Lifestyle & Design
Rooftop gardens in Dhaka: cooler homes, fresher food and what it takes
Engr. Sabbir Ahmed3 min read
A planted roof shades the top-floor flats, gives children somewhere green to play and can supply a surprising amount of vegetables. It also needs the right waterproofing, drainage and care. Here is what we have learned from the rooftops of our completed buildings.
Why bother?
A bare concrete roof in a Dhaka summer absorbs heat all day and releases it into the top-floor flats all night. Soil, plants and shade structures block much of that heat, and the flats below are noticeably cooler for it. A green roof also slows rainwater run-off during heavy showers, and a shared garden gives neighbours a reason to meet.
Dhaka's city corporations have at times offered holding-tax rebates for buildings with rooftop gardens, so check the current rules with yours.
Protect the slab first
Most rooftop garden problems are really roof problems. Before anything is planted:
- Waterproofing: the roof needs a proper membrane or coating, with a protective screed over it, before any soil or planter goes on top.
- Load: wet soil is heavy. Large planters and raised beds should sit over beams and columns, and any substantial installation should be checked by a structural engineer.
- Drainage: keep the roof outlets clear and use planters with drainage holes and a gravel layer, so water never ponds against the parapet.
- Water: a tap on the roof — ideally with a small rainwater tank — makes daily watering practical.
Plants that thrive up there
Roofs are hot, sunny and windy. Hardy choices include bougainvillea, hibiscus, jasmine and ixora for colour; lemon, guava, papaya and dwarf mango in large tubs; and chilli, tomato, aubergine, okra, bottle gourd and leafy greens in season. Herbs such as mint, basil and coriander do well in partial shade under a pergola.
Group pots so they shade each other's roots, mulch the soil to hold moisture, and water early in the morning or after sunset.
Sharing the work
A shared garden needs a plan everyone can follow. In our completed buildings, owners' associations set a small monthly budget for soil, seed and a gardener's time, keep a watering rota for residents who want to take part, and divide beds among families who want to grow their own vegetables.
At Asseto Blue Lotus, residents held a planting day soon after handover and now harvest greens and chillies through most of the year.
What we build in
Where a project includes a rooftop garden, Asseto designs the roof for it from the start: waterproofing with a protective screed, drainage sized for planters, a water point, lighting and a shaded seating area. Planting is completed before handover, so owners inherit a garden rather than a promise.
