Periodic Structural Inspection (PSI) in Singapore: The Owner's Guide

Singapore has required periodic structural inspections of existing buildings since the Building Control Act came into force in 1989.² The idea is straightforward: structures deteriorate, owners alter them, and usage changes, so a Professional Engineer should look at the whole structure at regular intervals and say whether it is still sound. The Periodic Structural Inspection (PSI) is the older sibling of the Periodic Façade Inspection (PFI), and owners of many buildings in Singapore are now subject to both. BCA groups the two, together with window safety and air-conditioner safety, under its periodic building inspections programme.⁹

The PSI is often treated as a paperwork exercise. It should not be. BCA tightened its guidelines in September 2022 with minimum inspection coverage for concealed structural elements, lessons from past incidents and specific attention to ageing buildings, and since February 2023 it has applied a risk-based “Differentiated PSI Approach” that scrutinises inspections of ageing buildings more closely.⁶ For owners, that means more access, more opening-up of finishes, and reports that are expected to say something meaningful.

This guide covers the PSI cycles for residential and non-residential buildings, when the first inspection falls after TOP, who may inspect, what is checked, what the report contains, what owners must rectify, the penalties, and how PSI and PFI interact on the same building. For the façade regime, see our complete PFI guide.

PSI at a glance

Which buildings, and which cycle?

The PSI applies to all existing buildings other than detached, semi-detached, terraced or linked houses used solely as places of residence, and temporary buildings.² Unlike the PFI, there is no height threshold.

Residential versus non-residential

BCA’s PSI page states the cycle simply: once every 5 years for non-residential buildings and once every 10 years for residential buildings.¹ The owner’s guide gives examples: buildings used for residential purposes only, such as condominiums and apartments, are on 10-year intervals; commercial, industrial and institutional buildings are on 5-year intervals.³

The detail matters for mixed-use developments. BCA’s guidelines for structural engineers specify that the 10-year cycle applies to buildings where at least 90% of the floor area is used solely for residential purposes, and the 5-year cycle to all other buildings.² A development with shops on the lower floors and apartments above may therefore fall on the 5-year cycle, depending on how the floor areas are apportioned. The Act frames the 10-year category as “special buildings” and buildings used solely for residential purposes.⁴

Civil engineering structures

PSI also applies, at 5-yearly intervals, to certain civil engineering structures with public access: jetties, docks and wharves (notices from December 2024) and bridges, underpasses and floating structures (notices from March 2025). Culverts, sewers, drains and retaining walls are currently exempted.³ When inspecting a building, the engineer should also inspect surrounding structures within the premises and include them in the report.²

When is the first PSI after TOP?

Section 28 of the Building Control Act fixes the earliest timing of notices:⁴

• Non-residential buildings (other than special buildings): a notice may be given after the 5th year commencing from the date the first Temporary Occupation Permit (TOP) or first Certificate of Statutory Completion (CSC) was issued, whichever was earlier, and thereafter at intervals of not less than 5 years from the date of the last notice.
• Special buildings or buildings used solely for residential purposes: after the 10th year on the same basis, and thereafter at intervals of not less than 10 years.
• Buildings with no TOP or CSC: a notice may be given at any time the Commissioner considers appropriate, with later notices at the 5- or 10-year intervals.

Two consequences follow. First, the clock starts at the first TOP or CSC, which for a phased development is the earliest partial permit. Second, the intervals run from the date of the last notice, not from the date the last inspection was completed, so a delayed inspection does not push back the next cycle.

Illustrative: an office building that received its first TOP in March 2010 could receive its first PSI notice at any time after the 5th year from that date, and later notices at intervals of not less than 5 years from each notice. A condominium with a first TOP in March 2010 would wait until after the 10th year.

Use the PFI checker to see how the façade regime applies to the same building; the PFI counts age differently, as explained below.

