Substrate preparation is paramount to the success of any waterproofing project and with a large percentage of all building defects associated with waterproofing, it pays to get the preparation right.  Waterproofing is only as strong as the weakest point of the substrate and that is why it’s so crucial during the preparation process to identify those weak links and avoid membrane failure.

The five Ps; proper preparation prevents poor performance – is a simple yet effective formula, but not all practitioners take the time to get the preparation done right.  Following are some of the key areas that need careful attention on every waterproofing job.  Do it right, do it once!

Laitance

Laitance is a powdery layer often seen in concrete substrates that have been over watered, over vibrated, over worked or rain effected.   Laitance should be removed by mechanical means such as grinding or shot blasting.  It is essential to remove laitance because waterproofing requires a stable uniform concrete finish to accept coatings.  Check for laitance by scraping the surface with a sharp object.  Image 1 below shows laitance on concrete & image 2 below shows laitance removed.

Curing compounds

Curing compounds are sometimes used to slow down the evaporation process in fresh concrete however, can become the catalyst for coating failure if not removed.  Waterproofing over curing compounds will lead to adhesion failure, due to not forming a solid bond between the concrete and the waterproofing coating.  Check for curing compounds by performing the water-bead test.  The below image shows curing compound on concrete.

Cracks 

Shrinkage during the concrete drying process can cause cracks that can remain active with the changing seasons.  Cracks should always be treated with a low viscosity injection compound or with bond breakers such as tape or silicone.  It’s good practice to reinforce the membrane with fabric over any cracks.  Failure to treat the crack can result in the membrane fracturing over the crack and then water can breach the membrane.  The best way to expose cracks is to vacuum not sweep the concrete substrate.

Moisture

Before commencing any waterproofing project, a moisture reading must be taken to determine what level of moisture is present.  High levels of moisture require proper treatment such as applying a moisture vapour barrier to prevent blistering of the coatings.  Two-part water-based epoxies can be used and are excellent in preventing water vapour issues.

Priming

The definition of priming in Australian Standards is good practice, yet is overlooked by most people.  Priming promotes adhesion of membrane coatings, suppresses the dust particles and consolidates the substrate, and helps for better and uniform curing of the membrane.

Wet-seal Franchisees are experts in addressing the preparation that is essential to successful waterproofing and are available to assist you to get the job done right the first time!  For any other advice of a technical nature, including system specifications, Wet-seal’s highly experienced technical team will be happy to take your call.  Wet-seal’s Technical Team can be contacted on 0800 436 000 or via email at technical@wet-seal.co.nz

Alternatively, please speak with your local Franchisee directly.  Details of how to contact your local Franchisee can be found at Find A Franchisee

Current construction methods associated with wet areas with concrete and/or fibre-cement sheet flooring is generally consistent with the below.  Waterproofing, including Type 5 Perimeter Flashings, are installed after the below is completed (in addition to concealed and exposed services such as plumbing/electrical, etc):

• Walls frames are constructed with manufactured timber frames, freighted to the building site, erected and securely fastened into position.  Alternatively, pressed galvanised or pre-coated steel framing is used in a similar manner but in much lower volumes in residential construction.  Commercial construction generally uses this method in much larger volumes.
• Walls within a shower area are sheeted with fibre-cement products OR wet area plasterboard products (providing the wet area plasterboard meets the requirements to comply with the NCC 2019).
• Bath faces, bath tops and adjacent wall areas are also sheeted in fibre-cement products or wet area plasterboard.
• Remaining wall linings are generally completed with the same products, as it is common place to continue the wall sheeting used within the shower rather than incorporate a different type of product with varying thicknesses.
• Walls outside of a shower area (and excluding the bath area) can technically be completed with regular Gypsum plasterboard sheeting.
• In accordance with AS/NZS2589-2017 – Gypsum linings – application and finishing, wall sheets must terminate a minimum of 6mm-10mm above the substrate floor level.
• In accordance with manufacturer specifications, wall linings not bound by the scope of AS/NZS2589 generally are to terminate 6mm above the substrate floor level.
• Stepped down recessed shower floors (recess within the concrete at the shower location only) or full room stepped down wet areas often will not have complying wall sheeting installations due to framing limitations and adequate fixing options of the wall sheet product edges.

For any other advice of a technical nature, including system specifications, Wet-seal’s highly experienced technical team will be happy to take your call.  Wet-seal’s Technical Team can be contacted on 1800 025 081 or via email at technical@wet-seal.com.au

Alternatively, please speak with your local Franchisee directly.  Details of how to contact your local Franchisee can be found at Find A Franchisee