Commercial Flat Roof Waterproofing
80% of Commercial Flat Roofs We Survey Have No Valid Warranty. Yours Probably Doesn’t Either.
We survey it. We specify it. We install it. And with Roof Shield™, we maintain it — so the warranty you paid for actually stays valid.
The UK’s Flat Roof Warranty Crisis
According to industry data, over 70% of UK commercial flat roofs have no valid warranty. Not because the roof failed — because the warranty was voided through lack of maintenance, undocumented modifications, or simple neglect.
Most building owners don't know this until they make a claim. By then, they're paying for a full replacement out of their own pocket.
Vanguard exists to fix this. We don't just waterproof your roof — we give you a maintenance strategy that keeps it protected.
Why Flat Roofs Fail
- Poor original specification — wrong system for the building
- Uncontrolled modifications — HVAC units, aerials, cables
- Blocked outlets and failed drainage
- No planned maintenance — warranty quietly voided
- Inadequate upstand heights at edges and penetrations
- Single-ply welds failing after 10–15 years
The Vanguard Approach
Survey. Specify. Install. Maintain. That’s how we keep commercial flat roofs watertight.
Specification-Led Approach
We don’t just install — we specify. Every project starts with a detailed survey and a written specification that tells you exactly what’s going on and what we recommend.
Seamless Liquid Systems
Triflex PMMA membranes create a joint-free waterproof barrier. No laps, no seams, no weak points. Independently certified to 25+ years.
Roof Shield™ Maintenance
Our flagship Roof Shield™ programme gives you planned maintenance, bi-annual inspections, and a 5-year no-leak guarantee — so your warranty actually means something.
All Build-Ups Covered
Warm roofs, inverted roofs, green roofs, cold roofs. We specify the right build-up for your building — compliant with BS 6229 and current Building Regs.
Detail Obsessed
Upstands, penetrations, outlets, and edge trims — these are where 80% of leaks originate. We detail every junction to current British Standards.
Transparent Pricing
We publish our pricing ranges. No games, no hidden extras. You’ll know the cost before we start.
Buildings We Protect
Commonly Asked Questions
Why does my flat roof keep leaking even after repairs?
Because most flat roof “repairs” are patches applied over the symptom, not the cause. Water tracks horizontally under membranes, so the leak you see inside is often metres away from the actual point of failure. We use thermal imaging and moisture mapping to find the real source — then fix it properly.
How do I know if my flat roof needs replacing or just repairing?
That’s exactly what our condition report tells you. We survey the membrane, test adhesion, check insulation U-values, and assess drainage. If 70% of the membrane is sound, a targeted repair and overlay may be all you need. If the membrane is beyond economic repair, we’ll tell you — and specify the right replacement system.
What systems do you use for commercial flat roofs?
Primarily Triflex PMMA liquid waterproofing — cold-applied, seamless, BBA-certified with 25+ year expected service life. For premium architectural projects, we also specify Soprema Copper Art and Silver Art decorative membranes. The right system depends on your building, your budget, and your maintenance strategy.
Is there a warranty?
Every system we install comes with a manufacturer-backed product guarantee. But here’s the truth most roofers won’t tell you: a warranty is only as good as the maintenance behind it. That’s why we created Roof Shield™ — a planned maintenance programme that keeps your warranty valid and your roof watertight.
What does commercial flat roof waterproofing cost?
For a Triflex PMMA system: typically £70–£140 per m² installed, depending on build-up, access, and substrate condition. A 500m² office roof might cost £45,000–£70,000. We provide a detailed breakdown with every quotation. See our Pricing page for published ranges.