I had an addition put on my house. How come it leaks where the new foundation wall meets the old one?
When new concrete is poured up against existing (cold) concrete, this is referred to as a cold joint. Cold joints are notorious for leaking because while the new concrete abuts the old concrete fully, as it hardens, and shrinks, it pulls away a tiny amount, and that’s all water needs to find a way into your basement. The best way to remedy a leaking cold joint is an epoxy injection (see CRACK-X) that fills the entire depth of the foundation wall, and creates a water-tight structural bond between the two surfaces of concrete.
