Knowledge Guide to Office Interior Construction Costs and Workflow! Key Points for Choosing an Interior Design Company

Office interior construction involves much more than simply changing wallpaper or arranging furniture. It includes a wide range of specialized trades required to create a safe, comfortable, and functional working environment. Below are the main types of construction involved.

Architectural work refers to general construction that builds the basic structure of the office space, including walls, floors, and ceilings. Specifically, this includes light-gauge steel framing to build wall structures, drywall installation, and wallpaper finishing. It also covers raised access floor installation—which hides wiring beneath a secondary floor—and carpet tile laying. This is one of the most critical stages as it establishes the office's functionality and first impression.

Electrical and telecommunications work provides the essential power and internet infrastructure required in modern offices. Primary tasks include installing or relocating lighting fixtures, adding electrical outlets, laying LAN cabling, and setting up wireless network environments (Wi-Fi). Ensuring enough outlets based on desk layouts and equipment usage—along with a well-planned lighting scheme—directly impacts employee productivity.

To maintain a comfortable environment year-round, heating, ventilation, air conditioning (HVAC) and plumbing work are essential. Services range from installing or relocating air conditioners and ventilation systems to fitting plumbing for pantries and restrooms. It is particularly important to select equipment with adequate cooling and heating capacities for the room size and occupancy. Comfortable indoor temperatures and air quality tie directly to employee focus and health.

Installing fire protection and security systems is necessary to safeguard the workplace. Under relevant fire codes, installing fire alarms, sprinklers, and emergency exit signs is required by law. Furthermore, implementing security cameras and access control systems to protect confidential information and assets has become increasingly important. Properly installing these systems creates a secure environment where employees can work with peace of mind.

The question of the most concern in office buildouts is likely to be: "How much will it cost?" Knowing the market average is essential whether you are setting a budget or presenting to executive management. Below, we look at general per-area unit prices and how costs vary depending on the condition of the property.

The cost of office interior work varies greatly depending on the size and grade of the property, but unit costs provide a good baseline. Generally, interior construction costs range between 100,000 JPY to 300,000 JPY per “tsubo” (approx. $25 to $75 USD per sq. ft.). For example, a 30-tsubo (approx. 1,000 sq. ft.) office would require a budget of roughly 3 to 9 million JPY, while a 50-tsubo (approx. 1,800 sq. ft.) office would range from 5 to 15 million JPY. This estimate typically includes wall and floor finishes, partition installations, and electrical/data cabling. However, incorporating custom design furniture or specialized architectural work will push costs higher than these averages.

Use the following table as a reference for budget planning:

If you need to keep costs down, consider layouts that leverage existing fixtures or allocate higher budget grades strictly to visitor-facing areas like the reception entrance. Rather than spending equally across all areas, strategically prioritizing your budget is the smartest approach. 

Additionally, as material prices and labor costs continue to rise, we recommend maintaining a buffer in your budget.

Another major cost factor is the condition of the property when handed over. Properties generally fall into two categories: Shell Space (Bare Shell) and Second-Generation Space (As-Is/Fitted). The choice between them dramatically alters the scope of work and budget.

• Shell Space: A bare concrete space with no interior finishes or utilities. While it offers complete freedom to design from scratch, basic structural work (walls, ceilings, flooring) is required, driving costs up.
• Second-Generation Space: Features existing interiors and equipment left behind by the previous tenant. Reusing these assets can significantly reduce construction costs.

Here is a comparison of their features and financial impact:

If cost is your top priority, a second-generation space is advantageous; if you want to express brand originality, a shell space is appropriate. Clarifying whether your top priority is "budget" or "design freedom" is key to avoiding property selection mistakes.

When planning and negotiating office buildouts internationally, it is vital to understand construction categories. Office construction is typically divided based on who selects the contractor and who bears the cost—often categorized as Base Building Work (Landlord Work) and Tenant Work (Fit-Out). Proceeding without understanding these distinctions can lead to unexpected expenses or an inability to hire your preferred design firm.

The table below outlines the differences and key considerations for each:

Furthermore, Tenant Improvement Allowances (TI Allowances) serve as an essential negotiation card in commercial leasing. This is an incentive provided by landlords to attract tenants by funding or subsidizing a portion of the fit-out costs (typically calculated as a fixed dollar amount per square foot or square meter).

There are two main procurement models for executing tenant work:

When planning an interior project overseas, thoroughly evaluating the landlord's TI allowance, lease terms, and delivery condition (Turnkey vs. Tenant-Led) during contract negotiations is the single most critical factor in optimizing total relocation costs.

Office relocations and renovations involve numerous stakeholders. Schedule delays can lead to postponed launch dates or overlapping rental expenses. Careful planning and understanding the necessary steps are critical to success.

We recommend kicking off the project at least 6 months prior to your target move-in date. Six months may sound long, but when factoring in property hunting, requirements definition, vendor selection, design, and actual construction, such an amount is needed. If you desire a highly customized design or specialized infrastructure, extra lead time will be required.

Below is a standard project timeline:

Note: Contractors face peak seasons during year-end and fiscal year-ends (e.g., March in Japan), making scheduling difficult. If your project coincides with peak periods, consider starting 1–2 months earlier.

Before contacting interior design firms, solidify your internal office concept and functional requirements. Leaving these ambiguous causes off-target vendor proposals, repeated revisions, and wasted time.

First, articulate your core objectives: Why are we changing the office? What working style do we want to achieve?

