How to Insulate Overhangs and Cantilevered floors
Overhangs have more surface area
exposed to the outdoors
relative to other parts of the house and the more surface you have
faster you loose heat. Floors
directly to the outdoors are prone to air leakage because they are
covered with just one layer of sheathing. See
also band joists, rim joists, and between floors.
- Pipe freeze ups
(see recommendations below)
- Cold and drafty
- Poor energy
- Cold floors
- Cold interior walls
- Excessive heat
loss in ductwork
Insulate the overhanging portion of
the floor to the same
level that you would insulate a roof or attic in order to compensate
additional surface area losses.
installing plumbing in a cantilevered floor.
If you have to run plumbing out into a cantilevered floor
for a bathroom
or radiant heating, make sure to build airtight and insulated “boxes” around the plumbing to reduce heat loss and the chance for pipe freeze
ups. Leave the box
“open” to the
interior side so the plumbing gets the benefit of the warmth of the
house. You want the
plumbing to be trapped in the
warm side of the cantilevered floor with plenty of R-value below. Where
floor joists pass from outside to inside make sure there is a thermal
“block” in the plane of the exterior wall at the end of each floor bay.
- Overhangs and
cantilevered floors are “peninsulas” that jut out from the main house
and have higher surface area exposure than other parts of the house. More surface area to
radiate and conduct heat to the outdoors.
- The floor bay goes
from inside to outside and needs an airtight stop in the plane of the
exterior wall to prevent cold air from entering.
If this stop is not complete then...
- Cold air has easy
access to the rest of your house. Traveling
between floors until it finds plumbing, ductwork, interior walls,
- Any plumbing in an
overhang should be inside an insulated box.
Insulation-Guide has seen many pipe freezes in this
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