Rain-Proof House Design for Sylhet's Climate

If you design for Sylhet, you design for water. The city sits between the Khasi and Jaintia hills in India and the low land of the Surma and Kushiyara rivers. Annual rainfall is commonly quoted at around 4,000 mm, the highest in Bangladesh. Reports in recent years have described storms dropping well over 150 mm in a few hours on parts of the city, enough to cause waterlogging.

A house that ignores this suffers damp walls, leaking roofs, peeling paint and mould. A house that plans for it stays dry and comfortable for decades.

A steel roof frame going up above a brick lattice (jali) wall. Wide overhangs and open lattice work shade walls and let air through, both useful in a wet climate.

1. Make the roof shed water

Roofs fail at details, not in the middle. Pay attention to:

• Slope. Flat slabs still need a fall towards outlets, so water does not pond
• Waterproofing layer. Continuous, with upturns at parapets
• Joints and penetrations. Pipes, vents and expansion joints sealed with care
• Outlets. Enough of them, sized for heavy rain, with leaf guards
• Overhangs. They protect walls and windows from driving rain and summer sun

If you use a sloped roof in steel or timber, check that the connections and fixings are corrosion-resistant. Humid air attacks bare steel quickly.

2. Raise the plinth and plan the drainage

In low-lying areas, set the ground floor level above the highest known flood mark. Use local knowledge: ask neighbours how high the water came. Then plan how water leaves the site:

• Fall away from the building on all sides
• Drains sized for heavy rain, kept clear of silt and leaves
• Connections to the public drain where one exists
• Soak pits or permeable surfaces where space allows

On hill sites, surface runoff can erode soil around the foundation. See foundation and soil testing for Sylhet sites for how we handle slopes and retaining walls.

3. Waterproof below the ground and in wet rooms

Basements, retaining walls, water tanks and bathrooms all need proper waterproofing, applied by a trained crew and tested before finishes cover it. A leak in a hidden place is expensive to fix. Testing a bathroom floor with a few days of ponded water before tiling is a cheap way to find problems early.

4. Design walls that can breathe

Humidity in Sylhet stays high for much of the year. Walls that trap moisture grow mould. Good practice:

• A damp-proof course at the base of masonry walls
• Quality external paint systems suited to humid, wet climates
• Overhangs and sunshades so walls dry between storms
• Avoiding finishes that seal in moisture, especially in older buildings

5. Let air move

Cross-ventilation cools the house and dries the air. Openings on opposite sides of a room, high-level vents and screens such as brick or concrete lattice allow air through while keeping rain and sun out. Our article on on building for thermal comfort in Bangladesh goes deeper into orientation and shading.

6. Choose materials that tolerate damp

• Bricks and well-cured concrete handle moisture well
• Treated timber and marine-grade or water-resistant boards for joinery
• Stainless or galvanised fixings
• Aluminium or uPVC window frames in exposed positions

We look at material choices for the inside of the home in interior design in Sylhet.

7. Time construction around the monsoon

Plan excavation, concrete and roof work for drier months where possible. Protect open reinforcement and fresh concrete from rain. Check that plastering and painting are done on dry surfaces. Cost and scheduling go hand in hand: weather delays raise the price.

Planning a home that stays dry?

We design homes for Sylhet’s rain, heat and humidity. See our projects or contact the studio to talk about your plot.