Yes, you can have water seeping beneath your base rails if you do not have a sealant package applied during your building’s installation. Water seepage will occur because, while the base rail is laid flush with your foundation, it is still not completely sealed and there will be room water to enter. However, if you have purchased our sealant package, this will be applied directly to your base rail during installation and will prevent any water from seeping into your building. During installation, a foam strip is applied to the bottom of the base rail and, once the base rail is being set, the weight of the steel will push down on the base rail and flatten the foam strip until it is completely flat against the foundation and the rail. From there, a strip of polyurethane sealant is applied on both the inside and the outside of your building! Here you can find more info on water seepage and preventative measures.