Ben Stallings wrote:Hi, Jeff. The short answer is yes, this can work. I did it as one of the first improvements to my property, as the basement flooded twice in the first week we lived here! Our land doesn't slope much, so the swales are only a couple inches high, just enough to stop sheet flow from getting closer to the house. I dug them slightly off contour so that they overflow away from the house. Not only did the basement stop flooding, the lawn and garden were much healthier for the extra water!
Grading the ground around the foundation is also crucial. The magic ratio I've heard is 6" of rise over 6' of run. I built a wooden jig to help me determine if I had that much slope: a long board with a short board screwed to it at a right angle so that the inside measurements are 6' and 6" respectively; I strapped a level to the longer arm and walked around the house setting it down every few feet and marking the spots that didn't comply.
The final piece of the puzzle may be obvious, but I've seen many houses where people apparently didn't think of it -- your downspouts need to take the roof water more than 6' from the house and keep it there. If you don't have downspouts, the grading is all the more important. If you have rain barrels, make sure they have enough overflow to handle the heaviest rains and take it 6' or more away, or use a downspout diverter to reduce the flow to the barrels to a level their overflow can handle.
Rufus Laggren wrote:Assuming a concrete basement (also CMU - cinderblock), some sealers seem to work, both inside and outside the wall; outside usually works better, of course. I have used a "Thoroseal" product inside a CMU full height basement with regular flooding problems; in the last 3 years it seems to have helped a lot.