In the world of waterproofing contracts, substrate acceptance clauses are often an overlooked detail, but their relevance to liability cannot be overstated. A drain point underneath a planter box wall, as depicted in the photo accompanying this discussion, is an example of an unacceptable condition for applying a waterproofing system. Competent waterproofing professionals recognise this and understand the significant implications of applying a waterproofing membrane to an unsuitable substrate.

Why Substrate Acceptance Matters

Substrate acceptance is not just about technical compliance; it’s about ensuring the integrity and longevity of the entire waterproofing system. Accepting a substrate without proper inspection can lead to severe liability issues for the waterproofing contractor.

1. Foundation of Success 🛠️

A properly prepared substrate ensures that the waterproofing membrane adheres correctly and functions as intended. Any deficiencies or imperfections in the substrate can compromise this performance, leading to premature failure of the waterproofing system.

The Technical Perspective: From a technical standpoint, a substrate in poor condition can lead to inadequate adhesion of the waterproofing membrane. This inadequacy can cause blisters, delamination, and subsequent water ingress, which are detrimental to the integrity of the structure.

The Liability Perspective: If the waterproofing contractor proceeds without addressing substrate issues, they implicitly accept the state of the substrate. This acceptance can lead to significant liability if the system fails due to substrate problems. Contractors become responsible for the additional costs associated with repairs and potential legal consequences.

2. Extended Durability ⏳

High-quality substrate preparation is crucial for the long-term durability of the waterproofing system. A well-prepared substrate minimizes the risk of leaks and water damage over time.

Durable Outcomes: A properly prepared substrate supports the membrane’s durability, ensuring it can withstand environmental and operational stresses. This preparation helps prevent common issues such as cracking, bubbling, and water penetration.

Prolonged Liability: When a waterproofing system fails prematurely due to substrate issues, the contractor can face prolonged liability. This includes covering repair costs, potential penalties, and reputational damage. Ensuring substrate quality upfront can mitigate these risks and protect the contractor’s professional reputation.

3. Accountability 📜

Accepting the substrate means the contractor vouches for its suitability. Any subsequent issues due to substrate problems typically fall squarely on the contractor’s shoulders.

Written Documentation: Proper documentation and communication about substrate issues are essential. Contractors must note any deficiencies and seek written approval to proceed from stakeholders. This documentation can act as a shield against liability if substrate issues arise later.

Legal Ramifications: Failing to document substrate issues can lead to legal complications. Contracts often include clauses holding the contractor accountable for substrate complications. Without proper documentation, proving that the substrate was unfit at the time of application can be challenging, leading to unfavourable legal outcomes.

Mitigating Risks in Substrate Acceptance

Minimising liability and ensuring successful waterproofing applications involve detailed inspections, thorough documentation, clear communication, and ongoing education.

1. Thorough Inspection 🔍

Conducting meticulous inspections of the substrate before application is vital. Contractors should diligently look for issues like cracks, uneven surfaces, or moisture content that could compromise the membrane.

Inspection Protocols: Establishing a robust inspection protocol can help identify potential substrate issues. Using tools such as moisture meters, laser levels, and visual inspections can ensure comprehensive assessment.

Liability Safeguards: Accurate and thorough inspections safeguard against liability. Identifying and addressing substrate issues before membrane application can prevent future claims and disputes related to substrate acceptance.

2. Documentation 📸

Documenting inspections and findings is crucial. If issues are identified, communicating them to stakeholders and recommending necessary rectifications is essential before proceeding.

Visual Records: Taking photographs and creating detailed reports of substrate conditions serve as valuable records. These documents can be referenced if disputes arise regarding substrate suitability.

Stakeholder Agreements: Ensuring that all necessary rectifications are agreed upon and documented before proceeding binds stakeholders to a mutual understanding, reducing the contractor’s liability.

3. Clear Communication 🗣️

Explicitly stating the importance of proper substrate preparation in contracts and outlining steps to be taken if the substrate is found unsuitable is fundamental.

Contract Clauses: Including well-defined substrate acceptance clauses in contracts can protect contractors. These clauses should outline the protocols for substrate inspection, documentation, and necessary rectifications.

