5 Checks to Avoid Regrets During the Warranty Period for Building Construction

In construction work, after the work is completed and handed over, defects in finishes, malfunctioning equipment, water leaks, cracks, and defects in doors and fittings may be discovered. What becomes important then is the warranty period. However, the warranty period cannot be judged simply by "how many years it is guaranteed." You need to confirm which scope of work is covered, when the period begins, what kinds of defects will be addressed, and whom and by what method you should contact; otherwise, when a problem occurs, misunderstandings about the scope of coverage can arise.

Construction work in particular involves complex interrelations among structure, exterior, interior, equipment, site works, and the scope of renovations. The points that need to be checked differ between new construction and renovation, and the assumptions change between residential and non-residential buildings. For new houses, there are cases where the post-handover liability period becomes an issue under the law for parts that are essential to structural strength and parts that prevent the ingress of rainwater. On the other hand, not all defects are guaranteed for the same period or under the same conditions. Damage caused by interior finishes, equipment, site works, existing parts, or methods of use needs to be assessed by checking the contract, warranty documents, and maintenance conditions.

In this article, we explain five items that practitioners searching for information on "building construction" should check to avoid regrets during the warranty period. Not only legal personnel but also procurement officers, site managers, facility managers, and owner representatives can easily apply the guidance in practice; we organize the material to include how to review contracts and specifications, handover documents, photo records, and inspection records. Note that individual disputes, claims for damages, and the validity of contractual clauses can vary by case, so if you are unsure, it is important to consult a specialist.

Table of Contents

• Do not judge a warranty solely by the number of years

• Confirm the warranty's scope of coverage and exclusions in the contract

• Clarify the warranty commencement date and notification deadlines at handover

• Decide the method of contact and repair procedures after a defect is discovered

• Keep inspection records and on-site data to prepare for warranty responses

• Summary

Don't judge a warranty period only by "how many years"

When checking the warranty period for construction work, many responsible persons first look at "how many years" the warranty is. Naturally, the length of the period is important. However, in practice, simply looking at the number of years is not sufficient. The warranty period must be judged together with the scope of the work covered, the types of defects covered, the client's usage conditions, whether maintenance has been performed, the timing of notification, and the wording of the contract. Therefore, rather than simply thinking "a long warranty period means peace of mind," it is necessary to break down and verify the contents of the warranty.

For example, even in the same construction project, the way warranties are handled can differ between parts related to structure, parts related to rainwater intrusion, interior finishes, doors and fittings, equipment, exterior works, and temporary construction. Defects related to structure and waterproofing are more likely to directly affect the building’s safety and continued use, whereas minor scratches to interiors or deterioration from normal use may be excluded from warranty coverage or covered for a shorter period. Even if a contract states a "warranty period," if the scope included in it remains ambiguous, discrepancies such as "I thought this was covered" versus "I explained it was not covered" are likely to arise later.

One point that requires particular attention is that warranty periods, contractual nonconformance liability, after-sales service, periodic inspections, and warranties for individual equipment or components tend to be confused on site. From the client’s perspective they all look like “responses when something happens after construction,” so people often understand them as the same thing. In reality, however, their meanings differ: some are treated as contractual liabilities, some are measures the contractor provides voluntarily, some are responses based on conditions specific to particular equipment or components, and some involve only inspections. When checking warranty periods, it is important to read not the name but under what circumstances, who will respond, to what extent, and at whose expense.

Also, in construction work there are “defects that are not visible at the time of completion.” Details of the waterproofing layer, the condition of the substrate workmanship, the slope of piping, treatments inside the structural frame, and deficiencies in insulation or airtightness cannot always be fully confirmed by a visual inspection at handover. Even if there are no problems immediately after handover, defects may surface after a certain period due to rain, wind, temperature changes, or loads after the start of use. Warranty periods are intended to cover problems that become apparent after handover, but precisely for that reason you should avoid assuming that “everything will be handled unconditionally within the period.”

