Browse by area（97 terms）：Regulations & permits · Structure, methods & ground · Construction & quality control · Design, contracts & process · Cost & estimates · Performance & certification · Land & land prices · Investment, land use & tax

Regulations & permits

Use district / zoning (用途地域)
Under Article 8 of the City Planning Act, land inside an urbanisation-promotion area is classified into 13 residential, commercial and industrial zones. The zone fixes which uses are allowed (housing, shops, hotels, factories) and the applicable floor-area ratio, coverage ratio, height limits and shadow rules. It is the first thing to check on any site — a hotel, for example, cannot be built in an exclusively residential zone and is capped at 3,000 m² in a Category I residential zone. More →
Floor-area ratio (容積率, FAR)
The cap on gross floor area as a percentage of the site area (Building Standards Act Art. 52). The stricter of the zoned value and the value derived from the front-road width applies. Osaka commercial zones run 400–1,000 %, residential zones 100–300 %. Basement housing (up to 1/3 of floor area), garages (up to 1/5) and the common corridors and stairs of apartment buildings can be excluded — relaxations that materially change the achievable volume. More →
Front-road width limit on FAR
Where the front road is under 12 m wide, a second FAR cap applies: road width × 0.4 in residential zones or × 0.6 elsewhere (Art. 52-2). A residential site on a 4 m road therefore gets at most 160 % even if the zoned figure is 200 %. Overlooking this before buying land is the classic reason a planned storey count or unit count later fails. More →
Building-coverage ratio (建蔽率)
The cap on building area as a percentage of site area (Art. 53), zoned at 30–80 %. Corner lots earn +10 %, fire-resistant buildings in fire-prevention districts +10 % (no limit where the zoned figure is 80 %). Where FAR decides how much floor you can stack, coverage decides how much of the ground you may occupy. More →
Building area & gross floor area
Building area is the horizontal projection of the area enclosed by the centre-lines of the external walls (or their columns); eaves up to 1 m are excluded (Enforcement Order Art. 2). It is the numerator of the coverage ratio. Gross floor area is the sum of all floors and is the numerator of FAR. Quoted per-tsubo prices normally divide by gross floor area, so inclusion rules change the apparent unit price of the same building. More →
Frontage rule & non-rebuildable lots (接道義務)
A building site must touch a legal road at least 4 m wide for at least 2 m (Art. 43). A site that fails is 'non-rebuildable': once the existing building is demolished nothing new can be built — cheap to buy, but hard to finance or use. Approval under Art. 43-2 can sometimes unlock it, so always verify the road classification at the municipal office before purchase. More →
Article 42-2 roads, setback & designated private roads
A road under 4 m that pre-dates the Act and is designated by the authority counts as a road (Art. 42-2), but the site boundary is deemed 2 m from the road centre-line — nothing, not even a fence, may be built inside that setback. A designated private road (Art. 42-1-5) is one built privately and formally designated. Both directly reduce the usable site area and the coverage/FAR arithmetic. More →
Slant-plane height limits (斜線制限)
Limits that keep every part of a building below inclined planes so roads and neighbours retain light and air (Art. 56). Three types: the road plane (1:1.25 from the far edge of the road in residential zones, 1:1.5 elsewhere), the adjacent-site plane (20 m + 1:1.25 residential, 31 m + 1:2.5 elsewhere) and the north-side plane (5 m + 1:1.25 in low-rise residential, 10 m + 1:1.25 in mid/high-rise residential zones). The sloped top storeys of mid-rise buildings are mostly this rule at work. More →
Sunlight-shadow regulation (日影規制)
Controls height and shape so the shadow a building casts between 8:00 and 16:00 on the winter solstice does not cover neighbouring land beyond set durations (Art. 56-2, Table 4). It applies in residential zones and in designated neighbourhood-commercial and quasi-industrial zones; commercial and industrial zones are exempt. For mid-rise apartment buildings and hotels it often bites harder than the slant-plane limits. More →
Absolute height limit & height districts
In Category I/II low-rise residential and rural-residential zones the building height itself is capped at 10 m or 12 m (Art. 55) — the reason three storeys rarely work in the prime residential areas of Ashiya and Nishinomiya. A height district (City Planning Act Art. 9 / BSA Art. 58) is a municipal maximum (or minimum) height that stacks on top of the zoning slant-plane rules. More →
Sky factor (天空率)
An alternative to the slant-plane limits (Art. 56-7): if the proposed building leaves at least as much visible sky, measured from set points, as a building that exactly follows the slant planes, a shape that breaches them is still lawful. It can recover a great deal of top-floor area on mid-rise RC buildings, but must be verified separately for the road, adjacent-site and north-side planes. More →
Fire-prevention & quasi-fire-prevention districts
City-planning districts that limit the spread of urban fire (Art. 61). In a fire-prevention district any building of 3+ storeys or over 100 m² must be fire-resistant (or an equivalent fire-spread-prevention building); in a quasi district, 4+ storeys or over 1,500 m² requires fire-resistant, and 500–1,500 m² at least quasi-fire-resistant construction. Central Osaka and its arterial roads are almost entirely fire-prevention districts — one structural reason RC is chosen over timber. More →
Fire-resistant & quasi-fire-resistant buildings
A fire-resistant building has main structural parts (columns, beams, floors, walls, roof, stairs) of fire-resistant construction rated 1–3 hours, with fire-protective fittings in external openings (Art. 2-9-2). Quasi-fire-resistant means 45- or 60-minute performance (Art. 2-9-3). RC structure qualifies essentially as built; steel needs fire-protective cladding and timber needs protective linings or charring-allowance design. More →
