Talking about SIPS

[Brad_bb]

It was mentioned in the "Frame Raised" topic by Bigshow that he was using SIPS.  I asked if he was using Expanded Poly Styrene (EPS)SIPS or Polyurethane SIPS.  It seems he wasn't familiar with Poly sips.  Me either really, so I'm up for some discussion.

I looked online to find out who in the US supplies Polyurethane Sips and found the following.
There are far more suppliers of EPS sips and only a few poly suppliers.  EPS has been around far longer so it makes sense.  Polyurethane sips were at first made using CFC's to make the foam, but are no longer made that way and are more environmentally friendly.  The suppliers I found online were:
Murus, Polyurethane, Pennsylvania
KC Panels, Polyurethane, New Mexico
SIP supply, Polyurethane, Georgia
Winter Panel, Polyisocyanurate, Vermont

So the reason I am focusing on Polyurethane or Polyisocyanurate panels, besides the inherent features of SIPS in general, is that they appear to have higher R-Value per inch compared to EPS, and because they have a better flame rating than EPS.  Higher R-value means that you can use less thickness for the same R-value.  Apparently they are self-extinguishing and won't burn on their own, and can tolerate much higher temps before any damage compared to EPS.  Information I'd like to find is:
1)Are there any more suppliers in the us?
2)An idea of cost difference or cost in general.  Of course things change for custom work.
3)What is the difference between Polyurethane and Polyisocyanurate?
4)What is the lifespan of the foam?  I've had what i believe to be rigis foam panels in a pole barn for 20 years, and after that time, they seem to be more brittle or crumbly.  How do Poly SIPS  degrade over time?  If a frame is designed to live hundreds of years, when will the sips need to be completely replaced, or will they(Won't be me but could be my family)?

Please weigh in with any knowledge or experience you may have.  I'm sure I can find more info if I spend more time on the supplier websites too.

[moonhill]

Hi Brad, Foard Panel is an other source, they are in N.H.  The higher insulated panel is yellow in color the other type is white bead foam the same as you find in foam coffee cups.   I think the coffee cup panels are cheaper but are thicker for the same R-value.  I prefer the yellow/thiner type for ease of use and shorter screws.  I actually use a layered system, wrap and strap,  IMO it is cheaper and the money goes into the local builders pocket, but I start to veer of topic and if I don't stop I will go into natural building alternatives which I just did.  As I mentioned in a recent post you could skip the frame completely and build with SIPS alone, another reason to wrap and strap, job security. 

Tim

[bigshow]

See, I've always thought XPS is the way to go...there is documentation out there indicates polyiso loses some of its advantageous R value over time and really suffers when its wet.  A company I talked to that makes some non structural polyiso panels implored me to keep them dry forever and ever.  I did also read at one point that water diminished R value on EPS, XPS, and Polyiso.  I made my panel choice based on proximity to me..and the fact that the company I chose acted like they wanted my business, had fewer middle men, etc..unlike other places I talked to.  Each foam camp has their own rhetoric...PolyIso certainly looks best on paper. 

It comes down to give and take.  I went with EPS panels, and went with the best windows I could squeeze into the budget (Fibertech).  I'd imagine PolyIso panels with big box store winders would be inferior to EPS panels and upgraded windows/doors.  This country is so backwards with its windows for the most part..go Canada!

[Don_Papenburg]

XPS  has more crush resistance then polyiso
Polyiso will crush if you kneel onit or lean against it
EPS can be formulated with bug deturants easier than the others.
XPS is the most hydrophobic of all the foams and can be used subsurface.

[moonhill]

I did not know now that they made XPS Sips 'till now.  I have seen XPS saturated with water the sheets came off a flat roof which had a leak, they were heavy and broke easily. 

Pre cut window openings from the manufacturer is a plusss, imo.

Tim

[jmaine]

I'm struggling with some of the same questions.  I'm in the initial planning stages of a timber frame house and trying to get estimates as to the cost of the various components.   I asked Foard Panel to give me a rough estimate of the cost of polyurethane panels per square foot with an R value of 40. They came back with $5.50 a square foot delivered for a nail base panel (OSB on one side) and $7.00 for OSB on both sides.   They will install for $4.00 a square foot.  This is a recent price (2 weeks ago).