Under liability for nonconformity in a contract for work, when the type or quality of the deliverable does not conform to the contract terms, the time when the nonconformity was discovered and notification to the contractor become important. Generally, the issue is whether notification is given within a certain period from when the nonconformity was discovered, but the conclusion can vary depending on the contract terms, the contractor’s awareness, the content of the notification, the statute of limitations, and the nature of the project. When reading explanations of warranty periods, do not treat contractual warranties and legal liability as the same; be prepared to consult an expert when necessary.

For newly built houses, there is a system that stipulates a 10-year liability from handover for the main structural elements and the parts that prevent rainwater ingress. However, this is a concept that limits which houses and parts are covered, and not all construction work, parts, or defects are treated the same. For non-residential buildings such as offices, warehouses, shops, and factories, and for renovation work, partial repair work, and exterior works, it is necessary to check the contents of the contract, specifications, and warranty individually.

The first thing operational staff should do is organize the warranty periods into a format that allows them to be viewed at a glance. However, this listing is for internal management and is not a substitute for the contract. Divide items into structure, waterproofing, exterior, interior, equipment, external/site works, scope of renovation, separate works, etc., and for each confirm the warranty period, defects covered, reasons for exclusion, contact information, and required documents. When sharing internally, instead of a simple explanation like "this part is X years," wording it as "this is covered when these conditions are met" will make later misunderstandings less likely.

Understanding the warranty period correctly is not about distrusting the contractor. Rather, it is fundamental to aligning the client’s and contractor’s understanding and avoiding unnecessary disputes. If you check the warranty terms before signing the contract, it will be easier for the contractor to explain the scope of their coverage. It will also make it easier for the client to properly carry out inspections and record-keeping after handover. A construction warranty is not something to be read after a problem arises; it should be checked before problems arise.

Confirm the scope of warranty coverage and exclusions in the contract

The second item to check to avoid regrets over the warranty period is to confirm the warranty's scope of coverage and exclusions in the contract. Even if the warranty period is specified, if the scope is ambiguous it will be difficult to make a judgment when an actual defect occurs. In particular, construction work involves multiple documents such as the contract, drawings, specifications, estimates, Q&A responses, change orders, meeting records, and handover documents. When considering the scope of warranty coverage, you need to review not only the contract but the entire scope of work included in the contract.

The first thing to confirm is what is included in the scope of the work. For new construction, the entire building is likely to be covered, whereas in renovation or partial repair work, existing parts and newly installed parts are mixed. For example, even for roof waterproofing renovation, the judgment of warranty coverage changes depending on whether it includes the condition of the existing substrate, existing drainage equipment, surrounding upstands, equipment foundations, and the interfaces with existing exterior walls. The same applies to interior renovations: whether only surface finishes were applied, whether substrate repairs were included, or whether equipment relocations were included will determine what is covered by the warranty.

To clarify the scope of a warranty, it is effective to match the scope of work not only in words but also with drawings and photographs. If a contract contains expressions such as "interior work (all-inclusive)" or "waterproofing work (all-inclusive)," that alone can make practical judgments difficult. The term "all-inclusive" is convenient, but it can also tend to blur the boundaries of the scope. Organizing, before signing the contract or before starting work, where the work begins and ends, in what condition existing parts were taken over, and where the boundary with separately contracted work lies will make it easier to determine warranty coverage after handover.

Next to check are the conditions that are excluded from warranty coverage. Generally, damage caused by the client's method of use, normal aging, wear and tear, alterations by third parties, disasters and force majeure, and defects resulting from a failure to perform proper maintenance may be excluded from warranty coverage. However, which conditions are excluded depends on the terms of the contract. If exclusions are listed, it is important not to simply skim over them but to compare them with your company’s actual usage and verify.

For example, the way a building is used differs between factories, warehouses, retail stores, offices, apartment buildings, medical facilities, and educational institutions. The load on finishes and equipment changes depending on factors such as the handling of heavy goods, frequent comings and goings of people, generation of moisture and heat, exposure to chemicals and oils, cleaning methods, and equipment operating hours. If a contractor sets warranties on the assumption of general usage conditions, then special usage environments require additional specification confirmations and explicit maintenance conditions. You must check not only the warranty period but also the preconditions for the warranty to be valid, because otherwise there is a risk that it will later be judged “not normal use.”

