Substrate Preparation Is Paramount!

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