Where Water Can Enter The Basement: The Floor / Wall Joint
In order to know how to waterproof a basement, you need to know how water enters the basement. There are six different ways water can enter the basement:
1. Floor / wall joint
2. Floor crack
3. Wall crack
4. Bulkhead
5. Window
6. Over the sill plate and down the wall
In this post I am going to go over the first way water enters a basement –
the floor / wall joint.
Floor/Wall Joint
The floor/wall joint intersection is the most common entry source of water infiltrating the basement. This is where the foundation wall meets the floor. The water comes in from the outside over the footing under the foundation wall and up through the intersection where the foundation wall and floor converge. This type of wall seepage is seen most commonly when it rains. The reason for this is due to the over-dig mechanic previously described. If you have 3” to 4” or more of water in your basement, the source of the water is probably from the floor/wall joint. Water may seep in from other locations, but the most heavy water intrusion will be from the floor/wall joint.
Due to the nature of concrete, when one concrete structure is poured and another concrete structure is poured next to it (or on it), a seam is created between the two concrete
structures. For example, the footing is poured – the foundation wall is poured – and finally, the floor is poured. Each concrete structure (the footing, the wall and the floor) is poured separately. There is now a seam between each of these three structures. This allows the potential for water (under pressure) to come into the basement area. The points of entry are over the foundation footing, between the foundation wall, underneath the foundation and up through the seams between the foundation footing and the floor. This floor/wall joint seepage is very common and is a predominant reason for basement flooding.
