Written Answer by MND on rectification for HDB flats facing mould growth

Feb 6, 2023

4091. Dr Lim Wee Kiak: To ask the Minister for National Development (a) whether the deterioration of HDB building facades resulting in recent complaints can be attributed to changes in weather and climate conditions; (b) what are the potential safety risks that the Ministry is monitoring; and (c) how will the Ministry review and adapt construction and maintenance codes and standards to cope with the change of climate in the long term.

4114. Dr Shahira Abdullah (NMP): To ask the Minister for National Development (a) what percentage of HDB BTO flats are affected by mould formation before the end of the six-year exterior painting warranty period; (b) how often does the mould recur; (c) whether there are any health risks associated with prolonged exposure to mould; and (d) whether there are any predisposing factors which make certain blocks more susceptible to mould formation and what is being done to counteract them.

4142. Mr Edward Chia Bing Hui: To ask the Minister for National Development (a) what are the reasons that some HDB developments are more susceptible to mould; and (b) what preventive treatments does HDB undertake.

4153. Miss Cheryl Chan Wei Ling: To ask the Minister for National Development (a) whether there is a need to review the standards of paint work on buildings or infrastructures to prevent the effects of moulding; and (b) whether there is a need to update the maintenance practice for buildings that are near the coastline or along waterways.


Mr Speaker, may I have your permission to answer Question number 47 to 51 on today’s Order Paper, filed by Dr Lim Wee Kiak, Dr Shahira Abdullah, Mr Edward Chia and Ms Cheryl Chan?

2        Mr Speaker, my response will also cover the matters raised in the question by Assoc Prof Dr Jamus Jerome Lim which is scheduled for a subsequent sitting. I would invite the Member to seek clarifications if need be. If the question has been addressed, it may not be necessary to proceed with the Question for future sittings.

3        Prolonged exposure to severe environmental conditions, such as high temperatures and intense rainfall, may generally accelerate the deterioration of building façade materials. To ensure that façade deterioration is detected and rectified in a timely manner, BCA implemented the Periodic Façade Inspection (PFI) regime last year. Under the regime, buildings that are more than 20 years of age and over 13 metres in height must be inspected by a trained professional every 7 years. This will help building owners to ensure that their building façades are safe and well-maintained throughout the lifespan of their buildings.

4        BCA is also conducting a study on the impact of changing climatic and weather conditions on the service life of façade materials, which will contribute to the identification of more durable façade materials and the development of best practices for their maintenance. BCA will continue to review its requirements regularly to ensure that they are on par with international standards and take into account the latest climate projections.

Causes of Mould

5        To determine the cause of mould growth observed at Anchorvale Parkview and Matilda Court, HDB will be commissioning an independent professional technical study. The scope of this study will also address why some blocks are more susceptible to mould growth and include recommendations to remedy the current situation and to prevent future recurrence. This study is expected to take about 3 to 4 months to complete. Nonetheless, HDB has assessed that the mould growth observed for affected blocks does not affect structural components and poses no risks to the structural integrity of the building. 

Impact and Risk Assessment

6        Mould growth is not limited to a building’s exterior. Mould is also commonly found indoors, such as in bathrooms, where the higher humidity and dampness creates a more conducive environment for mould to grow. There are several factors that determines the presence and magnitude of the health risks caused by mould. For example, the level of risk faced by an individual is influenced by the individual’s activity patterns and proximity to mould, including the duration for which the individual is exposed to the mould, as well as the individual’s current health, such as whether he or she has any chronic illnesses (particularly, respiratory related). The impact of mould on one’s health would hence, for example, be less arising from the mould on the facades than in the bathroom. Nonetheless, the technical study mentioned will be identifying the species of mould found at Anchorvale Parkview and Matilda Court for further risk assessment.

Short-Term Measures to Rectify Mould Growth

7        To rectify mould growth on external walls, thorough cleaning of the external walls and patching of cracks is conducted, before repainting with sealer and algae-resistant paint. This is usually carried out by Town Councils as part of their management and maintenance of the common property.

8        The recommended schedule for Town Councils to carry out Repair & Redecoration (R&R) works is 7 years. Nonetheless, Town Councils have the discretion to decide whether to slightly advance or defer such works beyond the recommended schedule, depending on their’ operational needs. They can also engage a paint specialist to recommend a more optimal repainting method for any unique situation. If necessary, they may approach HDB for further advice.

9        For newly completed HDB blocks which are handed over to the Town Councils for management and maintenance, a 6-year warranty period for external painting is also provided. This warranty covers defects or imperfections such as peeling paint, discolouration and mould growth. During this warranty period, Town Councils can approach the building contractor and their paint specialist to rectify any defects or imperfections identified.

Longer-Term Measures and Review to Mitigate & Prevent Recurrence

10       The external walls of all HDB developments are painted with 1 coat of water-based sealer and 2 coats of algae-resistant emulsion paint. The water-based sealer enables better paint adhesion to the surface and is commonly used on external walls before the application of algae-resistant emulsion paint. The algae-resistant paint contains biocide which prohibits the growth of algae culture and gives the paint its algae resistant properties. The sealer and emulsion paint used in HDB blocks complies with the Singapore Standard 579 and the Singapore Standard 345 respectively, and they are also commonly used for buildings in Singapore, for both public and private sector projects. 

11       These standards, which have helped ensure that external façade walls remain clean and clear of mould over the last 20 years, were most recently reviewed with industry experts in 2021 to ensure that the standards are updated and remain relevant to the industry. These standards were also used in numerous other HDB projects, where no such incidents of mould growth have been identified, including developments located near waterbodies.

12       Depending on the outcome of the assessment commissioned by HDB, the Singapore Standards Council will assess the need to further review the relevant standards, on top of the periodic review carried out every five to eight years to ensure their relevance. Correspondingly, HDB will also assess the need to further review the specifications and maintenance practices for flats.