Posted By greentree on 18 Apr 2012 06:37 PM


I'm not talking scissor truss, ask about a parallel chord truss. You install proper vents lapped correctly up each bay.

I will run it past him but a scissor truss and parallel chord truss are pretty much dimensionally they same. A wood truss will always be dimensionally taller than a 12" steel SIP panel. I have yet to see a wood roof truss that is only 12" in height.

How does one get R-50 out of 12" of blown in cellulose?

Those 2 trusses are nothing alike. I already told you the answer to your query.

Posted By Lbear on 18 Apr 2012 07:21 PM

How does one get R-50 out of 12" of blown in cellulose?

How does one get R50 from 12" of Type I EPS?  Type I is what is typically used in SIPS.  Type I EPS has an R value of ~3.8 per inch at a mean temperature of 75F.  12" x 3.8R/in = R45.6.  Actually, cellulose at an R value of 3.6 - 3.8 per inch is roughly equal to EPS in R value and likely higher than Type I EPS at higher mean temperatures that would occur in a roof during the summer.

Posted By greentree on 18 Apr 2012 06:37 PM


I'm not talking scissor truss, ask about a parallel chord truss. You install proper vents lapped correctly up each bay.

My architect said that no truss design will work in the dining & living room area. It would have to be either stick framed or steel SIPs. If stick framed, it would be difficult to achieve anything higher than R-35 in that attic area. It would take a complete redesign and change the building height and pitch if wood trusses were used.

Posted By arkie6 on 19 Apr 2012 01:03 AM

Posted By Lbear on 18 Apr 2012 07:21 PM

How does one get R-50 out of 12" of blown in cellulose?

How does one get R50 from 12" of Type I EPS?  Type I is what is typically used in SIPS.  Type I EPS has an R value of ~3.8 per inch at a mean temperature of 75F.  12" x 3.8R/in = R45.6.  Actually, cellulose at an R value of 3.6 - 3.8 per inch is roughly equal to EPS in R value and likely higher than Type I EPS at higher mean temperatures that would occur in a roof during the summer.

Nominal 1# density is Normally used in most OSB SIPs, some steel SIP manufacturers use a denser EPS foam, which is another reason they can achieve greater span capabilities

If you use Type IX EPS (2# density) at R4.2/in @ 75F, you can get to R50 in 12". I hadn't heard of that being used in SIPS before.

Posted By cmkavala on 19 Apr 2012 07:08 AM


Nominal 1# density is Normally used in most OSB SIPs, some steel SIP manufacturers use a denser EPS foam, which is another reason they can achieve greater span capabilities

Which do you use/sell in the steel SIPS?

So what is the 12" steel SIP rated at, R-Value wise?

Lbear;
Type VIII is used and has shown to have the best adhesion properties, it is rated R4.25 @ 45F.
Arkie6,
While 2.0# density has the greatest R-Value, because it is denser it has a smoother surface that does not allow the glue to adhere as well, when tested under load to the point of failure, it will shear faster than Type VIII

I know that 2# density EPS has a very smooth surface compared to lower density EPS because that is what I am using to build my ICF home (LiteForm ICF).

Here is some generic R value ratings for the various types of EPS. Type VIII (1.25# nominal density) has an R value of ~3.8/inch at a mean temperature of 75F. Some manufacturer's data may vary from this number slightly. The FTC "R Value Rule" uses 75F as the mean insulation temperature for comparison purposes so you can compare apples to apples because some insulation types perform better or worse at colder/higher temperatures. EPS R value goes up as the temperature drops.

http://www.epsindustry.org/sites/default/files/C578%20Chart.pdf

http://www.insultech-eps.com/techdata.html

Posted By cmkavala on 20 Apr 2012 05:49 AM
Lbear;
Type VIII is used and has shown to have the best adhesion properties, it is rated R4.25 @ 45F.
Arkie6,
While 2.0# density has the greatest R-Value, because it is denser it has a smoother surface that does not allow the glue to adhere as well, when tested under load to the point of failure, it will shear faster than Type VIII

Have those glues ever come undone on a steel SIP?

What is the life expectancy of that glue when subjected to extreme temps?

Have those glues ever come undone on a steel SIP?

What is the life expectancy of that glue when subjected to extreme temps?






Lbear;
None that I have been associated with, failures usually occur when a product it used for a purpose not intended such as over-spanned.
I have an accelerated aging test that was done by Ashland Chemical who supplies adhesives to both the OSB and Metal SIP industry. I will send you the report that shows results of panels being subjected to 15 cycles of the following:
Test specimens were randomized, and sorted into 6 groups of ten per panel type. One group was tested as a control. The remaining five groups were subjected to accelerated aging in accordance with ASTM 1183 test condition C. One aging cycle consists of:
48 hours in an oven at 160°F
48 hours immersed in water at 72°F
8 hours in a freezer at -70°F
64 hours in an environmental chamber at 101°F and 100% relative humidity
At the end of the tests the metal panel was unaffected, the OSB panel however was untestable after the second test cycle
The report is all highly technical and I have been told by the experts that the life expectancy was 300 years.