Do I need a conductive substrate for electronic integrity testing?

Yes. Both low-voltage wet testing and high-voltage dry testing require a conductive substrate directly below the waterproofing membrane — typically a concrete or metal deck. On timber decks, a conductive medium such as wire mesh or conductive glass felt can be installed during construction to enable EIT. See LRWA Guidance Note 18 (2025) for full substrate requirements.

Can you electronically test a green roof or buried waterproofing?

Not with standard EIT once the overburden is in place. For buried waterproofing, the correct method is electrical field mapping (EFM) — a buried leak location technique that locates membrane breaches to within approximately one metre without lifting the overburden. CIRIA C817 and the GRO Green Roof Code both recognise EIT as a pre-covering QA method and EFM as the post-burial investigation method.

What is the difference between moisture mapping and leak detection?

Moisture mapping tells you where moisture has accumulated within the roof build-up. It does not tell you where the membrane has failed. Leak detection methods such as low-voltage EIT or electrical field mapping locate the actual breach in the membrane. The two are complementary: moisture mapping identifies which areas need investigation; breach-location methods find the source.

Is flood testing safe for flat roofs?

Flood testing carries real risks. A 150mm head of water adds approximately 150kg per square metre of loading — structural sign-off is essential. Water can take many hours to manifest internally, making short test periods unreliable. Flood testing can also cause structural deflection that opens up laps and details. It has a legitimate role in post-repair verification of specific, structurally appropriate areas only.

What qualifications should a roof leak detection specialist hold?

Look for: NVQ Level 3 in waterproofing testing and inspection; RAWTA membership (the Roofing and Waterproofing Test Association); and a demonstrable CV in flat roofing and waterproofing systems. Under the Building Safety Act 2022, appointing an incompetent inspector carries legal liability for duty holders.

Which leak detection method works on a single ply membrane?

For QA of weld continuity at laps and details, vacuum box testing is most reliable. For field-sheet investigation with a conductive substrate, low-voltage wet EIT is standard. High-voltage dry testing also works on non-conductive single ply on conductive substrates. Black EPDM membranes are generally not suitable for EIT due to carbon black content.

How does permanent sensor monitoring differ from leak detection surveys?

Leak detection surveys are point-in-time investigations locating a breach. Permanent sensor monitoring is continuous infrastructure embedded during construction, monitoring moisture in real time and triggering automated alerts. CIRIA C817 specifies permanent monitoring for blue-green roofs; BS 6229:2025 references electronic devices for detecting leaks between inspections.

Does electronic leak detection work in the rain?

Low-voltage wet testing requires a wet surface so rain is not a problem. High-voltage dry testing requires a dry membrane and cannot be performed in wet conditions. Tramex capacitance mapping works in most weather. Infrared thermography requires dry sunny conditions. Tracer gas is best in calm dry conditions as wind disperses escaping gas.

Service

Complete Roof Assurance

One appointment. One relationship. Protection from design through to end of life.

Most roofs fail not because of one catastrophic event, but because of gaps — between design and construction, between handover and maintenance, between the contractor leaving site and the building owner discovering a problem years later.

Complete Roof Assurance closes those gaps. It is a single, integrated service that protects the roof at every stage — from independent design review through construction quality assurance, sensor commissioning, continuous monitoring and planned preventative maintenance for the lifetime of the building.

One consultant. One continuous relationship. A complete evidential record from day one.

Five stages. One integrated service.

1. Waterproofing Design Review

We review the waterproofing specification at RIBA Stage 3 or 4 — falls, overflows, membrane selection, drainage strategy, roof build-up, penetrations, upstands and interface details. We identify material risks and recommend changes while the design can still be amended without cost or programme impact. For preferred clients, this initial review is provided free of charge.

2. Sensor System Design

We design a bespoke moisture sensor array tailored to the roof’s construction, risk profile and monitoring objectives. Sensor placement is determined by the waterproofing design, the drainage layout and the locations where moisture ingress is most likely or most consequential. We are independent — we specify the right system for the roof, not for a manufacturer’s margin.

3. Quality Assurance During Installation

We carry out independent quality assurance inspections during the roof installation to ensure compliance with best practice. Our quality assurance is via an appointment to the main contractor, not the roofing contractor, meaning that our work is more independent than industry standard. A visual inspection after completion cannot identify what was done wrong beneath the finished surface. Being present during the critical stages of installation is the only reliable way to verify workmanship.

At this stage we also commission the sensor system, verifying that every sensor is functioning correctly and reporting to the monitoring platform before the roof is closed up.

4. Continuous Sensor Monitoring

Once commissioned, the sensors monitor continuously. You receive alerts when moisture levels change, quarterly performance reports, and an annual condition review. Problems are identified in days — while access is still easy and remediation costs are still manageable — not years later when the water has already travelled and the damage is done.

5. Planned Preventative Maintenance

BS 6229 Clause 8.2 requires that flat roofs are inspected at least twice yearly — in autumn to verify the roof is clear of debris and draining freely, and in spring to identify and rectify any weather damage. These biannual inspections are not optional. They are a requirement of the British Standard and a condition of every major membrane manufacturer’s warranty.

Very few building owners have these inspections carried out by competent specialists. The warranty quietly collapses. The roof fails. Building owners discover they have no cover. Complete Roof Assurance includes the biannual inspections as standard — your warranty stays live, your roof stays maintained, and you have a continuous independent record of the roof’s condition.

Why this matters commercially

A failed roof membrane on a complex scheme — a green roof, a podium deck, a CLT structure — typically costs six figures to investigate and remediate. Insurance claims are contested. Warranty claims are rejected on the grounds that maintenance was not carried out. The contractor has long since demobilised. The architect’s PI insurer wants to know who checked the design.

Complete Roof Assurance eliminates this scenario. The design was independently reviewed. The installation was independently inspected. The sensors have been monitoring since day one. The inspections have been carried out on schedule. There is a complete, timestamped evidential record of the roof’s performance from design through to the present day.

That is not just peace of mind. It is a defensible position.

Who this is for

Developers and asset holders who want independent assurance over the full life of the roof. Tier 1 contractors who want a defensible paper trail at handover. Housing associations and institutional landlords managing long-term maintenance obligations. Architects and structural engineers who want to know the waterproofing is right before they sign off the design.

If you are building or managing a complex flat roof — a landscape roof, green roof, podium deck, inverted roof or CLT structure — this is the service that protects it from design through to end of life.

Talk to us

Every scheme is different. We price Complete Roof Assurance on a project-specific basis, with the design review typically provided free of charge to preferred clients. Contact us to discuss your project and we will confirm scope and fees within 48 hours.