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What
the experts say about Precision Engineered
Framing:
"It's
fabulous... a proven technology that
deserves much greater application in the
building industry."
- Bob
Vila,
" Home Again"
"For
new construction, I don't think there's any
reason to use anything but the panels."
- Norm
Abram,
" This Old House" and “New
Yankee Workshop”
“I was
really impressed with how easy and quick the
panels went together. This type of
construction is the wave of the future!”
- Ben
Mandell,
“ New Home Show”
“...
goes up incredibly fast...”
- Steve
Thomas,
“ This Old House”
"Every
once in a while a new technology comes along
that makes its predecessors obsolete.
John Henry couldn't compete with the steam
drill, power saws replaced hand saws, and
drywall replaced plaster and lath.
There is no going backward. Today,
structural insulated panels (SIPs) are in
the process of replacing the postwar norm of
stick-framed, fiberglass-insulated
houses"
- Michael
Morley,
author of “Building With Structural
Insulated Panels”
“I was
a firm believer in stick framing for years,
but I’ll never go back.”
-- Rick
Thompson
Short
installation time, reduced waste - builders
reap the benefits of advanced panel systems.
By:
Scott T. Shepherd, PATH Partners
A way to build better and
faster — what's not to like? Builders are prefabricated
building panels that form a structural
"envelope" for the home,
eliminating the need for conventional wood
framing. Panelized systems can be assembled
on-site faster by less skilled laborers.
Despite
these and other significant benefits,
panelized wall systems capture only about 8%
of the market, according to the Wood
Promotion Council. Builders wary of panel
systems point to the cost, noting that they
have to pay at least as much, and usually
slightly more, than they do for stick
building their walls. They also express
concerns about teaching crews new methods
and meeting building codes with a less
common product.
Change
is never easy, but there are real benefits
to builders willing to make the leap, says
Kirk Grundahl, executive director of the
Wood Truss Council of America, an
international trade association representing
structural wood component manufacturers.
“A lot of the hesitancy about panelized
walls is traditional mind set," says
Grundahl. "Builders who use them can
build homes better and faster."
Curtis
Stendel of Panelworks Plus in
St. Francis
,
MN
, wholeheartedly agrees. Stendel, who
teaches other builders about advanced
panelized construction, says that he and
other panel builders find that they not only
have less need for skilled labor, but they
also shorten their installation time, reduce
waste and have less risk of theft on-site
than their stick-building counterparts.
Different
Panels for Different Builders
Advanced
panel systems take many different forms. The
usefulness of each one depends on the
builder and the client.
The most common systems are
structural insulated panels (SIPs), which
are closed walls made from polyurethane foam
core adhered inside and outside to oriented
strand board (OSB) or plywood skins. The
foam has some strength, but when bonded to
OSB or plywood, it acts as a bridge to
augment the panel's structural capacity.
A
variety of materials can be incorporated
into other open- and closed-wall panel
systems, including wood studs or light gauge
steel with foam insulation, structural
concrete, concrete with foam core
insulation, aluminum, steel and fiberglass
skins. SIP panels usually come in modules of
4 feet by 8 feet or greater with a thickness
of 4 to 6 inches, depending on the type of
panel and the insulation required in that
region.
SIP
panels are assembled to form exterior walls
or roofs with minimal additional framing.
Installation techniques vary by type and
manufacturer. Typically, connections along
the top and bottom of the panel and at panel
abutment edges are required.
The
Pluses of Panels
Of
course, the builders who use SIP panels
didn't switch simply out of curiosity. They
were seeking — and are finding — bottom
line benefits.
Through the ease and speed of
assembly, SIP panel wall and roof systems
can be built in days rather than weeks. The
faster construction time also greatly
reduces the chance of theft and of bad
weather creating construction delays.
Because most of the cutting is done in a
remote factory, the builder has to deal with
much less waste on-site.
Only basic carpentry skills are
required for laborers which mean assemblers
don't need the skill of conventional framing
crews. For some builders, reducing the need
for skilled labor is extremely beneficial.
To
ease construction costs even more,
manufacturers offer prefabricated home
packages that compare with the cost of
conventionally framed structures. This is
helpful for standard builders, but is less
advantageous for custom builders since the
cost of producing and engineering panel
layouts may drive up the cost of custom
designs.
