When considering large-scale repairs for condominiums, apartments, or factories, attention often goes to exterior painting and waterproofing work, but equally important is “substrate repair“.
Painting and waterproofing are merely finishing processes, and if the underlying substrate is damaged, it cannot perform adequately.
If cracks, spalling, or lifting are left unattended during construction, re-deterioration can occur within a few years, necessitating rework.
If that happens, not only will repair costs double, but it could also shorten the lifespan of the building.
The key to successfully executing large-scale repairs lies in how thoroughly the invisible substrate can be repaired.
In this article, we will
discuss the necessity of substrate repair and signs of deterioration, as well as considerations for construction content and costs in detail.
What is Substrate Repair in Large-Scale Repairs?
Substrate repair is the foundational work that prepares the structural body or mortar layer inside the finishing materials such as exterior walls, rooftops, and waterproof layers.
If the substrate is not sound, no matter how high-quality paint or waterproofing materials are used, they will not last long.
Here, we will explain in detail the definition, role, and importance of substrate repair.
Definition and Role
Substrate repair refers to
the work of repairing deteriorated areas of concrete, mortar, tile substrates, etc., to restore them to a sound condition.
Typical tasks include filling cracks, repairing missing sections, removing lifting, and rust prevention treatment for rebar.
These tasks are not just for aesthetic purposes; they are fundamental operations to restore the building’s strength and waterproofing capabilities.
If finishing work is carried out while the substrate remains unstable, it becomes more likely that paint film peeling and water leakage will recur.
Thus, substrate repair is an essential process for “building a foundation to extend the lifespan of the building.”
Importance
The quality of substrate repair affects the overall durability of large-scale repairs.
If repaired properly, the paint and waterproof layer can maintain their original performance for a long time.
On the other hand, if the repair is insufficient, there is a high likelihood that rework will be needed within a few years.
Re-repair incurs scaffolding costs, significantly increasing the financial burden.
To keep costs down, it is crucial to ensure the substrate is properly prepared during the initial work.
Substrate repair is not easily visible, which is why a focused approach to inspection is required.
What Risks Are Associated with Deteriorated Substrates?
Deterioration of the substrate not only poses aesthetic issues but can also lead to serious problems directly affecting the safety and durability of the building.
Even if the initial signs appear to be minor symptoms like small cracks or lifting, it is not uncommon for issues such as rainwater infiltration and rebar corrosion to be progressing internally.
Here, we will introduce several typical risks that arise from the deterioration of the substrate.
✔️Increased likelihood of exterior wall cracks progressing
Cracks that occur on the exterior wall are the most obvious symptoms of initial substrate deterioration.
Even fine cracks resembling body hair can gradually expand due to temperature changes and vibrations if left unattended, eventually allowing rainwater to infiltrate and accelerate the neutralization of mortar and concrete.
Particularly, cracks wider than 0.3mm or those that extend diagonally can lead to structural problems, so caution is necessary.
Since simply covering the cracks with paint does not provide a fundamental solution, it is advisable to carry out substrate repairs at an early stage.
✔️Increased risk of concrete neutralization and rebar exposure
Concrete is inherently alkaline and protects the rebar, but when neutralization progresses due to rainwater and carbon dioxide, the rust prevention effect diminishes.
As a result, the rebar can rust and expand, pushing the concrete from the inside and causing spalling.
When spalling occurs, the surface of the exterior wall chips away, exposing the rebar, which is extremely dangerous.
Moreover, this not only reduces structural strength but also poses a risk of falling accidents, so it must be addressed urgently.
Conducting substrate repairs early to prevent neutralization is a crucial point for ensuring safety.
✔️Increased risk of tile and mortar substrate delamination
Tiles and mortar are held in place by adhesion to the substrate, but if moisture enters or the adhesive strength decreases, delamination can occur.
Particularly, caution is needed if hollow sounds are confirmed during tapping surveys.
If left in a lifted state, they can suddenly fall due to strong winds or vibrations.
Among these, high-rise apartments carry a higher risk of third-party damage, and in some cases, management responsibility may be questioned, so it is important to take proper measures regularly.
