I posted a question several days ago about grading land around my house to keep the basement from leaking, and I received many good suggestions. I have pretty much decided to buy topsoil and do this myself. My question is: How do I "stack" the topsoil or add plants to it to make sure that it stays firm after I establish the slope away from the house. There is a pretty significant depression of about 18 inches near one corner of the house, and I strongly suspect that merely piling topsoil in the low spots and sloping it away from the house is not enough to do the job correctly.
Is this a concrete foundation wall? What is the exterior of your house? Stucco/brick/siding? Has the wall been damp proofed? (does it have a layer of tar on it) When you add 18" of dirt, will there still be about 6" of concrete showing below your siding/ brick veneer weep holes?
If this were new construction and attempting the best practices, you would: Damp proof or water proof the walls to the top of intended grade. Install French drain system at base of wall/footing. Install protection board and/or drainage plane material. Backfill with native material, preferably clay, compacted to 88% Proctor density or better. Top off with 3-6" topsoil Minimum drainage grade 6" fall in the first 10 feet. Avoid plantings and downspouts within 4 feet of the foundation.
This is not how it usually happens. The backfill is shoved in loose and may settle over 2-3 years. Builders and home owners plant bushes and flower beds along the foundation, then water the day lights out of them. Most of your problem may be from this approach. It would be best for you to remove the sod and topsoil where you are changing the grade. Add compacted select fill (called different things in different areas - here it would be red select) to correct grade. Top off with your topsoil/sod or purchase new top soil.
You can just add dirt on top of what you have, but this method may take reworking each year for several years to develop a dense enough subsoil to shed water. Your old sod line will rot and decompose over several years. Top soils and loams tend to absorb and hold water. Clays and selects tend to shed water. Hope this helps some. ______________________________ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net
Thanks for your many fine suggestions. I will add that the low point that will need 18 inches of fill is basement block, which surrounds all of the house.
I have some follow-up questions. Is the tar sealer you referred to a special kind for basements and could you suggest several name brands. Also, if nothing is planted within four feet of the house, what keeps the top soil from blowing away?
emulsified (water based, water clean up) products are much easier with which to work
Sod is great. My reference is to not install bushes and flower beds. So many people build up a flower bed with landscape timbers, use plenty of peat moss, cover the ground with mulch, and water the mess daily. The timbers hold the water, the peat moss holds water and allows it to go deep, the mulch keeps the water in the soil and prevents the sun from drying it up, and pouring water on a leaking basement wall is begging for problems.
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