Interior waterproofing is really water control. Water in your walls is drained and directed under the perimeter of the floor before it enters the room. This option is frequently called for when outside additions or structural elements make outside excavation impractical. It is also less expensive than exterior waterproofing. Sometimes interior water control is necessary to remove water which is trapped below the floor.
Water entering the basement is usually most evident at the joint along the bottom of the basement wall or along expansion joints. Water beneath the floor can also push concrete upwards as the soil below swells, cracking the floor and then flowing into the room. Interior floor cracks and open joints allow both water and radon gas to enter the home.
A sump pump is almost always installed to collect the water and pump it outside. If you ever have power outages it is a good idea to have a battery backup pump to ensure your basement won’t flood. This method of water remediation works well to keep the interior floor dry and is a good lower-cost option. Often a white plastic panel is installed over the wall to direct surface water into the floor, hide any wall damage or discoloration and dress up the walls with a maintenance-free bright surface.
It will be necessary to clear an area of 5′ to 6′ from the walls before work can begin. The contractor will jackhammer and remove approximately 18” of the concrete floor along the entire length of the wall to be addressed. This area is then hand-excavated down to the bottom of the footing. The concrete and dirt are removed and hauled away. Small drain holes are drilled in the cores at the bottom of each block to drain the wall and relieve some of the outside pressure. Drain tile is installed along the inside wall trench against the footing. A thin white plastic panel called rigid sealer is placed in the trench to cover the small drilled drain holes. This plastic panel extends about 12” above the poured floor. Alternately, you can choose to cover the wall with a plastic panel that extends to the top. The drain tile is then buried in washed pea gravel. The entire length of the pipe is sloped to direct water into a buried sump pump located at the lowest point of the system, usually in a corner. An electric connection is made from the pump to the breaker panel. A heavy duty cast iron pump then takes the collected water and automatically pumps it outside through a drain pipe which is connected to the outside downspout. New concrete is troweled at the perimeter, which can be seen as a darker color in the photos below.