Special buildings (特殊建築物)
Buildings used by the public or with elevated fire risk — hotels, apartment buildings, shops, schools, hospitals, theatres, warehouses, garages and many others (Art. 2-2). Once the use area exceeds 200 m², building confirmation is required regardless of structure or size, and stricter evacuation, smoke-control, interior-finish and compartmentation rules apply. Offices are not special buildings. More →
Change of use (用途変更)
Converting an existing building to another use. Where the new use is a special building with over 200 m² of use area, building confirmation is required (Art. 87; relaxed from 100 m² in 2019). Office-to-hotel and house-to-guesthouse conversions are typical and must newly satisfy use-specific rules on escape routes, fire equipment, daylight and sanitary provision. Buildings without an inspection certificate face a much higher hurdle. More →
Existing non-conforming buildings (既存不適格)
A building that was lawful when built but no longer meets current standards because the law or the city plan changed (Art. 3-2). It is not an illegal building and may continue in use. However, extensions, major alterations and changes of use generally trigger compliance with current law, so any hotel conversion or extension starts by listing exactly which provisions the building fails. More →
Building confirmation & confirmation certificate (建築確認)
Pre-construction review by the building official or a designated inspection body that the design complies with the Building Standards Act and related laws (Art. 6). A confirmation certificate is issued on approval and work may not start without it. In Osaka a mid-size RC building typically takes 1–2 months, longer where structural peer review is required. The confirmation and inspection certificates are demanded again at every later sale, loan or change of use. More →
Interim & completion inspections; inspection certificate (検査済証)
The interim inspection is carried out when a designated stage is finished (in Osaka City, for example, the second-floor slab reinforcement of a 3+ storey apartment building; Art. 7-3); the completion inspection is applied for within four days of finishing and checks the whole building (Art. 7). Passing yields the inspection certificate. Without it, financing, change of use and extensions become seriously difficult — obtain and keep it at handover. More →
Shrinking of the Type-4 exemption (April 2025)
Timber buildings of two storeys or fewer and under 500 m² ('Type 4') used to have structural and energy documents exempted from confirmation review. From April 2025 two-storey timber houses and single-storey buildings over 200 m² became 'new Type 2' buildings whose structural and energy documents must be submitted and reviewed. Design and confirmation periods for timber houses grew, narrowing the procedural gap with RC. More →
Urbanisation promotion / control areas & development permission
A city-planning area is split into an urbanisation-promotion area and an urbanisation-control area where development is restrained (City Planning Act Art. 7); new housing and shops are in principle barred in the latter. Even inside the promotion area, development that reshapes land above a threshold (1,000 m² as a rule; 500 m² in built-up Osaka City) needs development permission (Art. 29), bringing road, drainage and park obligations. More →
Building agreements, district plans & landscape ordinances
A building agreement is a covenant among landowners, approved by the authority, setting uses, heights and minimum lot sizes stricter than the law (BSA Art. 69 ff.); Rokurokuso-cho's 'minimum lot 400 m², detached houses only, 10 m height' is the best-known example. District plans (City Planning Act Art. 12-4) are municipal area-specific rules; landscape plans and ordinances (Landscape Act) govern colour, materials and signage. All stack on top of zoning, so check them before designing in prime residential areas. More →
Hotel Business Act (旅館業法)
The law regulating paid lodging, licensed by the public-health centre. The 2018 amendment merged hotel and ryokan operation into one 'hotel-ryokan business', abolished minimum room counts and allowed substitutes for a staffed front desk under conditions. 'Simple lodging' covers shared-room formats. Zoning bars hotels from exclusively residential zones, and compliance with the Fire Service Act and the Building Standards Act (as a special building) is a precondition of the licence. More →
Private Lodging Act (民泊新法) & special-zone minpaku
A notification-based (not licensed) scheme letting dwellings be rented for lodging up to 180 nights a year (in force 2018). Year-round operation requires a Hotel Business Act licence. Osaka City is unusual in also running 'special-zone minpaku' under the National Strategic Special Zones (stays of two nights or more, no annual cap). In lodging investment, the choice between minpaku, special-zone minpaku and a licensed hotel shapes the whole revenue model. More →
Fire Service Act: fire-department consent & equipment
Consent of the fire chief (Fire Service Act Art. 7) is a precondition of building confirmation. Depending on use and size, automatic fire alarms, exit lights, extinguishers, indoor hydrants and sprinklers (hotels: in principle from 6,000 m² gross floor area) are mandatory, and hotels with 30+ occupants must appoint a fire-protection manager. This is a main reason the services share of construction cost is higher for hotels, shops and apartment buildings than for houses. More →
Building Energy Efficiency Act (mandatory from April 2025)
From April 2025 essentially every new building, residential or not, must meet the energy-conservation standard (insulation grade 4 and primary-energy grade 4 equivalent), reviewed in step with building confirmation. Energy-compliance assessment and calculation documents now sit inside the design programme, so insulation and equipment specifications feed directly into cost and schedule. More →