Also, in building work that includes equipment installation and machinery, the warranty for the overall construction and the warranty conditions for individual equipment and components may be separate. Here too, rather than relying on specific product or brand names to make a judgment, it is important to confirm in the contract which scope the contractor will coordinate. Defects in the equipment itself, defects in installation work, defects in piping or wiring, defects in control settings, and troubles caused by insufficient user instruction each have different causes. As the client, it is reassuring to confirm whether a single first point of contact can be established when a problem occurs, whether the construction company will act as the contact point, or whether it will be necessary to contact separate specialist contractors directly.

In renovation work, attention must also be paid to the relationship with existing nonconformities, existing deterioration, and hidden damage. If deterioration that was not visible before construction becomes apparent during the work or after handover, it is necessary to determine whether it is due to the current construction defect or originates from the existing parts. It is precisely this boundary that tends to cause disputes during the warranty period. If the pre-construction condition survey, photographic records, confirmation of the extent of deterioration, and clarification of areas outside the scope of work are insufficient, it becomes difficult to determine the scope of responsibility after handover.

When reviewing a contract, you need to read not only the parts that state "guarantee" but also clauses such as "exemption", "exclusions", "obligations of the client", "operation and maintenance", "inspection", "handover", "changes" and "consultation". Warranty handling is not something that can be completed by only a part of the contract. When a defect occurs, confirming which clauses will form the basis for the response, what cooperation obligations the client has, and how the scope of repairs will be negotiated will make it less likely to get confused in practice.

Checking the scope of the warranty should not be completed only before signing the contract. If specification changes or additional work occur during construction, you need to confirm whether those changed parts will be treated as warranty-covered. If the order form or change agreement for the additional work is ambiguous, after handover issues arise such as "Is the additional portion covered by the warranty?" and "Who will handle the interfaces with the existing parts?" When changes occur, it is important to update the warranty period and the scope of coverage at the same time.

Clarify the commencement date and notice deadline at the time of handover

When checking the warranty period, the commencement date is easy to overlook. The commencement date is the reference date that indicates when the warranty period begins. In construction work, multiple dates may be involved, such as the date of completion of the work, the date of the final inspection, the date corrective work was completed, the handover date, the date use begins, and dates of partial handover. Even if the warranty period is written as "1 year," "2 years," or "10 years," if it is ambiguous when the period starts to be counted, it will cause confusion later when making judgments.

Generally, it is common to count the warranty period from the handover date. However, in practice, the handover does not necessarily occur immediately after construction is completed. Items may be raised during the completion inspection, and the formal handover may take place after rectification. A portion of the building may be put into use ahead of the overall handover. In tenant fit-out work or facility renovations, construction may be carried out in phases to avoid interrupting business operations, with each section being put into use separately. In such cases, if the start date of the warranty period is not clearly defined, misunderstandings are likely to arise later.

At the time of handover, it is important to align the dates on the handover document, completion confirmation, inspection records, and corrective action completion records. If the dates differ between documents, you need to clarify the meaning of each. For example, if the completion inspection date and the handover date are different, confirm which date the warranty period begins from. If you accept the handover while corrective work remains outstanding, you should record how the warranty period will be treated for the unfinished portions and the items subject to correction.

When partial handovers occur, the start date may differ for each area, construction section, or piece of equipment. In large construction projects or phased renovations, using only the final handover date for the entire building as the reference can make the treatment of parts put into use earlier unclear. For portions put into use ahead of the overall handover, it is important to confirm in the contract and handover documents whether the warranty period begins from the date use commences or from the overall handover date.

Along with the starting date, you should also check the notice deadline. When a defect is discovered, the ordering party needs to know by when they must notify the contractor. In cases of contractual nonconformity concerning the subject matter’s type or quality in a construction contract, it is important, as a general rule, that the ordering party notify within one year from when they became aware of the nonconformity. However, exceptional treatments can arise—for example, if the contractor knew of the nonconformity at the time of delivery or if they were unaware due to gross negligence. Also, because the contract may stipulate a different warranty period or method of notification, it is necessary to check the contract and the legal treatment separately.

