Brickbat Coba Waterproofing for Flat RCC Roofs

In the realm of construction, finding effective methods for waterproofing and ensuring thermal insulation for flat RCC roofs is of paramount importance. One such age-old technique is Brickbat Coba waterproofing. In this article, we will delve into the procedure of Brickbat Coba waterproofing, its advantages, and the significant disadvantages that have rendered it somewhat obsolete in the modern construction industry.

Procedure of Brickbat Coba Waterproofing

1. Surface Preparation

Before embarking on the Brickbat Coba waterproofing journey, the surface preparation is crucial. For existing surfaces, any existing coating on the slab must be removed, and the surface thoroughly cleaned to eliminate any oil, grease, dust, or other contaminants. In the case of a new slab, the concrete surface must be roughened. Ensuring structural cracks are addressed as per standard practice is also essential.

2. Application of Slurry and Base Coat

The next step involves the application of a slurry made from cement and water to achieve the desired consistency. This slurry is carefully applied over the dampened surface, including joints, holes, and pipes in masonry or concrete. The prescribed quantity for slurry application is 2.75 Kg of cement per square meter.

Following the slurry application, a 25mm thick base coat is laid out while the slurry is still fresh. This cement plaster, with a mix ratio of 1:4, is evenly applied over the concrete surface.

3. Placing of BrickBat

While the base coat is still fresh, brickbats ranging from 65mm to 120mm in size are placed with gaps of 15 to 20mm between them. These brickbats should be thoroughly burnt and soaked overnight before laying. After brickbat placement, curing is carried out for a minimum of 24 hours, after which the gaps between the brickbats are filled with the same mortar mix used for the base coat.

4. Laying of Protective Coat

To enhance waterproofing, a waterproofing compound, in compliance with IS 2645, is mixed with cement and water following the manufacturer’s specifications. However, the usage should not exceed 3% of the waterproofing compound per 50 Kg of grey cement. A cement mortar of 1:4 ratio, prepared with the waterproofing compound, is then applied over the surface, including the haunches/gola and 300mm on the parapet wall.

5. Curing

The treated surface is flooded with water, creating bunds with low cement mortar. Curing is carried out for a minimum of 2 weeks to ensure the effectiveness of the waterproofing.

Disadvantages of Brickbat Waterproofing

While Brickbat Coba waterproofing has served its purpose over the years, it does come with some significant drawbacks that have led to its diminishing popularity in the construction industry.

1. Unnecessary Dead Load

One of the primary disadvantages is the substantial thickness of brickbats, ranging from 125mm to 150mm. This added thickness contributes to the dead load of the building, making it economically unfavorable, especially when compared to modern waterproofing methods.

2. Maintenance Challenges

Maintaining Brickbat Coba waterproofing can be a cumbersome task. The likelihood of water seepage over time can lead to persistent issues. Once water infiltrates the waterproofing, repairs or patchwork often offer temporary solutions at best.

3. Vulnerability to Cracks

The rigid nature of Brickbat waterproofing makes it susceptible to cracking due to climatic variations. Once cracks form, neither patchwork nor grouting can effectively prevent water from seeping in over an extended period.

4. Skilled Workmanship Requirement

The effectiveness of Brickbat waterproofing is highly dependent on external factors such as climate variations and heavy rainfall. To ensure its proper application, skilled manpower with prior experience in Brickbat waterproofing is essential. This includes expertise in tasks like leveling and grouting.

In conclusion, while Brickbat Coba waterproofing has been a trusted method in the past, it now faces competition from more modern waterproofing solutions. Understanding its procedure and drawbacks is essential for those in the construction industry seeking the most effective and economical waterproofing options for flat RCC roofs.

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