Structure, methods & ground

RC — reinforced concrete (鉄筋コンクリート造)
Concrete, strong in compression, bonded with steel, strong in tension. Excellent fire resistance, durability, sound insulation and watertightness with great design freedom — the mainstream for Osaka's mid-rise buildings, hotels and apartments. Statutory useful life for housing is 47 years. Its weight increases foundation and ground work, and formwork, rebar, pouring and curing make the programme about 1.5× timber's; guide price ¥1.2–1.9 million per tsubo for the main works (excl. tax). More →
S — steel frame (鉄骨造)
Columns and beams of rolled steel such as H-sections. Long spans, short programmes and low weight make it common for offices, shops, warehouses and factories. Steel loses strength in fire, so fire-resistant buildings need fire-protective cladding, plus corrosion protection. Heavy steel (useful life 34 years) and light-gauge steel (19–27 years) are distinguished by member thickness. Guide price ¥1.0–1.6 million per tsubo (main works, excl. tax). More →
SRC — steel-reinforced concrete (鉄骨鉄筋コンクリート造)
A steel skeleton encased in reinforced concrete, combining steel's ductility with RC's stiffness and fire resistance for high-rises and buildings that need both long spans and high seismic capacity. Because it involves both steel erection and RC work the sequence is complex, and at ¥1.5–2.3 million per tsubo it is the most expensive frame. For ordinary low/mid-rise buildings RC is usually sufficient; SRC is a scale-and-performance decision.
Timber (post-and-beam / 2×4)
Japan's conventional post-and-beam frame and the platform (2×4) method with sheathed stud walls dominate — about nine in ten detached houses. Cheapest at ¥0.7–1.2 million per tsubo (main works, excl. tax) and fastest to build. Fire-resistant timber is possible in fire-prevention districts but costly, and sound insulation, large openings and basements are constrained. Useful life is 22 years versus 47 for RC, which affects depreciation and loan terms. More →
Rigid (moment) frame & span (ラーメン構造)
Columns and beams rigidly connected so the frame alone resists gravity and seismic loads, leaving walls non-structural. This gives large openings, free planning and easy future remodelling — the standard for RC and steel shops, offices and hotels. The longer the span between columns, the deeper the beams and the greater the effect on floor height and cost; spans of about 6–8 m are the economical range for mid-size RC. More →
Wall-type RC (壁式構造)
Reinforced-concrete walls and floor slabs carry the loads without columns or beams, so no column or beam projections intrude into rooms and the structure is stiff and earthquake-resistant. Its permitted range — up to five storeys above ground and 20 m eaves height — is set by ministerial notification, and it is widely used for low/mid-rise apartment buildings and detached RC houses in Osaka. Structural walls cannot be removed, which limits later replanning and large openings. More →
Foundations (spread vs pile)
The element that transfers building loads to the ground. On good soil a spread foundation is used — a raft (one continuous RC slab), strip footings under walls, or pad footings under columns; where the bearing stratum is deep, piles (end-bearing or friction) are needed. For mid-rise RC the pile requirement and length follow from the ground investigation and are a major cost variable. Foundation design is part of the structural calculation and presupposes a ground survey. More →
Bearing / shear walls (耐力壁)
Walls that resist horizontal forces from earthquakes and wind. In timber these are braced or plywood-sheathed walls; in RC, walls of specified thickness and reinforcement. Required quantity and balanced placement come from Enforcement Order Art. 46 (timber), wall-quantity checks and structural calculation. Where they go directly determines planning freedom; in wall-type RC most external and party walls are shear walls. More →
Structural calculation (allowable stress / ultimate lateral capacity)
Numerical verification that members safely carry dead, live, seismic, wind and snow loads. Allowable-stress design checks that members are undamaged in a moderate earthquake; ultimate-lateral-capacity design checks against collapse in a major one. The required route is set by height and size, and above certain thresholds a third-party structural peer review is added to building confirmation — almost every RC building is in scope, one reason confirmation takes longer. More →
Seismic resistance, damping & isolation
Three earthquake strategies. Resistance relies on the strength and ductility of the structure itself and is mandatory for every building; damping adds devices that absorb shaking energy to limit damage; isolation inserts laminated rubber bearings between building and foundation so ground motion barely transfers. Isolation costs more and needs site clearance, but is chosen for hotels and hospitals where continuity matters. For houses, seismic grade 3 plus damping is the realistic upper specification. More →
Ground investigation (SWS test / boring & SPT)
Establishes soil strength, stratification and groundwater level. For houses the screw-weight sounding test (SWS, formerly Swedish weight sounding, JIS A 1221) is standard; for mid-rise RC, borehole standard penetration tests give N-values and the depth of the bearing stratum. Results decide the foundation type (spread or pile) and whether ground improvement is needed, fixing a major cost variable early. Doing it before the land contract is safest. More →
Ground improvement (地盤改良)
Strengthening weak soil to carry the building. Surface stabilisation (cement mixed into the top ~2 m), column stabilisation (soil-cement columns to ~8 m) or small-diameter steel pipe piles for greater depths. Often needed on the low-lying bayside and riverside land of Osaka; several hundred thousand to a few million yen for a house, and tens of millions for piling under a mid-rise building. The most volatile item within ancillary works. More →

