Article No: 59
By: Christopher Brooks
For many homeowners, the basement is like an additional story to their home. Installing an effective waterproofing system or product is essential in the construction stage. Nothing is worse for the homeowner — or builder — than to discover moisture. However, waterproofing manufacturers differ widely in their approach to the problem.
How mold gets started
All too often a homeowner's worst discovery — a true nightmare — is finding moisture in his new basement. For where there is moisture, mold is sure to follow. Moisture is the critical engine to mold growth. Control, management and elimination of moisture are fundamental to controlling mold in structures.
Water is a common element of the earth. Water constantly moves through the earth primarily in a seepage fashion always taking the path of least resistance or maximum pressure. For centuries we have built below grade foundations with three traditional methods of holding back moisture: do nothing, damp-proof the wall or waterproof the wall.
All of the above have one thing in common and that is the backfill is placed directly against the foundation wall. By placing the backfill against the wall we have created a perfect condition for moisture to enter the structure. We have provided the carrier for the moisture — the backfill material — and we have provided the necessary pressure by placing the backfill directly on the foundation, which forces the water to the wall. If the wall has any crack or opening, moisture will enter the home and the potential for mold growth has started.
DELTA-MS The Foundation Wrap
Tom Fallon, vice president of Cosella-Dorken, manufacturers of water control and protection products in Beamsville, Ontario, Canada, points out the key to preventing mold is to control the groundwater by isolating it from the foundation wall and directing it to a footer drain system.
This waterproof dimple-shaped sheet completely isolates the backfill from the foundation wall, creating a clean odorless "air gap" next to the foundation wall. The heavy-duty tear-proof dimple sheet bridges all cracks and imperfections in the wall and allows moisture vapor to escape from the wall while still offering complete waterproofing to the wall. With the five-sixteenth stud turned toward the wall, an air gap is created that will allow any moisture that might get past the "wrap" to freely drain downward to the footer drain.
"The air gap utilizes gravity to keep any moisture from entering the home," Fallon said. "If by chance any moisture can get by the 'wrap' it will be forced to literally leap five-sixteenth of an inch in the air gap to reach the wall. No way. The water will fall downward in the air gap and be drained away."
DELTA-MS comes in a variety of heights to suit the foundation height and comes in rolls 65.5 feet long. Fallon concludes that DELTA MS offers the best protection against moisture entry into basements and is the fundamental defense against mold.
Common moisture problems
Bill Emerick, general manager at Ideal Products LLC in Plymouth, Ind., said poor site location in urban or rural flat graded housing sites and developments with no elevation, combined with poor drainage of the entire site, are the most common factors or circumstances contributing to severe basement moisture in the newly constructed home. Ideal Products LLC manufactures the SANI-TRED LRB (Liquid Base Rubber) waterproofing product. "The only recourse is to accept the inevitability of a wet basement or install effective waterproofing inside the basement.
"One trend I've observed is homeowners and contractors installing useless 'water-resistant' contaminates on basement walls that do nothing useful in an attempt to prevent water problems," Emerick said. "Often, these types of useless products are required by local building code, regardless of common knowledge that exterior systems do little to prevent basement water problems."
Emerick cites such example products as cement-based, crystalline coating or patching materials: tar, oils, or silicone-based spray or brush-on sealers. "These are types of concrete bond breaking contaminates that eventually cost the homeowner up to 10 times or more then the original product and application labor cost to remove them."
Three separate pours
Emerick points out that leaking occurs in residential basements because concrete basements are poured in three separate pours, as he notes in this order: foundation footing, in undisturbed soil; foundation walls, positioned directly atop foundation footings; and basement floor slab, normally poured atop interior foundation footing.
"New concrete that is poured next to existing cured concrete will not bond new-to-old, and forms distinct gaps or cracks between these poured surfaces called 'cold joints.' These cold joints are unavoidable in basement construction."
Waterproof outside or inside?
Emerick is of the opinion that waterproofing the basement from the exterior is a wasted effort.
"There is no possible way from the outside to prevent groundwater from entering a critical 'cold joint' — the interior of the wall-to-floor junction of a basement — the one leaking point that all leaking basements have in common," he said. "It's also impossible to stop water from entering cracks or joints in the basement floor from the outside. A common and laughable practice is to install a plastic sheet vapor barrier under the floor slab.
"Even if the plastic sheeting is installed perfectly, and few are, the plastic sheeting offers no protection from groundwater moisture or humidity. A plastic vapor barrier is only as good as its installation and termination points. There is no possible way to terminate a plastic sheet vapor barrier to prevent water from either leaking through it via foot traffic punctures during floor slab pouring, or from water migration inwards over the top of the vapor barrier from the entire 360 degrees of the sheet's terminated end points."
Many unscrupulous companies use scare tactics to sell their waterproofing products, according to Emerick. They tell their customers that groundwater is harmful to their concrete foundation walls, giving the unknowing customer the impression that their concrete is made of water soluble materials that will effervesce and deteriorate with water contact eventually dissolving like Alka Seltzer tablets.
