|
WATER-MANAGED
FOUNDATION SYSTEM
Most basement water leakage is due to either bulk moisture leaks
or capillary action. Bulk moisture is the flow of water through
holes, cracks, and other discontinuities into the home’s
basement walls. Capillary action occurs when water wicks into
the cracks and pores of porous building materials, such as masonry
block, concrete, or wood. These tiny cracks and pores can absorb
water in any direction–even upward.
The best approaches for preventing these problems will depend
on the local climate and style of construction, but the following
general rules apply to most basement designs.
1. Keep all untreated wood materials away from earth contact.
2. Provide drainage, such as gutters, to conduct rainwater away
from the house.
3. Slope the earth away from all sides of the house for at least
5 feet at a minimum 5% grade (3 inches in 5 feet). Establish drainage
swales to direct rainwater around the house.
4. Add a sill gasket to provide air sealing.
5. Install a protective membrane, such as caulked metal flashing
or EPDM-type membrane, to serve as a capillary break that reduces
wicking of water up from the masonry foundation wall. This membrane
can also serve as a termite shield on top of the insulation board.
6. Damp proof all below-grade portions of the foundation wall
and footing to prevent the wall from absorbing ground moisture
by capillary action.
7. Place a continuous drainage plane over the dampproofing or
exterior insulation to channel water to the foundation drain and
relieve hydrostatic pressure. Drainage plane materials include
special drainage matts, high-density fiberglass insulation products,
and washed gravel. All drainage planes should be protected with
a filter fabric to prevent dirt from clogging the intentional
gaps in the drainage material.
8. Install a foundation drain directly below the drainage plane
and beside the footing, not on top of the footing. This prevents
water from flowing against the seam between the footing and the
foundation wall. Surround a perforated 4-inch plastic drainpipe
with gravel and wrap both with filter fabric.
9. Underneath the basement’s slab floor, install a capillary
break and vapor retarder, consisting of a layer of 6- to 10-mil
polyethylene over at least 4 inches of gravel.
BASEMENT INSULATION PLACEMENT
In most cases, a basement should be considered a conditioned space
with insulation installed in the exterior basement walls.
Even in a house with an unconditioned basement, the basement is
more connected to the other living spaces of the home than to
the outside. This makes basement wall insulation preferable to
insulating the basement ceiling.
Advantages of basement wall insulation include:
• Basement spaces, whether conditioned or not, are warmer
and more comfortable.
• Compared to insulating the basement ceiling, insulating
basement walls:
— requires less insulation (1,350 square feet of wall insulation
for a 36- by 48-foot basement with 8-foot walls, compared with
1,725 square feet of basement ceiling insulation),
— more easily achieves continuous thermal and air leakage
boundaries because basement ceilings are typically penetrated
with electrical wiring, plumbing, and ductwork,
— requires little, if any increase in the size of heating
and cooling equipment–the heat loss and air leakage through
the basement ceiling is similar to that through the exterior walls
of the basement.
• Piping and ductwork are located within the conditioned
volume of the house so they do not require insulation for energy
efficiency or protection against freezing.
Next:
Interior Basement Wall Insulation Stratagies
Energy
Efficiency Articles
Hardwood
vs Laminate
The difference is more than you think, or maybe not!
Good
Carpet is best!
There is nothing like walking barefoot on great carpet
Caring
for Hardwood is easier than you think.
Just vacuum and you are done.
More
Articles...
|