Construction & quality control

Formwork (sheathing & shoring)
The temporary mould into which concrete is poured — plywood sheathing supported by pipe props and shoring that must resist the pressure of wet concrete while holding line and level. Assembly and striking are skilled manual work, one of the main reasons RC costs more than timber (formwork, rebar, pouring, curing). For exposed concrete the panel material, layout and joint positions become the finish itself. More →
Rebar placement & inspection
Fixing reinforcement to the structural drawings and, before pouring, checking bar diameter, count, spacing, cover, laps and anchorage lengths. Once concrete is placed nothing can be seen again, making this the single most important quality checkpoint in RC work. It is inspected by the supervising architect and can also be a designated stage for the interim inspection and a site check under defect-warranty insurance. Photographs are kept as part of the completion records. More →
Concrete pouring
Placing and compacting fresh concrete in the formwork. On delivery, slump, air content, chloride content and test cylinders are checked; concrete is vibrated within the permitted re-pour interval to avoid voids. Summer demands protection against rapid drying and heat, winter against early frost (hot- and cold-weather concreting). The pour plan — volume, pump trucks, crew, weather — governs frame quality and is a key milestone in the programme. More →
Curing
Protecting freshly placed concrete from drying, chilling, vibration and load until it reaches its design strength and durability. Moist curing is the basic method and takes from several days to over a week depending on cement type and temperature. No following trade can start during curing, which is a structural reason RC programmes run longer than timber; cutting it short raises the risk of cracking and low strength. More →
Specified design strength (Fc)
The concrete compressive strength assumed in the structural calculation, in N/mm²; 24–30 N/mm² is typical for houses and mid-rise buildings. A durability design strength (24–36 N/mm² depending on intended service life) is also set, and the strength actually ordered adds a temperature correction. Higher strength costs more per cubic metre but can allow slimmer members; the structural engineer and contractor settle it together. More →
Slump & water–cement ratio
Slump measures the workability of fresh concrete in centimetres; 15–18 cm is usual — higher is easier to place but more prone to segregation and settlement cracking. The water–cement ratio is the mass of water to cement; the lower it is, the higher the strength and durability, with 65 % as the durability ceiling. Both are checked at delivery, and adding water on site to ease placing is strictly forbidden. More →
Rebar cover (かぶり厚)
The shortest distance from the bar surface to the concrete face, protecting steel from fire and corrosion and ensuring bond. Minimum values are legislated (Enforcement Order Art. 79: 3 cm for shear walls, columns and beams, 4 cm for parts in contact with soil, 6 cm for foundations). Designs add a construction tolerance, and spacer placement is verified at the rebar inspection. Insufficient cover sharply shortens an RC building's life through carbonation and rebar corrosion. More →
Cold joints & honeycombing
A cold joint is a discontinuity formed when fresh concrete is placed against concrete that has already begun to set, so the two never bond. Honeycombing is a porous zone of exposed aggregate caused by poor compaction or segregation. Both impair strength, watertightness and durability; they are prevented by the pour plan (re-pour intervals, crew) and proper vibration, and repaired according to severity. On exposed concrete they are also fatal to the finish. More →
Exposed concrete (打ち放し)
Leaving the struck concrete face as the final finish — a finish choice, not a structural one, applied to RC and SRC. Panel layout, tie-cone holes and joints become the design, so formwork drawings are fixed in detail at design stage and pouring and curing precision is decisive. The surface is protected with water-repellent coatings and carbonation and staining are managed over time. Nurtured in Kansai (Tadao Ando among others), it remains popular for RC houses and shops in Osaka. More →
Construction supervision by the architect (工事監理)
The architect's duty to verify that the works are being executed in accordance with the design documents and to report to the client (Architect Act Art. 2-8). Reinforcement, formwork, steel and waterproofing are inspected at key stages and non-conformities are ordered corrected. It differs in actor and purpose from the contractor's own site management: the supervisor stands on the client's side. In a design-build firm, whether supervision is organisationally independent of construction is the quality dividing line. More →
Site management: chief / supervising engineers & schedule (施工管理)
The contractor's management of programme, quality, safety and cost. The Construction Business Act (Art. 26) requires a chief engineer on every site and a supervising engineer where subcontract value exceeds a threshold (¥70 million for a building lump-sum contract) on a specified-licence contractor's site. The construction schedule sequences all trades, with pour, curing and inspection dates the critical alignment. Nationally qualified construction-management engineers (1st/2nd class) fill these roles. More →

