How to Waterproof your Terrace Garden

A terrace garden can be a refreshing getaway in a busy urban life. Waterproofing a terrace garden keeps away leaks and stops roots from growing into the roof slab, so that you enjoy years of beautiful blooms.

In order to do so we need a coating that
1. forms a waterproof barrier
2. Is flexible so as to accomodate movements in the roof slab and construction joints.
3. Forms a physical barrier to roots of plants.
4. Should be UV resistant as the terrace will be exposed to sunlight.

Sika's anti-root waterproof system for terrace gardens.

In the system shown in the above diagram, a PU based waterproof coating has been used which is overlayed with a water reduced cement concrete screed, protected by a UV resistant acrylic polymer modified cementitious(APMC) coating.

1. The PU coating provides a flexible waterproof coating.
2. The concrete screed does not allow roots to penetrate the roof slab.
3. The APMC Coating provides UV stability and also keeps the concrete screed waterproof.

Let us see the application procedure.

Application 

. The terrace slab is prepared so that there are no loose debris, cracks, potholes or fungal/algal formation on the slab. Methods such as wire brushing can be used to remove any organic growth on the slab. Slab repairs can be taken up using a polymer modified cement mortar.
. Once a sound surface is obtained, brush apply a coat of specified primer.
. Brush apply 2 coats of the PU based waterproof coating on the slab and upto the full height of the parapet walls with sufficient time between coats to allow for curing.
. Create a bond coat slurry by mixing sbr latex, water and cement in the proportion of 1:4:8 by volume.
. Apply the bond coat onto the cured PU waterproof coating. Once the coat is tacky, in about 30 to 45 mins, the screed concrete can be layed on top.
. For the screed concrete, a dry mix of cement, sand and aggregate is first prepared in the proportion of 1:2:3 by volume.
. A maximum of 23ltr of water should be added per 50Kg bag of cement. A water-reducing admixture in the proportion of 100ml-200ml (depending on the product used) per 50kg bag of cement should be added to the water.
. Add the water to the concrete mix and prepare the screed concrete.
. The screed concrete is spread onto the still tacky bond slurry making sure to provide slopes towards the water outlets.
. The screed is water cured for 2-3 days.
. Once cured, a acrylic polymer modified cementitious coating that is UV resistant is applied on top of the screed upto the level of soil contact with the slab and parapet walls.
. Cure the coating with water for 2-3 days.
. Over the coating, it is recommended to lay a geotextile fabric and spread loose gravel and silica sand on top of it. A uniform grill which will hold the soil and allow water to drain away should be laid on top of the gravel.

The soil can now be laid for that flower bed.

Products 

Products available for the above system at our store 

Shree Venkateshwara Traders, Modi Hospital Road, Bangalore are :

PU Coating

.Sikalastic 450I

Primer

. Sikalastic 450I Primer

Water Reducing Admixture

. Sikacim

. Dr. Fixit Pidiproof LW+

. Roff Hyproof

SBR Latex

. Sika Latex Power

. Pidicrete URP

Acrylic polymer modified cementitious coating

. Sika Topseal 109hi

. Dr. Fixit Fastflex

Above products Available in store now, at

Shree Venkateshwara Traders
712, Modi Hospital Road,
West of Chord Road, Mahalaxmipuram
Bangalore 560086

9036092531 - Namit Bhulani
080 - 23592523 - Landline

venkateshwara.traders@gmail.com