One thing to be careful about here is not to assume lightly that “if a defect occurred during the warranty period, it’s okay to report it after the period has ended.” Even if you were aware of a defect, if you continue to take a wait-and-see approach internally or information stops flowing between the people in charge, notification can be delayed. Defects in construction work can become more difficult to identify the cause of as time passes. Early documentation and early notification of issues such as leaks, cracks, lifting of finishes, and equipment malfunctions help both in confirming the cause and in arranging repairs.

To manage notification deadlines, it is important not only to share the list of warranty periods internally at handover but also to establish the communication flow for when defects are discovered. Decide in advance who the on-site staff member who finds a defect should report to, what form will be used to record it, and who will contact the contractor. If the facilities management department, general affairs department, site supervisors, procurement department, and management each hold information separately, notifications can be delayed or multiple contacts about the same defect may occur.

Calendar management is also effective for post-handover warranty management. Rather than rushing inspections just before the warranty expires, schedule in-house inspections at predetermined times before the expiration. For example, set inspection timings according to how the building is used—early after handover, after a change of season, and before the warranty period ends. Seasonal defects, such as leaks or condensation, may not be discernible immediately after handover. It is important to be mindful of checking the condition throughout the year.

You can't assume you're safe just because the commencement date and notification deadline are written in the contract. Unless they are converted into a form that can be used on site, they won't function in practice. Summarize the warranty period's start date and end date, the notification recipients, notification methods, required records, and internal persons responsible, and make them available for relevant parties to check; that practical approach will help prevent regrets.

Determine the notification method and repair procedures after discovering defects

When a defect is discovered during the warranty period, if the ordering party responds in a hurry, insufficient records and missed communications are likely to occur. To carry out warranty handling smoothly, it is important to decide in advance the method of contacting and the repair procedures to follow after discovering a defect. No matter how clear the warranty period is, if the post-discovery response is vague, confirming the cause and determining the scope of responsibility will take time.

The first thing you should decide on is the primary point of contact. At handover, confirm who should be contacted—such as the sales representative who handled the project, the site agent, the construction manager, the company's reception desk, or the maintenance contact. If you rely only on an individual’s personal contact details, communication may be disrupted by transfers, resignations, or vacations. Along with the individual's name, it’s reassuring to confirm the company’s reception desk or the standard company contact methods.

Next, decide how specifically to describe the defect. Simply reporting “there’s a leak,” “there’s a crack in the wall,” or “the equipment won’t operate” makes it difficult for the contractor to assess the situation. If you organize and report the date and time of discovery, location, symptoms, frequency of occurrence, weather, usage conditions, photos, videos, surrounding conditions, and whether any temporary measures were taken, the initial response will be faster. Records of the weather and the time of occurrence are especially useful for defects where reproduction conditions are important, such as rain leaks or water leaks.

It's important to be aware that the client may independently carry out repairs when they discover a defect. If the situation is urgent, temporary measures to ensure safety and prevent further damage are necessary, but carrying out full repairs or removals before identifying the cause can make it impossible to verify the condition of the original work. If you may seek warranty coverage, you should record the details of any temporary measures, contact the contractor promptly, and then discuss the subsequent course of action.

For repair procedures, assume a flow of on-site inspection, investigation of causes, presentation of a response plan, execution of repairs, confirmation of completion, and record keeping. Even minor defects will leave no history if handled only verbally. As the client, record when you were contacted, who carried out the inspection, what explanations you received, the scope of the repairs, and when they were completed. It is also important to confirm in the contractor’s explanation whether the cause is due to the construction, usage conditions, aging, or originates from existing components.

In warranty responses, the cause cannot always be identified as a single factor. For example, the cause of a leak may span multiple areas, not just the waterproofing layer, such as intersections with the exterior wall, around openings, equipment penetrations, and poor drainage. Equipment malfunctions can also have multiple causes, including the equipment itself, the power supply, wiring, controls, installation settings, and how it is used. When causes are complex, determining whether an issue is covered by the warranty can take time. Therefore, it is important for the ordering party not to rush to an emotional conclusion but to organize the facts and discuss them.

