Five years ago I nearly bought a duplex in the Kansai area where the previous owner had converted a storage room into a rentable third bedroom without ever filing a kakunin shinsei, the building confirmation permit required for that kind of work in Japan. I only caught it because I asked one blunt question at the second viewing: has anything on this property been renovated, extended, or converted since it was originally built. That single question sent me digging through the building ledger before I signed anything, and it likely saved me close to 1.2 million yen in retroactive compliance costs and lost financing options.
After 15 years and 9 rental properties, I have learned that a seller’s memory of what permits were actually filed is often generous at best. Some sellers genuinely cannot tell you the difference between a permitted renovation and a weekend job done by a handyman with no paperwork at all. Your task as the buyer is to ask specific enough questions that vague, reassuring answers stop being an option.
- Ask exactly which renovations happened and when
- Request the building confirmation and completion inspection records
- Ask whether any work touched structure, plumbing risers, or the building footprint
- Get the answer in writing, not just verbally
- A short checklist before you make an offer
- Why this matters more than most buyers assume
Ask exactly which renovations happened and when
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Do not settle for the property has been well maintained. Ask for a room-by-room list: which walls moved, which rooms were added, when the roof was last replaced, and whether the kitchen or bathroom plumbing was ever relocated rather than just resurfaced. On one of my properties, a seller casually mentioned during this conversation that a balcony had been enclosed into a sunroom about 12 years earlier. That single detail told me exactly where to focus my permit search instead of requesting the entire 30-year building history.
Request the building confirmation and completion inspection records
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In Japan, any renovation that changes the floor area, the structural frame, or certain fire-safety elements is supposed to go through a kakunin shinsei before work starts, followed by a kensa zumisho, the completion inspection certificate, after work finishes. Ask the seller directly whether they have copies of both documents for any renovation done during their ownership. If they only have the confirmation but not the completion certificate, that is a red flag worth investigating, because it can mean the work was never signed off and the building ledger at city hall may not reflect the current floor area at all.
I now budget about 25,000 yen and a half day to visit the local building department myself and pull the ledger independent of whatever the seller hands over. On two separate purchases, what the seller told me did not match what the ledger showed, and in both cases the gap was under 8 square meters, small enough to seem harmless but large enough to trigger a reassessment of the loan-to-value ratio with my bank.
Ask whether any work touched structure, plumbing risers, or the building footprint
Cosmetic renovations, new flooring, repainting, replacing fixtures, rarely need a permit and rarely cause problems. What you need to press on is anything that touched a load-bearing wall, moved a plumbing riser between floors, or extended the building’s footprint even by a meter. I ask this as three separate yes-or-no questions rather than one open-ended one, because sellers will often answer no to the general question and then say yes to sound sleep. In my experience, splitting the question into concrete categories triples the odds of getting a useful answer instead of a polite dismissal.
Get the answer in writing, not just verbally
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A verbal answer at a viewing is worth very little once you own the building. Ask your agent to include the seller’s disclosure about renovations and permits in the purchase agreement itself, ideally as a specific clause with a date and a signature. On one deal I walked away from entirely because the seller’s agent refused to put a two-year-old kitchen extension in writing, even though they had verbally assured me it was permitted. That refusal told me more than any answer would have.
A short checklist before you make an offer
Whenever I am evaluating a new property now, I run through the same short list before I even calculate the yield:
- Ask for a written, room-by-room history of every renovation done in the last 20 years, not just the last one
- Request copies of both the kakunin shinsei and the kensa zumisho for any structural or floor-area change
- Visit the building department yourself and compare the ledger’s floor area to the listing’s stated floor area
- Ask three separate structural questions, walls, plumbing risers, and footprint, rather than one general question
- Have the seller’s disclosure written into the purchase agreement with a date attached
- Budget at least 20,000 to 40,000 yen and a few hours for independent permit verification before closing
Skipping any one item on that list has cost me money at least once over the years, which is exactly why the list exists now instead of living only in my head.
Why this matters more than most buyers assume
An unpermitted addition does not just risk a fine. It can mean your bank refuses to count that extra room in its valuation, your insurance denies a claim tied to the affected area, or a future buyer’s lender walks away from the deal entirely when their own inspection turns up the same gap you could have found for the cost of an afternoon at city hall. I have seen a 6 percent yield property turn into a 3 percent yield property once the unpermitted room had to be excluded from the rentable floor area on paper.
That is the approach I use across all 9 of my properties now: ask specific questions, verify independently, and get the answer in writing before I ever hand over a deposit.
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15 years of landlord experience u00b7 3 apartment buildings u00b7 DIY renovations that saved millions of yen. Browse all articles at diytosan.com