Who inspects: the structural engineer

The Act requires the inspection to be carried out by a structural engineer, meaning a Professional Engineer registered in the civil or structural discipline who holds a practising certificate.² The owner may engage only a PE who has no professional or financial interest in the building; BCA gives the example of an engineer responsible for the design or construction of the building or any of its building works.³ BCA lists PEs on its PSI page and points owners to the Professional Engineers Board directory.¹

BCA is explicit about personal involvement. The engineer is expected to carry out a comprehensive visual inspection relying on professional judgement, and it is not acceptable for the engineer not to visit the building or to delegate the entire inspection to an assistant who is not a civil or structural PE.² The owner’s guide encourages owners to notify BCA if they have evidence of this.³

The engineer must meet the deadlines in the notice and BCA’s written directions, and if unable to do so must apply in writing to BCA for an extension of time at least 5 days before the deadline.²

The PSI process from notice to closure

BCA publishes the forms on its PSI page: Form D2 for appointment; Forms D3 and D4 for visual inspection certification (D3 where defects are non-structural or minor, D4 where structural defects are suspected in localised areas or the whole building); Forms D5 and D6 for structural inspection certificates after investigation; and Form D7 for supervision of remedial works.¹

What the engineer checks

The Stage 1 visual inspection must cover, with reasonable diligence and including a personal visual survey:²⁵

• the condition of the building: types and signs of structural defect, deformation or deterioration;
• the loading on the structure: deviation from intended use, misuse or abuse that could cause overloading; and
• unauthorised works: evidence of structural works carried out without required plan approval.

Before inspecting, the engineer obtains the latest structural layout plans from BCA to understand the structural system and to identify special and critical structures (such as transfer girders, slender columns and long spans), structures without redundancy (such as cantilevers, cantilever balconies and hanging structures), small or slender void-deck columns in residential buildings built before 1989 using grade 20 concrete, allowable imposed loads, and any unapproved structural works.²

Minimum inspection coverage

The guidelines start from inspecting all structural elements. Where 100% inspection is not possible, they set minimums:²

By meeting the residential minimums, BCA expects the engineer to visually inspect at least 70% to 80% of the building’s structural elements.² The engineer must also consider whether higher coverage is needed because of age, wet areas, defects observed, exposure to aggressive environments, maintenance history, or complex structure.²

Under s 28(5) and (5A) of the Act, owners must allow and facilitate the removal of architectural finishes when the engineer needs to inspect concealed structural elements.² BCA’s 2024 circular describes practical solutions shared by industry, such as drilling small holes through finishes (with owners’ consent) to insert a borescope, installing access points in column claddings for future inspections, and using existing vents or lighting points to inspect concealed structures.⁶

Surveys beyond the frame

The guidelines also expect the engineer to survey exposure to aggressive environments (for example columns immersed in water, or chemicals in industrial buildings), slopes and retaining structures, safety barriers such as parapets and railings particularly where crowds gather, and heavy suspended fixtures such as thick plaster or heavy board ceilings over food courts, atriums and seating areas.² If the engineer sees any building element, including architectural or M&E finishes, at risk of collapse, the owner should be informed as soon as possible and the matter highlighted in the report.²

What the report contains

The PSI report must describe the inspection and any full investigation, analyse the observations and tests, and recommend the building works needed.⁵ BCA’s guidelines describe what a professional report includes: general information and maintenance history; the structural system and materials; a diary and scope of inspection, including areas not covered and why; the loading survey; the unauthorised works survey; a survey of defects, deformation and deterioration with an assessment of severity; recommended remedial actions; an inspection coverage summary with plans; conclusions; and the engineer’s standard certification on the first and last pages.² A checklist (Annex A) must be included.²

Defects are graded into three severity bands:²

After submission, BCA vets the report and may seek clarifications, conduct a joint site inspection or require a presentation. After accepting the report, BCA writes to the owner to follow up on the recommendations.³

