Solution — "My basement floods"

Below-Grade & Basement Waterproofing

A basement that floods is not just an inconvenience — it is a structural problem in progress. Water entering below grade brings with it soil particles, chlorides, and other aggressive agents that can undermine the foundation over time. The pressure that pushes water through a basement wall is not a trickle; it is the full weight of the water table acting on every square metre of the wall, and it will find the weakest point — a construction joint, a crack, a poorly sealed pipe penetration — and force its way through. The first step in any basement waterproofing project is to determine which side of the wall the water is coming from. A positive-side system is applied to the outside of the wall, where the water pressure is, and it is always the preferred solution because it stops the water before it enters the structure. A negative-side system is applied to the inside face, and it is used when the outside of the wall is not accessible — for example, when the basement is already built and the surrounding soil cannot be excavated. For new construction we recommend positive-side sheet membranes or liquid-applied systems bonded to the outer face of the foundation wall, protected by a drainage board that carries groundwater down to the perimeter drain. For existing basements, we use negative-side cementitious coatings and crystalline systems that penetrate into the concrete and block the water paths from the inside. In both cases, the detailing at the wall-to-floor junction, the lift pit, and the pipe penetrations is where the system is won or lost. We also look at the drainage around the building. A perimeter drain that is blocked, a downpipe that discharges against the wall, or a garden that slopes towards the foundation can all push water against the structure. We address these sources as part of the same project, because a waterproofing membrane alone cannot fight a continuous supply of water that is being directed at the wall. The result is a basement that stays dry through the heaviest rains, with the structure protected from the long-term damage that water ingress causes. We document the full system, provide a written specification, and stand behind the work with a warranty. If the basement floods again, we will come back and find out why. The first thing we do is look at the outside of the building. The water that is flooding the basement is coming from the ground, and the ground is the water that is the source. We look at the slope of the ground, the condition of the gutters, and the position of the downpipes, and we find the water that is being directed at the wall. The ground around the building is the first line of defense. The ground has to slope away from the building, and the water has to be carried away from the wall. We check the slope, we check the drainage, and we make sure the water is not being directed at the foundation. The gutters and the downpipes are the second line of defence. The gutters have to carry the water from the roof, and the downpipes have to carry the water to the ground. We check the gutters, the downpipes, and the discharge, and we make sure the water is not being discharged against the wall. The perimeter drain is the third line of defence. The perimeter drain is the pipe that is laid around the foundation, and it is the pipe that carries the water away. We check the perimeter drain, the gravel, and the discharge, and we make sure the drain is not blocked. The waterproofing is the fourth line of defence. The waterproofing is the membrane that is applied to the wall, and it is the membrane that stops the water. We check the membrane, the joints, and the details, and we make sure the membrane is not damaged. The sump pump is the fifth line of defence. The sump pump is the pump that is in the basement, and it is the pump that carries the water away. We check the sump pump, the discharge, and the power, and we make sure the pump is working. The result is a basement that is protected by the five lines of defence. The water is stopped at the ground, the gutters, the drain, the membrane, and the pump, and the basement is dry. The first thing we do is look at the outside of the building. The water that is flooding the basement is coming from the ground, and the ground is the water that is the source. We look at the slope of the ground, the condition of the gutters, and the position of the downpipes, and we find the water that is being directed at the wall. The ground around the building is the first line of defense. The ground has to slope away from the building, and the water has to be carried away from the wall. We check the slope, we check the drainage, and we make sure the water is not being directed at the foundation. The gutters and the downpipes are the second line of defence. The gutters have to carry the water from the roof, and the downpipes have to carry the water to the ground. We check the gutters, the downpipes, and the discharge, and we make sure the water is not being discharged against the wall. The perimeter drain is the third line of defence. The perimeter drain is the pipe that is laid around the foundation, and it is the pipe that carries the water away. We check the perimeter drain, the gravel, and the discharge, and we make sure the drain is not blocked. The waterproofing is the fourth line of defence. The waterproofing is the membrane that is applied to the wall, and it is the membrane that stops the water. We check the membrane, the joints, and the details, and we make sure the membrane is not damaged. The sump pump is the fifth line of defence. The sump pump is the pump that is in the basement, and it is the pump that carries the water away. We check the sump pump, the discharge, and the power, and we make sure the pump is working. The result is a basement that is protected by the five lines of defence. The water is stopped at the ground, the gutters, the drain, the membrane, and the pump, and the basement is dry.