Examples:

Next, list specific functional requirements: seat count, meeting room sizes/quantities, storage capacity, and security levels. Grouping these requests into "Must-Haves" vs. "Nice-to-Haves" helps vendors prioritize their design proposals effectively. Organizing the opinions in your organization and clearly communicating your requests to the design vendor is the first step in creating your ideal office plan.

Once requirements are clear, select an interior design partner. Rather than choosing the first vendor, it is best practice to request proposals from multiple firms via a competitive bidding (RFP) process. Comparing proposals helps verify pricing validity and highlights differences in creative concepts and responsiveness.

When evaluating proposals, look beyond aesthetic appeal and cost. Pay close attention to communication quality: Does the firm understand your intent? Are they quick to respond? After choosing a preferred partner, review the itemized quote in detail before signing the construction agreement. Clearly verifying scope boundaries, change-order terms, and payment schedules prevents future disputes.

Once contracts are signed, construction begins. While daily site management lies with the contractor, you should perform periodic site visits and request regular progress reports. Unforeseen site conditions often require prompt client decisions on details not visible in floor plans.

Prior to handover, perform a formal completion inspection alongside the contractor. Inspect finishes, check for scratches or defects, and ensure all fixtures and equipment function correctly. Request immediate rectifications for any deficiencies found, verifying resolutions before accepting final handover. This careful step ensures a seamless start to operations in your new workplace.

If you are investing in a new interior, you want to create an attractive, inspiring workplace for your employees. Below are practical techniques for designing a functional, stylish office—even without formal architectural training. With these tips you can go beyond aesthetics and introduce features that psychologically motivate employees.

Effective spatial layout relies on zoning—dividing the floor plan into functional areas based on usage. Clearly separate areas dedicated to core work (desk zones), client receptions, employee relaxation (breakout zones), and active collaboration (meeting spaces).

For example, position secure work zones deep inside the office while keeping visitor zones near the entrance. Physical separation between quiet, focused spaces and noisy collaborative spaces can reduce noise-related employee stress.

With the rise of ABW (Activity Based Working), where employees choose work settings based on their task at hand, many companies now incorporate focus booths alongside open, cafe-style lounge spaces. Defining clear functional roles for every zone enhances both operational efficiency and physical comfort.

Wall colors, flooring textures, and lighting choices dramatically shift an office’s atmosphere. Color psychology plays a powerful role in human behavior, and tailoring palette choices to room functions yields benefits:

For lighting, alternate color temperatures: use cool white light in operational areas for readability, and warm light (amber/yellow) in lounges to promote relaxation. Adding accent walls or incorporating greenery (biophilic design) offers a cost-effective way to elevate design quality.

The primary value of working in a physical office is in face-to-face interaction. Designing intentional spaces that spark casual conversations strengthens organizational culture.

Creating a "Magnet Space"—such as placing standing tables near vending or coffee machines—encourages casual, cross-departmental interactions. Widening main corridors slightly or turning walls into magnetic whiteboards allows impromptu discussions to occur naturally. Incorporating casual seating—like booth sofas or diner-style nooks—fosters open, relaxed brainstorming. Intentionally building in these flexible spaces that might at first appear wasteful ends up providing opportunities for fresh ideas and stronger teamwork.

It is not an exaggeration to say that partner selection accounts for 80% of a project's success. However, there are many design firms to choose from, and they vary in their strong areas and other characteristics. Evaluate them on the following points to find the right match for your corporate needs.

Start by reviewing past projects on potential contractors' websites. Look for portfolios similar to your target aesthetic, space scale, and experience in particular industries (e.g., tech offices vs. medical clinics).

A good vendor does not just present impressive 3D renders; they explain the rationale behind spatial layouts and problem-solving strategies. Evaluate whether proposals consider day-to-day usability and maintenance, ensuring the firm designs from the user’s perspective.

Office projects involve complex workflows: space planning, interior buildout, electrical/data infrastructure, furniture procurement, move management, and original site reinstatement. Splitting these tasks across multiple vendor contracts creates enormous coordination overhead for your project lead.

Selecting a one-stop (turnkey) partner who manages the entire lifecycle through a single point of contact prevents miscommunication across trades, compresses schedules, and reduces project costs.

If internal project management resources are limited or this is your first office relocation and you have uncertainties, we recommend choosing a turnkey partner.

Quote transparency is critical in the final selection stage. Beware of generic estimates that use categories like "Interior Construction" instead of line items. Without detailed itemization, you face high risks of unexpected change orders later.

A reliable contractor provides itemized quotes detailing materials, labor costs, and overhead expenses. Avoid selecting a firm based solely on the lowest price—extremely cheap bids often omit necessary steps or rely on low-quality materials. A firm's willingness to explain line items clearly and offer value-engineering alternatives is a direct reflection of its reliability.

Office fit-outs must comply with local building codes, safety regulations, and fire safety laws (e.g., maintaining required evacuation routes and fire suppression coverage). Additionally, building management guidelines often restrict construction hours and approved materials. Failing to verify these factors early can lead to work stoppages and costly delays.

An office interior project is more than a space makeover—it shapes your corporate culture and work practices. Success requires clear project objectives, the right contractor, and structured planning.

Beyond spatial design, establishing robust power and IT network infrastructure is a critical component of any workplace buildout. KDDI offers turnkey solutions spanning interior design to advanced IT infrastructure implementation.

Reduce vendor management friction and ensure smooth project delivery. Learn more about building a functional, beautifully designed smart office with KDDI today.