Osaka duplex renovation: contingency and two very different bids

[measureTheEmber]

Choosing the lower bid before identifying its omissions could leave me committed to a renovation that the budget cannot finish. I am working with a preliminary allowance of ¥21,560,000 for a 195 m² duplex in Osaka, yet two contractors have returned very different prices for what should be comparable work.

The intended project covers kitchens and bathrooms, new floor finishes, painting, an assessment of the electrics and modest efficiency improvements. There is no planned extension. Before deciding, I want to understand the electrical scope, check likely moisture areas and find out whether material lead times will disrupt the sequence. What investigations would you commission first, and how much contingency would you keep outside the contract until those unknowns are narrowed?

 

[CleoDale]

At this stage I would keep roughly 15–20% outside the contract sum, then reconsider it after investigations and limited opening-up. The bid difference may be exclusions rather than pricing. Ask both contractors to identify assumptions for demolition, disposal, making good, electrical replacement beyond “checks,” plumbing access, moisture damage and any temporary protection. Compare those answers line by line.

 

[nia_sage]

How old is the building, what is its construction, and will either part of the duplex remain occupied? Also, are services shared between the two units? Those details could change both access and sequencing. I’d want moisture readings around bathrooms and the kitchen, plus confirmation of where pipes and cables run before treating either price as complete.

 

[sanna.lee]

I wouldn’t choose a contingency percentage first. A large reserve does not cure a vague scope, and it can hide an unrealistically low bid. Have each contractor separate fixed work, allowances and excluded work, then explain what would trigger an extra charge. For concealed plumbing or damaged substrate, ask how additional work would be measured and approved before proceeding.

 

[CleoDale]

That’s fair, although Nina still needs a cash reserve even after tightening the scope. I’d also ask each bidder for a basic sequence and procurement schedule. If one assumes the kitchen, bathroom fittings or energy-upgrade materials are immediately available while the other has allowed for lead times, their programmes and preliminaries may be quite different. Permit responsibility and timing should be stated rather than assumed.

 

[uma_valuations]

A practical order would be investigation first, then any agreed opening-up, followed by revised prices and only then major material orders. Map plumbing access, test suspect moisture areas, clarify the electrical scope, and record any structural concerns uncovered during demolition. Give both contractors the same room schedule and ask for revised bids in the same format; otherwise you are comparing two interpretations, not two prices.

 

[EarlyGlass]

Also ask what “no structural work” means in each proposal. No extension is clear, but removal of finishes may expose framing or substrates that need repair. One contractor may have allowed for minor repairs while the other excluded everything structural.

I’d make a simple comparison table covering demolition, disposal, access, plumbing, electrical work, moisture remediation, making good, permits, lead times and exclusions. Resolve the largest gaps before appointment, keep the remaining contingency separate, and have the relevant Osaka professionals confirm any permit or technical requirements for the actual building.