Do-It-Yourself Basement Care & Repairs
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Deep-Penetrating Concrete Sealers Do-It-Yourself Basement Care & Repairs |
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Basement Waterproofing SealerWaterproofing that lasts!Wet basements are the most frequent complaint of homeowners. Traditional decades-old basement waterproofing methods have not passed the test of time: "Over 60 per cent of basements have moisture seepage in one form or another, while 38 per cent experience mold and fungus growth due to an elevated moisture level." (The American Society of Home Inspectors) Slab-on-grade buildings suffer similar moisture problems.
Now, there is a better solution - RadonSeal Penetrating Concrete Sealer. It penetrates deep inside concrete (up to 4"), chemically reacts with lime and alkalis, expands into even microscopic pores, and hardens as a mineral. This seals concrete internally against water, water vapor, and even radon gas, combining concrete waterproofing, damp-proofing, concrete preservation, and radon mitigation in one product. This is not a "your father's" paint or waterproofing sealer! RadonSeal works inside the concrete and leaves no color or film on the surface. The internal seal is PERMANENT. RadonSeal contains no chemical solvents or VOCs. Its spray-on application is quick and easy for contractors or homeowners. Waterproof new or old basementsUse RadonSeal to waterproof bare (unpainted) cementitious materials including:
If you have a brand new basement, now is the best time to prevent future moisture problems, strengthen the concrete, reduce cracking, stop efflorescence ("white powder") and dusting, and to preserve the concrete. RadonSeal also waterproofs existing basements, even already leaking basements. It stops or prevents water seepage through concrete against a much higher hydrostatic pressure than is possible in basements or swimming pools. More on How to Repair a Wet Basement How can water get through concrete?Concrete is naturally porous – typically 10 to 18 percent air (with extremes 2–60%). To make concrete "workable," a water-to-cement ratio of 0.45–0.50 is the norm but cement only needs 0.25 w/c ratio for hydration. As concrete cures, the surplus water escapes to its surface where it evaporates. This "bleeding water" leaves a network of tiny capillaries (pores) inside the concrete. We cannot see the pores. Their size ranges from 3 nm (millionths of a mm) to 0.1 mm (the diameter of a human hair). The median is about 1 micron (1,000 nm) but a water molecule is 3,000 times smaller (0.28 nm). By all logic, concrete should leak like a sieve! So, what holds the water back? Not the concrete but the physics of water itself. Although water not as viscous as molasses, it takes pressure to push it through dry microscopic pores. Surface tension holds the "blob" of water inside the dry pore until its surface gets wet. But add a little water pressure during occasional rainstorms or by condensation on the interior and after a while, the pores get wet and the concrete starts leaking. Concrete is hygroscopic - it attracts water by sorption and once wet, the pores draw in water from the ground by wicking action (capillary suction). However, nothing holds back gases - invisible water vapor and radon gas flow right through the pores! More on Basement Damp-Proofing Exterior waterproofing is not forever!Tar waterproofing is brittle and has no "give." It cracks as the concrete constantly contracts and expands, and as the house settles. Similarly, tar paper or pargeting (a layer of mortar) on block walls are inelastic and crack. Concrete is "very strongly alkaline" (pH above 9). Migrating water carries dissolved alkalis to its surface, where they attack any waterproofing coating by saponification and even the concrete itself ("alkali attack"). Alkaline soils in some regions speed up this process and can "eat" away inches of concrete over several years. All waterproofing coatings gradually disintegrate or separate, even flexible elastomeric liquid membranes. Elastomeric sheet membranes separate as the alkalis attack the primer and taped joints - they are guaranteed for only 5 to 10 years. In the end, the concrete is on its own! It may continue to do a good job for several years but water will gradually activate alkalis, leach out the concrete, and enlarge the pores, making water seepage inevitable. Water is the root problem – in perfectly dry conditions, concrete and waterproofing would last forever. Wouldn't it be great to somehow stop water migration by internally sealing the pores and to neutralize the alkalis in concrete surface to protect the concrete and any waterproofing coating against "alkali attack"? That's exactly what RadonSeal does! How basements start leakingA rainstorm or melting snow temporarily raises the groundwater level. When water accumulates around the foundation, hydrostatic pressure builds up and causes the basement to leak. Clay-rich soils do not drain well and hold rainwater right against the foundation walls. Water pushes its way inside through any cracks or joints and the pores in concrete. As houses settle, concrete develops stress cracks that leak water. Exterior waterproofing cracks and disintegrates or separates due to the "alkali attack." Water also corrodes imbedded steel, which rusts, expands and cracks the concrete. Water penetrates into the pores in concrete, dissolves alkalis, and enlarges the pores. As concrete ages, it becomes more and more porous. Initially, the seeping water evaporates, leaving on the surface minerals and lime, which reacts with carbon dioxide in the air and forms limestone. This "white deposit" or efflorescence is a telltale sign of capillary water seepage. Concrete slabs, although much thinner than basement walls get even less waterproofing protection. The plastic "vapor barrier" soon disintegrates due to the lime in concrete and over time, the layer of gravel ("drainage pad") silts up. Then, the concrete starts pulling in groundwater by capillary action. Where does the water come from?Most basement leaks are caused by heavy rainfall or melting snow. For every inch of rain, a 1,500 sq. ft. roof sheds almost 1,000 gallons of water. Rain gutters and downspouts get plugged up with debris. New houses have a problem with "reverse grading", which occurs about five years after construction. Fill dirt around the foundation settles and directs rainwater right to the foundation. As the run-off seeps through the soft topsoil around the house, it pushes against the walls and stops at the undisturbed ground just beneath the foundation. Footing drains may break as the house settles, or silt up. If the soil is clay, water then starts rising around the foundation like inside a pool. Rising groundwater is sometimes the problem or even an underground spring. Houses settle and underground water flows change. New construction down the street may shift groundwater flows and cause basement leaks in your house. Why does concrete crack?There are various reasons. Basically, as concrete cures, it naturally shrinks. Although the shrinkage may be only 1/8-in. over a 20-ft. span, it may result in a spider web of hairline "shrinkage cracks."
