Expert: John-Paul Friend - 4/20/2004

Question
my question is mostly on drainage, the spot for the rock garden is in front of the house, the base of the garden is a concrete slab, if i build up dirt first then put rocks on top could i get a leak into the foundation? thanks steven  

Answer
Hi, and thanks for your question. Drainage is a problem with foundations. If the rock feature is to be touching a wall of your house, or will cause excess water to collect against walls of your house, then I would recommend against its construction. You may limit the water ingress problem with your choice of plants in the feature. Rock gardens are normally free draining as the alpine plants that are commonly used require these conditions. The foundation itsefl should not be affected by water, as they are normally built with the water table in mind. Also, there should be a damp proof course in the brickwork a few courses up from the ground to prevent the water rising up the wall. I'm afraid I can't be too certain as to your exact problem, but I hope this information helps. Ask again if it is unclear. Thanks again for your question.