Proper grading is a key factor in maintaining your home. Over time poor grading caused by settlement or poor landscaping can funnel water towards the foundation, potentially causing a damp basement and the accompanying health concerns. Most people give site grades and drainage next to no consideration. Other factors are far more eye-catching and thus relegate drainage to an issue that homeowners only consider after the damage has been done.

Hillside catches water	Sloping patio stones
Border holds water	Driveway settlement collects water

The first picture shows a more extreme example than is often found, but clearly displays the concern. The terraced hillside surrounding this home acts as a funnel capturing rain and feeding it down the hill towards the house. No doubt in this case storm drains have been installed to capture the runoff. However, at properties with much less severe grades the necessary measures can be overlooked. It only takes a few inches of slope in the right or wrong direction to turn the tide, so to speak. I inspected a home this summer with moisture in the basement where the backyard and the neighbours lot behind it sloped directly to the back wall of the house. This usually escapes notice but once you are aware it can readily be evaluated at a glance. The good news is that in many cases the matter can be addressed with a truckload of topsoil and some grass seed.

Walkways and patios have runoff that should be directed away from the house. In this case the slope of the patio stones is clearly feeding water to the foundation wall. Although some hard work is required, often interlock pavers and patio stones can be lifted and relaid on a regraded base. Poured concrete slabs are more problematic and may have to be repoured. Before committing to that, take some time to investigate services that hydraulically relevel slabs.

Another common problem is landscaping that captures and holds water against the foundation rather than releasing it to flow away. Consider this flowerbed and its border. There are multiple drainage ‘sins’ at work here. First, the downspout has no extension and delivers it’s water right at the edge of the foundation. Second the porous pea gravel cover encourages water to soak straight down into the soil rather than draining away. And finally, the attractive border of interlock bricks turned on their sides creates a dam that prevents any water escaping. A little redesign and downspout extensions can improve things greatly.

Nearly every asphalt driveway we see has settled at the mouth of the garage. Sometimes the drop can be four or five inches resulting in water ponding in front of the garage. The fault is not with the asphalt but the material beneath it. After the excavation is back-filled with loose fill, compaction occurs gradually over the first few years resulting in settlement of the driveway surface that sinks far below the garage slab. The real solution is starting out with a properly prepared base the first time out. After the fact an asphalt patch or complete driveway replacement will have to considered.

When touring homes for possible purchase, add lot grading to your list of items to make note of. Some grading repairs amount to some hard work and a few dollars of materials. Others can require considerable expense and it would be best to know that before it becomes your problem. Don’t forget that the main reason we care about the grading is to protect the basement from water infiltration.

Author: Rob Cornish is a Home Inspector in Ottawa, Canada. © 2014 HomeXam Inc.
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