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Defect Diagnosis,

Dispute Resolution

Commercial mixed-use site
Client: Private

GWE Property & Advice were instructed to try and determine a persistent roof leak by the commercial tenant of this large, complex mixed-use site.

The landlord had recently replaced the roof covering near the leak and had asked the contractor to return on a few occasions, but the roof leak persisted. Whilst a roof leak is generally a nuisance, this one was significantly impacting the tenant’s business, so there was a real motivation for both landlord and tenant to work together to resolve the leak.

We established early on that this did not have to be some long-drawn-out report, but we simply needed to establish the origin of the leak and indicate how to repair it. We understand that the leak had suddenly appeared internally, with the immediate assumption being that the roof covering was to blame. As a result, a ‘friendly’ roofing contractor was engaged to quote to ‘fix the leak’.

For whatever reason, the owner advised that the recommended repair method should be to carefully chop off the promenade tiles (which almost certainly had been fixed to the roofing membrane with an adhesive), patch repair the membrane and then lay new promenade tiles on the top.
The original contractor had returned a few times. He believed that the roof was not leaking, and the damage was caused by condensation dripping onto the suspended ceiling beneath the air conditioning ductwork. Both landlord and tenant were becoming frustrated. Meawhile the builder was adamant that it wasn’t his work.

Having developed the site 25 or so years ago, the landlord, fortunately, had a comprehensive set of all the construction drawings. Still, as is often the case, it became apparent that what was drawn was not necessarily built. Similarly, the replacement roof had been procured without any specification; it was a simple case of ‘replace the roof in this section’.

So, at this stage:

  • we didn’t know what was originally specified in the design.
  • we didn’t know what materials had been used or how it had been built,
  • we didn’t know the nature and extent of the repair.
Thankfully, it was obvious where the repair had taken place but in the absence of any details around what had been done, there was very little to establish whether the roof covering was the cause of the leak. Back to first principles, then, where nothing can be ruled out as the cause – best to try and understand this building and how it performs.

In New Zealand, we have seen many Consultants jump in and start to ‘open up’, or in simple terms, drill or cut a hole in the roof or the ceiling to look at its composition. We didn’t believe that was necessary at this stage, as we could see that the building was built using in-situ steel-reinforced concrete. We could see where the water was appearing in the retail unit below, and we could remove the ceiling tiles easily. Most importantly, we were very aware that the tenant had been inconvenienced enough.

Following a visual inspection process, using a compact ‘key-hole’ camera and dye testing, we established that the leak was not caused by condensation from the roof deck or the air conditioning plant in the ceiling void above.

Based on the visual and test evidence, we confirmed that the leak was because of a failure of the roofing system. We were able to eliminate the rainwater outlets and gutters, which were all performing adequately. We were not able to determine the exact cause, given the lack of information relating to who did what repair and on what basis.

We formulated a straightforward two-page report based on our findings with recommendations on the next steps.

How could we have helped to prevent this?

A simple but thorough check of the cause of the leak, as it may have been that the roof covering wasn’t at fault at all. The contractor had removed, and not replaced, coping flashings and other critical protection around the parapet wall. None of these things had been considered.

The internal and external faces of the walls were painted with an elastomeric paint which was exhibiting blisters indicating that water was finding its way in or becoming trapped between the junction between the paint and the wall substrate.

The reality of deciding to chop off or remove promenade tiles was never going to work, regardless of how careful they may have intended to be.

GWE Property & Advice would have recommended a simple inspection of this area of the building. As a result, scheduled up a specification identifying what work and material needed to be used where on the roof and procured the work through a reputable and cost-effective contractor (either by tender or negotiation).

The work could have been managed and supervised to ensure that the repairs specified remained appropriate as work progressed, as it sometimes needs to adapt or change based on findings.

As part of this supervision, we would have kept notes and photographs to ensure it was executed correctly.

We would have gathered all essential documentation together (specifications, warranties, and producer statements) for the work completed for the client.

Whilst we cannot be sure, our experience suggests that the cost of engaging GWE Property and Building would have been disproportionally less than the cost now facing the landlord who has paid for something that does not work on his building. Best to do it right and do it once.

As Henry Royce (half of Rolls Royce) said

“The quality remains long after the price is forgotten”

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