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SIP -
stands for Structural Insulated Panels
History
The
US Forest Products Laboratory built the
first SIP structure in 1935; however, energy
efficiency concerns didn't exist until fuel
prices increased. The first increase, in
1974, saw the cost of crude oil rise from
$11.45 per barrel to $18.21, a jump of over
$6.75 per barrel or 59%. Product
performance and affordability were impacted
by the introduction of oriented strand board
in 1981, which eliminated the use of
plywood.
Benefits
to the Builder
SIP
builders establish a specialty market that
separates their business from other builders
because they provide the community with a
final product that has superior energy
efficiency and structural performance.
SIP
combine structural framing, insulation, and
sheathing into one step, therefore providing
the opportunity for more projects per year.
SIP are easier to work with during the cold
winter months. After quickly installing the
panels, the rest of the project can be spent
completing the work on the interior.
The
pre-built nature of the SIP system requires
fewer framers. In the
United States, fewer people are choosing building as a
career. Less than 30% of these construction
positions are being filled. Sips can help
lessen this manpower shortage because it’s
much easier to learn how to build with SIP
panels than with traditional framing.
SIP
reduce job site waste by reducing the cost
of waste disposal. According to statistics,
the average builder pays $511 per 2,000 sq.
ft. home for waste disposal. Wood
products account for 35% of this waste.
The typical exterior framing waste of an SIP
home can be hauled off in a 55 gallon
container.
Also,
every builder experiences job site material
theft. It's much more difficult for
SIP panels to be stolen than it is with
standard lumber.
SIP reduce the margin for framing errors. Each panel is
numbered to correspond with a blueprint. Panels
are built to specifications, taking the
guesswork out of design and quality control
on-site.
Maintaining a consistent profit margin becomes easier with SIP,
since the builder knows costs upfront for
the exterior framing.
Stick
framing relies on the integrity of a
multitude of connection points between 2x's
and sheathing. With SIP loads are
distributed across the entire panel due to
the continuous bond between the sheathing
and rigid insulation. A SIP panel can
be compared to an I-beam, with the sheathing
acting as flanges and the insulation as the
web. Because of this, a SIP structure is
many times stronger than a conventional
structure.
Benefits
to the Homeowner
The biggest benefit of the SIP system is energy efficiency.
The home is wrapped in polyurethane
insulation without the thermal breaks
experienced in 2x framing at each stud and
around the electrical work. Also,
polyurethane insulation maintains its
integrity over time, whereas batt insulation
settles and absorbs moisture.
The
US Department Of Energy compared 5 different
building systems for clear-wall R-value
(Measures the R-value of an uninterrupted
insulation cavity section of a wall) vs. whole-wall
R-value (Takes into account the
areas where most thermal performance is
lost, such as corners, studs, wall to roof,
window, and door areas). The test
concluded that SIP maintain 88% of their
clear-wall performance after whole-wall
R-value is measured. This is 58%
better than 2x6 stick framing.
SIP Panels provide a quieter and healthier
living environment. Polyurethane insulation
is an excellent sound barrier, and the
naturally tight construction of a SIP shell
helps prevent dust and allergens from
penetrating the home. The installation
of air exchangers is recommended to promote
healthier air quality and control humidity.
A SIP home provides flexibility and freedom of interior design.
There is no need for a stud-finder. The
entire inside is sheathed with oriented
strand board. Finding a place to
support a nail for pictures, curtains, or
cabinets isn't a problem. There is
time and money to be saved when it comes to
applying sheet rock! It should be noticeably
faster since you don't have to worry about
hitting the studs.
SIPS
are typically composed of two materials- OSB
and EPS or OSB and polyurethane, and are
environmentally safe. The OSB is
derived from short growth, or
“Replaceable” tree crops. The
polyurethane insulation does not contain any
CFCs, (chlorofluorocarbons) or formaldehyde.
Compare
SIP technology to Stick Framing
The cost of SIP is always compared to stick-frame
construction, but is not an
“Apples-to-apples” comparison, since 2
times the construction cannot compete with
the thermal efficiency or strength of SIP.
To build a house out of conventional
materials that would perform with the same
thermal efficiency and strength as a SIP
house would cost 40-50%
higher than a SIP home. Although the
material cost of SIP is higher than 2x
construction, you are actually paying for
some of your framing labour when you
purchase panels. The finished home
cost difference is only 3%-5% more than a
stick-framed home. The difference
depends on labour and materials costs in
your area. The minimum 50% energy
savings quickly recoups any additional
initial investment over the cost of
conventional framing. The savings
continue even when you sell your home.
A study released by the EPA in 1998 revealed
that energy efficiency increases the resale
value of homes by $20 for every $1 in annual
energy cost savings.
The
results of yet another construction process
analysis was written in a 1998 report to the
U.S. DOE, Department of Industrial
Engineering and Management Systems,
University of Central Florida, Orlando, FL.
The study focuses on the construction of two
similar single-family homes, one SIP and one
stick-built, built by Habitat for Humanity
during fall 1997. The data indicated that
the SIP home saved 65% of the site labour
when compared to the stick-built home. Cycle
time savings are of similar magnitude.
Volunteers were interviewed after framing
the SIP house to gauge their perception of
SIP construction. The results suggest that
both construction professionals and other
volunteers believed that SIP reduced
construction effort significantly, averaging
about one-half the effort of conventional
construction.
The EPA has developed a program called
Energy Star Homes to help homebuyers offset
the up-front cost of building a better home.
Some incentives include Energy Efficient
Mortgages through lending partners such as
Chase Manhattan Bank. The perks of
Energy Efficient Mortgages include
debt-to-income ration loan stretches,
closing cost rebates, and lower interest
rates. Also, congress is debating a tax
credit of 1% of the purchase price with a
maximum of $2,000 for newly built homes,
which use at least 50% less energy than the
Model Energy Code.
Today some builders are still resistant to change their
construction methods, but this is only
temporary because customer demand will
dictate acceptance. In
the future, all builders will give customers
the option of building with panels, after
all, why would anyone build with anything
else?
Labor Savings
Labor
today is the one single component of the construction
costs that if properly controlled will benefit the
contractor the most. SIP’s
can help to manage and better control those costs in
several ways.
Because
of the superior structural strength of SIP’s over
conventional stick-built construction, the erection of the
building shell does not require the workforce to
understand all aspects of construction.
This is achieved by the manufacturer in their
planning and design stage.
For example, door and window openings of less than
48” wide do not require the normal building components
as in conventional construction.
This allows for the journeyman carpenters to plan
and construct other aspects of the job.
The
erection of SIP panels on the job site is much faster than
the stick-built construction of those same walls.
Once again the design and layout is the
responsibility of the manufacturer and builder long before
construction begins. Once
the panels arrive on the site, the job of the contractor
is to set them in place according to a detailed drawing
showing their placement.
Once
the SIP panels are in place and secured, the construction
of the shell is complete and ready for windows and doors
to be installed. The
openings for these items will have already been done in
the manufacturer’s facility leaving any structural
concerns to the manufacturer and their structural
engineers and not to the contractor.
The
last and most important time saving advantage of SIP
construction is the insulating of the shell.
With SIP’s this has already been done.
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