Basement Remodeling Starts with
Sealing the Concrete Your step #1 in basement remodeling Before finishing the basement, deep-seal your concrete against water seepage,
water vapor, and soil gases like radon. RadonSeal penetrates deep into new
or old concrete (up to 4 inches), reacts and seals it internally to provide:
- Waterproofing
- Damp-proofing
- Radon mitigation
- Concrete preservation
The spray-on application is quick and easy for basement remodeling contractors
or homeowners. RadonSeal is non-toxic, nonflammable, and emits no VOCs.
And best of all, the seal is permanent! Basements slowly self-destruct Moisture problems are the most common complaint of homeowners and most
basements develop water seepage within 10 to 15 years. One out of five homes
have elevated radon levels. Concrete is naturally porous (12%-18% air)
- when it cures, surplus water escapes and creates a network of interconnected
capillaries, much smaller than human hair (10-100 nm). The capillaries draw
water from the ground by wicking action or let in water under hydrostatic
pressure. The pores also let in water vapor and radon gas, which are pulled
in by the lower air pressure and concentration indoors. Concrete is highly alkaline (pH 9 -11). The
alkalis disintegrate exterior waterproofing coatings - even the best membranes
are guaranteed for only 5-10 years. The plastic sheet under the slab (vapor
retardant) gets "eaten" by lime from the concrete. As soil and
gravel settle, water and soil gases pool in the void right underneath the
slab. Water migration gradually leaches out concrete and makes it more and more
porous. As concrete ages, the seepage of liquid water, water vapor, and radon
gas steadily increases. How alkalis attack the finished basement Water carries dissolved alkalis from the concrete and soil. Water vapor
condenses on cool surfaces ("sweating walls" in the summer) or
when trapped under a covering, and activates the alkalis in concrete. Alkalis dissolved in water attack fatty acids in paints and adhesives (saponification).
All paints or surface sealers will peel or blister. If you install floor
tiles, sheet vinyl, linoleum, glue-on wall panels, it will trap moisture
and the glue will disintegrate. The alkalis even attack carpeting, floor
coverings, and the concrete itself. Lime from inside the concrete forms efflorescence
(whitish minerals), which easily lifts paints and floor tiles. RadonSeal reacts with the lime and alkalis in concrete, stops efflorescence,
and seals the capillaries against water and vapor. Protect your basement remodeling investment Even if your basement looks dry, moisture is pouring in as invisible vapor
and by evaporation of water seeping through capillaries. The basement is
by far the largest source of moisture in your
home (over 15 gallons/day). Covered floor and walls in the finished basement
trap moisture and eventually cause:
- Damp or wet basement (high humidity, seepage, condensation)
- Musty odors (from molds devouring organic materials)
- Molds and mildew (spread by ventilation through the house)
Basement finishing is a cost-effective home improvement project. But first,
seal all under-the-grade concrete with RadonSeal to protect your investment
and your family's health. Afterwards, seal or caulk any openings, gaps, or
cracks. Molds and mildew love finished basements! Moisture promotes molds, mildew, dust mites, and other biological air contaminants,
which cause allergies, asthma, or other health problems. Ventilation spreads
humidity and contaminants through the house. Molds also need high humidity and organic or moist porous materials (concrete).
They thrive in carpeting, upholstered furniture, drywall, and wood paneling.
