Size is not the only measure of construction quality: Decoding Conquas workmanship bands for private homes

Boutique developments of fewer than 50 units made up nearly 60% of assessed private residential projects that fell into the lower half of the workmanship scale (Bands 4 to 6). That is based on an analysis by EdgeProp Singapore of data from the Building and Construction Authority (BCA) over the past six years.

Those bands come from BCA’s Construction Quality Assessment System (Conquas), which assesses construction workmanship on completion and sorts projects into six bands, with Band 1 the highest.

While smaller builds are over-represented in the lower Conquas bands, project size alone does not tell the full picture.

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Project size alone is a weak guide to build quality

Analysis of BCA data for the past six years suggests that project size can explain about 31% of the differences in scores, as there is an R² (a statistical measure of how much one factor explains another) of 0.31 between project size and Conquas outcomes.

In other words, while project size has some influence on quality outcomes, most of the variation is due to other factors.

Developments with above 300 units averaged a higher Band 1.8, compared with a lower Band 3.77 for projects with under 50 units.

Projects become progressively smaller across the bands, with median project size falling from 429 units in Band 1, to 16 units in Band 5.

Meanwhile, larger projects were much more likely to rank more highly for workmanship quality. About 83% of projects with 300 or more units achieved either Band 1 or 2, compared with just 21% of those with fewer than 50 units (see Table 1).

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That said, those averages tell only part of the story, as performance can still vary widely.

Boutique projects span the full range from Bands 1 to 6. Eden (20 units) and Baywind Residences (24 units) each achieved Band 1, while Lavender Residence (17 units) and Mooi Residences (24 units) were the only two Band 6 projects in the six-year period.

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As for larger developments, not all achieved top Conquas outcomes either. For instance, Pullman Residences Newton (340 units) was rated at Band 5 and Affinity at Serangoon (1,052 units) rated Band 4.

The builder’s band is the stronger signal

Compared with the development's size, the builder's Conquas band is far more closely linked to a project's band.

Across all builder bands, more than 90% of their projects stayed within a single band (see Table 2).

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Builder bands accounted for about 78% of the variation in project bands.

Overall, seven in 10 projects landed in exactly the same band as their builder, and 95% within one band.

This trend is even more pronounced within boutique projects, where 84% of projects were in the same band as their builder, and every project fell within a single band of their builder’s band.

Individual portfolios show the same consistency. All five projects completed by a Band 1 builder were assessed at Band 1, from the 20-unit Eden to the 592-unit Amber Park. One Band 5 builder delivered Band 4 at Tedge (42 units), and Band 5 at the 140-unit RV Altitude.

Developer track record matters, but again, it is not the whole picture

The developer band is a reliable guide at both extremes. Every project from a Band 1 developer was rated at Band 1 or 2, and all from Band 5 developers were assessed at Band 5.

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The linkage is less clear for mid-tier developers. Band 3 developers show the widest spread, with 28% of their projects at Band 1 or 2, 44% at Band 3, and 28% at Band 4.

A potential explanation for this may lie in the builder hired. Across the ten developers using two or more builders on three or more projects, the builder's band tracks the outcome closely.

One Band 4 developer illustrates the point. The nine projects it developed alone were built by seven different builders, with results from Band 1 to Band 5. Its Band 2 builders delivered The Addition (26 units) at Band 1, and Mayfair Gardens (215 units) and Mayfair Modern (171 units) at Band 2. Where it engaged Band 5 builders, Sea Pavillion Residences (24 units) and The Verandah Residences (170 units) both came in at Band 5.

What portfolio depth tells us at the boutique end

Notably, many builders of boutique developments have only a limited track record.

Builders of projects under 50 units had, on average, 1.7 assessed projects over the period in review, as compared with 5.1 projects for those working on developments with 300 homes or more.

Among the boutique projects, 61% were built by a builder who appears only once in the sample, versus just 14% of projects with 300 units or more. It suggests that builders of larger developments typically have more extensive track records.

This matters because a builder with only one assessed project on record will have a builder band that reflects that single project's result. While the band is still valid, it is worth considering it alongside other information known about the builder.

This pattern does not seem to apply to developers. Unlike builders, developers of boutique and large projects had similarly sized track records.

Small-project developers averaged 2.2 assessed projects against 2.5 for large-project developers. Also, most have only one or two banded projects, regardless of the scale they build at.

In essence, portfolio depth separates builders, but not developers.

Ultimately, Conquas measures the work of a whole project team. The builder matters, but other factors including the specification, the site and the design also bear on the outcome.

Bands are drifting downward, market-wide

Beyond differences between individual projects, the data also points to performance gradually declining across the market during the period analysed.

The mean project band fell from 2.18 in 2022, to 2.75 in 2025. Meanwhile, the share of projects rated as Band 1 or 2 shrank from 64.7% to 52.7%.

Three factors — a labour shortage, the mix of projects being completed, and the assessment method — may have influenced this.

First, the manpower crunch. Ministry of Manpower (MOM) data shows the construction and real estate sector's workforce fell by roughly 52,000 in 2020 compared to 2019. Headcount has since recovered past pre-pandemic levels, but ManpowerGroup's February 2026 survey found 77% of Construction and Real Estate employers struggling to fill roles.

Second, the composition or mix of projects completed each year had changed. Boutique projects' share of annual completions rose from 9.1% in 2021 to 29.1% in 2025. Given that such smaller projects tend to skew towards the lower workmanship bands, their growing share lowered the overall average.

Bands slipped among bigger developments of 300 units or more as well, from an average of 1.14 in 2022 to 2.27 in 2025 (see Chart 1).

Lastly, the assessment method was adjusted. Conquas revised internal-finishes weightings from June 2022, and restructured the assessment into three components for tenders called from July 2023.

As a result, projects assessed early in the six-year period were not scored on the same rubric as those assessed today.

What it means for buyers

Project size explains about a third of the variation in Conquas outcomes across the market.

The builder's band tracks the project bands far more closely, accounting for roughly 78% of the variation across all projects and also matching the outcome exactly in 84% of developments under 50 units.

The developer's band holds at both extremes but weakens in the middle, where the choice of builder accounts for much of the spread.

To be sure, these are associations rather than causes, as the analysis does not control for budget, specification or site complexity. Besides, a builder's band itself partly reflects the developers that hire it and the brief that the latter sets.

For a boutique launch, buyers may want to consider the builder's band, the developer's record and the number of assessments behind each figure, alongside unit count.

Note: This analysis is based on EdgeProp Singapore's compilation of BCA Conquas band data for private residential projects assessed over the past six years, together with the developer and builder bands recorded for each project.