Summary of application
NOTE: Do flood Test after Step 4.
When it comes to the waterproofing of overhead tanks in private residential projects, we believe in having a system of waterproofing which is maintenance free and should stand the test of time. It is essential that the concrete pouring of the overhead tank should be planned accordingly so that there is not much work to be done to the tank once it is in use. It is also essential to use potable water friendly materials in the waterproofing of the tank so that there are no adverse chemical effects, and the stored water remains fit for human use.
When planning for the overhead tank, it is important tom take sure that the water pipe sleeves are carefully planned within the formwork to have proper water inlet and outlet points. If there is breaking or hacking of the concrete after the overhead tank has been casted, it becomes difficult to stop the water leakage from pipe inlets and outlets.
Step 1: Pouring of the concrete and form work.
Good quality formwork should always be used when pouring an area as sensitive & essential as the overhead tank. It is essential to make note and plan all the pipe inlets and outlets within the form work to avoid leakage problems from these points when the overhead tank is in use. The concrete to be poured should be of exceptional quality. The addition of a good integral waterproofing admixture is essential to make concrete as water resistant as possible. Max Flo integra 3 (Powder) is recommended as an admixture for the pouring of overhead tank concrete. 1 KG of Max Flo integra 3 (Powder)) per 50 KG bag of cement is the recommended dosage for the pouring of concrete. It is also essential that all the concrete should be poured in one go to avoid the formation of any joints between the base & the walls of the overhead tank.
Step 2: Filling & repairing of the concrete voids.
Once the formwork has been removed. It is essential to repair all the defects of the concrete with a suitable repairing material. Patch 365 Plus is a suitable repairing material for the minor concrete defects and the voids created by the metal strips (Incase wooden formwork has been used). Once the concrete is repaired & of a sound nature subsequent treatment of various waterproofing materials can be done over the concrete surface of the overhead tank.
Step 3: Application of Water Guard Crysta Coat 101 over the prepared concrete surfaces.
Water Guard Crysta Coat 101 is a high end crystalline waterproofing slurry coat which is to be coated over the prepared concrete surface on all the exterior & interior surfaces of the overhead tank. At least two coats of Water Guard Crysta Coat 101 are recommended in right angled patterns. If the first coat is applied in top to bottom pattern the second coat should be applied in left to right patterns. It is recommended to make sure that all the concrete that has been casted internally & externally is coated properly with Water Guard Crysta Coat 101 (For further application guidance, please refer to the product datasheet).
Step 4: Making of internal chamfers.
It is recommended to make internal chamfers at the base and on all the walls of the overhead tank. All angles of 90° in the base and the walls of the tank should be neutralized. The chamfer should be at least 6 inches tall and wide throughout the all the corners of the overhead tank. (Please see the illustration for better understanding). The ideal material for the making of chamfer for the overhead tank is Patch 365 Plus (Please refer to the technical datasheet of the product for mixing & application guidelines). Once the making of the chamfers have been completed, they too should be coated with crystalline coating of Water Guard Crysta Coat 101.
Note: Once the chamfers work has been completed and coating of Water Guard Crysta Coat 101 has been done both internally and externally over all the concrete surfaces, it is recommended to have a flood test for 72 hours of the overhead tank (Filling up the tank with water) to check if there are any leakages in the tank, the points with leakage should be rectified prior to plastering. It is essential that all pipe inlets and outlets should be checked thoroughly for any water leakage at this time.
Step 5: Internal & External Plastering
Once all the chamfer work has been properly executed and the flood test has been successfully executed, the inner and outer surface of the overhead tank should be ready to plaster.
It is recommended to add 1 Liter of Silmix along with 1 Ltr of Ressi SBR 5850 with every bag of cement used for the plastering of internal and external areas of the overhead tank. It is to be ensured that the internal plaster of the overhead tank should be finished slightly rough, exposing some grains using a foam (Foam finish plaster). This will provide a good key for the subsequent coating of Waterproofing Membrane.
Step 6: Internal coating
of Waterproofing Membrane
Once all the internal and external plastering works have been completed, it is recommended to apply at least 2 coats of Waterproofing Membrane in all the internal areas of the overhead tank. It is recommended that both the coats are applied in opposite right-angled directions. If the first coat is applied with vertical brush strokes, the second coat is to be applied with horizontal brush strokes. (For further application and mixing guidelines of Waterproofing Membrane, please refer to the technical datasheet of the product).
What is a Chamfer?
Is a transitional edge between two faces of an object. Sometimes defined as a form of bevel, it is often created at a 45° angle between two adjoining right-angled faces. ( Wikipedia). In waterproofing systems, making a chamfer is of great significance. Water normally gets stuck in areas which have sharp corners of 90° & on several occasions the leakage of water occurs from this the sharp angle of the water retaining bodies or areas where significant waterproofing is required. To minimize the effect of this, a chamfer is usually created to make sure that there are no sharp angles in the structure to minimize the effect of water coming in & out of the structure.