4-component waterproofing for rooftop garden

by Darren
4 component waterproofing for rooftop garden KAYTECH

Kaytech supplied a four-layered waterproofing system for the creation of a rooftop garden in the Waterfall Equestrian Estate.

The Waterfall Equestrian Estate, situated on a hilltop in Midrand, is home to some of Johannesburg’s most luxurious houses. For the creation of a rooftop garden on one of the homes, Kaytech supplied an innovative drainage system that would effectively maintain the integrity of this special feature.

Also nestled in the beautifully landscaped grounds are stables, paddocks and an equestrian arena that add to its sustainable and integrated ecology. This environment provided the ideal backdrop for the rooftop garden designed by Rekopane Landscapers.

When approached by the landscapers for assistance in the vitally important drainage of the rooftop garden, Kaytech’s Winnie van der Merwe suggested a four-component system consisting of a layer of bidim A4, then a layer of Flownet DN3, a third layer of Kaytape S270 and finally a layer of bidim A2.

1.    Bidim A4 layer
After installing waterproofing directly onto the roof, Rekopane Landscapers used bidim A4 as the first layer of protection.

Bidim is Kaytech’s multi-graded continuous filament, nonwoven, needle-punched geotextile manufactured from 100% recycled polyester. The needle-punching process affords several advantages including an appreciable thickness, high porosity and a high drainage capacity. When incorporated in a subsoil drain, bidim allows the highest possible through-flow rate while still providing excellent filtration characteristics.

2.    Flownet DN3 layer
To control the flowpath of water, Flownet DN3, a heavy-duty, extruded, HDPE drainage net with directional flow, was installed over the bidim A4. Used as a drainage core, Flownet replaces the need for stone aggregate in subsoil and structural drains.

3.    Kaytape S270 layer
The third component, a layer of Kaytape S270, was subsequently rolled out over the Flownet. This slit film, woven polypropylene tape geotextile acts as a high modulus separator that, in this application, would keep open the flow paths and prevent the low modulus bidim intruding into the Flownet openings.

4.    Bidim A2 layer
The composite drain was completed with the installation of a top filter layer of bidim A2.

In total, 100m2 of each product was used for the drainage of the roof garden. To add filtration diameter to the drainage system and help prevent clogging of the bidim, a layer of a minimum of 50mm thick, high-quality, clean river sand was placed over the drainage system and covered with a final layer of topsoil.

Rekopane Landscapers was highly impressed with the ease and speed of installation of these high-quality Kaytech products that enabled them to complete the entire project within one day.

Kaytech Engineered Fabrics
Tel: 031 717 2300
Website: www.kaytech.co.za

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