Effective Communication: Engaging in clear and continuous communication with all parties involved ensures everyone acknowledges the criticality of substrate conditions. This transparency can prevent misunderstandings and liability issues down the road.

4. Training & Education 📚

Ongoing education of the team on best practices for substrate preparation and the risks associated with inadequate preparations is crucial.

Continuous Learning: Establishing continuous learning programs that focus on the latest techniques and standards in substrate preparation ensures that the team is equipped with the necessary knowledge.

Risk Awareness: Instilling a culture of risk awareness can lead to better decision-making at all levels. This awareness can help the team understand the stakes involved and the importance of meticulous substrate preparation.

5. Independent Third-Party Inspection 🔍

Engaging a competent waterproofing quality technician from outside your organization to conduct an independent review can provide an objective assessment of the substrate’s condition.

Objective Assessment: An independent third-party inspection offers an unbiased evaluation of the substrate, ensuring that any issues are identified without internal pressures or conflicts of interest. This objective perspective can be invaluable in confirming that the substrate meets the required standards.

Expert Recommendations: These inspectors can provide expert recommendations for rectification if any issues are found, ensuring the best possible outcome for the waterproofing application. This expert advice can lead to better decision-making and adherence to best practices.

Reduced Liability: Having an independent third-party inspection documented can further protect against liability, as it demonstrates a commitment to quality and due diligence. This additional layer of scrutiny reinforces the thoroughness of your approach, minimizing potential risks and enhancing the project’s success and your credibility.

Conclusion

By taking proactive steps such as thorough inspections, detailed documentation, clear communication, ongoing education, and independent third-party inspections, waterproofing contractors can safeguard not just the integrity of their projects but also their professional reputation. Substrate acceptance clauses, while often seen as minor details, carry significant weight in determining liability and ensuring the success and durability of waterproofing systems.

One of the typical areas of concern that I come across regularly on site is, without a doubt, membrane application in conjunction with sealants. To explain the applications, this is regarding Class III bond breaker/fillet joints at:

• Floor-to-wall or wall-to-wall junctions
• Expansion joint details
• Window threshold membranes requiring a joint sealant from the window to the membrane; and
• Membrane termination details; just to provide examples.

People regularly say, ‘just put some Sikaflex in it’ or ‘throw some PU in there’ and think that this is perfectly fine and compliant. As a supplier, I can state that we sell multiple types of PU sealants (and membranes) and that if we could have only one type of sealant to do all applications don’t you think we would simplify what we offer to the market? Not all sealants are the same! Whether it’s chemical composition, or the physical properties of the product, they all react and perform differently, and you should consult your local manufacturer on what is the most suitable product for the application you are undertaking.

Curing – This would have to be the most common defect that is seen throughout the market. Typically, a PU sealant will ‘tack off’ within a couple of hours but only 1-2mm will cure on the first day. Generally, a fast cure PU sealant will take a couple of days to reach full cure. This is completely dependent on the thickness of the application so expect to allow more time if you’re filling larger gaps with the product. Now how many job sites do you really see the sealant left for multiple days before membrane application? It’s a scary thought.

There are plenty of ‘MS polymer’ or ‘solvent free’ PU sealants on the market these days; regardless of the technology they all generally release some form of biproduct during the curing process and most importantly must be left to fully cure. Regularly, I hear from contractors that using a solvent free sealant means they can install the membrane quicker; this is not the case, it may not gas and cause bubbling of the membrane, but you still must allow for full cure of the sealant before membrane application, no exceptions. Therefore, if you are waiting for full cure of the sealant, does the technology of what is being installed really matter? Food for thought.

Applying a membrane over a sealant before it’s fully cured typically can cause two main issues:

1. The sealant is still gassing and will retard the membrane from curing; this causes bubbles/blisters in the membrane and even if it eventually cures and membrane is now defective.
2. If the membrane is applied over the sealant too quickly, the sealant may run the risk of not curing completely. Most sealants are moisture curing, so with no access to moisture/atmosphere, as it’s sealed from a membrane, the curing reaction will slow down and eventually stop. I’ve been on various sites where sealant details/joints have been cut out 6 months after installation and the sealant is still uncured once you cut into the surface.