Stevens
points out that SIP panels also offer
greater durability than stick-built walls.
Panels can be produced in an automated
factory environment using
computer-controlled equipment that transfers
panel-cutting instructions directly from
digital computer aided design (CAD)
drawings. The resulting components are
precisely engineered and easy to inspect for
quality control.
Beyond
the greater durability, SIP panels have
other attractive selling points. With better
overall air tightness and thermal
performance of the walls and insulation —
common traits of SIP panel systems —
customers will be warmer in winter, cooler
in summer and they'll enjoy energy savings
to boot. SIPs, in particular, can improve
energy efficiency by replacing lumber or
other structural thermal bridges with
insulation material. In addition, the
thicker walls will also add some
soundproofing as well.
Making
the Switch
Before
switching to advanced panel construction,
Stevens suggests builders consider the
availability of skilled labor, time for
design and the time to learn a new
technology.
The time a builder is able to commit
to design issues figures prominently because
the factory relies on receiving accurate
measurements and data from the builder in a
timely fashion. How far in advance the
builder needs to do this depends greatly on
the type of panel and the manufacturer.
"If measurements are inaccurate
or incomplete — as is often the case —
then the designers have to make assumptions
and there is a chance for problems on
site," Stevens says. Taking the time to
get those measurements right the first time
will save some headaches down the road.
Several
big builders — including Pulte Homes, NVR
Homes and Toll Brothers — are willing to
commit that time because of the time they
save in the end. Big builders can easily use
panel systems because they have specific and
repeatable designs.
"You want it to be repeatable
because of the time investment necessary to
properly develop the factory's software to
cut the panels," Stevens says.
Small
builders may also benefit from using panels
if their building designs are fairly
reproducible. Because of the difficulties
managing wood use and costs, panels provide
a way for builders of any size to develop
more predictable fixed costs for the
project.
"Builders can get a better
handle on fixed costs, and managing the
quantity of material is always a big issue
with wood," Stevens says. "When
using panels, it's much easier to estimate
those numbers."
The
Cost of Quality
While
it may be easier to estimate fixed costs
with advanced panels, do they cost less?
With improved quality and speedier
on-site construction time often comes
greater material cost, because now the
builder pays for partially fabricated walls.
While
cost varies greatly with the different types
of advanced panels and the size of the
structure, most panels are somewhat more
expensive per square foot than a stick-built
home of comparable size.
During
the transition period, inexperienced crews
or poorly coordinated panel dimensions can
make the process more costly. However, panel
builders say these issues are easily
overcome with experience.
"For a typical builder, the
proficiency comes after maybe three to five
projects," Stendel says. "But for
some projects, you get it right the first
time and they are off and running. It's not
really difficult."
Weighed
against the additional cost is the prospect
of greater savings — from reduced time for
construction, reduced chance of theft and
weather delays, less waste and less need for
skilled labor. The equation will differ for
every builder, but advanced panels may be
most cost-effective in those areas where
labor is difficult to obtain.
Learning
Curve
While
it may not be difficult, there is a learning
curve, as with any change in building
methods. That was certainly the case for
Scott Bergford, founder and president of
Scott
Homes
in
Olympia
,
Wash.
Eleven years ago, Bergford was using the
conventional stick building method when a
customer asked him to use SIPs.
"We had never even heard about
them," says Bergford. He was intrigued
by what he learned. To experiment, he built
his business partner's home with SIPs.
"We had to redo things and we made
mistakes, but we worked them out," says
Bergford. This decision led to a long-term
commitment to panel building.
For
Bergford, the biggest difference was
learning how to manage utilities while
installing wall panels, particularly SIPs
that have foam attached to the panels.
Bergford learned he needed more
chases in the kitchen walls. The panel
provider was happy to oblige. Bergford and
his crews also started using a flexible
drill bit to make their own chases to snake
wiring through the walls.
"Every once in a while we get a
new subcontractor and he doesn't follow the
directions and he will have sliced the panel
in half," Bergford says. "So now
we have learned how to fix a SIP panel once
the plumber has destroyed it."
"At this point, I really don't
know what we could run up against that we
wouldn't know how to fix."
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