15-21 Onslow Square

Solving a long term water ingress issue to cantilevered balconies
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The seven cantilevered balconies from 15 - 21 Onslow Square in South Kensington, had been subjected to years of water ingress. After several repairs attempts, no solution was found. Until now...
South Kensington, London
Authorised Contractor
Carringtons Building & Civil Engineering Ltd

The challenge

Onslow Square before

Onslow Square is a prestigious garden square estate located in South Kensington, London. The properties are 3 storeys high and feature cantilevered balconies with steel handrail stanchion penetrations. The balconies had been allowing water to ingress for several years, which had caused areas of damp within the properties below.

The client had tried several unsuccessful repair attempts including completely overlaying the existing asphalt with new asphalt. Over time, this too had failed and had left the client looking for alternative solutions.

Following a thorough site investigation by the Triflex Business Development Manager, it was established that the water ingress was not caused by a failure within the main area waterproofing, but in fact the detailed handrail penetration to the asphalt substrate.

The solution required particular consideration to the large amount of detail waterproofing. If these detailed areas continued to be insufficiently waterproofed, not only would any future system fail, but it may cause structural damage to the balcony deck.

The solution

After Onslow Square

Triflex Authorised Contracting Partners, Carringtons Building & Civil Engineering Ltd. were chosen to carry out the works to the 7 balconies. Prior to installation, the tiles which partially covered the balcony required removal. This ensured that there would be no underlying issues with the asphalt and achieved the best possible adhesion between the Triflex and the substrate.

Overbands were installed to movement joints and cracks using Triflex ProTerra, a fully reinforced system that provides maximum strength and dynamic crack bridging. Triflex ProFloor Quartz Design was installed as the main area waterproofing system, a partially reinforced system for use on cantilevered structures that’s highly durable, ultra-fast curing, cold liquid applied and flexible enough to accommodate movement within the structure. The small grain quartz in the finish provides enhanced anti-slip properties.

Triflex ProDetail was installed to all penetrations, handrails and vertical surfaces, where its factory-set thixotropic formula was perfectly suited to these difficult areas.

The fast curing properties of Triflex meant the project was completed quickly, without the use of hot works, and with minimal impact and disruption caused to the residents. Thanks to a close cooperation between the Triflex technical team and the skilled work from Carringtons Building & Civil Engineering Ltd. areas of concern were identified and issues were resolved. The client has been left with reliable waterproofing, overcoming years of issues.


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