Additionally, if repairs are made at the stage of partial lifting, costs will be limited, but if a complete replacement is necessary, significant expenses will arise.
Early detection and planned substrate repairs are effective in both accident prevention and cost reduction.
✔️Deterioration of waterproof substrate increases the likelihood of leaks
The waterproof layer on rooftops and balconies only performs effectively when the substrate is in a healthy condition.
If waterproofing work is carried out with cracks or unevenness in the substrate, the waterproof material will not adhere properly, leading to early blistering or rupture.
This can cause rainwater intrusion, resulting in ceiling stains, corrosion of interior materials, and equipment troubles.
In the event of a leak, it can directly lead to tenant complaints, significantly impacting rental management.
Some may consider repairing only the waterproof material, but this does not lead to fundamental improvement.
By simultaneously conducting substrate repairs, the waterproof performance can be maintained for a longer period.
Main Construction Contents of Substrate Repairs in Large-Scale Renovations
Substrate repairs encompass a wide range of actual construction contents.
Depending on the type and degree of deterioration, appropriate construction must be selected to achieve sufficient effectiveness.
Here, we will specifically explain the characteristics and purposes of substrate repair work commonly performed in large-scale renovations.
1. Mortar Repair
Mortar repair is a construction work that involves filling in areas where there are losses, bulges, or peeling with new mortar material and smoothing it out.
If small peeling or unevenness on the exterior wall surface is left untreated, the paint or waterproofing material will not adhere uniformly, significantly reducing durability.
During repairs, the deteriorated parts are removed to expose the sound areas, and adhesives or resin mortar are used to shape the repair.
This restores the adhesion of the finishing material and allows for an improved appearance.
If addressed while symptoms are minor, partial repairs can suffice, but if left unattended, extensive replacement may be necessary, so caution is required.
2. Crack Repair
Crack repair is an important construction work that involves filling and bonding cracks that have occurred in concrete or mortar to prevent water intrusion and deterioration.
For fine hairline cracks, surface treatment agents can be applied, but for wider structural cracks, methods such as epoxy resin injection are employed.
By allowing the resin to penetrate internally, the cracks can be unified, achieving both strength recovery and water-stopping effects.
By the way, simply painting the surface tends to lead to recurrence and does not provide fundamental improvement.
Therefore, it is important to choose the appropriate method according to the symptoms.
3. Tile Base Repair and Reinstallation
In tile exterior walls, bulging of the base mortar and reduced adhesion can lead to peeling or falling off.
To prevent such situations, areas confirmed to be bulging through tapping surveys are removed, and new base work is done before reinstalling the tiles.
If left bulging, there is a risk of sudden falling due to earthquakes or strong winds, which can lead to serious accidents, so caution is necessary.
If the stage allows for partial replacement, the cost burden is limited, but if it progresses extensively, full renovation will be necessary, so consider early repairs.
4. Concrete Spalling Repair
Concrete spalling repair is a construction work that restores areas where concrete has cracked and suffered losses or spalling due to internal pressure from rusted rebar expansion.
Spalling is particularly dangerous among forms of base deterioration, and if left unattended, it can lead to reduced structural strength and falling accidents.
In repairs, the deteriorated parts are first removed to expose the rebar, rust is removed, and anti-corrosion treatment is performed.
Surface-only treatments will lead to recurrence, so internal treatment is very important.
Proper spalling treatment is an essential process to ensure the safety and long-term durability of the building.
5. Waterproof Base Repair
Waterproof base repair is a fundamental maintenance work done to prolong the waterproofing work on rooftops and balconies.
If waterproofing materials are applied to a base with cracks, unevenness, or irregularities, it can lead to poor adhesion and blisters, potentially resulting in leaks in a short period.
Therefore, it is important to perform crack repairs, loss filling, base adjustments, and slope corrections before waterproofing, creating a smooth and stable surface.
Particularly, areas where puddles form are prone to deterioration, requiring careful treatment.
