Chuck07;

This morning I noticed that it was 74 degrees /80% humidity outside ............

in Our 600 sq. ft. steel SIP office it's 72 degress/ 25% humidity


Al Cobb;

You can deal with theories and I'll deal with reality,
 
factual things always work,  theories don't

As many of you read this thread, you possibly are sipping your coffee out of an EPS foam cup. Funny how you don't get coffee on our fingers as the foam cup is non-absorbent and water. Last time I checked steel is also non-absorbent.

I lworked on my home for a year before I was able to put any roofing on the roof, (today it has steel shingles), and before I finished the outside with just elastomeric paint. That means the house was up for 18 months with just the steel panels protecting me from the elements, and it went through four hurricanes, countless frog choker rain storms, that drop up to several inches in an hour, all with no condensation on the inside or leaks. When we went through the hurricanes we hadn't had time to even put any caulk in the seams of the roof panels. They were just snapped locked together and on a 4/12 pitch still shed the water with no leaks.

With steel sips using the eps foam there is no water absorption, no condensation on the inside and no chance for a wind to get under your roof tho lift it off or fill the inside with water as happened with many conventional roofs here in Florida. I will take my experience over theory any day!

Hey guys,
It's not my theory. It's the priciple that Joe has explained in his book and you don't want to accept. I'm fine with that. I think it's a long shot that any moisture would migrate through a screw hole. However, don't confuse air impermeability with water impermeability. It's a fact that foam will absorb moisture.
If you need proof , you can take your EPS coffee cup and fill it with water. Leave it sit for a few days and tell us next week if their isn't a puddle under your cup.
If that one dosen't convince you, find an EPS foam hot-tub cover that's been in use for more then a year or two and feel how heavy it is. That's right it absorbed moisture. It will loose moisture just as easily if you set it in the sun without the cover on.  However, if you cover the moisture-laden foam cover with a complete envelope of steel, it will never dry out. That's the point Joe is making. It's a fact.

Al Cobb

Al,

The principal that if and it should be "IF" you expose EPS long enough to water that it will eventually absorb water or moisture is true. It is the practical that is what is objectionable, ie a steel sip dosesn't expose the eps to moisture. there is no way for moisture to get to or at least to mine. everything is sealed and encased, there is no exposed foam. However my brother has done considerable construction or refers on stucco homes where the stucco was applied to osb sheeting. The wood and the concrete stucco expand and contract at different rates and so the stucco cracks and moisture gets behind the stucco and over time rots out the osb. You have to pull off the osb and replace the sheeting. I guess this could still happen in Florida with osb sips and the eps could be exposed to moisture over time. But with steel sips even though the concrete stucco and the steel expand and contract at the same rates reducing the possibility of stucco cracking, yet even if a chunk of the stucco flakes off, the water still has to get past a sheet of steel. there just is no way the eps will be exposed to moisture for any length of time in a steel sip product and that is way yes in theory if the foam got enough water on it to absorb moisture and then it is encased in steel which is an oxi-moran thought anyway,( if it is encased in steel then how is it possible to be exposed) but any way if the foam absorbs moisture and then is encased yes there is no way for the moisture to get out. But if there is no way for the moisture to get out then how did it get in in the first place. I am confused this theory thing has me going in circles. Which came first the chicken or the egg. Which happened first the steel encasing the foam or the moisture getting to the encased foam????

I think the concept is similar to EIFs where the impermeable foam (EPS) was also covered by an impermeable top coating so there was no need for a drain plane.  When the impossible happened (repeatedly, and lawsuits followed) the design of EIFs changed (to include a drain plane).  I think the EIFS usually took some time to fail.  While I think the steel panel is much more robust, a house does not depend on EIFS for structural support and the steel panle depends on the steel/foam bond to provide support.  The point Joe makes in his book is that everything gets wet regardless of how well it is sealed so allow for assemblies to dry out.  Reading Joe's book on SIPS was the first I had considered this as a concern within the metal panel itself. 

I'm interested in the science of how this works because I want something that will work well, be energy efficient and last.  I have already had the experience of having a house built by the builder with "25+ years experience of knowing how things work" whereas I was just a young engineer with theories.  I very happily parted ways with that home years ago.  While I think the builder was unusually bad the experience of fixing so many things on my dime that would have been cheaper to build right in the first place is a rather vivid memory.  I purchased land several years ago that I will be building on once I'm sure of how I want it done.

I appreciate your input Al and found it interesting/surprising that you have also worked with steel SIPs.  I would really like to know what you view as the pros and cons of steel panels.  (It didn't sound like you are quite as opposed to them as the responses you received indicated.)  I originally looked at OSB SIPS but was concerned about how they would do in the hot, humid climate of Florida.  The metal would also be more insect resistant.  I thought I had seen where holes were drilled in the outside edge of the track (bottom plate) holding the panels so that water could get out.  I don't know if that allows the panel to also drain.  I was intending to place standard stucco on the exterior walls using a paper backed lath.  For the roof I was planning on concrete tiles (mostly for aesthetics) but it should also prevent any telegraphing of panel joints.  Any input on what you think would work best in this climate and why would be appreciated.

Thanks,

Chuck

Al;

you may want to reconsider your statements and Joe's principle after reviewing post based on actual experiments

http://greenbuildingtalk.com/Forums/tabid/53/forumid/5/postid/38105/view/topic/Default.aspx

maybe the foam density is different?