The purpose of the application of waterproofing is to prevent the water to percolate or penetrate into any underground concrete members. When the water penetrates into the sub-grade concrete like foundation such as: mat foundation, footing, tie beam etc. the steel reinforcement that embedded in the concrete would corrode due to chemical reaction caused by water and the structure would eventually fail.
Application of water proofing especially for large structures would have to be strictly supervised by a quality engineer in order to prevent failure of application or nonconformity to the quality procedure.
In this method statement we’ll going to use the membrane type waterproofing, this type of water proofing is advisable for structures like high-rise building which has deeper foundation where water pressure is extremely high.
Here is the method statement for application of water proofing membrane.
Method Statement for Application of Waterproofing Membrane
2. Purpose and scope
The purpose of this method statement is to describe the measures and ways of proper application of waterproofing membrane in our project. Work shall be carried out as per the drawing and project specification.
3. Work procedure
- Work preparation and application of primer:
- Any undulations or protrusions on the surface would be removed in order to obtain smooth surface. The surface must be thoroughly cleaned and free from dust, dirt loose materials, oil or grease.
- 50x50mm1 size fillet made of cement-sand (1:3) mix would be placed along corners of walls or neck columns and any other junctions.
- For horizontal waterproofing membrane application. Two layer of 4mm thick modified bituminous membrane shall be laid fully torched on blinding concrete with minimum of 100m end laps and 150mm side laps.
- The blinding surface shall be primed with the primer recommended by the manufacturer of the membraneprior to placing the membrane. Prior to succeeding works the applied primer shall be inspected by the Engineer 24 hours after the placement.
- Waterproofing membrane installation shall be performed using cylinder fed propane gas torch, trowel to seal the seams of the membrane and knife for cutting.
- The membrane is then placed in the correct torching on position then re-rolled for about half of its length without changing its orientation.
- The membrane is then un-rolled again and torched on pressing the melted area against the substrate.
- All works shall comply with safety procedure or instruction as set out in project safety plan and municipality rules and regulation. All safety recommendations as advised by the approved sub-contractor.
- Basic PPE to be worn by all staff or laborers.
- Provide lighting when work at night.
4. Equipments and tools
- Bobcat or JCB
- Wheel borrow
- Metal tape
5. Materials and references
- Modified Bitumen Membrane
- Specification Section – Waterproofing