Is it a good idea to use dirt to grade away from foundation?

Question

A reputable/recommended house inspector suggested that we can just pile up dirt to create a grade that will prevent water from collecting around our foundation. We have a crawl space so the dirt will basically be against the outer wall of the crawlspace. He suggested putting dirt against this outer wall.

We live in Los Angeles so we don't get that much rain.

My concern that if the dirt is against the wall, won't this just trap the moisture and keep the wall wet?

Is his advice sound or should I look for alternate solutions?

Answer 1

I live in a very wet climate and that is exactly what we do. Often, the level of the dirt on the outside of the foundation is higher than the level of the dirt on the inside. This is acceptable as long as the soil slopes away from the house on all sides. (Yes, the outer surface of the crawl space wall will be wet/damp, but it would be wet in a rain storm too and this moisture will evaporate...especially in LA.) When we have problems is when one side slopes down to the house and then the "surface" water wants to "stand" (puddle) against the foundation wall and eventually seep into the crawl space.

I think your Inspector is correct. (If you have a basement, then things are different, but you said crawl space.)

Answer 2

There is an alternative or complementary technique for draining water away from a foundation whether the foundation type is pier-and-beam or slab-on-grade. This is to create a swale around the house say 3 or 4 ft from it. The water drains into the swale and is carried away at low points in the swale.

I am not a fan of piling soil up against the outside of a foundation as the only intervention, because I have seen and continue to see cases with slab foundations where the soil level is too high, too close to the sill plate. This promotes termite infestation and possibly water migration into the slab.

Also, 40 years ago my wife and I rented a pier and beam house in a very nice area of Dallas under which several inches of standing water appeared with heavy rain. I noticed this because the floor boards would cup and loosen after a heavy rain. I looked in the crawl space and, yikes, a lake! The floor was getting saturated with water from 100 % humidity in the crawl space. I informed the landlord, but he seemed unconcerned or at least at a loss as to what to do.

I admire the pier-and-beam foundation for access to the plumbing, but there are plenty of cases of rotted out beams, joists, and floors.

Our current neighborhood of 50-year-old slab houses is on a long down slope from "Hillcrest Rd" on the east to a creek on the west. The streets go east-west; the houses face north or south. Over the decades the original swales on the uphill sides of the houses filled in and drainage problems developed. Some people have at considerable expense had contractors install so called French drains. I simply re-established the swale on the uphill side of our house.

I did the same for a neighbor on the next street north of us. She has a natural yard with no turf grass. Eight man-hours of work in three sessions (by a 72-year-old man with atrophied upper body) with a mattock, a shovel, and a wheel barrow redirected the water around her house. She had told my wife she thought she had a roof leak and what could be done? The water had been coming in the "weep holes" in the brick on the uphill side.

I believe some people don't want to damage the turf grass they worship and so spend $10K to leave the surface contour as it is (original code required swale filled in). Competent workers can remove the turf, remove soil then replace the turfgrass. That would be a struggle for me, but we have a xeriscaped 10,000 sq ft lot and so there is no absurd St Augustine or other turfgrass next to the house. We do have some St Augustine in front between the sidewalk and the street on the far east and far west sides. This is to blend in to the neighbor's absurd St Augustine and maybe to prove that we could grow the stuff if we wanted to.