When considering the purchase or investment in real estate, the structure of the building is one of the most important factors in making a decision. In particular, RC (reinforced concrete) construction is a structural type widely used in condominiums and commercial buildings, and a proper understanding of its characteristics directly leads to a wise real estate selection.
In this article, we will explain the basic structure of RC construction, its merits and demerits, useful life, and actual points for property selection in an easy-to-understand manner for the general public. Based on our expertise cultivated in the real estate industry, we will provide practical information to help you make your property selection.
RC construction is an abbreviation of "Reinforced Concrete" and is called " Reinforced Concrete Construction " in Japanese. This structure is a composite structure that combines reinforcing steel and concrete, and is an excellent building construction method that complements the disadvantages of each material while taking advantage of its advantages.
Concrete is very strong against compressive forces, but weak against tensile forces. Conversely, reinforcing steel exhibits excellent strength against tensile forces, but does not perform as well as concrete against compressive forces.
The construction process of RC construction begins with the placement of reinforcing bars according to the design drawings, followed by the pouring of concrete. As the concrete hardens, it is integrated with the reinforcing bars and functions as a single structure. This integration provides excellent resistance to external forces such as earthquakes and wind.
In on-site construction, the accuracy of rebar placement, quality control of concrete, and curing period are important factors. When these processes are properly managed, an RC building that performs as designed is completed.
In addition to RC construction, other types of building structures include wood, steel-frame construction (S construction), and steel-reinforced concrete construction (SRC construction). The following table compares the characteristics of the main structural types.
| Structural Type | Main materials | Earthquake resistance | Fire resistance | Sound Insulation | Construction cost | Main Applications |
|---|---|---|---|---|---|---|
| Wooden construction | Timber | Medium | Low | Low | Low | Detached houses, low-rise apartments |
| Steel construction (S construction) | Steel | High | Medium | Medium | Medium | Medium and high-rise buildings, factories |
| RC Construction | Rebar + concrete | High | High | High | Medium to high | Condominiums, commercial buildings |
| SRC Construction | Steel + Rebar + Concrete | Highest | High | High | High | High-rise building |
As can be seen from this comparison chart, RC construction offers an excellent balance of earthquake resistance, fire resistance, and sound insulation, making it a suitable structural type for mid- to high-rise residential complexes and commercial facilities.
The greatest feature of RC construction is its superior earthquake resistance. The structure, which integrates reinforcing steel and concrete, exhibits high resistance to horizontal forces caused by earthquakes. In particular, RC buildings constructed after the new seismic resistance standards enacted in 1981 are designed to withstand an earthquake of intensity 6 or 7 without collapsing.
In fact, many RC buildings that were properly designed and constructed escaped serious damage in the Great Hanshin-Awaji Earthquake and the Great East Japan Earthquake, demonstrating their high earthquake resistance performance. This is an extremely important factor in real estate investments and home purchases from the perspective of preserving long-term asset value.
Another major advantage of RC construction is its high fire resistance. Concrete is a noncombustible material and can maintain its structural strength for a long time even when exposed to high temperatures. Under the Building Standard Law, RC construction is certified as a fire-resistant structure, and is evaluated as a structure that can ensure sufficient evacuation time in the event of fire.
This fire resistance performance also leads to reduced insurance premiums. Fire insurance premiums vary greatly depending on the structure of the building, and RC buildings are classified as "T Structure (fire-resistant structure)" with the lowest insurance premiums. Compared to wooden buildings, insurance premiums can be reduced to about half, contributing to lower long-term maintenance costs.
Sound insulation performance, an important factor in urban living environments, is another major advantage of RC construction. The high density of concrete effectively blocks the propagation of sound from the floors above and below and neighboring units. In particular, properties with a floor slab (concrete portion of the floor) of 200 mm or more in thickness will provide sound insulation to a level where most of the sounds of daily life are not bothersome.
This sound insulation performance is also an important factor in rental management. It is expected to improve tenant satisfaction, thereby increasing long-term occupancy and reducing the risk of vacancies. It also greatly reduces the risk of problems in the neighborhood, which is a great advantage in terms of management.
