Common causes of home drainage problems
I am asked this question often. So the answer deserves repeating. Although, in this blog on home drainage, articles cover this subject and the ability to ascertain if you have a groundwater drainage problem, I will highlight a few of the common home drainage “smoking guns” again in this article.
The evidence is usually groundwater in your crawlspace or basement. But what really is at the root of the problem? How does the groundwater wind up there? The most common causes of home groundwater drainage problems are as follows.
1. The topography of the home site slopes to the foundation. This is called a negative grade. An adequate grade is 6″ per 10 lineal feet away from the foundation wall according to most building codes. This does not mean that a more severe grade that is compacted is not advisable.. A negative grade causes the rain water, or runoff from sprinkler systems, to lay against the foundation wall causing saturation below grade. The event causing it is hydrostatic pressure.
2. Downspouts are not connected right, or are plugged up with debris from years of gutter use and collection of debris on the roof of the home. Install cleanouts on new systems to flush the lines periodically.
3. Sump pumps are installed within a basement or crawlspace without exterior hand excavated french drains to remove groundwater from the foundation area when it rains. Hand excavated french drains with splash blocks of compacted clay or soil against the foundation reduce the hydrostatic pressure and subsequently cuts off the groundwater running below grade.
The groundwater running below grade, many times, is referred to as a spring, but is, in most all cases, the rain water allowed to saturate to that depth from the periodic rains, and the constant addition of groundwater weight to the surface at the foundation wall. Almost always, the homes with groundwater problems have improperly installed french drains or no hand excavated french drains.
4. Gutter systems with gutter helmets or guards designed to make for less gutter cleaning and less debris in the gutters, actually run the roofwater right over the edge of the gutters in hard rains, causing groundwater problems at the foundation wall without a compacted grade spash block sloping back to the inside of the french drain.
5. Foundation plantings that include bamboo, trees, and other species with large deep root systems make pathways to the lower foundation areas and can cause damage to your foundation. This makes it easy for the rain water to follow them below grade.
6. Berms in front of the foundation wall will trap rain water against the foundation. No slope away from the home can contribute to the groundwater problem. Great curb appeal. Terrible for drainage.
7. Heavy additions of barkdust next to the foundation which trap rain water and create a spongy surface that sends groundwater below grade and causes problems as discussed.
Read the articles within this blog on home drainage to find more detailed information on groundwater drainage systems.