.” Does it mean inspection and testing only, moving outlets, adding circuits, replacing the panel, or supporting new kitchen and energy-upgrade loads? Give bidders the same equipment and load list, then ask them to identify routing constraints and anything excluded behind finished walls or ceilings.

 

[woodworksAndAnchor]

Plumbing access would concern me more than finishes. Confirm where the risers, shut-offs, traps and drainage connections can actually be reached, and whether access panels remain after completion. For bathrooms, ask who tests supply, drainage and waterproofed areas, at what stage, and who pays if another trade closes the work before testing.

 

[bikesAndEcho]

I wouldn’t automatically reserve 15% if the scope can be investigated properly before contract. A large contingency sometimes lets vague quotations remain vague. Spend effort on a trade-by-trade tender comparison, with every bidder listing assumptions, exclusions and provisional items. Once those are reconciled, something nearer 8–10% may be defensible for a non-structural fit-out.

 

[knitsAndAtlas]

Lara’s lower range makes sense only after Isabella’s handover question is answered. Until then, the risk isn’t necessarily defective construction; it’s the interfaces between the developer’s work, building systems and the renovation. I’d split the current allowance into design development, unresolved existing conditions and a smaller construction contingency rather than showing one undifferentiated percentage.

 

[ada.heath]

Also build the programme backward from materials with uncertain lead times. The contractor should identify which selections must be frozen first, the final ordering date, approved alternatives and storage responsibility. Wet-area layouts and electrical loads should be fixed before cabinetry and finishes are released, otherwise one late change can disrupt several trades.

 

[knitsAndAtlas]

Permit timing needs the same treatment as procurement. Don’t assume “no extension” means no approval or building-management process. Ask the contractor and designer to state, in writing, which proposed works may require consent, who submits each item, and what the programme assumes. Energy upgrades touching shared systems or the exterior deserve particular clarification.

 

[zia_titles]

No extension does not necessarily mean no structural interaction. Coring, deep chasing, ceiling suspension and heavy fixed items may still affect slabs or walls. Before demolition, ask for marked-up drawings showing permitted routes and no-cut areas, plus a procedure for approving any unexpected drilling or penetrations.

 

[zia_titles]

One more tender question: request a schedule of exclusions rather than accepting exclusions scattered through the quotation. It should cover demolition disposal, temporary protection, making good, testing, cleaning, delivery handling, access equipment and work outside normal building hours. You can then price omissions deliberately instead of discovering them mid-project.

 

[noor_grove]

For moisture risk, record baseline conditions before flooring, cabinetry or paint begins. Ask how substrate moisture will be assessed, whose criteria will be followed for each specified finish, and what happens if drying delays installation. The important point is agreeing responsibility and sequence before materials arrive, not inventing a universal pass figure.

 

[gate.strong]

I’d organise the ₩334,100,000 into three columns: fully defined contract work, pending selections or investigations, and true unknowns. Contingency should protect only the third column. Otherwise upgraded appliances or finishes quietly consume the reserve, leaving nothing for concealed plumbing, electrical routing or remedial work.

 

[bikesAndEcho]

Agreed on the three columns, but the total still can’t be judged without a cost plan by trade. Two bids at the same price may carry very different risk if one includes testing and making good while the other labels them provisional. Ask bidders to use the same breakdown and respond to the same list of assumptions; comparisons become much clearer.

 

[gate.strong]

Before appointment, I’d issue one final written questionnaire covering: accessible drawings, structural restrictions, electrical definition, plumbing access, moisture testing, approval responsibility, material lead times, work-hour constraints and every exclusion. Attach the answers to the scope and programme. That should give you a better basis for choosing between the higher early contingency and Lara’s lower post-investigation range.