Long-term durability of RC buildings is a particularly important factor in real estate investment. With proper design, construction, and maintenance, RC buildings can withstand 50 to 100 years of use or more. This is by far the longest service life of a building, compared to the typical service life of a wooden building, which is about 30 years.
Long-term durability is also directly related to the maintenance of a building's asset value. Since there is little structural deterioration even after the building is built, stable rental income and sale value can be expected over a long period of time through appropriate maintenance.
One of the major disadvantages of RC construction is its high construction cost. Compared to wooden buildings, both material and construction costs tend to be high. In particular, construction costs are higher due to the many processes that require specialized skills, such as formwork, reinforcing steel, and concrete work.
High construction costs lead to higher initial investment. When considering real estate investment, it is important to develop an income/expenditure plan that takes this high initial investment into account. However, considering the aforementioned long-term durability and low maintenance costs, there are many cases where investment efficiency is good from a long-term perspective.
RC buildings are structurally characterized by their heavy building weight. As a result, ground improvement work such as piling work may be required on land where the ground support is insufficient. In addition, when rebuilding an existing building, the ground may need to be reexamined and reinforced.
The weight of the building also affects the degree of freedom in design. Structural calculation restrictions may arise when large openings or vaulted ceilings are installed, which may affect the design plan.
In RC buildings, condensation control is an important issue. Since concrete has high thermal conductivity, condensation tends to occur when there is a large difference between outdoor and indoor temperatures. In particular, in buildings with inadequate insulation, condensation can occur in winter, causing mold.
Appropriate insulation, installation of ventilation systems, and humidity control are important measures to prevent condensation. Failure to take these measures can lead to deterioration of the living environment and building deterioration, so sufficient consideration must be given from the design stage.
The legal useful life of RC buildings is 47 years according to the tax law. This is the number of years used in depreciation calculations and differs from the actual useful life of the building. The actual life of an RC building depends largely on the quality of design, construction, and maintenance, but it is possible for a properly managed building to last 100 years or more.
According to a survey by the Ministry of Land, Infrastructure, Transport and Tourism, the average life expectancy of RC buildings is approximately 68 years, but this is a statistic for the time of demolition and does not indicate structural limitations. In fact, with periodic repairs and proper maintenance, the building can be used for an even longer period of time.
Periodic inspections are essential for extending the service life of RC buildings. Of particular importance is the early detection of cracks in exterior walls, corrosion of reinforcing steel, and deterioration of the waterproof layer. If left unchecked, these problems can lead to structural deterioration and the need for major repairs.
The Building Standard Law requires periodic reporting for buildings above a certain size, but it is recommended that other buildings be inspected by a specialist about once a year.
An important part of the maintenance and management of RC buildings is the implementation of planned repairs. The main repair items and their cycles are as follows.
| Repair items | Repair cycle | Estimated cost (per m2) | Remarks |
|---|---|---|---|
| Exterior wall painting | 10-15 years | 3,000-5,000 yen | Maintain aesthetics, ensure waterproof performance |
| Rooftop waterproofing | 15 to 20 years | 8,000-12,000 yen | Important work to prevent leaks |
| Water supply and drainage facilities | 20 to 30 years | 15,000-25,000 yen | Complete renewal of plumbing |
| Major repair of exterior walls | 25-30 years | 80,000-120,000 yen | Complete repair of exterior walls |
Planned implementation of these repairs will help maintain building performance over the long term and preserve asset value.
In many cases, condominiums and other condominium buildings under condominium ownership have a long-term repair plan in place, which estimates the repair work required over a period of about 30 years and its cost, and establishes an appropriate reserve fund for repairs.
Long-term repair plans are an important element not only in building maintenance, but also in income and expenditure planning for real estate investment. By accurately grasping the projected repair costs, more accurate investment decisions can be made.
The most important factors to consider when selecting an RC condominium are the year of construction and the seismic resistance standards applied.