Design, contracts & process

Design-build (設計施工一貫)
One company takes responsibility for both design and construction. A single point of contact speeds decisions, and cost, buildability and programme are built in from the design stage, so budget overruns and drawing-versus-site conflicts are rarer, with responsibility undivided. The trade-off is weaker independent checking of the builder by the designer — so confirm the firm keeps construction supervision organisationally separate from construction. Towa builds mid-rise RC hotels, houses and renovations this way.
Design-bid-build (設計施工分離)
Design and supervision are commissioned from an architectural office and construction separately from a builder. The designer sits on the client's side to supervise the builder, giving strong independence, and competitive tendering among several contractors is straightforward. Against that, the construction cost is not fixed until design is complete, responsibility for design changes and drawing inconsistencies is split, and the client runs two contracts. Standard for public and very large projects. More →
General contractors, komuten & design offices
General contractors (zenekon) are large prime contractors coordinating many specialist trades on big projects; komuten are local builders of houses and small buildings; design offices are architects who design and supervise but do not build. Between them sit design-build firms with in-house design and construction departments that deliver mid-size RC buildings, hotels and houses under one contract. Choose by project scale and by whether you want third-party supervision or single-point responsibility.
Basic design vs detailed design
Basic design resolves site, regulations and brief into layout, plans, sections, elevations and a preliminary cost. Detailed design develops it to the precision needed for tendering and building confirmation — architectural, structural and services drawings plus specifications. For a mid-size RC building allow about 2–3 months for basic and 3–5 months for detailed design. The detailed estimate produced after detailed design underpins the contract sum, so decisions here govern later variations. More →
Preliminary vs detailed estimate
A preliminary estimate is produced at basic-design stage from per-tsubo rates and comparable projects and carries a ±10–20 % band. A detailed (tender) estimate takes quantities off the detailed-design documents and prices each trade, and becomes the contract sum. Contracting on a preliminary figure invites increases once specifications are fixed, so before signing check the detailed estimate and its assumptions — the specification and the scope of excluded works. More →
Lump-sum vs itemised (bill-of-quantities) estimates
A lump-sum estimate shows only a total per trade ('carpentry, lump sum ¥X'); an itemised bill lists material, quantity, unit rate and amount line by line. Only the itemised form allows comparison between bidders, pricing of specification changes, progress-payment verification and scrutiny of additional works. Most estimate spread comes from differences in included scope and specification, so compare on identical drawings and identical scope. More →
Value engineering (VE) & cost-down
VE lowers cost by revisiting specification, method or material while keeping the required function and performance — substituting an equally durable material, adjusting structural spans, changing the services system. It is distinct from simple cost-down, which lowers specification. Design-build can fold VE in from the design stage; when an estimate overshoots, the question becomes 'how do we deliver the same value cheaper' rather than 'what do we cut'. More →
Construction contract: standard conditions & payment terms
The builder undertakes to complete the works and the client to pay. Standard general conditions such as the Seven-Society (formerly Four-Society) private-works contract conditions are used, with the agreement, conditions, design documents, estimate (itemised) and schedule forming one contract. Payment is typically staged — deposit, interim (at frame completion) and final at handover — and should track actual progress. Read the delay, variation, termination, warranty and dispute clauses before signing. More →
Liability for contract non-conformity (formerly defect liability)
Where the delivered building does not conform to the contract in kind, quality or quantity, the client may demand cure (repair), price reduction, damages or termination — renamed from 'defect liability' in the 2020 Civil Code reform. The test is no longer whether a 'defect' exists but the gap from what was agreed, which makes the content of the specification and drawings decisive. Notice must be given within one year of discovering the non-conformity. More →
10-year defect warranty law & after-service
Builders and sellers of new housing are liable for ten years from handover for defects in the main structural parts and in parts preventing rainwater penetration (Housing Quality Act Arts. 94–95), and must secure that liability by insurance or deposit under the Housing Defect Warranty Performance Act. Separately, fittings, equipment and finishes are covered by each company's after-service terms (1, 2, 5 years) and periodic inspections. Warranty documents and inspection records feed directly into resale value. More →
Construction business licence (general / specified; governor / minister)
A licence is required to contract works of ¥5 million or more (¥15 million, or timber houses over 150 m², for building lump-sum contracts) (Construction Business Act Art. 3). Offices in one prefecture take a governor's licence, in several a minister's. A prime contractor placing subcontracts totalling ¥45 million or more (¥70 million for building lump-sum) needs the stricter 'specified' licence with higher financial and technical requirements. Towa holds Osaka Governor's specified licence (特-7) No. 163973. More →
First-class architect (一級建築士)
Licensed by the Minister of Land, Infrastructure, Transport and Tourism to design and supervise buildings of any size or structure (Architect Act). RC buildings over 300 m², or over 13 m high or 9 m to the eaves, may only be designed and supervised by a first-class architect. Design and construction supervision are reserved to architects, so even under design-build the firm's architect is the responsible person for design and supervision. More →