Window Thresholds – This is an area of concern that needs to be addressed nationally. Most contractors think that a water-based membrane and a PU/MS sealant is all that’s required. Sometimes this is the case, but contractors/builders need to realise that not all water-based membranes are the same. SBR/Latex membranes really don’t like PU sealants and typically require primers for adhesion, water-based PU acrylic membranes typically adhere well but UV stable versions of these membranes with titanium dioxide and certain pigments can perform very differently and require primers for adhesion in some instances. In summary, the only membrane and sealant that should be used on a window threshold is the one where a supplier can provide an ‘adhesion test report’ showing adhesion and compatibility testing between the two materials otherwise you are taking the ownership on and this can end up being a costly exercise.

Key Message – Compatibility Is King!

Contractors are not chemists and aren’t expected to know all the answers; utilise your product supplier’s knowledge and only use tested systems to mitigate liability.

Contributed by Kieran Biber – Consultant – Brisbane

This article originally appeared in the Australian Institute of Waterproofing Newsletter, Issue 18, November 2021

At this point in time, it is relatively common knowledge in our construction industry that a waterproofing system should be applied to a substrate with falls to drains in order to achieve suitable performance and lifespan of the system. This close connection between waterproofing, water-shedding and performance outcomes is appropriately explained in the TAFE NSW online course ‘Waterproofing Design Principles’ released this year. However, the question “but what is the minimum we can do and still achieve compliance with the NCC” is still voiced daily on construction sites when structural falls are identified to be insufficient.

This review is intended to address that question directly and in order to do so we have to start at the top of the NCC compliance hierarchy with ‘performance requirements’. Performance requirements typically define an outcome such as ‘water shall not enter the building’ and there are effectively two pathways for demonstrating that a design and/or construction has satisfied this requirement. The first being the use of a deemed-to-satisfy (DTS) solution and the second being the development of a performance solution. It is critical to note that where a design does not comply with DTS provisions adopted by the NCC, it will be considered a performance solution by default. This will be discussed further in the context of waterproofing external areas of a Class 2 residential project.

Typically considered the simplest option is a solution following DTS provisions, in this case that is AS4654.2:2012 is a standard provided by Standards Australia that has been adopted into the NCC. The provision for falls is covered with Part 2.5.2. Falls, that states a fall must exist to ensure water drains to the drainage outlet and the fall gradient should be 1:100. This wording of this provision is not overly detailed on the fall being located at the waterproofing level or the floor finish level and often leads to contention.

This wording of this provision is not overly detailed on the fall being located at the waterproofing level or the floor finish level and often leads to contention. Statements such “the standard does not say falls are needed at the waterproofing level so we will just put a fall in the floor finish screed” are often made to justify unsuitable construction works.

This reasoning is a fallacy that does not align with the NCC functional structure we established earlier and will result in non-compliant design/ construction.

This is due to the standards referenced by the NCC being deemed-to-satisfy provisions, meaning that if something is shown/stated in the standard it can be done and will be compliant. However if something is not clearly shown/stated then we must effectively fall back to consideration of performance and fit for purpose. So the next question is, is it possible to verify that a design without 1:100 falls at the membrane level provides sufficient performance to be considered a Performance Solution and compliant with the relevant NCC performance requirements? There are a few things to consider here.

The NCC provides the following requirement for performance solutions to be successful ‘the solution is at least equivalent to the Deemed-to-Satisfy Provisions’. Since AS4654.2:2012 states that there must be a fall in the substrate we can say that any performance solution must also include a fall to be considered suitable.

Many waterproofing materials currently available in the marketplace are not suitable for scenarios without falls that would result in ponded water. This is often clearly stated in the product data sheet to ensure the intended performance is achieved and where this is ignored will result in a voided product warranty and accelerated deterioration of the waterproofing system. A product that does not provide a warranty period for a specific scenario is typically not considered fit for purpose and would not be a valid performance solution.

Where fall does not exist to shed water to drains at the waterproofing level ponding will occur, often resulting in accelerated or other unwanted consequences such as efflorescence and debonding of finishes build-up.

