Renovation budget for a 45 m² warehouse in Osaka (5 bed)

[measureTheEmber]

¥20,920,000 is my working budget for fitting a five-bed layout into a 45 m² warehouse in Osaka, but two contractors have returned very different prices for what is meant to be the same job. The plan includes a kitchen, bathrooms, new floor finishes, painting, electrical testing and some energy improvements. There is no extension in the scope.

I can simplify the finishes if necessary; correcting concealed moisture or rerouting inadequate services would be much harder. Before comparing the totals, I intend to have each contractor identify exclusions and price the work line by line.

What contingency would be sensible at this stage, and which investigations should happen before a contractor is selected? I am particularly concerned about plumbing routes, dampness, available electrical capacity and any structural work that one bidder may have assumed away.

 

[loft.balanced]

I would tentatively hold around 15–20% until the warehouse has been opened up enough to understand the services and moisture condition. More important, put both bids into the same line-by-line scope: demolition, disposal, electrical remedial work, plumbing routes, waterproofing, making good, permits and temporary protection. A lower quote may simply leave several of those items outside the price.

 

[SimpleLane]

Is the five-bed arrangement intended for one household, and how many bathrooms are proposed? In only 45 m², the wet-area locations could drive the whole sequence. I’d ask whether existing drains and water connections have been traced, whether the slab or walls show dampness, and whether the electrical quotation includes repairs discovered during testing rather than testing alone.

 

[EarlyGlass]

I’m not convinced a flat 15–20% reserve solves this. If one contractor has excluded drainage alterations or moisture remediation, even a generous contingency can disguise an incomplete comparison. Ask each contractor to identify assumptions and exclusions in writing, then price the same likely unknowns as separate allowances. Also clarify whether any layout or use approvals affect when work can start; permit timing and material lead times could alter the sequence without changing the nominal scope.

 

[EarlyGlass]

One practical next step: arrange a joint site walk using a single checklist and issue the same follow-up questions to both contractors. Photograph existing damp marks, service entries, the electrical board and proposed wet areas. Then compare not just totals, but who owns each interface—especially demolition to plumbing, plumbing to waterproofing, and electrical testing to remedial work. Those handoffs are where “not included” disputes tend to appear.