Basement Water Penetration

The recent heavy rains we received over the past weekend combined with melting snow to force water into the basements of many homes.  With the winter thaw and early spring showers being just a few weeks away, basement water penetration is a problem many home owners are going to have to face again in the upcoming months. 

Water in a basement is never a good situation.  It creates conditions that are conducive to mold growth and termite infestation.  Mold needs moisture to take hold and grow and termites are attracted to a scent given off by wet wood.  To prevent this from happening, moisture in the basement must be taken out of the equation.

The primary causes for basement water penetration are poor grading and ineffective gutters and downspouts.  Below are excerpts from the Strong Foundations Home Owners Manual on basement water penetration causes and cures. 

Grading & Drainage
  1. Maintain sloped exterior grades going away from your house (at least ½ inch of slope per foot of run for at least six (6) feet.
  2. Grading should be improved with the use of clay-based soil (red in color and otherwise known as clean fill). It swells when wet and inhibits the infiltration of water.
  3. Do not use top soil for improving grades! It is very permeable and allows water to flow right through it.
  4. Driveways, walkways, and patios next to the house should be installed to slope away from your house. This will prevent water from draining towards your house. All horizontal to vertical intersecting points of driveways, walkways, and patios next to your house should be sealed with silicone caulk to prevent water infiltration.
  5. Driveways should have drains in low-lying areas near your house to collect ponding water and drain it away from your house.
  6. If water collects and ponds in low-lying areas of your yard, install swales to carry the water away. A swale is a wide, shallow depression that channels surface water away from your house.
  7. Adequate gutters and downspouts should be in place on your roof in order to collect roof water and drain it away from your house (at least six (6) feet away)

 

Trees, Vegetation, & Landscaping
  1. Don’t plant trees, shrubs, or vegetation too close to your house. They hold water next to your walls and increase the chances of water infilitration into your house. Plants with expansive root systems can also damage foundation walls and footings.
  2. Keep all vegetation trimmed at least one (1) foot away from any area of the house. Tall trees should be kept trimmed back at least five (5) feet from the house due to their tendency to sway in heavy winds and damage walls and roofs. Vegetation is a perfect nesting area for bugs and wood-destroying insects. Take their pathway to your house away but keeping all vegetation trimmed back at least one foot.
  3. Landscaping applications that involve the used of stacked landscaping blocks or pressure treated wood to create borders or raised beds next to an exterior wall can act as dams. These dams trap water next to your house and can lead to basement water penetration. These types of landscaping applications need provisions installed to allow any water that collects behind them and against the house to drain out and away from the house.

 

Foundations and Basements
  1. Basements need to be kept dry. Wet and damp basements create conditions that are conducive to mold growth and the presence of wood destroying insects.
  2. Refer to the section on Grading and Drainage to maintain a dry basement.

 

Water Control Systems
  1. Sump pits attached to under-slab drain tile, sump pits with sump pumps, and perimeter troughs connected to sump pits are all examples of water control systems. Don’t mistake water control for water proofing. Water control means collecting the water once it gets into your house and draining it all into a common area. Water proofing means keeping water out of your house altogether.
  2. Perimeter troughs are trenches in the outer most edges of a basement floor that catch water and divert it towards a sump pit. The water is then pumped out of the house by a sump pump.
  3. Perimeter troughs should be kept free of debris that could clog the trough and prevent the flow of collected water back to the sump pit.
  4. Do not fill perimeter troughs! Some troughs are left filled with rigid foam after construction of the house is completed. If this foam is never removed from the trough, the trough will not be able to collect any water that gets in the basement. The trough is then useless and unable to do the job for which it was designed. This foam will need to be removed.
  5. Sump pump discharge pipes should terminate outside the house and be long enough to divert water pumped out from the sump pit as far away from your exterior house walls as possible. If water is discharged too close to your exterior walls, it will come right back into your basement.
  6. In most areas, it is illegal to connect your sump pump discharge line directly to your sanitary sewer drain line. Consult your local municipality before considering this type of connection.
  7. Brush-on "water proofing" paints rarely work except under the most minor cases of basement moisture problems. The coating invariably peels off due to the static pressure of water pushing it’s way through the wall.
  8. Aftermarket water control systems are not recommended until all attempts at improving the grading and drainage as outlined in the section on Grading and Drainage have been exhausted. Aftermarket water control systems are very expensive and still allow water to enter your house. They may be necessary in areas with high water tables.

 

Gutters and Downspouts

  1. Gutters should be installed on any area of a roof where roof water can be expected to drain. Gutters should have enough downspouts based on the total roof area to adequately drain all the roof water which collects in the gutters. Gutters should also have enough of a downward slope towards the downspouts to drain the water which collects in the gutters. Downspouts should extend far enough to drain all roof water at least six (6) feet away from the exterior walls of the house. Gutters that are installed improperly, not maintained, or not present are one of the biggest contributors towards water in a basement. Your houses’ gutter and downspout system must be properly installed and maintained as needed in order to drain roof water and get it as far away from your house as possible.