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rockies
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# Posted: 9 May 2016 08:50pm
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http://www.net-zerostructures.com/products/cost-comparisons.html
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AK Seabee
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# Posted: 12 May 2016 02:57am
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If I had to do it all over again I would more than likely use the structural insulated panels. They are a bit more spendy but since time is a factor I am convinced they are the way to go.
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Don_P
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# Posted: 12 May 2016 06:51am
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I was pretty enthusiastic until I used them. They seem like a great idea on the surface but like with most things... there is no free lunch.
There is very little framing in the panel. This is a good thing energywise but it also means that anything you attach to the panel is holding on to just 7/16" osb. Changes during construction will most likely result in structural re-evaluation and rework. The powder room and laundry had a funky cathedral ceiling and the client had really visualized an 8' high flat ceiling in those rooms. There is nothing to attach to.
Side rant. Several times folks have posted glowing reviews about some company. It is hard to politely say "yeah but their engineering is mighty lightweight". The response to the dilemma above was illegal, and stupid. I smiled and punted, not a comfortable place to be. There is a structural frame inside the sips in those rooms, posts in the corners to a beam that support the ceiling, independent of the sips. That load then had to be supported back down to the ground. Vet the supplier, there are better ones, I was surprised. Their crew, I assume they were out on bail. I probably should have sent the sheriff after them but I was happier to see their taillights.
Make certain the electrical and openings are correct. The manufacturer missed the window sizes and electrical on one large wall, the architect and I did not catch it on the approval drawings. I caught it when unloading the window truck. Back through engineering in order to cut and reinforce the sips. When I cut inside there were multiple voids. it convinced me if I ever went that route again there would need to be thermal imaging pics proving full foam fill. We were given permission to vertically trench in the missing electrical chase, it was a low stress area but I don't need a degree to know we destroyed the structure there.
The panels were square, they were not flat. The framed edges were on dimension thickness-wise, the field of the sips were sunken where the foam had contracted a bit. This is especially noticeable on the roof.
The remnants of a hurricane were moving through the day of the lift. We finally had to call it when the wind was having too much fun with the big panels, pack up the crane and send him home and waited it out. I've had the same issue with other crane jobs and wind, just something to bear in mind if you're in a windy place.
The panel is the structure. If the claddings fail and moisture gets to the skin of the panel, the structure of the building is shot. I get into lots of rotten sheathing and even structural members, splash and flash zones. That would be a very big deal in a sip home, I'm not sure what the repairs will look like yet.
Oh, the woodpecker... she found one of the injection holes in the edge of a panel, pecked it open, then tunneled a nest into the foam. I evicted her, filled it with sprayfoam and sided. She pecked through it all once more, I repaired and replaced and googled all kinds of advice but happily the season was changing and she moved on.
We had dinner there last weekend, its about 8 years old and doing fine. If I had it all to do over again I would prefer to wrap and strap a frame structure with sheet foam or a combination of that and sprayed in foam but every situation is different.
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creeky
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# Posted: 12 May 2016 03:12pm
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Quoting: Don_P I would prefer to wrap and strap a frame structure with sheet foam
exactly.
i suspect a lot of the time savings are based on "time to put up the walls." nobody mentions the time and hassle of running electric, plumbing, fixtures etc.
not to mention woodpeckers
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rockies
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# Posted: 12 May 2016 08:10pm
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I suspect that the quality of the panels will improve immensely when ordering them from a larger company but then again who knows? I'm hoping that a larger company will stand behind their product.
I plan on using "Insulspan" panels and the reason I'm leaning towards an all SIP cabin is the remoteness of the location. It's the difference between hauling studs, plywood, insulation, vapor barrier, drywall (or another interior finish) out there and then having to cut everything onsite and frame it versus having the panels cut to size in a factory and standing them up on the subfloor. I would be sure to use a crew that was experienced with SIPS though.
At the bare minimum I would want to use the panels for the flooring and the roof. The floor is up on piers and having one panel as structure, insulation and vapor barrier would be great (they will be resting on beams on top of the piers). I plan on having an 8 inch deep false floor in the bathroom in order to run all the plumbing.
