Cooperative Living June 2015 - 18

WI$E ENERGY U$E
THE LATEST IN
WAYS TO BUILD
A STURDY HOME
by James Dulley, Contributing Columnist
Q.
We are empty
nesters and
have decided to
build our dream home.
What are some of the
most efficient homeconstruction
methods?
Severe weather is a
concern in our town,
so options that offer
strength and ruggedness
would be best. ― Ian P.
A.
There are several relatively
new home-construction
methods that are much
stronger and efficient than
typical insulated, wood framing built to
code. Some of these methods use more
than double the insulation value of typical
framed walls and can even withstand
hurricane- and tornado-force winds.
If you decide on a wood-framed
house, use staggered, double-stud walls
on 24-inch centers. This construction
method not only provides double the
insulation value, but by staggering the
wall studs, it minimizes thermal bridges
(direct non-insulated heat-flow paths
from indoors to outdoors through the
wood studs).
For a wood-framed home, install rigid
Once the insulated
forms are erected and
the reinforced steel is
installed, the concrete is
pumped in from the top.
16
foam wall sheathing on the exterior so
that all of the lumber's thermal mass is
inside of the insulation envelope. This can
be covered with any type of exterior finish,
such as siding, brick or stucco. Use a
relatively square or circular shape to
minimize the exterior wall and roof area.
With similar insulation levels, a wall that
is twice as big as another will lose about
twice as much heat. Generally, squareand
circular-shaped homes resist the
forces of storm winds best. This is why
animals typically build round nests and
dens, which can withstand major storms.
The " stay-in-place " home-construction
method uses concrete and rigid
foam insulation; this method is efficient
and strengthens the home. The insulation
forms, which hold the wet concrete,
are not removed, and they provide the
insulation and substrate surface for
installing the interior and exterior wall
coverings. Wall insulation values are as
high as R-40 when this method is used.
A similar method uses hollow foam
blocks made to fit your home's plans.
The blocks are designed so there is an
open cavity throughout the inside. Concrete
is pumped into the openings at the
top of the walls and flows throughout
the blocks, which creates a strong, efficient
structure.
SIP (structural insulated panel) systems
are a subset of standard foam insulated
panels, which have a thick foam
core sandwiched between two rigid
sheets of various materials. The standard
panels are often used for the exterior
walls to enclose post-and-beam-framed
and steel-framed homes for some of the
highest insulation levels possible.
The rigid sheets in SIP panels are
unique because they are made of OSB
(oriented strand board), which creates
a strong, highly insulated panel. The
panel is self-supporting and does not
require additional basic wall framing.
Once the panels are attached to the
foundation and are connected, the SIP
panels support themselves, the floors,
ceiling and roof.
Steel-framed construction is an excellent
construction method if strength is
the goal. Steel is strong. It does not burn
or change shape over time as lumber
does, and each steel piece is nearly identical.
Also, much of the steel used today
in home construction is recycled from
scrap materials.
From an efficiency standpoint, steel is
superior to most other framing materials.
Although steel is not a good insulator, its
strength allows for thinner studs and
wider spacing. This leaves much more
room for additional insulation inside the
walls and fewer thermal bridges.
Efficient straw-bale homes date back
more than a century in the United States.
When placed on its side, each threestring
bale is about 23 inches wide.
When packed to a normal density, it
produces an insulation value greater than
R-50. The bales are stacked and bolted to
a concrete foundation with vertical
Cooperative Living/June 2015
PHOTO COURTESY OF ECO-BLOCK
Cooperative Living June 2015

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