Imagine all of this water flowing directly into a building’s foundation…and what if that building has multiple downspouts doing the same thing? This is a great example of how moisture can invade a slab. During a heavy rain, if the water isn’t diverted from the building, all of this water can flow directly into the foundation. We often hear “This building is 40 years old, there is no way there’s moisture in that slab.” But that isn’t true. In fact, existing slabs can be very unpredictable.
First, there typically isn’t a vapor retarder installed and if there is, it can be at the end of its lifespan or can be compromised. Plus, there are additional environmental conditions to consider. Different soils create different moisture levels beneath the slab. If you add a high volume of rain water seeping into the foundation, that existing slab can be holding moisture and can cause a floor failure.