Basement Waterproofing Techniques | Procedure | Internal and External
Basement Waterproofing Techniques
Basement waterproofing and preventing ingress of water into basement is one the major challenging task in constructing basements. It is often considered considered as an expert procedure and is performed by skilled personals from the product suppliers for efficient waterproofing.
Originally, weeping tiles are installed at the bottom sides of the footing. Typically a damp-proof spray is applied at the walls, not a water-proof membrane. Excavated soil is then backfilled; however it is not as dense as the soil around it. When it rains, water will find the excavated angle and travel back to the bottom of the foundation.
This is why weeping tiles are installed. Once the weepers clog, the water will begin to build on the outside of the foundation causing hydrostatic pressure. Once the pressure builds, water will enter at the floor wall joint either from underneath or over the top of the footing.
External Waterproofing Procedure:
- The soil around the foundation is excavated
- The weeping tiles are removed and the foundation walls are cleaned
- Small holes are drilled into the bottom blocks to remove moisture in the wall
- The walls and footings are coated by hand with a high quality rubberized urethane
- Dimple board is installed with steel brackets and a finishing strip
- New weeping tile with geotextile filter cloth are installed and connected to proper drainage
- ¾ inch clear gravel is installed on top of the weepers to a minimum of a 1 ft depth
- A geomembrane filter cloth is installed on top of the gravel. This will prevent the soil from clogging the system.
- Excavated soil is then backfilled.
Internal Water-proofing Procedure:
- The concrete floor is broken 12-14 inches from the foundation wall.
- A trench is dug to expose the inside of the bottom footing
- Weeping tiles are then installed and graded toward the sump pump
- ¾ inch clean gravel is installed over the weepers
- Waterproof membrane is then installed over the gravel extending to the top of the foundation wall
- New concrete is poured over the system in flush with the existing slab
How do Weeping Tiles Work?
Weeping tiles are installed around the perimeter of building foundation. They have holes in them that allow them to collect water and either sends it to a city drainage system or to a sump pump.