After concrete is poured, water evaporates from small pores in the cement paste while the surface tension of water remaining in other pores pulls them together, causing fine "drying shrinkage" cracks. The surface of a concrete slab dries out before its lower, water-saturated layer and shrinks. This would curl the slab up but it is not yet strong enough and thus develops "plastic shrinkage" cracks. This is particularly a problem when the concrete is poured directly on a plastic sheet ("vapor barrier"). Hydration of concrete generates heat and its surface cools faster and shrinks, causing "thermal shrinkage" cracks. Another problem arises when water seeping into the concrete reaches embedded steel and causes corrosion. The rusting steel forcefully expands and cracks the concrete. Cracks may develop later when the house settles as "stress cracks." In extreme cases, unstable soils may cause "structural cracks" which require professional repairs. Outdoor concrete cracks when water penetrates from above or below and repeatedly freezes (the "freeze-thaw" cycle). Road salts or seawater contain chloride ions, which gradually disintegrate concrete. Pros have learned how to minimize the inevitable cracking in several ways. This includes slowing down hydration by "wet curing," concrete admixtures, and plowing deep "expansion control joints" into the wet concrete during finishing. If you have cracks, you can fix them like a pro - check out our do-it-yourself Crack Injection kits and Epoxy Crack Filler Kits. Curing a new concrete slabSlowing down water evaporation is the key to a denser and stronger concrete. RadonSeal can be used on freshly poured concrete slabs as a curing sealer instead of water misting, temporary sealers, or burlap covers. It slows down water evaporation by plugging up the pores in concrete. Unlike wax or chemical sealers, it does not expose workers to VOCs and leaves the surface suitable for painting or tile adhesives. Apply RadonSeal Standard as soon as the concrete can be walked on, right after finishing, usually in 3-5 hours after pouring. Spray on one application (a thin, continuous film) of RadonSeal Standard at a rate of 2,000 sq. ft. per pail. It forms a colloidal dispersion on the surface, which retards water evaporation. This eliminates/reduces shrinkage cracking and results in less porous and significantly stronger concrete. (Deep-sealing the concrete with RadonSeal is a separate application.) Waterproofing new concreteAs concrete cures, it inevitably develops capillaries. Allow the concrete to cure for at least 28 days and then, deep-seal the poured walls and slab with RadonSeal Standard in 2 applications. This seals the concrete against water, vapor, and gasses, as well as bonds and strengthens the concrete. In case of concrete block walls, let the mortar cure for at least 14 days before applying RadonSeal Plus. Waterproofing new foundation wallsRadonSeal is often used in combination with an exterior waterproofing coating, which is required by building codes in most counties. Exterior coating bridges cracks, holes or defects in the concrete. Applying RadonSeal first extends the life of the coating by neutralizing alkalis and provides the waterproofing function once the coating deteriorates. In general, the lower the quality of concrete the higher the need to apply a waterproofing coating over RadonSeal. Unfilled cinder blocks and concrete blocks have only thin walls (1-1/4") on either side of the hollow core and some have visible holes rather than microscopic pores. The most effective RadonSeal application is waterproofing both sides of the walls. But first, the concrete has to cure for 28 days, or 14 days for mortar in block walls. Afterwards, let the concrete dry out for at least 3 days if you wish to apply an exterior waterproofing coating. However, many contractors have to backfill in just a few days. In that case, use the usual exterior waterproofing coating and later, apply RadonSeal on the walls' interior only. Although it cannot protect the outermost layer of concrete, it still waterproofs the walls and extends the life of the exterior coating. Waterproofing an existing basementRemove any old paint or tile adhesive. More info on removing paints at FAQ's The spray-on application is quick and easy, just visit the Application Instructions & Tips. You can move all your "stuff" to one side of the basement and seal the other side first. Let the concrete dry out for a couple of days and then, seal the other side. Seal both the floor and the walls. More on How to Repair a Wet Basement How to check for moistureMany home sales get re-negotiated or even canceled when the building inspector discovers moisture. What will the building inspector look for?
Check for leaks any visible cracks in the concrete, the floor-to-wall joints, expansion control joints in the floor, and all penetrations. Next, test for moisture transmission through the concrete: Place a foot-square of plastic or aluminum foil on the floor or wall, seal the edges with duct tape, and check after a couple of days for drops of water. Any questions? Please contact us by e-mail, MADE IN USA |
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