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

Waterproofing Design Review

An independent check on your waterproofing specification — typically provided free of charge. We review the design before systems are locked in, before mistakes become expensive, and while you still have time to change something.

Why this matters at design stage

Most waterproofing failures were decided at design stage. By the time the problem shows itself — years after completion, after the contractor has demobilised, after the defect liability period has run — the scope for recovery is limited and the cost is high.

The design stage is the critical window. The specification hasn’t been procured. The contractor hasn’t priced the detail. This is when an independent design review delivers the most — whether you’re at RIBA Stage 3, preparing for tender, or refining details at Stage 4.

Vector reviews the proposed waterproofing strategy, the membrane specification, the drainage strategy, the roof build-up and any areas of design complexity or interface risk. We produce a written report identifying material issues and recommended changes — specific, actionable, and designed to protect the building over its full life.

We are independent consultants — no installer relationship to protect and no warranty agenda. Our advice is right for the roof, not for a margin.

What we review

Waterproofing strategy and system selection
Membrane specification and compatibility
Drainage strategy and outlet design
Roof build-up and thermal performance interface
Penetrations, upstands and edge details
CLT or timber structural interfaces
Areas of design complexity or interface risk

What you get

Written report — specific, referenced, actionable
Material issue identification with recommended changes
Delivered within 5 working days of drawings issued
Optional: follow-on quality assurance inspections during construction, sensor commissioning and monitoring, or our full Complete Roof Assurance service from design through to maintenance

Who this is for

Architects protecting their PI position. Developers who want independent assurance before committing to a waterproofing strategy. Tier 1 contractors who want a defensible paper trail before handover.

If you’re working on a complex scheme — a landscape roof, green roof, podium deck, or CLT structure — this is the right time to get an independent eye on the design.

Request a Design Review

Tell us about the scheme. For standard projects, the initial design review is provided free of charge. We’ll confirm within 24 hours whether your project qualifies, and most reviews are delivered within 5 working days of drawings being issued.

Why we offer this free

Getting the waterproofing right at design stage protects the building for decades. Getting it wrong creates costs that dwarf anything spent on review.

One failed investigation by a previous contractor. One membrane replacement event. One insurance claim that could have been avoided. The downstream cost of a missed design issue is always disproportionate.

Independent review at design stage is the most efficient risk-reduction measure available — which is why we offer it free of charge for standard schemes.

“The defect liability period expiring is when your real risk begins — not when it ends. The clock has already been running on any latent moisture.”

— Ben Hickman, Technical Director