Houses – Roof Water Ponding – Potential Issue

Many homeowners have already experienced leaking roofs and balconies and, while “past performance is not a reliable indicator of future performance”, such issues understandably give rise to concern regarding potential latent defects that may only become apparent after the NHBC 10-year insurance-backed warranty has expired and/or the developer has left the site.

The pitched roof sections appear, overall, to be well constructed, and the Residents’ Association is not currently aware of any systemic construction defects affecting these elements.

However, the flat roof perimeter sections, which are critical for roof drainage, appear in some cases to be poorly constructed. Concerns relate both to the application of waterproofing materials and, more significantly, to an apparent lack of adequate drainage falls.

While it is difficult to verify the thickness and integrity of the waterproofing membrane without intrusive investigation, what is clearly observable in several instances is persistent water ponding. This indicates that drainage falls are either insufficient or entirely absent.

Persistent ponding is undesirable for several reasons. It leaves the waterproof membrane in a permanently saturated condition and, during winter months, subjects it to repeated freeze–thaw cycles. This can significantly accelerate material degradation and reduce the effective lifespan of the roof covering.

NHBC standards require flat roofs and associated drainage systems to be designed with a nominal fall of 1:40, achieving a minimum fall of 1:80 in practice after allowing for construction tolerances and settlement.

In practical terms, if standing water remains more than 48 hours after heavy rainfall, the roof is unlikely to comply with NHBC standards.

Although upper roof areas are inherently difficult to inspect, it is now evident that many properties across the development experience prolonged standing water following rainfall. This has been evidenced through drone imagery, publicly available aerial photography (e.g. Google Maps), and visual observation from nearby vantage points, including the Clock Tower.

While the Residents’ Association is aware of these concerns, the developer has indicated that it will not consider a “group complaint,” as the Association does not have a direct contractual relationship with them. Accordingly, any formal action must be initiated by individual homeowners, who do have such a relationship and who are also beneficiaries of the NHBC warranty.

For this reason, it is important that at least one resident within each terrace block, where ponding may be prevalent, raises the issue directly with the developer, both on their own behalf and in the interests of other properties within the same terrace.

This issue has now been raised on behalf of one terrace, and the developer has agreed to instruct Peter Dodds Ltd to undertake an inspection and produce a condition report.

Peter Dodds Ltd will already be known to several residents who have undergone roof repair works, and they appear to be a competent and experienced roofing contractor.

Further updates relating to this terrace will be published on the website as they arise.
In the meantime, any resident wishing to discuss this issue in relation to their specific property or terrace is welcome to contact: admin@cwra.co.uk