Cost & estimates

Per-tsubo price (坪単価)
Main construction cost divided by gross floor area in tsubo. By convention it is quoted excluding tax and covers main works only — not ancillary works, soft costs or consumption tax. Our Osaka guide bands: timber ¥0.7–1.2 million, RC ¥1.2–1.9 million, steel ¥1.0–1.6 million, SRC ¥1.5–2.3 million per tsubo. Within one structure the figure moves with storeys, ground, services density and finish grade, so align 'what the price includes' before comparing.
Tsubo (坪)
The unit used for building and land areas in Japan: 1 tsubo ≈ 3.305785 m² (about two tatami mats); 1 m² ≈ 0.3025 tsubo. A 40-tsubo house is about 132 m². Laws and drawings use m² throughout, but estimates, advertising and land deals still use tsubo, so rounding in the conversion can make the same per-tsubo price look different. More →
Main construction cost (本体工事費)
The cost of building the structure itself — temporary works, foundations, frame, roof, exterior, interior, doors and windows, electrical, plumbing, HVAC. It is 70–80 % of the total and is the basis of the per-tsubo price. Firms differ in what they count as 'main' (lighting, curtains, air-conditioners, ground improvement), so always confirm the scope when comparing estimates. More →
Ancillary works (付帯工事費)
Works needed beyond the building itself: ground improvement, demolition of an existing building, external works (gates, walls, parking, planting), water/gas/power connections, grading and retaining walls — typically 15–20 % of the total. They vary sharply with site conditions and are the part most often missed when budgeting from a per-tsubo price alone. Checking utilities, ground and demolition before the land is chosen sharpens the figure. More →
Soft costs & contingency (諸経費)
Costs outside the works: design and supervision fee, confirmation and inspection fees, registration (title, preservation, mortgage), acquisition tax, fire and defect insurance, ground-breaking ceremony and neighbour relations, moving — about 7–10 % of the total. In addition, a contingency of 5–10 % of construction cost for ground, prices and specification changes is prudent. Build the total as main + ancillary + soft costs, remembering per-tsubo covers main works only. More →
Design & supervision fee
The architect's fee for basic and detailed design and for construction supervision. The Ministry's fee standard (notification) provides the reference, and in practice it is set as a percentage of construction cost or by staff-hours. Under design-bid-build it is a separate contract with the design office; under design-build it is usually a line in the estimate. Because it is carried differently, align the breakdown before comparing totals across the two methods. More →
Price-escalation clause
A contract clause allowing the contract sum to be adjusted when material prices or labour costs move significantly after signing. Public-works standard conditions provide general, single-item and inflation escalation; private conditions carry similar provisions. With steel, timber and energy prices volatile, check — together with the estimate's validity period — exactly what triggers an adjustment before you sign. More →
Additional & variation works
Changes in scope after contract from client requests, site conditions (buried obstacles, ground, an existing building not as assumed) or regulatory responses. Most disputes arise from settling additional works agreed only verbally, so fix content, price and programme effect in writing (variation order and estimate) each time. A contingency allowance and fully detailed specifications at design stage are the best prevention. More →

Performance & certification

Insulation grade & UA value
The housing insulation grade under the Housing Quality Act's performance indication system — grades 1–7 since grades 5–7 were added in 2022. It is judged by the average envelope heat-transfer coefficient UA (lower is better); in Osaka (zone 6) grade 4 = 0.87, grade 5 (ZEH level) = 0.6, grade 6 = 0.46, grade 7 = 0.26 W/m²K. Grade 4 equivalent is mandatory for new buildings from April 2025, and grade 5 or above is the practical condition for the mortgage deduction and subsidies. More →
Airtightness (C value)
Leakage area per square metre of floor area (cm²/m²); the lower, the tighter. Airtightness is what converts insulation into real room temperatures and energy savings and lets designed ventilation work. No statutory limit exists — it is measured on site. High-performance houses target 1.0 or below, often 0.5. RC structure is inherently airtight, so performance is decided at openings and penetrations. More →
Seismic grade (耐震等級)
The structural earthquake-resistance grade under the housing performance indication system. Grade 1 is the Building Standards Act minimum (no collapse in a once-in-several-centuries earthquake); grade 2 is 1.25× that and a condition of long-term quality housing; grade 3 is 1.5× — the level of fire and police stations — and earns a 50 % earthquake-insurance discount. Mid-rise RC buildings demonstrate seismic capacity through structural calculation rather than this grading. More →
ZEH — net zero energy house
A house with high insulation (grade 5 or above, UA ≤ 0.6 in zone 6) and efficient equipment cutting primary energy by 20 % or more, plus on-site generation such as solar to bring the annual balance to about zero. It qualifies for national subsidies, a higher mortgage-deduction ceiling and Flat 35 rate benefits. The apartment version is ZEH-M; for offices and hotels the equivalent is ZEB. Roof shape, orientation and urban solar access decide feasibility. More →
Long-term quality housing
Housing certified by the local authority as meeting standards for deterioration control, seismic grade 2 or above, ease of maintenance, energy performance (insulation grade 5, primary-energy grade 6), living environment and a maintenance plan (Long-term Quality Housing Promotion Act). Benefits include a higher mortgage-deduction ceiling, reductions in registration, acquisition and fixed-asset taxes, subsidies and Flat 35S rates. Apply before construction starts. More →
Housing Performance Indication System
Under the Housing Quality Act, a registered evaluation body grades a house in ten areas — structural stability (seismic grade), fire safety, deterioration control, maintenance, thermal environment (insulation grade), air quality, light, sound, accessibility and security — on a common scale. There are design and construction evaluation stages; the certificate unlocks earthquake-insurance discounts, access to dispute-resolution bodies and a documented basis for asset value. More →

