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If you're like most architects, you can't contemplate designing a new house with out thinking about stud framing.  Well think again.  My firm won't build another stud-framed house if I can help it.  Not that light wood framing isn't a great structural system.  Its strength and resilience have been proven again and again.  But energy conservation has always been an afterthought.

Critics misjudged stud framing in the 1830s when they called it "balloon" framing, thinking it so light the wind might carry houses away.  Cold wind blew right through instead.  Insulation, vapor barriers, air barriers, and seal strips were subsequent fixes.  Yet
stud work promotes thermal bridging and uninsulated voids, even today.

the alternative
Structural insulated panels (SIPs) offer a better way to build a tight, well-insulated
envelope.  SIPs are stressed-skin sandwiches of rigid insulation bonded between two
wood-fiber facings.  Panels typically are 4 by 8 feet with nominal thicknesses of 3 1/2, 5
1/2, 7 1/2, 9 1/4, and 11 1/4 inches, coordinating with conventional lumber dimensions.
Using SIPs, a small custom house can be erected, sheathed, insulated, and sealed for
air-tightness in a single day.

house # 1 — sips
I wasn't looking for an alternative to stud framing when I stared to design a house near
Woodstock, N.Y.  The clients asked for a home that would deflect north winds, welcome
the winter sun, and stay cool in the summer without air conditioning.  We developed a
barrel roof that curved down near the ground on the north side, exposing and shading
three stories of glass on the south.  But the owners wanted more insulation than rafters or
studs could hold:  R50 in the roof and R30 in the walls.  How could we give them that
amount of insulation if we used wood framing?
 
An associate suggested SIPs.  At first I was suspicious of the panels' claimed
R-values.  But the values proved credible, since the joints are far apart and the panels are
factory-made.  Houses made with SIPs have fewer joints, so they are more airtight than
framed houses and usually don't need a vapor barrier, rood vents, or housewrap.  And
much to my surprise, the local building inspector in Woodstock was all in favor of using
SIPs, having recently approved another panel house nearby.
 
We wanted to avoid roof trusses in our design, because we planned to use that
curving roof shape inside the house, too.  This led to another pleasant surprise:  the
spanning capabilities of SIPs.  A stressed-skin panel develops strength the way an I-beam
does.  The skins act like flanges, taking compressive and tensile loads, while the insulation
works like an I-beam web, distributing shear forces and keeping the skins from buckling.
 
The Woodstock house proved to be warm, draft-free, and solid.  "Once people
have selected panels," says Mike Tobin of AFM Corp., a partnership of SIP
manufacturers, "they start to connect the dots, picking better windows and doors,
heat-recovery ventilation systems, and combined heating systems."

house #2 — stud framed
When we got a call to design another energy-efficient house in the Catskill Mountains, we
jumped at the chance to use SIPs again.  The house was to step down a mountainside,
encompassing a rocky cliff.  The panels enforced the simple geometric discipline of a
monopitch roof.  The framing plan was simple, and construction promised to be quick.
 
Although initially receptive to SIPs, the owner was concerned about the premium
he was paying for this efficiency—more so after he discovered he might have to relocate
soon after the house was finished.  Since the contractor was a proud old framer with little
experience, he offered a 2-percent credit to frame the house with 2x6s instead—with half
the insulation.  Over my objections, we were commissioned to recalculate the structure,
this time using stick framing.  The house is now being finished—alas, without SIPs.  We
call it the Marilyn Monroe house, beautiful on the outside, but hurting inside.

learning curve
To those in the SIPs industry, it's a familiar pattern.  "We do well with quality-conscious
'step-up' home-owners," says AFM's Tobin.  "But if they care more about $400 faucets
than what's inside the walls, they will stick with frame construction."
 
As for builders, few small contractors are willing to bet their businesses on the
time savings promised by houses built with SIPs.  Until they're familiar with the system,
most will estimate labor costs comparable to stud framing.  It usually takes a few SIP jobs
before a builder can appreciate the efficiencies of panel construction.  Still, "it isn't rocket
science," says Structural Insulated Panel Association director Cynthia Gardstein, AIA.
"Erection savings are generally clear with the third house."
 
SIPs currently account for only 1/2 percent of housing starts.  But production of
SIPs is on a 30-percent per-year growth curve, and will likely claim a substantial portion
of the market within a generation.  The system is part of a trend toward engineered wood
products—plywood, roof trusses, wood I-beams—that are straighter and more predictable
under load than conventional lumber.  Because they are fabricated from "farmed" trees
rather than older-growth wood, engineered wood products are more environmentally
responsible, too.
 

 Most makers of SIPs provide instructional videos, span tables, test certificates, and
detail binders.  And once they receive a contract, they provide signed and sealed panel
shop drawings for approval prior to fabrication, shipping, and erection.

sips vs. studs
So a stick-framed house is no longer the best house you can build.  "The difference in
construction quality is like the difference between site-built and shop-built cabinets," says
David Wright of Better Building Systems, a SIP prefabricator and erector in Grass Valley,
Calif.
 

 Stud framing will likely remain common for the next decade in affordable and
mass-built housing, and in regions with low-cost energy and labor.  But for high-end
homes in areas with high fuel or labor costs, and wherever owners are interested in real
quality and energy efficiency, SIPs are now the construction method of choice.  And I
believe it's only a matter of time before SIPs replace stud framing in most houses.