Gravity is inescapable. It forces water to seek the lowest possible point, which is your home’s foundation, basement, or crawl space. When 1? of rain falls on a 2,000 square foot roof, approximately 1,250 gallons of water pours from the roof. If the home has four downspouts, there are over 300 gallons of water dumping near the foundation in four different areas…. that’s a lot of water.
Your home’s wellbeing is dependent upon controlling water draining from the roof by diverting the water away from the foundation walls to prevent water penetration. You must take preventive and, in some cases, corrective measures, to keep water where it belongs – away from your home. Let’s focus on two strategies: ground water control and roof water control.
Grading:
Surface water is water that is introduced to the soil when it rains. If not properly controlled, surface water may penetrate your home’s interior and create damage to the structure, interior surfaces, and personal belongings. Controlling surface water around your home is the most important step to ensuring a proper defense against water penetration. Regrettably, it’s almost always the most often overlooked strategy.
Most homeowners look at their pretty landscaping and pretty flowers and pretty green grass without considering the effects of landscaping on water control. When you’re landscaping, it’s not just important to make it attractive, but also consider the slope of the ground and any obstacles to water flowing away from the house. Flowerbeds close to the house can damage the home by holding water directly against the foundation walls.
Installing barriers (retaining walls, landscaping timbers, vertical plastic edging, stones) can exacerbate the problem because barriers don’t just hold flowers and mulch – barriers block drainage. Make sure downspouts extend beyond the barriers.
The term “grading” is simply a term to help describe surface elevation changes when compared to other areas around or near the house. Proper grading is when the grade or slope of the elevation slopes downward and away from the home at a rate of 1? per foot for the first 6? and then a continued slope for at least 10? from the foundation. A proper grade allows water to flow away from the home and foundation; an improper grade allows moisture to flow back towards the home and seep into the soil. With improper grade, rain saturates the soil, pressures the foundation, and eventually forces moisture through the foundation and into the basement or crawlspace. Although there are other strategies for keeping water out (drain tiles, damp proofing coatings, sub-slab drainage pump systems), grading is the easiest and most cost effective primary defense against water.
Roof Control:
Gutters and downspouts are inexpensive and simple ways to keep rainwater from dripping down and accumulating around the foundation and saturating the soil near the foundation. Unfortunately, most homeowners ignore gutters and downspouts. Gutters must be sloped or pitched to allow water to drain to the downspout area. Too little pitch and there’s not enough flow to remove debris in the gutter; too much pitch isn’t aesthetically pleasing. Generally speaking, an effective gutter slope is roughly ¼ inch drop for every 10? of gutter. Gutter runs in excess of 30? should have downspouts installed at each end, pitching the gutter from the center towards each downspout. Over time, gutters sag as attachment points loosen; this phenomenon allows water to stand in the gutter and concentrate debris in low areas, the weight of which makes gutter attachments even looser and creates more sagging until the gutter hangers or spikes fail completely. It is essential to clean the gutters regularly; check to make sure that hangers are tight to prevent sagging.
Downspouts collect water from gutters and divert water to the ground. Downspouts must terminate at least 3? from foundation walls. Problems occur when downspouts don’t direct water properly or where there is blockage directly in front of the downspout. If the turnpiece where the downspout meets the ground (90° or elbow) is missing, the downspout will direct all water straight down the foundation, erode the area, and pond water directly against the foundation.
Even with the best of water prevention intentions, heavy and prolonged rain episodes can push water into the basement or crawlspace. And unless you live in an area with near zero rain, ground water is almost always present, and water may well up under the slab during times of heavy sustained rainfall even when grading is proper and roof water is controlled. In addition to a sump pump, there are other ways to address ground water, including sub-slab drainage, and directing drainage lines to the exterior.
Controlling ground water in a crawlspace is a similar battle. Add a sump-pump or drainage system and if the crawlspace is dirt, cover the area with a vapor barrier (heavier weight plastic), which helps to prevent moisture from escaping into the crawlspace area. The vapor barrier won’t stop ground water from flowing into the crawlspace, but it helps to reduce humidity and acts as a deterrent to keep water vapor and dirt smell out of the crawlspace.
The challenge of water control is just like anything else in life – prevention is the best cure. If you properly employ simple and inexpensive water control methods – grading, gutters, and downspouts – you will greatly reduce your risk of long-term damage caused by water.