SIPS R factor and building codes.

[Tremel]

Okay, I live in the country in SW PA and I'm fighting with our local building inspecter.  He's not use to working on homes that require the removal of axles.  So, he fires back at my house design and demands that I install SIP Panels that have a wall rating of at least R19 and Roof at R38.  I had originally planned on using 4 1/2" wall and 6" roof nailers.  But I can't find comperable information compared to stick built.  If I need to meet his standards, I'll have to install 8" panels for the wall and 16" for the roof.  I know for a fact that other home have been built in my area with 4 and 6 inche panels.  But they are in different townships with different inspectors.

I'm dealing with a real jerk who doesn't undertand Timberframing, SIPS and a tin roof.  I want my building permit so I can break ground.  He let three other homes go up in the last year that have been cheaply built (conventionally stick built).  But he's being a stickler with my Timberframe home.

Basically, he told me that my home must meet the national residential codes.  I can't see how the 2x4 stick built home down the street passed last fall?

Anyone know where I can get info that shows the R-Value comparison of 2x6 stick built with fiberglass insulation -vs- 4" SIPS? (EPS)? 
 

[Jim_Rogers]

Start here:
http://www.sips.org/
Structural insulated panel system association

[Mortice]

New Lerking member here.... I would consult the manufacturer of the sips you plan to utalize. Sips.org is a good place to start but if you have a company you plan to use than they should be very specific to the r value thier product is tested to.

Most manufacturers web pages have very good detail drawings on how the sip should be installed as well as the r-value of the product.

Most of the time when you are looking for a building permit the town will require a list of types of materials that will be used (the specification sheet). If you have your design done, or have a company that you plan to use or have sips quoted from, thats where I would start. One thing maybe you would like to do is use a couple different companys in your specifications to give yourself a little wiggle room once you get quotes when you go to purchase. That way your not pigion holed into one product.

[Thehardway]

This is the Prescriptive Method for SIP construction doc.  I believe this is only proposed at this time and has not been ratified and adopted into code.  Perhaps it will be in the next update?

http://www.sips.org/elements/uploads/files/fileManager/SIPPM5-17-07.pdf


As you read you will quickly become aware of the fact that it is written primarily from a structural standpoint dealing with loads, spans, shear and uplift considerations.  The only mention of insulative properties is to say that you must conform to state, local or regional code for R-values.  This is where your LAHJ is being a butt-O.  He can technically do this if going strictly on calculated R-value.  A 4.5" SIP would typically be calculated at R-15 - R-17.  Keep in mind that this is strictly the PANEL value and has nothing to do with WALL ASSEMBLY value and calculated value is not the same as performance value.

Another approach would be to reason with him logically.  It is obvious that not all homes have a calculated wall R-value that meets his standard.  You might want to use a log home as an example.  A EWP log is worth a calculated R-value of 1.25 per inch.  A 8" D-log gives you a calculated value of a whopping R-10.  I assume he is making all log home buildiers in your area use double walls?  Or maybe they have to staple batt insulation to the inside?  .  You see where this is going, performance R-values are demonstrable with SIP construction just as they are with log or mass wall construction. 

Oak Ridge National Labs ( DOE) has published articles that prove a 4.5" SIP out-performs 2X4 stick and batt construction and equals or surpasses a 2X6 stick and batt construction.

Bottom line is since it is not prescriptive you will have to get engineering documentation from manufacturer to satisfy.

[Don P]

Welcome Mortice 

I looked for something in the ICC ES reports, icc.org, and found one acceptance report, pretty much along the lines of what THW posted but far less detailed, strength info but little on R value acceptance. I'd toss it in the suppliers lap, they're bound to have dealt with the situation before.

[EastMark]

They are pricey but with the price of fuel oil and where it could possibly go..........
I assume the seam assembly/install is critical to your real R value.

Mark in Maine

[jdtuttle]

Go online & look for a free program called rez check. There may be some information on r-values for sip panels. The new code uses an envelope approach now. The normal r-19 wall & r-38 ceiling has changed. I can check tomorrow also when I'm at work. I'm one of those code guys. Only I work with people to help them comply with the "minimum standards" required by codes.
jim

[witterbound]

It's rescheck.  Looks like a great tool.

http://www.energycodes.gov/rescheck/

[shinnlinger]

This is dumb,

BUt would mr inspector let you sheath the timber frame in "stick built" walls instead of panels?

#1 it would be less $$ than panels, and I would build two 2x4 walls right next to each other 2 ft OC but staggered so if you looked at it head on it would seem to be 1 ft OC.  Doing this staggers your studs to lessen thermal breaks.

Why cant showing him all the standing 150+ YO timber frames in your county be enough?

I would like to see that double wide or your neighbors 2x house in 150 years .

[Don P]

I'm pretty curious what a SIP will look like in 150 years myself  ???. We're using them for structure and insulation. In a generation I wonder if the TF is potentially economically about done if they go. Its an interesting blend of ancient and cutting edge.

[jdtuttle]

SIPS were actually around in the 30's. They gained popularity in the 70's. New technology is changing so fast producers can't keep up with it. Kind of like computers.
jim

[Tremel]

Good news is that I have my permit.  But our inspector requires that my home meet or exceed IECC codes. 

Rescheck is fantastic.  Now I need to figure out how to use it.  Anyone have an example I can borrow?

Also, I read into the codes and non-attic areas only require R-30, not R-38.

Thanks for all the help.

So, my next real question is simple.  How many of you are building homes required to meet IECC code?  Should I tune/tweek my panel selection? 4" wall, 6" ceiling?  I'm also using windows that exceed the minimal requirements of u-.35.  I think the u factor is u-.33.

On another note, we spent the day staking out the foundation.  We'll look at it for a week or two before we break ground, but we think we have it right where we want it.

Thanks again.  This forum is great...

--Bill