Detecting a Defective Roof

by Terry Davis MIoR

Early Detection of Roof Degradation: Key to Prolonging Roof Life

Learning to identify early signs of roof degradation and underlying system damage is crucial for maintaining the integrity of your roof and preventing major problems before they arise. Spotting potential issues early can save you significant time and costs, reducing the need for extensive remedial work to restore and repair your roofing system.

?Flat roofs, in particular, require regular inspections and annual maintenance to preserve their condition and maximise their lifespan. Unfortunately, the first noticeable sign of a defective roof is often the unwelcome sight of an internal leak. However, there are many earlier indicators of roof failure that can be easily spotted externally.

This guide is designed to assist in the long-term care of your roof assets, helping you avoid the need for premature repairs or replacements. Below are some of the subtler signs to watch for:

External Indicators – Stopping problems in their tracks

?Ponding Water

Ponding water on the roof is a clear indication of a problem with the roofing substructure, often pointing to issues such as sagging, an insufficient slope, or drainage problems. Standing water increases stress on the affected area, which can eventually lead to the failure of the roofing system.

Splits and Cracks

Roofs are continually subjected to movement, whether from expansion and contraction due to temperature changes or shifts in the building structure itself. Over time, this movement can cause splits and cracks to develop in the detailing and the installed waterproofing system, eventually allowing water to penetrate the building's fabric.

Additionally, poor workmanship during installation can result in weakened membrane seams, where proper watertight adhesion to the substrate was not achieved from the start.

Deteriorated Flashing

Flashings are often overlooked as a crucial component of roof maintenance. While proper detailing and installation of flashings can significantly extend a roof's lifespan, they can deteriorate over time due to UV exposure, physical damage, and movement in the building structure. When flashings become loose or fail, leaks are likely to occur.

Ageing

All roofing materials have a lifespan during which they remain effective. Over time, UV exposure, movement, and physical damage will inevitably impact the roofing structure. Identifying signs that the roof's surface is nearing the end of its life cycle before it fails will provide more options for repair, potentially avoiding the need for a complete roof replacement.

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The issues mentioned earlier—ponding water, splits and cracks, and deteriorated flashings—are all indicators of an ageing roof structure. Another key sign of ageing in bitumen membranes is "Alligatoring," a pattern of crazed cracking on the surface that resembles alligator skin. If left unaddressed, this condition will worsen, eventually leading to the roof to fail.

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?Blistering

Blistering occurs when pockets of air or moisture become trapped between layers of the roofing membrane or between the membrane and the roof deck. As the sun heats the roof surface, these pockets expand, stretching the membrane and causing blisters to form.

Blistering itself isn’t necessarily problematic, as roofs can accommodate some movement. However, it’s important to monitor blisters to ensure the membrane isn’t detaching from the blistered area, that no cracks have formed in the surface, and that the blister isn’t close to a seam, which could lead to seam failure and water ingress.

Organic Growth

While algae, lichens, mold, moss, fungi, and other vegetation might not seem alarming, they are actually early indicators that your roof needs immediate attention. Organic growth often signals prolonged water retention, which could point to an underlying issue with the roof structure. Additionally, if left untreated, the vegetation itself can cause further damage to the roofing surface.

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??Lack of Maintenance

TDRC recommends that your roof be inspected regularly and maintained at least once a year to prevent problems before they cause significant and costly damage. Neglecting regular maintenance inevitably leads to the issues mentioned above, requiring immediate remedial work to prevent further deterioration.

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Internal Indications – Resolving Problems Before They Deteriorate

Internal indications of roof issues are often easily visible, such as peeling wallpaper, brown ceiling spots, cracked paint, or mold on walls or ceilings. In more severe cases, you may notice an internal leak.

Unfortunately, by the time these internal signs of water ingress appear, one of the external indicators mentioned earlier has likely progressed to a failure in the roof structure. While this is not ideal, taking swift action is crucial to resolving these problems before they worsen, helping to minimize both repair time and costs.

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Next Steps

At TDRC, we are committed to enhancing your roof assets through proactive management and maintenance, aiming to avoid unnecessary roof replacements whenever possible. Our highly skilled Technical Manager provides a range of technical support services to thoroughly analyze your roof's condition and implement the best solutions for any challenges faced by your building.

Site Visit and Survey

During a TDRC site visit, we will access the roof to assess the overall condition of the existing roof system and substrate. Our methods include:

Core Sampling: Removing a small area of the roof to analyse the build-up and current condition of the roofing system, along with moisture probe analysis. This helps identify any disruptive water issues beneath the roof's surface.

Moisture Mapping Survey: Utilising advanced testing equipment to map the entire roof area and digitally highlight detected levels of subsurface moisture. This less intrusive method is ideal for flat roofs.

Condition Report

Following the evaluation of the defective roof, TDRC will provide a comprehensive Condition Report,which including:?

Core samples

Moisture probe analysis

Photographic summary

Observations

Recommendations

Performance waterproofing specification

Ongoing Solution

TDRC will offer a comprehensive Roof Asset Management Programme to ensure continued effective management and maintenance of your roof.feel free to reach out oremail: [email protected]