The roof is another area I think SIP panels are the way to go. No venting required, no baffles, no air gap, and no vapor barrier. Just lay the panels across the ceiling beams and seal and tape the joints. A 12 inch thick SIP is about an R58 which you could never get with a 12 inch thick framed roof.
Using SIPs for just the roof and floor I could still use 2x6 studs for the walls but why bother? The exterior wall electrical chases can be drilled in the factory and all the interior walls would be 2x6 anyway so lots of ways to solve wiring problems.
As for hanging things like cabinets you could add a 5/8 sheet of plywood to the interior osb and use cabinets that come with that mounting track that screws into the walls.
The weather also plays a big part. If I can get the frame up and weather tight in a week versus a month then I'm happy. A company down the street from my city house is putting up a SIP house and they had 3 floors up and the roof on in four days. A 4' x 8' panel weighs about 125 lbs. Three guys could probably build my whole cabin easily in a week.
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Don_P
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# Posted: 12 May 2016 10:51pm
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Keep researching and verify rather than suspect before finalizing. I suspect an EOR is needed for what you describe to keep warranty intact.
The wall panels will run unbroken from floor to roof, the floor will run from wall to wall or beam to beam, the roof panels will be full "rafter length". 8' wide jumbo panels will have fewer seams in the structure, a good thing. Typically they'll come up to 8x24'. You'll need some equipment along with the crew.
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AK Seabee
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# Posted: 15 May 2016 09:21pm
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I am sure there are multiple designs and methods for SIP construction. Both positive and negative reasons have been mentioned here and both are valid.
Location and weather should be a primary concern when deciding on a method of construction. I dont confess to know it all and I enjoy this forum because of the open and civil discussions between folks with a ton of knowledge and others with minimal experience searching for the right answers.
I like the post and beam construction using log posts and log trusses with the SIPs providing the shear in between the posts.
Hopefully this thread lives on.
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Don_P
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# Posted: 16 May 2016 09:34am
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I think it would be fun to work with you.
I've been following the development of CLT's as well, cross laminated timber. The same advantages as far as quick assembly and great in plane shear strength. There is definitely something solid to fasten to. The same concerns about rot and structure although being solid wood the structure is more than just skin deep so it can take more decay. With either a rainscreen wouldn't be a bad idea.
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creeky
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# Posted: 16 May 2016 10:24am
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Rockies, you've done a lot of research and planning. I would think that the company would have no trouble putting your electrical chases etc into the sips simplifying the build.
I look forward to seeing your build unfold.
This is a neat place to look at post and beam with SIP.
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Jabberwocky
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# Posted: 18 May 2016 08:32am
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creeky
Those timber frames are really cool. Thanks for the link. Can't afford any of them, but I can dream! LOL
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rockies
Member
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# Posted: 18 May 2016 07:59pm
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Creeky, thanks for the compliment. I have been designing this cabin for a year now. It gets a little bigger, then a little smaller, the windows change size and position and the roof pitch changes but it always comes back to the same basic layout. The problem with being an architect is that whenever you see a cool idea from some other building you want to include it in some way. Right now I just chopped 100 sq' out of the plan and it functions even better than before.
Don P. I did look at a website for a company that makes CLT (cross laminated timber) products and they look very interesting but I think they are meant to be purely structural. All I could find on the insulation value was a line about how wood has an R value of 1.5 per inch of thickness so I would have to build an entire stud wall against the inside the CLT panels in order to insulate (unless I'm missing something).
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Don_P
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# Posted: 18 May 2016 09:10pm
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Depending on climate the mass timber numbers would start to work at 6-8" thick. I'd be tempted to wrap the exterior in foam and rainscreen it. That would put the mass inside the thermal envelope.
Plank and beam is another way to get the post and beam look that might be more affordable than a custom timber frame. I think the old publication is still on the awc.org site. Basically using "bent" style glulam post and beam framing clad in sips rather than planks... or lighter paneling and sip. The panels then no longer need to span as far, oriented from bent to bent across the roof, 4-8' spans, and potential break points at those length intervals rather than spanning from front to back wall in one piece with no frame, bear in mind a panel joint is a "weak" spot thermally so bigger is still better.
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