Buildings built under the new earthquake-proof standard are designed to withstand an earthquake of seismic intensity 6 or 7, and earthquake insurance premiums are lower than those for buildings built under the old earthquake-proof standard. In addition, financial institutions often offer more favorable terms for loans for buildings built to the new earthquake-proof standard.
An important factor in judging the quality of a building is the track record of the construction company and designer. Buildings constructed by a major general contractor or a construction company with a proven track record in the region generally have high construction quality and a sense of long-term security.
The track record of the structural designer is also important: structural design of RC construction requires a high level of expertise, and a building designed by an experienced structural designer is likely to be safer and more rational.
Appropriate management is essential for maintaining the asset value of RC condominiums. It is important to confirm in detail the management status of the management association, the state of the reserve fund for repairs, and the history of past repairs.
Particular attention should be paid to the shortage of the repair reserve fund. If an appropriate repair reserve fund is not secured, there is a possibility that a large lump-sum payment will be collected in the future or repair work will be postponed. This is a risk that could lead to deterioration of the living environment and a decline in asset value.
When selecting an RC condominium as an investment property, location is the most important factor. It is important to comprehensively evaluate the distance from the station, the surrounding environment, and future development plans, and to select a location where long-term rental demand can be expected.
Especially in urban areas, walking time from the nearest station has a significant impact on rent levels. In general, properties within a 10-minute walk can expect stable rental demand and low vacancy risk.
In RC condominiums for investment, it is important to select a floor plan and facilities that are suitable for the target group. Generally, 1K to 1DK apartments for singles and 2LDK to 3LDK apartments for families are in high demand.
In addition, properties that are equipped with facilities that meet the needs of modern tenants (Internet access, delivery boxes, auto-locks, etc.) are highly competitive and can be expected to provide stable rental management.
Accurate income/expense calculations are essential for RC condominium investment. It is necessary to calculate the actual investment yield by comprehensively considering the purchase price, expenses, annual rental income, management fees, reserve for repairs, taxes, etc.
Especially for RC condominiums, it is important to calculate the income and expenditure by properly estimating these expenses, since the repair reserve fund and management fees tend to be higher than those for wooden apartments.
RC (reinforced concrete) construction is a building structure with excellent earthquake resistance, fire resistance, and sound insulation properties, and is widely used in condominiums and commercial buildings. Although construction costs are high, its long-term durability and ease of maintenance and management make it a structural form that can realize excellent investment efficiency from a long-term perspective.
When considering the purchase or investment in real estate, it is important to properly understand the characteristics of RC construction and to comprehensively evaluate the year of construction, construction company, and management status. In particular, by selecting a property that conforms to the new earthquake resistance standards of 1981 or later and is properly maintained and managed, you can expect long-term preservation of asset value and stable income.
INA&Associates Inc. provides comprehensive support for your real estate investment, from the selection of RC properties to their management. If you have any questions about RC properties, please feel free to contact us.
RC (reinforced concrete) construction is a combination of reinforcing steel and concrete, while SRC (steel reinforced concrete) construction has an additional steel frame. RC construction is the most common type of construction for general condominiums and offers adequate performance.
The general guideline for the repair reserve fund for RC condominiums is about 200-300 yen per square meter of exclusive area per month. However, it varies greatly depending on the size, age, and location of the building. Guidelines from the Ministry of Land, Infrastructure, Transport and Tourism recommend setting an appropriate reserve amount based on a long-term repair plan.
A 30-year-old RC condominium can be a suitable investment if it is properly maintained and managed. What is important is the state of implementation of large-scale repairs, the state of the repair reserve fund, and the state of management of the management association. In addition, compliance with the new earthquake resistance standards (1981 or later) is a prerequisite.
The sound insulation performance of RC construction is determined by the thickness of the floor slab and the wall construction. In a property with a floor slab thickness of 200mm or more, general household noises (footsteps, talking, etc.) will be insulated to a level that is barely noticeable. However, playing musical instruments and loud TVs may disturb neighbors even in RC construction.