Obviously that's very expensive so I'm looking at alternatives.  For the roof, stacking multiple layers of polyiso insulation would provide the r value I'm looking for (3 layers of 2" thick sheets).  I saw that someone on this board did something similar (I forget who).   I did this on the roof of my workshop.  Laid the polyiso down flat against the pine shiplap boards;  two layers, staggered the joints and taped all the seams. Then I put 2 x 4s down flat on top of the polysio as nailers and screwed 8" screws through the 2x4s, insulation and into the rafters/purlins.  This created the necessary airspace to vent the roof.  On top of the 2x4s I used ½ inch plywood, tar paper and asphalt shingles.   I didn't notice that the polyiso crushed significantly when I was working on it. Maybe slight indentations but nothing terrible. 

Maybe wrap and strap for the wall panels?  I noticed that Yankee Barn homes uses what they call their "True Panel". There is a diagram of it here:

http://yankeebarnhomes.com/building-process/true-panels-compared-to-SIPs.html

It looks to me like they use 4" polyiso sheets  in 2x6 framing.  The sheets are put flat against the outside sheathing which leaves an airspace between the insulation and interior sheathing so you have space to run  wires (1.5 inches or so).  I found this interesting.  I was thinking of doing something similar but adding an additional layer of polyiso on the exterior sheathing to get closer to r-40.  I would run strapping vertically or cedar-breather and nail the clapboards to this.

The benefit of this method is that I could frame out any window and door openings in the panels.  Or, perhaps I could build the panels and have someone spray foam insulation into the panels?  This wouldn't leave a space for wiring however and I have no idea as to how much it would cost. 

Doing my own panels would be labor intensive so I'm trying to figure out exactly how much I would save by building my own.

Does anybody here have any experience with site built panels?  Any advice or thoughts on the cost versus buying SIPs?

Joe

[bigshow]

I think the original idea of the post was should we as consumers be demanding even better panels?  But, I think one must take the entire building envelope into consideration.  My HVAC guy does analysis of various buildings - he's a geek that way.  Best house he's ever tested for air infiltration and overall insulation performance was 2x6 cellulose with 2" rigid on the on the outside of the studs.  He's tested SIP homes that have performed not as well as expected.  He indicates that SIP performance lives and dies on assembly - if your not head to toe mastic at the end of the day and foam gushing out the seams - odds are, your SIPS are not installed properly.  So I think there are so many factors in which is the best product or best way.  Poor installation will trash the greatest product - be it DIY or pros.

The only reason I'm doing SIPS is that I locked myself into it.  The building inspector wants an engineer stamp.  But, there are no really good timberframe engineers here or ones licensed for SD - so, the stamp basically says that the frame will easily stand on its own, but will be nothing more than a decoration once panels are on it.  I wish I would've done a ton more bracing and did 2x6 (walls).  I cant install SIPs alone or without heavy machinery.  2x6 I could've done alone, cheaper, and if properly done - nearly equaled a SIP job providing it was done right.  SIPS arrive on friday!! :(

[Brad_bb]

No, my intent with this post is simply just to get more information on Polyurethane and Polyisocyanate SIPS, being that the flame rating, and high R-value are attractive features to me.  This will help me to make a decision when it comes time for me to decide for my future timberframe. 

[moonhill]

I think it comes down to budget, how much cash do you have to spend on the project.  Sips are a huge expense but efficient, and that depends on the installer as mentioned previously.

Tim

[frwinks]

Brad, check out www.thermocore.com they're in IN and make Polyurethane panels with plenty of good info on their site...
last time I checked their prices were great compared to other suppliers (can't believe I just put price, SIPS, great in the same post : :D )
Still too much $$$ for my blood... I'm with the yankee builders on the enclosure as I found a local supplier of poly blanks

[Raphael]

I went with XPS from Foard...  No sign of them taking on water.
In fact the ground wet cut offs still won't release the OSB after 3.5 years fermenting under a tarp.
Bo Foard dropped Polyurethane because it had some unresolved curing issues (SIPs w/ gooey centers and bad R values).

