Scope matters, not duration
The phrase ten year warranty sounds reassuring at first. But if what the warranty covers is not written down, the duration is meaningless in practice. Two companies can quote the same period and take on completely different responsibilities.
Material warranty and workmanship warranty are separate
The material warranty belongs to the manufacturer and covers the product retaining its technical properties. The workmanship warranty belongs to the company doing the installation and covers application errors. Since the large majority of failures seen on site come from application rather than material, the workmanship warranty is the valuable one. A quote offering only a material warranty leaves the risk with the customer.
Clauses to look for in the contract
- The start date and duration of the warranty
- A statement that material and workmanship are covered separately
- The response time after a fault is reported
- That repair is free of charge, and which items it includes
- An explicit list of exclusions
- What happens to the warranty if the company is transferred or ceases trading
Typical exclusions
These clauses are reasonable and it is normal to see them in a contract:
- Leaks arising from structural movement and earthquake related cracking
- Damage caused by subsequent drilling, anchoring or alteration work
- Drainage chambers left unmaintained and allowed to block
- Unauthorised covering or filling placed over the waterproofing
- Mechanical damage caused by the user
The maintenance obligation
In buildings with a drainage system, checking the inspection chambers is usually the owner's responsibility. A simple check once a year keeps the warranty alive and prevents the system from clogging. Writing this obligation explicitly into the contract protects both parties.
What makes a warranty meaningful
A warranty is a measure of the installer's confidence in their own work. A company that issues a written warranty is agreeing to carry the cost of a faulty application itself. That is why a low quote without a warranty is not actually cheaper; it is the quote that transfers the risk to you.
Five headings to look for in a guarantee document
Whose guarantee is it? A manufacturer guarantee and an installer guarantee are different things. The manufacturer guarantees the technical properties of the product, the installer guarantees the workmanship. Since leaks mostly arise from workmanship, the second is what matters.
What does the term cover? The phrase ten year guarantee says nothing on its own. What is guaranteed for ten years must be written down: watertightness, the structural integrity of the material, or merely product defects?
Response time. How quickly an on site inspection will follow a reported problem should be stated. A guarantee with no stated response time is vague in practice.
Exclusions. The exceptions detailed below should be written out explicitly. An exception that is not written down becomes a matter of dispute when a problem arises.
Transferability. If the building is sold, does the guarantee continue for the new owner? This is worth asking, particularly for investment property.
Why certain situations fall outside cover
A guarantee covers work within the installer control. Interventions and events outside that control are reasonably excluded. Common exceptions are as follows.
Drilling carried out afterwards. Every hole drilled after the waterproofing is complete, for a balustrade, air conditioning unit, awning or aerial, pierces the waterproofing. Unless each hole is individually sealed a leak is inevitable, and responsibility rests with whoever drilled it.
Lack of maintenance. Outlets and drainage lines accumulate leaves, silt and debris. An outlet that is not cleared holds water on the terrace and subjects the waterproofing to a load it was not designed for. Regular maintenance is usually a condition of the guarantee.
Structural movement. Wide cracks caused by settlement, earthquake or a problem in the structural system can exceed the bridging capacity of the material. This is a structural condition, not a waterproofing defect.
Intervention by another contractor. Another team working over the waterproofing may damage the membrane. This risk should be understood during refurbishment.
Problems arising from design. If drainage was never installed or the falls are wrong, the problem persists even where the waterproofing was applied correctly. This is why a complete scope at quotation stage matters for the guarantee as well.
What to do to protect your guarantee
Check outlets and drainage chambers at least twice a year, in autumn and spring. Watch the joints in terrace and balcony finishes and report darkening or debonding early. Consult the installer before any fixing that will pierce the waterproofing. Do not disturb the falls around the building or the discharge point of rainwater downpipes. Keep the photographs taken during application and the handover documents.
What to do when a problem appears
First record the symptom: where, when, how long after rainfall, in which season. This information speeds up identifying the source considerably. Then notify the installer in writing and request an on site inspection. Not starting to strip anything out before that inspection matters for both cost and guarantee.