By thoroughly repairing the base, the lifespan of the waterproof layer can be extended, ultimately lengthening the reinstallation cycle, so it is advisable to do so at the appropriate timing.
6. Repair of Iron and Metal Bases
Iron parts and metal bases such as steel staircases, handrails, door frames, and equipment supports are also subject to base repairs.
These are susceptible to rainwater and humidity, and when the paint film deteriorates, rust progresses rapidly.
If corrosion advances, it can lead to reduced strength and component damage, significantly impacting safety, so caution is necessary.
In actual repair work, rust and old paint are removed through scraping, and after applying anti-rust paint and primer, re-painting is carried out.
In some cases, component replacement may be necessary, but if addressed early, many cases can be resolved with just painting repairs.
However, if left unattended, it will lead to complete replacement, increasing costs, so it’s important to be proactive about repairs.
Cost Estimates and Considerations for Base Repairs
When considering base repairs, many owners are troubled by the “cost“.
However, base repairs cannot simply be expressed as “a set price”.
The amount can vary significantly depending on the degree of deterioration, the scope of repairs, and the methods used, so it is important to assess the validity by checking the breakdown and quantities rather than relying solely on market estimates.
Here, we will outline the basic structure of base repair costs and provide guidelines for unit prices, explaining how to determine fair pricing.
Basic Structure of Base Repair Costs
Base repair costs are not determined solely by material costs; they are calculated based on multiple factors.
The main breakdown includes costs for scaffolding and temporary facilities, inspection and deterioration diagnosis fees, actual repair work costs, repair material costs, disposal fees, and site management fees.
Especially in large-scale repairs, scaffolding costs account for a significant portion, so the total amount increases as the scope of repairs widens.
Additionally, labor-intensive work such as explosive repairs or tile replacements tends to have higher labor costs.
Thus, the costs of base repairs consist of multiple elements, each with significantly different cost implications, so it is essential to confirm what each cost entails.
Unit Price Guidelines for Base Repair Costs
The unit price for base repairs varies by method, but general guidelines are as follows:
・Crack repair → around several thousand yen per meter
・Mortar patch repair → around several thousand to 10,000 yen per square meter
・Explosive repair → around several tens of thousands of yen per location
・Waterproof base adjustment → around several hundred to several thousand yen per square meter
Costs may increase further for tile replacements or large-scale cross-section repairs.
However, these are merely reference values, and actual costs can vary significantly depending on the deterioration condition and work environment.
To accurately understand costs, it is essential to calculate quantities based on on-site surveys.
Rather than relying solely on market estimates, obtaining quotes based on specific evidence leads to fair pricing for the work.
For Large-Scale Repairs of Condominiums, Apartments, and Factories, Trust “Kakeru Koumuten”!
Base repairs require specialized diagnosis and construction techniques, and inexperienced contractors are prone to overlooking deterioration or executing inadequate work.
As a result, re-deterioration or additional work may be necessary, often leading to increased cost burdens.
At Kakeru Koumuten Co., Ltd., we provide a comprehensive response from on-site investigation to deterioration diagnosis, planning of repair, estimation presentation, and construction management, allowing us to propose optimal substrate repairs tailored to the condition of the building.
By clearly distinguishing between necessary and unnecessary work, we can perform repairs that enhance durability while keeping unnecessary costs down.
On-site investigations and estimates are free!
We can accommodate various uses, including condominiums, apartments, and factories, so please feel free to consult us if you are in need!
Summary
Substrate repairs in large-scale renovations are the most crucial foundational process that precedes finishing work.
If symptoms such as cracks, peeling, and waterproofing failures are left unattended, the durability and safety of the building will decline, leading to increased future repair costs.
On the other hand, if repairs are carried out reliably based on appropriate judgment and planning, the lifespan of finishing materials will be extended, resulting in long-term cost savings.
To achieve this, it is essential to correctly understand the cost trends, scope of work, and methods, and to collaborate with a trustworthy construction company.
At Kakeru Koumuten Co., Ltd., we offer flexible proposals tailored to your situation and budget, so please feel free to consult us if you are in need.
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