Question
I have a bad smell in my basement that I believe is due to water seepage.  I have been told that the rock beds outside my house need to be redone, and elevated right next to the house.  First, how much of an elevation change do I need from the house to the end of the bed?  Also, some people have told me to use sand instead of dirt to build up the rock bed close to the house. Please help me out.

Answer
Hello,

I do not understand what you mean by "rock bed".  Are you speaking of a drainage channel similar to a french drain or a seepage area?

It sounds as if you are describing the structure as constructed above ground but such structures are always below ground. Piling rocks and soil against your foundation wall will make the water seepage worse. Sand is used as a filter layer in retention areas. For quick drainage,use gravel.

Retention areas for water should be kept a minimum of 10 to 15 feet from the house wall. Drain water away from the foundation wall by using a footing drain and gravel. Consider placing a 6 inch thick clay cap around the top perimeter of the foundation wall.  This will create a semi permeable layer that will stop some water from soaking into the ground below around the foundation. Alternatively,if a growing area for plants is desired around the top of the foundation wall,the clay cap can be placed underground. Or,a concrete or concrete paver apron or plastic sheeting can be used around the foundation wall.  Slope all drain pipes and other drainage structures a minimum of 1 to 3 percent (1/4 inch to 3 inches fall in elevation for every 10 feet).  Maintaining a proper slope will reduce sediment buildup in the drain structures.

I would also suggest you damp proof or waterproof your basement walls. Consider removing all soil away from the foundation wall and replacing it with gravel. The gravel will greatly aid drainage away from the wall and into the footing drain,where it can be carried to an outlet. Or consider using a FIN drain or "waterboard" against the foundation wall. This will allow you to skip the expense and labor of bringing in gravel and will allow you to keep the soil around the foundation in place. These drains are also known as "dimble membranes" because of their dimbled surface appearance.  The membrane releases its water at the footing drain.  Good luck. Let me know if I can be of further help.

Mark Harshman
http://www.mahdrafting.com
http://www.scribd.com/markscrib47
Email: [email protected]