In summary, where the need for fall at the membrane level is not clearly defined in the DTS provisions we must instead consider the design on a performance basis.

As there are numerous issues with a design that does not include water shedding it would often be difficult to justify that the design provides performance suitable to be considered a performance solution. Because of this we would say that most often a design without suitable falls at the membrane level is noncompliant with NCC performance requirements.

Any optimistic interpretation of requirements and provisions contrary to this is easily refuted will carry significant risk to the designer and builder.

David Previte – Managing Director

This article was originally published in the Australian Institute of Waterproofing Newsletter, Issue 21, January 2023

To discuss with our team, please complete the form below.

The construction sector is provided an array of waterproofing systems for designers and/or installers to choose from in order to achieve project requirements. However, the choice can be limited if an individual lacks the pre-requisite knowledge on their strengths and limitations. Proper design and inspection of the waterproofing systems are therefore vital to ensure waterproofing quality, and it dictates the ultimate quality of waterproofing services. The quality of the services, therefore, depends on proper design criteria and artistry activities adhering to the standard guidelines. Under performing waterproofing is often costly for an asset owner; therefore, construction stakeholders must have should endeavour to implement quality improvement techniques to offset such a situation in the future. Methods for improving the quality of waterproofing vary depending on the stage of installation and the materials available to achieve the service. Here are 5 effective ways of improving waterproofing quality.

1. Design Documentation

These documents should be developed by professional with an in-depth knowledge of waterproofing products inherent strengths and limitations. The materials selection process should ensure that the best quality products are available with awareness on all environmental conditions known to the experts. Conformity to applicable standards is a requirement to quality since the design process is always aware of the diverse parameters. The documentation would also require a quality control regime to with the intention of ensuring conformity to the design. The documentation will incorporate inspection protocols that will ensure that the objectives stipulated in the document are met.

2. Installation

Installation works should be performed by licensed professional suitably trained with the specific materials stipulated in the design documentation. Field verification of the design is fundamental to confirm that the workmanship conforms to the initial design criterion. As a developer, you should ensure that part-time or approximate percentage inspection is adhered to for systematic monitoring of the ongoing works. The timing of the inspection should be such that it is before installation of topping, over burden, backfill or concrete pour as this will allow repair, replacement, or correction of components that are non-conforming or damaged. The firm in charge of quality control inspection should be reputable with significant knowledge in the field to ensure quality control inspections are undertaken effectively.

3. Warranty

Warranty is a guarantee that there will be a repair to the defective system once it becomes defective within a specified time. Waterproofing materials with warranty are most likely to conform to quality, as the manufacturer would not want to incur the extra costs related to maintenance. However, it is important to acknowledge that incorrect installation of a product will likely void the warranty being offered. A proactive waterproofing quality control program should focus on the common installation issues that lead to unwarranted waterproofing installations.

4. Pre-Construction Meeting

This meeting prior to waterproofing would focus on sequencing, techniques of construction, materials for waterproofing, and design criterion. It also assures warranty eligibility for the project as it entails the quality assurance plans. In the meeting, the representatives from the manufacturing firm focus on the guidelines for installation, criteria for reporting, relevant corrective actions for non-conformance, and the conditions acceptable for the substrate. In the same regard, there will be an opportunity for assessment and review of the sequencing and interface between trades, which improves clarity and increases the ultimate success of construction.

5. Reporting

The should contain information on all the aspects related to the activities, including all the deficiencies, which, according to the inspector, could potentially compromise the integrity of the waterproofing system. The report includes photos of the installation, inspection date and time, weather conditions, name of the inspector, and non-conformity actions. Action may include rework or repair so that the non-conforming section finds a lasting solution. The report illustrates the shortcomings and achievements of the installation process, which one can employ to inform future works or the best systems for waterproofing.

These techniques can work to improve the quality but are limited to the knowledge that one has in informing his or her choices. Choosing the best materials or inspection firm may be difficult if you do not have sufficient information on the market and trends that inform current materials. At Waterproofing Integrity, we recognise that every project is unique and we work together with our clients to develop a quality control regime targeting their specific needs.

Do you want to implement a waterproofing quality control regime? Call 1300 025 944 or complete our Contact Form to find out how today.