Half the trick with panels is to check the manufacturer out very well, not all sips are made alike.

As far as expense, my ideal wall insulation would have cost me far more money and time than having Foard come in w/ a truck crane.  The recycled bluejean batting and thermal barrier I'm using in my bump up works out almost the same as sips (cost wise), and of coarse it isn't a continuous R value.

On a side note XPS will fuse to the shaft of an arrow moving at high velocity.
Stops them real good but extraction is a pain.  :D

[witterbound]

I am using 2x6 walls on my timber frame.  I plan to have the insulation sprayed into the walls, after all the wiring and plumbing in run.  I have been told that the cost for this is in the neigorhood of $2.50 a sf.  However, I understand there is an alternative, which is to have a thinner layer of foam sprayed in to stop the air infirtation, then use fiberglass bats. 

[Hilltop366]

I looked into sips when I was building and could'nt spend the extra $ for them For almost 1/2 the price of the sips I bought all the lumber for the inside and out side walls roof and loft floor and insulation, what I did was build the timber frame parts in enough to leave enough room for 2x6 (24" oc) walls are filled with fiberglass and covered with 1 1/2" foam ( I started with the blue foam(Extruded Polystyrene) at the footing and switched to white foam (eps) above the foundation wall) wind barrier then straping, T&G boards, tar paper , ewc shingles. The reason I switched to eps above the foundation is the eps will let moisture that is in the wall out where the blue foam is nonpermeable and because I use a vapour barrier under the drywall I would of had a wall that would trap any moisture and would rot . It seems to work well, there is no cold spots on the wall where the studs are, the eps over the studs seems to reduce thermal bridging a lot

On the timber roof  I put a layer of t&g pine that is seen on the inside then vapour barrier, a 1 1/2" layer of foam, then 6" x24" eps blocks with 2"x8" in between them, boards & then shingles the 2x8s leave a air space in between the insulation and the boards.

The non timber roof/ceiling was framed with 2x10s and then put eps rafter vents between the rafters along with fiberglass insulation and covered it all with 1 1/2" eps, strapping and then drywall.

[Raphael]

I never seriously considered fiberglass or Polyiso ...
One makes me itch :D the other puts me into respiratory distress
Stone, cordwood, strawbale, hemp or straw-slip, wool or wool/hemp batting, various sprayfoams & foam boards etc.

Ultimately it was decided by the frame I started with (spruce with braces referenced to the outside), the ledge it was going to sit on and the three man labor pool available (me, myself and I).  :D

[ljmathias]

Hey, Raphael- you been stealing out of MY labor pool!  No wonder my productivity is down- lost "myself" and have been working at two-third speed lately...

Lj

[Thomas-in-Kentucky]

I used polyurethane SIPs from Thermocore for my walls.  One attractive feature was they were available in a thickness equivalent to 2x4 walls, so I could use standard windows without jamb extensions.  I would highly recommend polyurethane SIPs.  I would NOT recommend Thermocore in Indiana.  They strung me out with the delivery schedule and kept putting me off.  They must have decided their CAD technician was as incompetent as I thought she was, because they fired her (or she quit) and they neglected to tell me.  Tried to act like nothing was going on there - problem was, after her rapid departure, they picked up an old revision of my files and started working on it...  that set us back even further when I discovered the problem.  Then after getting sick of the run around, I turned them into the BBB.  (In my 38 years on this planet, that's the only time I've ever turned anyone into the BBB)  The president of the company called up and I was not home so he cussed my wife on the phone (she had nothing to do with any of this!).  Very unprofessional company, IMO.  YMMV.

For my roof, I used a built up system of 2x10's and polyiso.  I'm happy with it, the best feature being that my roof does not have plywood or OSB in it, so hopefully the structure will last as long as the slate on top of it.  The downside is that it took longer than SIPs would have, and so my structure was subjected to the rain longer than I would have liked.

Now for some anecdotal, but no less real observations...

