Mr Matthew Chang's proposal to tweak the percentage of home owners who must consent before a collective sale is allowed, based on the age of the property, is a commendable one (Collective sales a key part of urban renewal; Jan 21).

But it must be emphasised that the age of a property should not be the only or most pertinent factor in deciding whether or not it should be sold. As safety is paramount, the structural condition of residential properties should perhaps be given more weight. Under the law, all non-landed residential buildings are subject to periodic structural inspections by professional engineers to ensure that they are free from structural defects.

As a legal and communications manager of a civil and structural consultancy firm, I have read numerous reports by engineers certifying old properties to still be in satisfactory condition.

Conversely, there are fairly new properties whose structural integrity is compromised owing to design issues or poor maintenance. Extensive structural repairs and strengthening works could be needed, which would be costly and disruptive to the residents. The property value may also be adversely affected.

It would make more economic sense for these properties to be sold en bloc than older properties that are in satisfactory condition.

Tung Ying Ying (Madam)