| Structural Insulating Panels (SIPs) is another high insulating technique to build a house. They can be used for
walls and roof but we only used them for a roof. Like the ICF's they are not
inexpensive. In my case I estimate they added about 35% over the cost of a
conventional truss roof. I spent about $8600 for the SIP
part of my roof and I estimate a standard truss roof to be about $6400 for
materials.
But with the SIP roof we were able to have cathedral ceilings making
the house appear far larger than it is. So we have the illusion of a
large home but we do not have to clean or heat such a large home.
The roof is also very solid.
Labor was about the same as a truss roof as it took 2 good days to do the SIP portion
of the roof. The larger panels were heavy at
about 225lbs for the 15 foot ones we used. We had a carpentry crew
of 4 and myself and a strong helper. I would not try to wrestle
the panels with any less people. Many jobs use a crane for the
placement.
I used 8" panels for my roof which have a nominal
insulating value of 31. But Styrofoam insulates better than fiberglass.
R values are measured at conditions ideal for fiberglass and
for most conditions the stated R value of fiberglass is significantly less
than advertised. An SIP roof is also excellent in reducing air
infiltration furthering your energy savings. Like ICF's they are
stronger. I have seen
adds where an elephant stood on an 16 foot long 8 inch thick
panel. For
more information on SIP's
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Here we are placing the panels on the roof. They make
for a very solid roof, much more solid than 5/8 plywood upon rafters.
At about 225 pounds they were heavy but manageable. The front or south wall was framed in because with so many windows and doors we thought
it would be too difficult to work with SIP's or ICF's. |
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Here we are dong the final alignment. After they are
aligned we used a large 10" screw to fasten the panels into the top
beam and the 2x6 we embedded into the top of the ICF wall. SIP's
are a very strong way to build a roof and are rated for areas with bad
weather. Of course I hope we never see a tornado or earthquake to
test it, but the engineering calculations say it would survive. |
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We had to make a few angled cuts to make sure the sheetrock
would span from the ICF's walls to the nailing board. This
made a nice channel for running wiring in the rear wall.
The top of
the ICF has a 2x6 with anchor bolts embedded in the
concrete. We screwed the SIP's securely into the 2x6 embedded in the
concrete ensuring they will not come out. The joint was sealed with insulating foam
and fiberglass insulation. |
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Here is the detail of the gable end where we connected the
SIP roof to the ICF's. The ICF has a pressure treated 2x6 embedded
in the top of the concrete which gives a good surface to attach the
framing. The center beam is a laminated wood beam which
supports the top end of the SIPs. The ceiling framing was done to
allow some space to run present and future wiring. |
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Unfortunately the quality control on the SIP's were not
exact. Here you see the top edges not meeting and you can see the
foam was not cut straight. This had to be corrected with a
scoop. A scoop is a hot knife (like a soldering iron) designed to
"scoop" or melt out the foam. The carpenters got a
great laugh when during one attempt I started a fire. It went out on
its own indicating it does not readily burn. |
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Here you see the left panel after it was scooped. I
still had the right one to do. The unevenness made it difficult to
put the fascia in straight. |
