What is a Sump Pump?
A sump pump is generally a small pit (also called a crock or vault) that extends through the slab and into the ground below to provide a drainage place for excess water. Accumulated water can cause interior damage and encourage the growth of mold, mildew and fungus.Water management strategies that help remove excess water from the foundation often include the installation of a reservoir, called a sump, in the basement or crawlspace of the home. Pumps should be maintained and equipped with all their necessary components in order to ensure their reliability.
When building a home, the best way to protect the foundation from moisture issues is with proper site grading, the installation of gutters and downspouts, and the installation of an exterior footing drainpipe that drains to daylight, a dry well or a storm sewer. This will ensure that there is no excess water that could damage the foundation.
When renovating a house that has evidence of water issues, if it is not feasible to construct an exterior drainage system, a drainpipe can be installed along the interior footing that drains to a sump pump, which collects the water and sends it to the storm water, sewer, dry well, or other approved location. A sump pit is sometimes installed in the basement floor slab as a precaution. If there are future changes in groundwater levels, a pump can be installed in the sump pit.
Sealing the Sump Pit
The sump pit should be covered with a gas-tight lid. While sump pumps are very effective in removing water, if they are not covered and installed properly, they can create additional water management issues, as well as indoor air quality concerns for the house. Sumps usually have standing water. If the sump pit is open or has a loose-fitting lid, this water can evaporate into the air, raising the relative humidity inside the home, basement, and crawlspace. This can promote mold growth, which is a health concern, and can increase the moisture level of wood framing, inviting fungal decay and wood-eating pests.
Uncovered or improperly sealed sump pumps can also allow radon and other soil gases to enter the basement and crawlspace, and then mix with the air inside the home. Radon is a naturally occurring radioactive, carcinogenic gas found in varying levels in the soil and air. In high-radon areas, if soil gases are allowed to enter the home, radon can accumulate inside the home at potentially toxic levels.
Figure 1. An open sump pump can allow moisture, soil gases, and radon to enter the home.
The electric sump pump should be installed according to the manufacturer’s specifications, making sure the float is unobstructed. The pump should be installed after the home’s electric meter has been set. This will allow testing of the pump to ensure that it’s operating properly and discharging water as intended.
The sump pump model should have a tight-fitting cover that seals the entire surface of the crock or vault. Sump covers should be made of durable plastic or other rigid material and designed for airtight sealing with a built-in gasket. The sump pump lid should have built-in air-sealing grommets around all penetrations for electrical wiring, water ejection pipes, or radon vent pipes.
The cover should be mechanically fastened in place with screws or other means that will maintain tight contact between the lid, the gasket, and the rim of the crock. Sump covers that permit observation of conditions in the sump pit are recommended. If the sump is installed in a concrete slab, there should be caulk around the outside edge of the vault where the vault meets the concrete (EPA 1994). If the sump is installed in a crawlspace with a dirt floor covered by a polyethylene vapor barrier, check that the polyethylene covers the ground around the sump pump and that it’s taped to the rim of the vault.
Figure 2. This sump pump is properly sealed with a mechanically fastened and gasketed lid.
Figure 3. A sump pump is installed in the basement slab to pump away water that collects in the foundation drainage system. The sump has a tight-fitting cover to keep soil gases and water vapor from entering the basement.
A sump pump is used to remove excess water from a home. There are multiple types, but they all monitor the water level to ensure that the water doesn’t exceed a pre-set level and cause moisture intrusion or property damage. While most sump pumps are effective in removing water, they should always be covered with a gas-tight lid to avoid moisture problems, as well as to prevent the seepage of radon into the home. Home inspectors should encourage their clients to follow a scheduled maintenance routine and get an Annual Home Maintenance Inspection to ensure that their sump pump is operating efficiently and according to its estimated service life. Here’s a link for more do-it yourself sump pump tips: https://goo.gl/zUySKN
Premier Home Inspections ( JPR Home Inspections LLC)