Waterproofing warranty: what it should include and what to ask before you sign

A waterproofing warranty is what protects you when leaks, damp patches, or water ingress show up after the job is “finished”. The key is not the headline years—it’s what is covered in writing, for how long, and under which conditions.

Legal warranty vs commercial warranty (why it matters)

In waterproofing, three ideas are often mixed together:

• Legal liability for the works: linked to the works contract and applicable regulations (timeframes and responsibilities depend on the type of defect and the scope of intervention).
• Contractor’s commercial warranty: an additional written commitment offered by the company (its own terms).
• Manufacturer’s warranty: sometimes available, but usually conditional on using a full system, correct substrate preparation, and certified application.

If it’s not written down with a clear scope, it’s hard to enforce.

What a waterproofing warranty should include (checklist)

Before signing, make sure the warranty states:

• Installed system: material, brand, product references, number of layers, thickness/weight, primers and reinforcements.
• Area and included zones: m², perimeters, parapets, drains, junctions, joints, and all critical details.
• Warranty term: start date (typically practical completion/acceptance) and duration.
• What counts as a “failure”: water ingress, loss of watertightness, cracking, debonding, etc.
• What is covered: investigation, labour, materials, reinstatement, access equipment (scaffold/boom), and whether interior damage is included (often excluded unless agreed).
• Exclusions: lack of maintenance, third-party works, punctures, structural movement, blocked drains, missing falls, etc.
• Maintenance requirements: periodic inspections, drain cleaning, joint checks.
• Notification procedure: who to contact, time limits, and how to document (photos, date, exact location).
• Supporting documents: materials report, detail drawings, photo record, test/inspection records.

Secondary keywords: common exclusions and the “small print”

Typical waterproofing warranty exclusions

Watch for overly broad exclusions. Common ones include:

• Third-party damage: satellite/antenna installers, solar installers, HVAC contractors, etc.
• No maintenance: clogged drains, vegetation, standing water.
• Poor substrate not repaired: active cracks, loose tiles, friable screeds.
• Change of use: turning a non-trafficable surface into a trafficable one without protection.

What if the real issue is falls or drainage?

If the quote doesn’t include correcting falls, overflow outlets, or drainage upgrades, ponding water may persist and lead to related failures. Make sure the scope explicitly addresses it.

Tests and documentation you should request

To make the warranty enforceable, ask for:

• Completion/acceptance record signed.
• Photos of critical details: parapet junctions, drains, joints, service penetrations.
• System technical datasheets and material batch info (where applicable).
• Watertightness testing where feasible (e.g., controlled flood test on certain roofs/terraces) or at least a documented inspection.

Multi-owner buildings: how to manage the warranty

For apartment buildings and shared roofs/terraces, good practice is:

• Issue the warranty in the building/community name and store it with the property manager.
• Attach a simple maintenance plan (twice a year and after storms).
• Define who can approve third-party works on the roof to avoid invalidating conditions.

How to make a claim if a leak appears

If you see damp or leaks during the warranty period:

• Document it: photos/video, date, recent rainfall, exact location.
• Notify in writing (email) and request a site visit with a brief report.
• Don’t tamper with the area if it could affect evidence.
• Ask the contractor to state whether it’s an installation defect, a detail issue, third-party damage, or maintenance-related.

A professional response includes inspection, diagnosis, and a repair plan with timelines.

What to require in the quote so the warranty has real value

A warranty stands on a well-defined scope. Ensure the quote includes:

• Clear scope (what is included/excluded)
• Substrate preparation
• Treatment of critical details
• Final protection (trafficable/non-trafficable)
• Recommended maintenance

Need a clear, written waterproofing warranty?

At Impermyna we deliver defined waterproofing systems, job documentation, and transparent warranty terms for homes and multi-owner buildings. If you want, we can review your project and confirm the right scope before you sign.