FIRE:
I have tried burning PolyIso slabs and polyurethane SIPs.   Commercial polyiso will burn a little bit when put in a really hot trash fire, but when you pull it out, the fire goes right out.  It really doesn't want to burn.  Polyurethane is the same way, but the OSB laminated on it will burn like crazy.  The effect of the polyurethane is to deprive the OSB of oxygen on one side, slowing down the burn of the OSB.  To summarize, you can not get rid of polyiso or polyurethane by burning it, and it would not contribute to a house fire (not a professional opinion, just an opinion!!!).  One notable exception is the 3/4" polyiso you can buy from Lowes with the silver metallic backing.  I don't know why, but that silver metallic backing burns like crazy - better than paper.  I would have thought it to be fireproof, but it is a fuel, not a retardant.  Probably the glue that holds the silver backing to the foam is flammable. Blue extruded polystyrene will eventually melt into globby fluid that becomes a real fuel for fire.  And we all know coffee cups burn, so I assume the white beaded foam burns too, but I've never tried the exact white stuff that comes on a SIP.  (BTW, this is all pretty much moot if you have asphalt shingles on your house - they burn like gasoline!!!)

MOISTURE/SUN:
I've left both polyiso slabs and polyurethane SIPs (pieces, like last minute window cutouts) laying on the ground, in the rain and sun, for over two years.  They both tend to bow nasty when one side gets wet, but I've never noticed them getting any heavier (i.e. taking water into the foam).  Of course the OSB on the SIP pieces looks like hell, but that's to be expected.  Blue foam, polyiso, and polyurethane all get crusty and brittle (powdery in the case of blue foam) on the outer surface when exposed to sun, but I haven't noticed any degradation of the pieces in my barn.

Just some amateur observations! 

I think one big consideration for the DIY timberframer is to get his frame dried in as soon as possible.  SIPs are a big help in this regard.

[Raphael]

I used polyurethane SIPs from Thermocore for my walls.  One attractive feature was they were available in a thickness equivalent to 2x4 walls, so I could use standard windows without jamb extensions. 

That was one reason I went with the XPS, it had enough 'R-factor' over EPS to get away with the 4-9/16" SIPs.
Unfortunately the (former) lumberyard employee who ordered my windows managed to order them with jamb extensions installed.  :

[Brad_bb]

Ok Thomas, after your post I had to go back to your blog to try to understand your roofing system.  Would you please describe what we see in the following photo of your roof - How are the 2X10's attached to the roof?  What are infilled between them, thickness?
http://photos0.blogger.com/blogger/1284/2164/1600/P6210056.jpg

Then in the following picture it looks like you've attached some 2X4's? to the top of the 2X10's and then installed 1X4's across those?  Is there an air space left between the infill material and the 1X4's?  Is all of this framing white pine?  Are the 1X4's pine also?  Is there a vapor barrier anywhere- I found one pic where it looked like your vapor barrier was on the inside against your tongue and grooved pine ceiling?
http://photos0.blogger.com/blogger/1284/2164/1600/P7250068.jpg

[Brad_bb]

Sorry, here are the two photos respectively.  For some reason the direct links to Thomas' blog pics wouldn't work.

[Rooster]

Hey,

If you click on his username, left of any of his postings, you can look at Tom's user profile.  Under the heading of "website", you can access his blog from there.

Rooster

[Thomas-in-Kentucky]

Let me reiterate... I am a rank amateur, having built exactly one timberframe structure in my life.  (but currently living in it!)  This roof system is an amalgamation of stuff I've seen in books, saw at a friend's house,  and read on the internet.  With that said, here's a picture that shows what I did...



Bottom-most (not shown in picture) are timberframe purlins, mostly OAK, averaging 6x8 inches (some are 8x8s and some are 6x10), spanning 10 to 15 feet, on no more than 4 foot centers.  I used the classic (but maybe not historically accurate or theoretically optimal) Benson type dovetails to join the purlins to the principal rafters.  Then I put 7/8 OAK tongue and groove (made at  a friends shop with my lumber... but I could have bought it cheaper.) on this.  Then I put down the vapour barrier.  Just heavy plastic.  Then I nailed galvanized simpson brackets through the t&g (and unavoidably, through the vapour barrier), into the purlins.  They're just 90 degree brackets you can buy at lowes.  The other side of the bracket is nailed to (lumber yard) store bought 2x10's (yellow pine - better than white pine IMO) that stand tall-ways. 

