Why Basements Leak
Basement leaks are common problems in most areas. Determining where water enters the building is an important step in diagnosing the problem. Structural problems, an area’s soil condition, grading around a structure and many other factors can contribute to a water problem. The three areas of a house that influence the proper diagnosis of a water problem are the basement floor, the foundation walls and the sill area.
When water rises above the level of the basement floor it is commonly referred to as “hydrostatic pressure”. This phenomenon is caused by either ground or perched water. Perched water is water that is trapped in soils before entering into the aquifer and levels are usually highest after heavy rains. Pressure caused by perched water can work its way into basements through cracks in the basement floor, seams caused by construction and cracks or imperfections of a foundation wall. Ground water, or the water table, usually remains at a constant depth, but increased periods of precipitation or influence by tidal surges can cause fluctuations in this level. Because of this, improper drainage at the lowest point of your basement’s foundation can lead to flooding.
What is That White Powder on my Foundation Wall?
That white powder is known as efflorescence and is caused when soluble salts and other water dispersible materials come to the surface of concrete and mortars. It’s induced by low temperatures, moist conditions, condensation and water. It can occur either very soon after exposure to moist or cool conditions, or gradually, especially when it comes from within the concrete or from the sub–grade foundation wall.
Any material containing Portland cement results in efflorescence. The most usual reaction occurs when calcium hydroxide (lime) formed when the hydration reaction of Portland cement (approximately 140 pounds per cubic yard of concrete) is transported by water to the surface through capillaries in the concrete. There it combines with carbon dioxide from the air to produce calcium carbonate (an insoluble material) and water. Efflorescence can also be caused by hydroxides and sulfates of either sodium or potassium, which are much more soluble in water than calcium. They form efflorescence more rapidly than calcium hydroxide. These salts can come from cement, aggregates, water, or admixtures.
What Is “Sick Home Syndrome”?
Sick building syndrome has become such a serious problem in the United States in recent years, you can now find the phrase in the dictionary. It is defined as an illness characterized by skin irritations, headache, and respiratory problems caused by indoor pollutants, inadequate ventilation, and microorganisms including mold.
Toxic molds have been making people sick since biblical times, but the scope of the problem came to the forefront in 1996 when tests by the Centers for Disease Control and Prevention (CDC) revealedthat they had killed one infant and sickened nine others in a Cleveland housing project. The babies, who lived in close proximity to one another, all suffered from the same rare lung disorder characterized by pulmonary hemorrhaging. The likely cause: Stachybotrys chartarum, a greenish-black mold. It was found in every one of their homes.
In recent years, the same toxic mold has been responsible for countless other incidents of sick building syndrome at schools, public offices and even single family homes. “Part of the problem is our current construction practices,” says Seth Norman, CEO of Walled Lake, Michigan-based Mold Free, a nationwide mold inspection and remediation service. “We close our buildings tight to make them energy efficient, and as a result, building materials exposed to moisture never get a chance to dry out.”
Visible mold can be cleaned off surfaces with a weak bleach solution. Mold under carpets typically requires that the carpets be removed and replaced, but what do you do about mold in the insulation or wallboard? It goes without saying, they too have to be replaced, but how do you know you have a mold problem behind your walls? “That’s the first place we look if there aren’t any other visible signs of what’s making someone sick in their home,” says Norman. Signs of mold exposure include nasal stuffiness, eye irritation, wheezing, fever and even shortness of breath. People with chronic illnesses, such as obstructive lung disease, may develop mold infections in their lungs.