Also, even for repairs covered by the warranty period, you need to confirm the extent of the repair. The practical burden will vary depending on whether only the defective part is repaired, whether restoration of the surrounding finishes is included, or whether temporary works, protective measures, cleaning, and responses during downtime are included. For example, repairing piping inside a wall may require opening the wall, repairing the pipe, restoring the substrate, restoring the finish, and cleaning. Even for warranty-covered repairs, if you do not confirm in advance how much the contractor will handle, you may be left dissatisfied when the work is completed.

In commercial facilities, shops, and factories, the timing of repairs is also important. If repairs cannot be carried out during normal business hours, night or holiday responses may be required. Even if the warranty covers the repairs themselves, how special time-frame responses or temporary measures are treated contractually is a separate matter. Organizing the hours during which repairs can be performed after handover, emergency contact methods, whether attendance is required, and the procedures for work permits will help prevent confusion during actual repairs.

When reporting defects, internal information sharing is also important. If the on-site representative contacts the contractor directly and another staff member asks about the same issue via a different route, information becomes dispersed. The contractor then finds it hard to determine which contact is the official request. By designating a single point of contact on the client side and consolidating information from the site before making contact, the history of warranty responses will be kept organized.

Upon completion of repairs, always perform a completion check. Do not judge solely by appearance after repair; it is important to carry out checks appropriate to the cause. For a leak, perform a water spray test or an inspection after rainfall; for equipment, perform an operational check; for doors and windows, check opening and closing; for finishes, check how they integrate with surrounding areas, and record that the issue has been resolved. Also confirm how to handle cases where the same defect recurs after repair, as this will make subsequent responses smoother.

Retain inspection records and field data to prepare for warranty claims

The fifth item to check to avoid regrets during the warranty period is to keep inspection records and on-site data. In warranty handling, records that show the on-site condition are as important as the contract terms. When a defect occurs, even if the client says “it was like this before,” it is difficult to verify objectively without photos or records. In construction work, recording the condition at handover, changes after the start of use, and the situation when defects occur helps with warranty assessments.

First and foremost, the record at handover is important. Organize and file the completion documents, inspection records, corrective action completion reports, photographs, equipment instruction materials, and documents related to operation and maintenance. If there are small scratches, dirt, issues with fit and finish, or unfinished items at the time of handover, record them on the spot and confirm whether corrective action is required and how they will be handled. Even items that are verbally described as “we’ll deal with this later” should ideally be retained in writing or as a shared record.

Photos taken at handover are most effective if, in addition to overall shots, you focus on areas that are likely to become problematic later. Roofs, exterior walls, areas around openings, equipment surroundings, pipe penetrations, floor finishes, areas around ceiling inspection hatches, interfaces with exterior landscaping, and drainage routes are locations that may require condition checks after handover. When taking photos, combine wide shots and close-ups so the location is identifiable, and record the date and the shooting position. Even if you have a large number of photos, they become difficult to use for warranty purposes if it’s not clear where each photo was taken.

Records made during construction are also important. Areas that will be concealed after completion cannot be inspected after handover. Substrates, reinforcement, piping, wiring, waterproofing layers, insulation, fixings, and penetration treatments, among other things, may prove useful later when documented with construction photos and inspection records. Even if it is difficult for the client to record everything, it is important to obtain the construction photos and inspection records submitted by the contractor and confirm that the necessary items have been recorded.

After handover, records of periodic inspections are kept. Inspections are not merely about finding defects. They are a way to continuously monitor changes in the building’s condition and to manage checks so that items that should be confirmed during the warranty period are not overlooked. During inspections, we check for cracks, signs of water leakage, lifting or detachment of finishes, movement of doors and windows, abnormal noises from equipment, drainage flow, external deterioration, and changes in the surrounding ground. Even when there are no abnormalities, recording "No abnormalities" makes it easier to compare changes in condition later.

When recording a defect, in addition to photos and videos, record the date and time of discovery, the person who discovered it, the location, the situation, the operating conditions, the weather, work performed immediately beforehand, and whether any temporary measures were taken. In the case of a leak, record the rainfall intensity, wind direction, the location where it occurred, the amount of leakage, and the extent of interior damage. For cracks, record the length, width, direction, location of occurrence, and any changes in the surrounding area. For equipment malfunctions, record the displayed information, operating noises, frequency of occurrence, and conditions for reproduction. Having this information makes it easier for the contractor to investigate the cause.

