In a recent site visit, I observed an interesting but unfortunate scenario—a client had set up a beautiful terrace garden with real grass and plants, only to have it removed due to severe seepage issues. Despite multiple waterproofing attempts, they continued facing moisture problems, which eventually led them to dismantle the entire setup. This incident highlighted a common challenge: very few people know the correct method to build a waterproof terrace garden on their roof.
In this blog, I’ll walk you through a reliable step-by-step process to create a terrace garden that not only looks beautiful but also stands the test of time without causing seepage issues. With these methods, you can execute your terrace garden plan cost-effectively without hiring expensive services.
1. Preparing the Base Structure
- Identify the Area: First, decide the area where you want to set up your terrace garden. If you plan to have plants directly on the terrace without pots, create a defined brick boundary to contain the soil.
- Brick Work: Build a brick boundary as per your garden layout, with a slope to direct water towards drainage points. If the terrace already has tiles, have them chipped off within the planned garden area to expose the concrete or masonry layer underneath.
2. Apply a Layer of Waterproof Plaster
- Apply a waterproof plaster layer over the brickwork and terrace floor. This creates a base that helps protect against moisture build-up, especially if your terrace will have real grass or water elements.
3. Waterproofing with Dr. Fixit URP 301
- Waterproofing Process: Use Dr. Fixit URP 301 mixed with cement in the recommended ratio. Apply the first coat with a brush over the plastered base.
- Fiber Net Application: Once the first coat is dry, apply a fiber net over it to reinforce the waterproof layer. Then, apply a second coat of the waterproofing mixture over the fiber net. Allow this layer to dry before moving on.
4. Lay a Thick Plastic Sheet
- Use a durable plastic sheet (at least 800 microns thick) to cover the waterproofed base, including the walls and floor inside the brick boundary. This plastic sheet will act as a secondary barrier, ensuring that water does not penetrate further down to the terrace base.
5. Drainage Points for Water Exit
- Set up multiple drainage points across the garden area in a grid pattern. For example, if your garden area is about 10 feet by 2 feet, install at least three to four drainage points along the length.
- Ensure the slope directs water towards these drainage outlets to prevent water accumulation.
6. Install Drainage Cells and Geo-Textile Fabric
- Drainage Cells: These cells allow water to pass through them while preventing soil from clogging the drainage outlets. Install drainage cells on the base layer to ensure effective water movement.
- Geo-Textile Fabric: Place a layer of geo-textile fabric over the drainage cells. This fabric lets water flow through but prevents soil from seeping into the drainage layer.
7. Adding Soil and Finishing Touches
- Add Soil: Now you can add soil for your plants. You may consider using coconut coir for better plant growth as it retains moisture well.
- Tile or Stone Finishing: To make the garden look visually appealing, cover the exterior of the brick boundary with tiles or paint. On top of the brick boundary, install stone or a similar material for a polished look. Ensure the soil level is about 4-5 inches below the boundary top to prevent soil washout.
Maintenance Tips
Regularly check drainage points to prevent clogging, especially during the rainy season. With this setup, rainwater or excess watering will flow seamlessly through the drainage cells, geo-textile fabric, and out through the drainage outlets.