The 4 foot space is filled with 3 layers of polyiso to get the exact height to allow me to lay a 2x6 sleeper on top of the foam.  The 1x4 (true dimensions) WHITE OAK (no sap wood) battens rest on the 2x6 sleeper (store bought dimensions), which rests on the polyiso which rests on the T&G.  Relying on 7.75" of polyiso to distribute some of the substantial slate roof load was a gamble that has paid off so far, but time will tell if I see creep or not.  The steep pitch of my roof makes it all more believable, but I doubt you'd ever get an engineer to sign off on it.  The other option was to spend ridiculous amounts of time ripping the 4x8 sheets of polyiso into 2x8 sheets, and putting in twice as many 2x10s (therefore doubling the number of thermal breaks in my roof).  In most places, we pounded to polyiso between the 2x10's and got a very tight fit.  It was still necessary to use about 2 cases of great stuff to get a good seal.  We became master of foamology.  (living with great stuff o our hands)

What I ended up with is a roof with NO PLYWOOD, no tar-soaked felt paper, an R-value of almost 50, 1.5" of airspace under the slate, and a radiant barrier pointed back up at the slate.  There is also no need for soffit vents or ridge vents - the slate is like a big giant louver system on my roof.  The biggest problem with this system, IMO, is that it would be virtually impossible to diagnose a hidden leak in the roof.  And that is a significant flaw.  It hasn't caused me any problems, but the reality of a 200 year slate roof is that one should expect to replace at least one slate every decade or so.  Hopefully, these slates will make themselves obvious from the outside.  And I used stainless in the valleys and was super-hyper detail oriented when I did all the flashing work, as that would be just as hard to diagnose.  I will readily admit that the proper sub-roof for a slate roof is an unheated attic... but mine works too... so far.  And I think it's better than slapping slates on SIPs... which still require battens nailed to sleepers on top of the SIPs.

wow - that was a lot of typing.  sorry to get wordy. 

[Rig]

I put up some of the first SIP houses in New Mexico and Alaska, starting in the 80's. I have done something like 15 panel houses, with and without timber frames.

When they first began, the producers kept the costs down so that they were on a par with conventional walls, as far as cost of construction. Now they are much more expensive.

I've gone exclusively to wrap-and-strap, using extruded polystyrene panels and locally milled lumber, or cellulose blow in, or a combination of the two. With attention to detail, you can get a timberframe wrap-and-strap house just as tight and energy efficient as a timberframe/SIP house.

[Hilltop366]

I've gone exclusively to wrap-and-strap,

? Could you explain please.

[Brad_bb]

Thank you for the explanation Thomas.  Whether you call yourself an amateur or not, your speaking from your research, intelligence, and now some experience.  What did you use to fasten the oak batting?  Stainless screws or regular nails?  and what did you drive through the simpson brackets to your purlins with?

Others, I would also like a proper definition of wrap-and-strap too.   Good info in this post so far.  Thanks, Brad

[moonhill]

Wrap the building in 4'x8' sheets of foam and strap the outside to hold the foam in place and as a nailer for siding/roofing.  I use at least two layers, staggering the seams, the last layer is gapped 1/4" and filled with spray foam, no tape.  I have noticed at times the sheets will shrink after installed and setting in the direct sunshine, something to think about.

Window buckets are used to extend the window frames out flush with the foam and flush to the inside of the planks, the straps are applied to them as well.  I use a wider strap/board around the windows.  Everything is screwed with panel screws.  The wall foam runs up under the roof foam where a 1/4" gap is left and is sealed with expandable foam.  The roof strapping extends over the eve and is tied into the wall strapping forming the soffit box.  I am using thicker planks on the walls of my frames, 1-1/2" to 2-1/2", allowing the screws to be applied anywhere, just don't get your lengths mixed up.  In the roof I shoot for the rafters or purlins.  The strapping is applied on 2' centers, one covering the freshly foamed seam and the other in the center of the two seams. ( note: don't let the foam dry before the straps are screwed on)   

I then run a layer of house wrap over the straps and install full 1/2" x 4" clap boarding with a 3" exposure varying where needed.   

Tim