When keeping records, it is important not to let them be scattered across individual staff devices or paper documents. Warranty periods for construction work can span personnel transfers or retirements. The person in charge at handover may not still be in the same department several years later. If records are managed individually, you may not be able to find the necessary materials when a defect occurs. It is important to designate an internal shared storage location and centrally manage contracts, drawings, photos, inspection records, and repair histories.

Site photos and location information in particular are effective in warranty-handling operations. If you can accurately show where a defect occurred inside or outside the building, communication with the contractor will be quicker. In large facilities, multiple-building complexes, extensive exterior works, or projects that include rooftops and site boundaries, simply explaining locations can take a lot of time. If you attach location data and notes to photos and manage them, scheduling on-site inspections and confirming the scope of repairs will be smoother.

In warranty handling, it is also important to avoid "he-said, she-said" situations. Even when contact is made by phone, briefly recording and sharing the details afterward creates a traceable record. For explanations received during on-site inspections, record the confirmation date, participants, explanation details, and the actions to be taken. Ensuring that both the client and the contractor can access the same information helps prevent unnecessary misunderstandings.

Records management is useful not only for warranty responses but also for future renovation planning and maintenance. If you know which parts are prone to defects, when inspections should be carried out, and what repairs have been performed in the past, that information can be used to inform specification decisions for the next construction work. Building construction does not end at completion; management continues as the building is used. Using the warranty period as an opportunity to establish a system for continuously retaining site data contributes to long-term quality management.

In this regard, establishing a system to efficiently record on-site information is highly significant. Relying only on paper notes, individual photos, and reports from each responsible person makes it easy for necessary information to become scattered. If photos, locations, notes, and inspection details can be recorded together on-site, it will be easier to confirm defects during the warranty period and to explain them to the contractor. In warranty management for building construction, creating a system to accurately document the on-site condition is indispensable, along with verifying contract details.

Summary

To avoid regretting the warranty period for construction work, it is important not to judge it solely by "how many years the warranty is." The warranty period must be checked together with the scope of coverage, exclusions, commencement date, notification deadlines, methods of contact, repair procedures, and inspection records. Especially in construction work, where structure, waterproofing, interior finishes, equipment, exterior works, and the scope of renovations are intricately related, leaving the warranty terms vague will make it difficult to determine responsibility when defects occur after handover.

First, check not only the length of the warranty period but also which parts are covered and what types of defects are included. In new homes, some elements are subject to legally mandated liability periods, but not all defects are treated the same. It is important to review the contract, specifications, drawings, estimates, and change records together and to clarify the scope of work and the scope of the warranty.

Next, clarify the warranty period’s start date and the notification deadline. If the construction completion date, inspection date, handover date, and start-of-use date differ, confirm which date will be used as the basis. If a defect is discovered, do not leave it unaddressed internally; promptly record it and notify the contractor. Even within the warranty period, late notification can make it difficult to verify the cause or to negotiate an appropriate response.

Furthermore, it is essential to decide in advance how to report defects and what the repair procedures will be. If you organize the primary contact, the information to be recorded, the on-site inspection process, the scope of repairs, and the method for confirming completion beforehand, you can respond calmly when a problem actually occurs. In particular, defects such as roof leaks, water leaks, cracks, and equipment malfunctions benefit from photos and condition records taken at the time of occurrence for cause investigation.

Finally, it is important to establish a system for retaining inspection records and on-site data. Organizing the condition at handover, concealed parts during construction, regular inspections, the circumstances when defects are discovered, and repair histories will make the information useful not only for warranty responses but also for future maintenance and renovation planning. Make sure the information is kept in a format that can be shared internally so it can be handed over even if personnel change.

The warranty period for building construction is not something to be consulted only when problems arise. It only becomes a management item that is useful in practice if it is checked before the contract, recorded during construction, organized at handover, and inspected after handover. To make effective use of the warranty period, both contractual confirmations and on-site records need to be put in order, and stakeholders must be able to access and confirm the same information.