Water arrives at our home through many different means. It falls as rain, seeps through the ground, is added by irrigation, and can emerge from snow melt. Our buildings have gutters, downspouts, and perimeter drainage to manage water on the building but we also need to manage the surface water on our property or it may come back to damage the home.
Building on High Ground
The best way to protect our homes from property water is to build the building on the highest point in the area so water flows away from the building with gravity. Unfortunately, we can't all live on the peak of a hill, but it is possible to place our home on its foundation such that we can 'grade' the soil to direct water at least 6' away from our foundation walls. Once we have the water draining at least 6' away from our buildings, we can use other systems to take it off our property such as:
- Ditches - Ditches are indents in the ground intended to drain surface water safely to a drainage point. Ditches tend to be effective on very flat properties as they provide a lower path than the property for water to follow with gravity.
- Swales - Swales are like upside down ditches. The raised landscape of a swale directs water to a desired drainage location. Unlike ditches, Swales need to be on a slope to be effective at redirecting moving surface water.
- Natural Features - Streams, rivers, and ravines are all natural features that manage ground water. As we've built homes along these natural features, we have changed the paths that water takes to get to them but providing we keep our surface water clean of contaminants, directing water to a natural feature is a great way to remove water from our properties.
- Drainage Systems - Most homes have some type of drains to help carry water from local low points like driveways, basement entrances, or window wells. These drains can be an excellent way to manage surface water but they require maintenance to ensure they do not become plugged with debris or freeze up.
Managing Surface Water on Very Flat or Negative Slope Areas
If your property is too flat or even negatively sloped, you cannot rely on gravity to carry surface water from your property. Two common ways to manage this water are mechanically through pumps, or passively using a controlled drainage system into the ground soil.
- Sump Pumps - Water can be collected at the low points of the property to a sump pit where a sump pump will eject water to a higher point that gravity can carry the water away from. Sump pits and pumps can be a risk for home owners as they rely on electricity to operate the pump and in the event of a power outage or pump failure, water could rise and flood the home.
- Substrate Drains - Depending on your local water table, it is possible to direct drain water into the ground soil. This is commonly done by directing water to an open water storage area like a slough or marsh, or to a device like a french gravel drain.
What Do Home Inspectors Look for with Property Drainage?
As water is one of the leading cause of damage to homes, home inspectors are very interested in the flow of water away from the building during a home inspection. Home Inspectors will be looking for correct drainage slopes and the performance of drainage systems on the property that they are correctly protecting the buildings. It is not uncommon in a home inspection to see negative grading of property to the building. This should be a significant concern for home inspection clients as we want to drain water away from the building although unless there has been very serious settlement issues or the house was built to low, it is usually possible to re-grade the property for correct drainage.
On the Canadian West Coast where we can see 100" of rain a year, managing ground water is very important to the health of our homes. Managing ground water effectively can also prevent many other water ingress related issues like leaky basements and mold growth. As always, if you are looking at buying any new home, a home inspection from a great home inspector is an excellent protection to help you know your new home will be safe and solid.
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