"If it were true that water dissolved concrete, many of the 100-year-old-plus bridges in the world would have tumbled many years ago. Their concrete is as sound today as when it was poured more than 100 years ago. Foundations crack when hydraulic cement is either poured in place or pre-cast as concrete blocks, and laid up with mortar that is also made from hydraulic cement.
"Hydraulic cement by its very nature is intended and designed to fully cure or harden under water and is completely waterproof, but often too porous to seal out water. The fact is, only water that is allowed to flow freely through porous concrete foundation walls will harm concrete and eventually weaken it in these leaking areas. Many waterproofing companies try to make customers believe that it is critical to drain all of the water in the ground around the foundation or redirect the ground water by allowing the water to enter the basement and then be pumped out with a sump pump. This is very damaging to the foundation footing, causing eventual settling and wall cracking."
Emerick said he believes it is essential that you never redirect water to a sump pump. "Groundwater that is freely allowed to enter a basement to be redirected to a sump pump carries with it critical undisturbed soil that is washed away from under the foundation footing, causing foundation settling and eventual foundation failure if unchecked. You can see traces of this soil in basements that leak as earthen residue that accumulates at the base of the walls. This is why massive settling and foundation wall cracking is seen in older homes with water problems and active sump pumps that are allowed to run often.
"SANI-TRED is an indoor system that is cost effective," Emerick said. This method that will eliminate all water, moisture and humidity from entering the basement from all possible locations including power failure and or sump pump failure which is a common problem during heavy rain storms."
The product is rolled and brushed on the interior basement walls and floors in a three step process sealing all holes, gaps, cracks and joints in the procedure, protecting the entire basement from all exterior moisture, flowing water and humidity.
"This liquid rubber primer penetrates from one-sixteenth inch to over one inch into the surface of the concrete through the microscopic pores," he said." Upon curing, these little rubber fingers act as o-rings, stopping the water at the microscopic level before it can reach the actual coating and being pushed off en-mass and forming blisters like paints or other coatings. The more the tiny, flexible rubber tentacles are compressed by groundwater pressure, the greater the seal. The product hardens with age and remains flexible. Not even freeze thaw cycles can detach SANI-TRED from its original bond to the concrete's surface."
According to Joe Cumpelik, president of Shelton, Conn.-based Novion Inc., manufacturers of RadonSeal Waterproofing product, both exterior and interior waterproofing is important to new basements.
"First of all, we should take full advantage of the wonderful material - concrete. Its only weakness is the capillaries that develop during hydration," Cumpelik said. "Let us seal the capillaries first and at the same time, strengthen and preserve the concrete before dealing with waterproofing coatings or membranes.
"Initially, the curing concrete releases large amounts of 'free' (surplus) water. As the concrete cures, capillaries develop and water vapor (a gas) flows in from the soil. Vapor is drawn by the lower pressure (advection) and lower concentration (diffusion) indoors. As concrete ages, the capillaries get larger and draw in by capillary action liquid water, which quickly evaporates.
"Exterior waterproofing systems are not permanent and eventually crack or separate due to concrete movement or lime from the concrete. Vapor barriers gradually disintegrate. High indoor moisture combined with low air exchange rate causes molds and mildew. Water migration gradually disintegrates the concrete."
Cumpelik says many home sales get renegotiated or cancelled when the building inspector discovers moisture, often finding the following indications: dampness at the base of the walls, rust at the base of steel posts or the heater, efflorescence (white powder) on the concrete, peeling floor tiles or mildewed carpeting, stains or mildew on objects stored on the floor, and condensation on windows and concrete.
Novion's product RadonSeal deep-penetrating sealer seals concrete internally against water in liquid and vapor form, and even radon gas. It reacts chemically with lime and alkalis in concrete and forms silicates inside the pores — like injecting cement into the concrete. It bonds, strengthens and preserves concrete.
"RadonSeal should be complemented by a flexible exterior membrane or coating, which will take care of joints or cracks," he said. "The sealer is sprayed on with a low-pressure sprayer. The application is quick and easy. It is a waterborne sealer without any VOCs. It's a very safe application. Spray it on cured concrete at least 28 days old - interior or exterior. It penetrates deep inside concrete, reacts with lime and alkali, and seals the concrete walls, floor or ceiling against liquids or gases." It is not a surface sealer or paint. It permeates up to four inches inside concrete and seals the concrete internally. The seal lasts for the life of the concrete. Once sealed, no reapplication is ever needed.
"RadonSeal is particularly suitable for concrete homes," he said. "The contractor can use his favorite exterior waterproofing and back-fill. After letting the concrete cure for at least 28 days, he can seal the whole interior with RadonSeal. Because it neutralizes alkali inside the concrete, this will also extend the life of the exterior waterproofing and prevent efflorescence, the bane of all surface sealers."
Manufacturers' waterproofing systems and products vary in their application or installation. Surf the Internet and check out these and other companies' products to find the most suitable materials for your next project.