Lime terracing is provided with how much slope to drain off rainwater from the roof to gutters?
đ§ Detailed Explanation: Lime Terracing on R.C.C. Roofs
R.C.C. (Reinforced Cement Concrete) flat roofs require a protective covering to shield them from weather elements like rain, snow, and heat. One traditional and effective method is "lime terracing."
This process involves adding a layer of lime concrete (typically 10 cm thick), often mixed with a waterproofing compound, over the structural R.C.C. slab. This layer serves two primary purposes:
- Waterproofing: The lime concrete, when properly compacted, creates a hard, impervious barrier that prevents water from seeping into the R.C.C. slab, thus making the roof leak-proof.
- Thermal Insulation: The thick layer also provides a degree of thermal insulation, helping to keep the building cooler.
The Importance of Slope
For the waterproofing to be effective, rainwater must be drained away quickly and efficiently. If water is allowed to pool on the surface (a phenomenon known as "ponding"), it increases the risk of leakage over time. To prevent this, a gentle slope is crucial.
The lime terracing is therefore laid with a specific gradient. The standard slope provided is usually between 1 in 60 and 1 in 100. This means that for every 60 to 100 units of horizontal distance, the roof level drops by 1 unit. This slope is subtle enough not to be noticeable but effective enough to ensure rapid and easy drainage of rainwater towards the gutters.
âšī¸ Additional Information on Flat Roof Construction
Besides R.C.C. with lime terracing, other methods of flat roof construction include:
- Mud Terrace Roof
- Brick-Concrete Terrace Roofs (including Madras Terrace Roof)
- Jack Arch Flat Roofs
- Reinforced Brick (R.B.) Slab Roofs
- Bengal Terrace Roofs