Copyright Goodheart-Willcox Co., Inc.
268 Section 2 Foundations and Framing
Green Note
The thermal envelope is a protective shell that curbs
unwanted air leakage in or out of a building. It allows a
building to conserve energy and reduce heating costs by
passively preventing heat loss through use of insulation,
air barriers, and advanced framing techniques (AFTs).
Advanced framing techniques (AFTs) minimize waste
by eliminating redundant lumber use without weakening
the structure. Since heat escapes faster through wood
than insulation, using less lumber and more insulation
strengthens the building’s thermal envelope.
11.14 Housewrap
Housewrap is a thin, tough, plastic sheet material that
is applied to exterior walls. It prevents movement of air
into or out of a building. See Figure 11‑49. Manufac-
tured under such trade names as Tyvek® and Typar®,
it comes in rolls of various widths up to 10′. House-
wrap can have numerous functions depending on its
type and its installation as part of the building enve-
lope. It is efficient at preventing air infiltration. At the
same time, it is water resistant. Housewrap is designed
to prevent bulk water from entering the structure, yet
allows interior water vapor to pass through and escape.
This property is known as vapor permeability.
The typical housewrap is made from high-density,
spun, polyethylene fibers. These fibers are virtually
tearproof. Housewrap is stapled to the sheathing before
exterior doors and windows are installed.
Housewrap can also be applied to concrete block walls
as an air- or weather-resistant barrier. Usually, block ma-
sonry is then faced with stucco or brick. Caulk is used
at 6″ intervals as the preferred fastening method. Fol-
low the manufacturer’s instructions. For more on the
functions and installation of housewrap, see Chapter 15,
Building Envelope and Control Layers.
11.15 Estimating Materials
To estimate wall and ceiling framing materials, first
determine the total lineal feet of the walls. Add the
length of each wall and partition. The plans include
the dimensions of outside walls. These can be added
together. Very short partitions may not be dimen-
sioned. In this case, use a scale on the drawing. It is a
good idea to place a colored pencil check mark on each
wall and partition as its length is added to the list.
For plates, multiply the total figure by three (one sole
plate plus two top plates) if you are using a double top
plate or by two if you are using a single top plate. Add
about 10% for waste. Order this number of linear feet
of lumber in random lengths or convert to the number
SV Production/Shutterstock.com
Figure 11‑48. This SIP wall is being lifted into place with a crane. It has all of the door and window openings already
prepared.
brizmaker/Shutterstock.com
Ken Wolter/Shutterstock.com
Figure 11‑49. Housewrap is installed over the sheathing
on exterior walls. The wrap is a tough plastic fabric that
prevents air infiltration.
268 Section 2 Foundations and Framing
Green Note
The thermal envelope is a protective shell that curbs
unwanted air leakage in or out of a building. It allows a
building to conserve energy and reduce heating costs by
passively preventing heat loss through use of insulation,
air barriers, and advanced framing techniques (AFTs).
Advanced framing techniques (AFTs) minimize waste
by eliminating redundant lumber use without weakening
the structure. Since heat escapes faster through wood
than insulation, using less lumber and more insulation
strengthens the building’s thermal envelope.
11.14 Housewrap
Housewrap is a thin, tough, plastic sheet material that
is applied to exterior walls. It prevents movement of air
into or out of a building. See Figure 11‑49. Manufac-
tured under such trade names as Tyvek® and Typar®,
it comes in rolls of various widths up to 10′. House-
wrap can have numerous functions depending on its
type and its installation as part of the building enve-
lope. It is efficient at preventing air infiltration. At the
same time, it is water resistant. Housewrap is designed
to prevent bulk water from entering the structure, yet
allows interior water vapor to pass through and escape.
This property is known as vapor permeability.
The typical housewrap is made from high-density,
spun, polyethylene fibers. These fibers are virtually
tearproof. Housewrap is stapled to the sheathing before
exterior doors and windows are installed.
Housewrap can also be applied to concrete block walls
as an air- or weather-resistant barrier. Usually, block ma-
sonry is then faced with stucco or brick. Caulk is used
at 6″ intervals as the preferred fastening method. Fol-
low the manufacturer’s instructions. For more on the
functions and installation of housewrap, see Chapter 15,
Building Envelope and Control Layers.
11.15 Estimating Materials
To estimate wall and ceiling framing materials, first
determine the total lineal feet of the walls. Add the
length of each wall and partition. The plans include
the dimensions of outside walls. These can be added
together. Very short partitions may not be dimen-
sioned. In this case, use a scale on the drawing. It is a
good idea to place a colored pencil check mark on each
wall and partition as its length is added to the list.
For plates, multiply the total figure by three (one sole
plate plus two top plates) if you are using a double top
plate or by two if you are using a single top plate. Add
about 10% for waste. Order this number of linear feet
of lumber in random lengths or convert to the number
SV Production/Shutterstock.com
Figure 11‑48. This SIP wall is being lifted into place with a crane. It has all of the door and window openings already
prepared.
brizmaker/Shutterstock.com
Ken Wolter/Shutterstock.com
Figure 11‑49. Housewrap is installed over the sheathing
on exterior walls. The wrap is a tough plastic fabric that
prevents air infiltration.