Land & land prices

Land category & farmland conversion
The land category is the registered use class (residential land, paddy, field, forest, miscellaneous). Turning paddy or field into a house or shop site requires permission or notification under the Farmland Act (Art. 4 for own use, Art. 5 where rights transfer): notification inside urbanisation-promotion areas, permission outside them, and some farmland classes cannot be converted. Registered category and actual condition can differ either way, so check both before buying. More →
Flagpole lots (旗竿地)
A site whose road frontage is a narrow strip (the pole) leading to a wider building area at the back (the flag). Cheaper than a regular lot, but the strip must satisfy the 2 m frontage rule, and local ordinances require greater width for longer strips (Osaka City: 2–3 m or more depending on length). Access for vehicles, materials and machinery is constrained, pushing construction cost up; on the other hand daylight and privacy can be turned to advantage in the design. More →
Land sold with a building condition
Land sold on condition that the buyer signs a construction contract with a builder named by the seller within a set period (usually three months). The land price is lower, but the builder cannot be chosen and freedom over plan, specification and competitive pricing shrinks. If no construction contract is concluded in time, the land sale is in principle cancelled with the deposit refunded. Buying out the condition for a premium is sometimes negotiable. More →
Private-road burden
Part of the site is given over to a private road (a designated private road or Article 42-2 road) and cannot count as site area or be built on. Advertised land areas sometimes include the road portion, so recompute coverage and FAR on the effective site area. Check before purchase how the road is owned (shared interest or subdivided), whether passage and excavation consents exist, and who bears maintenance. More →
Boundary-confirmation survey
Fixing the site's boundary points with the attendance and agreement of neighbours and the road authority, setting markers and producing a confirmed survey plan. Registered and measured areas often differ, and coverage, FAR, setbacks and clearances all rest on the measured figure. Making the seller's confirmed survey a condition of sale is the safe course; cost is a few hundred thousand yen and duration one to three months depending on neighbours' cooperation. More →
Cliff ordinance (Osaka Prefecture)
Prefectural ordinances (under Building Standards Act Arts. 19 and 40) requiring a building above or below a cliff higher than 2 m to be set back at least twice the cliff height, or protected by a sound retaining wall or by the building's own construction. Both Osaka and Hyogo have such rules, and they weigh heavily on design and cost in the sloping residential areas of Hokusetsu and Hanshin. Existing retaining walls must be checked for legality (inspection certificate, structure). More →
Buried cultural property zones
Land known to contain archaeological remains — widespread in central Osaka (Naniwa Palace, the Osaka Castle town) and Nara. Works there require notification under Article 93 of the Cultural Properties Protection Act 60 days before starting; the board of education may order trial trenching and then full excavation. Surveys can delay the programme by weeks to months and may carry cost, so check the municipal zone map when selecting land. More →
Hazard maps & liquefaction
Municipal maps of flood, inland-water, storm-surge, tsunami, landslide and liquefaction risk. Since 2020 the Real Estate Brokerage Act requires flood-hazard maps to be explained in the important-matters disclosure. Liquefaction is loose, water-saturated sand turning fluid in an earthquake; in Osaka risk is highest on the low bayside and along the Yodo and Yamato rivers. Even a strong RC frame suffers from differential settlement, so the answer lies in ground investigation and foundation type. More →
Roadside value, posted land price & market price
The posted land price is MLIT's benchmark for standard sites as of 1 January each year. The roadside value, set by the National Tax Agency per road, is used for inheritance and gift tax and runs about 80 % of the posted price; the fixed-asset assessed value about 70 %. Market (transaction) prices often diverge, exceeding posted prices in central Osaka and sought-after residential areas. Budget land at market, but estimate taxes on roadside and assessed values. More →
Fixed-asset assessed value
The municipality's valuation of land and buildings, revised every three years, forming the tax base for fixed-asset, city-planning, acquisition and registration taxes. Land is about 70 % of the posted price and a new building 50–70 % of its rebuild cost, so it matches neither purchase price nor construction cost. Buildings are assessed after a municipal survey on completion; RC is valued higher than timber and depreciates more slowly, so holding taxes are relatively higher. More →