Mildew munching on cellulose produces volatile organic compounds (e.g. aldehydes),
which we detect as musty odors. Moldy furnishings have to be discarded. The key to fighting or preventing molds and mildew is removing
the source of moisture. Seal your basement with RadonSeal against
capillary water seepage and water vapor. Radon problems in basements Several years after finishing the basement, you might find that the radon
level has increased above the EPA's action limit (4 pCi/L) and must be reduced
to make the house marketable. But once the basement has been finished, you
have to get a fan-based radon mitigation system ($1,200 on average). The
radon fan and piping will not enhance the house value. You may want to reduce the radon level to a minimum just to protect your
family's health, particularly, if the children spend lots of time in the
finished basement. Before basement remodeling, seal the concrete with RadonSeal to reduce
radon to a minimum and to keep it that way. You already have moisture problems? Without fixing any existing water seepage or dampness problems, whether
visible or not, you cannot finish the basement. There are various options: Exterior waterproofing of the walls is a proven and expensive
solution (say $10,000) but does little against moisture seeping through the
slab. Interior perimeter drains (say $6,000) under the slab
do little for seepage through the walls. Interior channels (say
$3,000) take water seeping through the walls to a sump pump but do nothing
for the slab and release lots of vapor and radon. These methods do little
against water vapor seeping in through the concrete. Waterproofing surface sealers applied on the interior
cannot hold back negative-side water pressure or efflorescence. Cementitious
waterproofing coatings stop active seepage and last longer. But
over time, they will crack and separate because of the alkalis in concrete
and they cannot stop the main source of moisture - vapor. Never cover the floor or walls with a plastic sheet! It
cannot stop water being drawn inside by the force of capillary suction or
as water vapor - it just traps it. After a couple of years, you would likely
discover musty odors, molds and mildew. Running dehumidifiers is expensive and they pull in more
moisture through the concrete, speeding up its deterioration. If the concrete is cement-based (not lightweight blocks) and still sound, RadonSeal will
seal it against the seepage of water and vapor. After application, increase
ventilation in the wet area or install a dehumidifier/fan for several days
to let it dry out and cure. Re-spray if necessary. Afterwards, seal or caulk
any cracks or openings. How NOT to finish basement walls! Most finished basements are constructed with interior insulation – stud
wall framing filled with paper-faced fiberglass batts, often covered with
polyurethane vapor barrier, or fiberglass “blanket” insulation
with impermeable vinyl or aluminum interior surface. But according to the
latest research, this common construction is unsuitable
for the building home industry due to serious problems with mold,
decay, and odors. (Building Science Consortium) It traps water vapor
coming from the exterior, small leaks let humid interior air reach the cold
wall, and any ground water seepage cannot dry out. "The use of vapor barriers (polyethylene or vinyl wall coverings)
has caused many building failures and facilitated the growth of molds in
many buildings. The wide spread use of double vapor barrier basement wall
in Minnesota has resulted in many failures, in some cases within a year of
construction." How to build interior basement walls Heat loss from an uninsulated basement can account for up to one
third of the heating cost in an average home. The walls must be insulated
on the exterior or interior for the house to be called "energy efficient." How
much insulation? Department of Energy recommends total R-values for existing
houses in most regions R-11 for interior basement walls (R-19 for crawlspace
walls). Exterior insulation of extruded polystyrene
panels is best. It stops exterior moisture and keeps the walls warmer, which
prevents condensation, and lets them dry out to the interior. But it has
not been widely accepted because of potential damage during backfilling,
needed design modifications, and concerns about termites. Interior insulation must be permeable to water vapor coming in from the
exterior and must allow any groundwater seepage to dry out. And it must also
stop moisture laden interior air from contacting the cold concrete surface,
in order to avoid condensation in the summer. We need not
a "vapor barrier" but an "air barrier." And the
insulation must be moisture-tolerant. The proper solution:
- Seal the concrete with RadonSeal against water seepage and water vapor.
- Glue on the walls extruded polystyrene (XPS) sheathing (1-2
inches) or expanded polystyrene (ESP or "beadboard" is cheaper
but more permeable to moisture, less moisture-resistant and has a lower
R-value). Seal joints either with tape or fiberglass mesh and mastic.
- Hold the panels in place permanently by wood furring strips attached
through the XPS by power driven nails, or build 2"x3" 24” o.c.
wood stud wall attached to floor and floor joists.
- Polystyrene is flammable and must be covered with a 15-minute fire-rated
material - 0.5 inch gypsum board without paper facing. Hold up from the
floor at least 1/2 inch. Unfaced batt insulation is optional.
- Use only latex paints (semi-permeable to moisture) on the gypsum board.
A simpler alternative solution - avoid any plastic vapor barriers and build
a stud wall about 1-inch away from the concrete wall,
using unfaced insulation batts (or slash the paper backing with a knife) and gypsum
board. The space allows for evaporation of water from the concrete and avoids
a direct contact of moisture-sensitive materials with the concrete. And by
all means, seal the concrete first with RadonSeal against water seepage and
water vapor. An ounce of prevention ... Your finished basement has to hold back water, vapor, and radon, and needs
a little help. As the first step, seal the walls and slab with RadonSeal penetrating concrete
sealer to protect your remodeling investment and your family's health, to
preserve the concrete, and to avoid costly basement repairs in the future.
Any questions? Please contact us by e-mail,
telephone (203) 225-0366 or toll-free 1-800-472-0603
MADE IN USA
Products not sold through retail stores. Available exclusively from:
Radon Mitigation & Waterproofing Concrete Sealer Co.
Novion Inc., 18 L'Hermitage Drive, Shelton, CT 06484 USA
RadonSeal™ is a registered trademark. Copyright © 1998-2008. All rights reserved.
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