Sealer and Waterproof Paint
The No. 1 Enemy of Finished Basements - Moisture
Finished walls and floor coverings trap moisture, which accumulates and causes molds and mildew. The musty odor found in many basements is the telltale sign of molds, which may be growing inside the carpeting or walls, or in upholstered furniture.
As houses age, most basements start seeping water through the concrete or cracks after a heavy rain or snow melt. The walls, carpets and furniture get wet and molds start growing in just several days. Moldy drywall, carpeting and furnishings have to be discarded.
Why risk your basement remodeling investment (typically $15,000 or more!) and more importantly, the health of your family? Before finishing the basement, seal it against moisture!
Basement as a Source of Moisture
Sooner or later, most basements develop water seepage. At first, it is just intermittent after a heavy storm or snow melt raises the groundwater level but over time, the leaks become more and more frequent.
However, most moisture infiltrates into basements in the form of water vapor, which is invisible, unlike steam condensing above a pot with boiling water. Low air pressure inside buildings draws in soil gas with water vapor from the ground through all openings and pores in the concrete.
Basements are the largest source of moisture in homes and typically, let in over 15 gallons of moisture each day! That is much more than cooking and showering combined (3-5 gallons per day). See more in Basement Waterproofing. Concrete is Very Porous Concrete cures by cement reacting with water (hydration). But concrete mixes contain much more water than needed, in order to make them easily workable. Almost half of the water is surplus and has to evaporate as concrete cures. While water pushes through the concrete to the surface, it leaves behind a network of tiny capillaries (pores), much smaller than a human hair. As a result, concrete is more porous than Swiss cheese residential concrete contains 12 to 20 percent air! Gases and vapor (water molecules) flow easily through the pores. But liquid water has is tougher the water molecules are held back in a blob by surface tension until the pore surface gets wet. Then, liquid water starts seeping through the wet pores in concrete (capillary seepage). Moreover, the pores draw in water like a sponge by capillary action water comes up through a concrete slab against gravity.
Homeowners often paint walls with a store-bought waterproofing sealer, which is merely a latex-based paint. Sooner or later, it will crack and peel under the attack of lime from the concrete (specification). And it cannot hold back efflorescence (white powder) or a high negative side water pressure. More importantly, it is porous and cannot stop water vapor or most of the moisture seeping through the concrete. Some cover the concrete with plastic sheets or use plastic covered insulation "pillows" on the walls. But this traps any moisture coming through the concrete and is known for causing severe mold and mildew problems. We strongly recommend against trapping moisture - all moisture coming through the concrete should be allowed to evaporate. Floor slabs are usually poured on a plastic sheet a "vapor barrier". But it gets usually punctured during construction and over the years, it slowly disintegrates under the attack of lime in the concrete. To stop water vapor, concrete slabs are sometimes painted with epoxy or urethane paints, which are impermeable to vapor. They trap all the moisture for a while, but after several years, the paint starts bubbling or cracking and loses its purpose. We strongly recommend sealing the concrete with a top-quality silicate-based penetrating sealer. It penetrates deep into the pores in concrete, reacts with lime and alkalis, expands and hardens, which bonds and seals the concrete permanently! Seal the Concrete before Finishing the Basement Concrete is not a rock! It is porous and it ages, becoming more and more porous. Just like wood, it needs a sealer - protection against water and deterioration.
The 3 Brothers Waterproofing Sealing Solution
Sealing all sources of moisture, and eliminating internal sources of moisture, by doing the following:
- Vent the clothes dryer to the outside
- Insulating air conditioning ducts against condensation
- Keeping rain water away from the foundation
- Installing proper gutter and downspout extensions
- Properly sloping grading around the foundation
- Shallow swales or French Drains to steer water away
- Sealing all openings and covering sump pit air tight
- Taping a plastic sheet to isolate a crawlspace, if there is one
- Installing check valves in any and all floor drains to stop vapor
- Sealing open cores in block walls with expandable foam
- Sealing all hollow lolly columns
- Caulking all gaps and joints, including floor-to-wall joints and expansion control joints
- Caulking around all penetrations
- Sealing concrete against water and vapir