Investment, land use & tax

Land use / development (土地活用)
Generating income from idle, inherited or under-used land by building rental apartments, a hotel, shops, offices or an owner-occupied rental building. What can be built follows from zoning, FAR, coverage and the front road; what will pay follows from location (station distance, inbound-tourist flows), licensing and the operating model. Building also cuts land fixed-asset tax through the residential-land relief and lowers the inheritance-tax valuation as rented land — tax effects that belong in the decision.
Owner-occupied rental building (賃貸併用住宅)
One building combining the owner's home with rental units. Where the owner's part is at least 50 % of the floor area, many lenders will finance the whole building with a residential mortgage, and rent income offsets repayments. In Osaka the typical plan is RC, three to five storeys, rentals below and the owner's home above. Sound insulation, separated circulation and the future treatment on inheritance or sale (strata or whole building) should be settled at design stage. More →
Yield (gross, net, NOI)
Annual return as a share of the investment. Gross yield is full-occupancy rent divided by total investment; net yield divides net operating income (NOI — rent less management, repairs, fixed-asset tax and insurance) by total investment and runs one to two points lower. For new builds the total includes land, building and soft costs. For hotels, revenue is room rate × occupancy × room count, less the operator's fee, before yield is computed. More →
Depreciation & statutory useful life
Spreading the building's acquisition cost over the statutory useful life by structure as an annual expense for accounting and tax. For residential and retail use: RC 47 years, heavy steel 34, light-gauge steel 19–27, timber 22; RC hotels 39 years. Land is not depreciated. RC's long life means a small annual write-off, timber's short life a large one — affecting both tax shelter and loan tenor. Second-hand buildings use a simplified remaining-life formula. More →
Real-estate acquisition tax
A one-time prefectural tax on acquiring land or buildings (purchase, new build, gift). The standard rate is 4 %, reduced to 3 % for housing and land until 31 March 2027. A new house deducts ¥12 million (¥13 million for certified long-term quality housing) from the tax base and residential land has its own relief, so ordinary houses often owe nothing. Commercial buildings and hotels pay 4 % without relief; the notice arrives six to twelve months after acquisition. More →
Fixed-asset & city-planning tax
Municipal taxes on whoever owns the property on 1 January. Fixed-asset tax is 1.4 % (standard rate) of the assessed value; city-planning tax up to 0.3 % inside urbanisation-promotion areas. Residential land is assessed at one-sixth (city-planning: one-third) up to 200 m² and one-third (two-thirds) beyond, and a new house's building tax is halved for three years (five for fire-resistant buildings of three or more storeys). Commercial buildings receive no residential relief. More →
Registration tax & stamp duty
Registration tax is the national tax on property registration: title preservation for a new building 0.4 % of assessed value (0.15 % for housing), land transfer 2 % (1.5 % until 31 March 2026), mortgage 0.4 % of the loan (0.1 % for housing). Stamp duty falls on construction, sale and loan contracts at a few thousand to tens of thousands of yen by contract value (reduced rates for construction and sale contracts). Electronic contracts need no stamp. More →
Capital-gains tax on sale
Income and resident tax on the profit from selling property (price less acquisition cost and selling expenses). Held five years or less as of 1 January of the sale year: short-term at 39.63 %; over five years: long-term at 20.315 % (including the reconstruction surtax). A primary residence enjoys a ¥30 million special deduction, a reduced rate after ten years and an optional replacement relief. For business buildings the depreciated book value becomes the acquisition cost. More →
Mortgage tax deduction
Where a home is built or bought with a mortgage, 0.7 % of the year-end loan balance is credited against income and resident tax for up to 13 years (10 for resale). The loan ceiling depends on energy performance (highest for certified long-term quality or low-carbon housing, then ZEH level, then energy-standard compliant), and from 2024 new homes not meeting the energy standard are in principle excluded. Conditions include floor area of 50 m² or more (40 m² below an income threshold) and total income of ¥20 million or less. More →
Bridge loan (つなぎ融資)
Short-term finance covering land payment, deposit and interim payments that fall due before the mortgage is disbursed at completion and handover. The rate is higher than the mortgage, interest only is paid during the term, and the main loan repays it in full at completion. Some lenders disburse in tranches for a land-first purchase, so lay the payment dates and loan drawdowns over the construction schedule when planning finance. More →
Inheritance-tax valuation (rented land, small-lot relief)
For inheritance tax, land is valued by the roadside-value method (value × area × adjustment) and buildings at assessed value. Building rental property lowers the land to 'rented-building land' — own-use value × (1 − leasehold ratio × 30 % tenancy ratio × let ratio) — and the building itself is valued 30 % lower as let property. The small-lot relief can then cut 50–80 % on up to 330 m² residential, 400 m² business or 200 m² rental land. These reductions are the core of land-development tax planning. More →
Brokerage fee & purchase costs
The brokerage fee is the licensed agent's commission, capped for prices over ¥4 million at price × 3 % + ¥60,000 + tax (Real Estate Brokerage Act). Land-purchase costs add registration, acquisition tax, stamp duty, loan fees and guarantee, fire insurance and survey — about 6–9 % of the land price in total. They are needed on top of construction cost, so the full budget is land + purchase costs + main + ancillary + soft costs. More →
Important-matters explanation
Before a sale or lease contract, a licensed real-estate transaction agent must explain and hand over in writing the key facts about the property and terms — title, legal restrictions, roads, utilities, hazard maps, cancellation conditions (Real Estate Brokerage Act Art. 35). For a building plot, the entries on zoning, coverage, FAR, frontage, private-road burden, buried cultural property and the cliff ordinance decide whether the project works, so have your building team review it in advance. More →