Sikalastic-560 waterproofing case study

The double-decked garage roof of House Apostle, in Llandudno, Western Cape, which is also used as a seating area, needed waterproofing maintenance due to water seeping through weak areas.

This is a common problem for homeowners, especially so when prior waterproofing systems are damaged, or failing with age. In this case, the old bitumen torch-on membrane was no longer watertight, so the owners were looking for new solutions to end their battles with leaks. To avoid having to remove the existing membrane, they sought a waterproofing product that could simply be applied over it. Sika were consulted for advice and concluded that the company’s premium liquid applied waterproofing system, Sikalastic®-560, was the appropriate solution.

Sikalastic®-560 is a one component, liquid applied roof waterproofing solution, based on Sika Co-Elastic Technology (CET). It is a cold-applied coating and is highly elastic and UV resistant. Popular with many homeowners for its seamless finish, it also facilitates easy application on the more complex detailing prevalent on many rooftops. Furthermore, its reflective coating contributes to a cost-effective reduction in cooling costs by enhancing energy efficiency in the house.

Application of Sikalastic®-560:

Surface preparation: A thorough cleaning process began with removing all the paving and sand, and was followed by pressure washing the more stubborn dirt. After surface preparation, and prior to application, Sikalastic®-560 was properly stirred for a minute, to achieve a homogenous mixture.

Roof waterproofing application:

1. Apply first coat of appr. 0.75 kg/m² (for non-absorbing substrates) – 1.00 kg/m² (for absorbing substrates) of Sikalastic®-560 on a length of approx. 1m.
2. Roll in the Sikalastic® Fleece-120 or Sika® Reemat Premium and ensure that there are no bubbles or creases. Overlapping of the fleece is minimum 5 cm.
3. Apply second coat of approx. 0.25 kg/m² – 0.5kg/m² coat right into the wet fleece to achieve the required film thickness. The entire application should occur while Sikalastic®-560 is still liquid, wet on wet.
4. Repeat steps 1–3 until the roof area is waterproofed.
5. After the two coats are dry, seal the roof area with one or more additional coats of Sikalastic®-560 (≥ 0.5 kg/m² per coat).
6. Please note: always waterproof the detailing prior to doing the horizontal surfaces. Refer to the datasheet for correct waiting times for drying of coats.

Once the waterproofing coatings had dried and cured, the final paving was returned to place so that the roof could resume its dual role as a seating area. Not many challenges were encountered, but one of them was the sealing of the outlet pipes, given their complex geometry. However, since Sikalastic®-560 was designed for roofs with many details, and can be used even when accessibility is limited, the outlet pipes were sealed without any major hassle.

The contractor, Claude Darries, was more than impressed with the one component and cold application properties of the product. He added that it was not only easy to use, but also had a seamless and flexible finish. “A contractors’ dream.”

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