Stage 2: full structural investigation

Where the visual inspection finds suspected defects of structural significance, the engineer may recommend a full structural investigation of a localised area or the whole building, subject to BCA’s approval.³ The scope typically includes obtaining design, construction and maintenance information; checking structural adequacy against plans and calculations (reconstructing plans if unavailable); testing materials and elements; load testing if necessary; and recommending safety precautions and remedial measures.² A localised investigation may itself lead to a whole-building investigation.²

For residential buildings with small, narrow or slender void-deck columns built before 1989 using grade 20 concrete, BCA asks engineers to be especially thorough and to seriously consider recommending a full structural investigation where early signs of distress appear, because maintenance lapses, rebar placement, settlement or vehicle impact can significantly reduce capacity.²

Rectification: what owners must do

If the report recommends measures or building works, the owner must carry them out within the period, and subject to the conditions, specified by the Commissioner of Building Control.⁴ Typical recommended actions listed in the guidelines include restricting usage or relocating heavy machinery, removing or regularising unauthorised works, termite treatment, timber specialist advice for mass engineered timber, regular checks of heavy suspended fixtures, tapping checks for spalling, further monitoring or investigation, and major repairs or strengthening.²

Major repairs and strengthening are building works, so plan approval, permit and supervision procedures apply.² On completion, the owner submits the engineer’s certification on completion of remedial works where applicable.³ Selling the building does not remove the duty: BCA’s owner’s guide says an owner cannot be exempted from carrying out recommended repairs because of an intended sale.³ Unauthorised works found during PSI must be removed or regularised; see our guide to unauthorised works and regularisation, and for alterations to structural elements, hacking walls and structural elements.

Penalties

How PSI and PFI interact on the same building

Most buildings taller than 13 m and older than 20 years are now subject to both regimes. They are run under the same section of the Act and the same 2021 regulations, but they are distinct.

Because the two inspections share a building, its drawings and often its access equipment, many owners ask one engineering practice to plan both: the PSI engineer and the PFI Competent Person can then work from one set of records and one access programme, while each report is still prepared and signed separately. CVC Engineers, RRD’s independent engineering partner, handles both periodic structural and periodic façade inspections; whichever practice you choose, check that the PSI engineer is a registered PE (civil or structural) and that the PFI Competent Person appears on BCA’s list.

Sources: BCA PSI guidelines and page; BCA PFI FAQs and guidelines; Building Control Act s 28.¹²⁴⁷⁸

Key interaction points:

• No substitution. A completed PSI does not exempt a building from the PFI, because the scopes differ.⁷
• One engineer, two reports. If you receive PSI and PFI notices concurrently, you may appoint the same PE (civil or structural) who is eligible for both, but two separate reports are required, and BCA will accept them on that basis only when the notices are served concurrently.⁷ Remember that for the PFI the PE must also hold the Certificate in Façade Inspection.⁸
• Different clocks. Because the PSI counts from the first TOP and runs on 5- or 10-year intervals while the PFI counts from the last whole-building TOP and runs on a 7-year cycle, the notices will coincide only occasionally. Plan access and budgets for both.
• Overlapping elements. External concrete elements, cantilever balconies, safety barriers and exterior suspended ceilings sit at the boundary. PSI looks at structures without redundancy such as cantilever balconies and at safety barriers; the PFI scope includes exposed parts of concrete walls, slabs, beams and columns, external balustrades and exterior suspended ceilings.²⁸ Share each report with the other inspector.
• Shared access. Gondolas, MEWPs and opening-up of ceilings can serve both inspections if timed together; see choosing façade access.

Key takeaways

• PSI applies to almost all buildings: every 10 years for residential (at least 90% residential floor area) and every 5 years for others.
• The first notice may come after the 5th or 10th year from the first TOP or CSC; later notices at intervals of not less than 5 or 10 years from the last notice.
• Only an independent civil or structural PE may inspect, personally, within the coverage minimums in BCA’s 2022 guidelines.
• Owners must provide access, including removing finishes, and must carry out recommended works within BCA’s period.
• PSI and PFI are separate regimes with different clocks; plan both together.

See the glossary for terms used here, or contact us about works arising from a PSI.