I am considering using SIP foundation panels for a new construction in central MN--I think it's mostly sandy soil, 'though I haven't evaluated the lot fully. Although I have not made a firm decision yet, I have done a search and found plenty of debate about wood foundations. I did not find much information about- if an OSB-EPS-TreatedPlywood panel were to be used below grade, what, if any, special procedures I should consider. I even bought the latest BuildingScience publication on SIP building, and it mentions nothing nothing about SIP foundations. Is an SIP foundation really that ridiculous? I have a few colleagues who have them and like them. Could anyone provide advise? Of note, I do plan on having two bedrooms in the basement, if possible.

The question is indeed moisture, but I do appreciate the plug and contact info.

....jc,

The only reason for my blog is just to show others interested in finding that there may be better ways to build. Being in the modular and building supply trade I have always been interested in new and perhaps better ways to construct our most expensive investments in life.

I also live in MN and plan to build a SIPs home with a SIPs basement. I have worked with the panel company and multiple SIPs builders who have assured me that using SIPS below grade would not be a problem in sandy soil. The skins of the SIP would be 5/8" treated plywood vs traditional 7/16" OSB. I have helped build a SIPs home in the area that used them below grade and to my knowledge they have not had any issues. The house is only 6 years old though. I'm interested in more details of your home if you're willing to share. I've been planning my own SIPs build for a few years now and hope that it can take flight in 2009.

It seems to me that using plywood below grade in a structural capacity is just asking for trouble.  Sure, a case can be made that it might not fail, for some period of time, but is there a compelling case in favor of using it?  What is wrong with ICF or traditional poured or masonry foundation with external rigid foam insulation?  Or what about AAC?  Or if you're simply infatuated with SIPs, look at fiber cement or MgO skins for the below grade portion.

In short: Avoid swimming upstream just for the heck of it, even if you're technically a good enough swimmer to do it.

Thanks for the replies. 

I'm just exploring my options.  I understand the concerns about wood foundations, and those I know who have SIP foundations built less than 10 years ago.  I'm continually reading posts debating wood foundations. 

Cement foundations are not without problems either.  I read a lot of methods of making an insulated and dry cement foundation, but have not seen discussion of (if there are even any) options on an SIP foundation install.  If it's really just a matter of shoving the panel in the dirt with a moisture panel, that's where the benefit lies--it would be easy, cheap, and dry.  In the end, though, I don't have any experience, so I don't really know what I'm talking about.

I am looking into fiber cement skinned SIP, but I don't think I can get them locally and I'm trying to avoid trucking materials in from long distances. 

I haven't investigated MgO skins and I don't know what AAC is, so I'll hold comment 'till I've read more.

MgO (magnesium oxide) is a magnesium cement -- an alternative to Portland cement -- and has similar characteristcs to fiber-reinforced cement board.  It is new on the scene in the US, but has been used in China for a long time.  As far as I know, most of the MgO available here is manufactured in China and sent over on boats (which is less energy-intensive than you might think -- ocean shipping sometimes uses less energy than shipping something across the country).

AAC stands for Autoclaved Aerated Cement.  It's basically foamed cement, with something like 80-90% air.  It usually comes in blocks, so you make a masonry wall with it using thin-set adhesive mortar, but it's also available in panels with steel reinforcement built in.  It is not quite as strong as cement, but it is very lightweight, uses much less Portland cement, and is actually insulating while being structural (around 0.9 - 1.25 R/inch, depending on density).  However, despite the fact that I suggested it above, I'll caution you that it's an open-cell foam structure and will transmit moisture even more readily than normal concrete.  Water itself won't come through, but water vapor will.  You still need to find a way to stop the moisture if you're using it below grade.  In the end, it's really not an ideal solution for a foundation wall.  I was just rattling off some options that might be a better fit than SIPs.

The best way to handle moisture in a foundation, no matter what materials, is good drainage.

rnortman;

actually it stands for Autoclaved Aerated Concrete:

To manufacture AAC, Portland cement is mixed with lime, silica sand, or recycled fly ash (a byproduct from coal-burning power plants), water, and aluminum powder or paste and poured into a mold. The reaction between aluminum and concrete causes microscopic hydrogen bubbles to form, expanding the concrete to about five times its original volume. After evaporation of the hydrogen, the now highly closed-cell, aerated concrete is cut to size and formed by steam-curing in a pressurized chamber (an autoclave). The result is a non-organic, non-toxic, airtight material that can be used for wall, floor, and roof panels, blocks, and lintels which according to the manufacturers, generate no pollutants or hazardous waste during the manufacturing process

as far as light weight? we installed 8" x 24" x 13ft. floor planks that weighed 800lbs. each requiring a lift to hoist into place. (46 lbs. per cu. ft.)
although they are much lighter than regular concrete planks they are still pretty heavy
We also experienced problems with moisture vapor and the bambooo flooring even though a membrane was troweled on first

Right, concrete, not cement.  I do know the difference -- I guess my brain was still in the last paragraph, where I was talking about magnesium and portland cement.  And yes, I meant they are lightweight relative to normal concrete and CMU, not compared to, say, those EPS SIPs with galvalume skins that some folks might favor.  The standard 8"x8"x24" blocks can be handled easily by one person, with considerably less effort than CMUs; the jumbo blocks and pre-fabricated panels are a different matter.  For the jumbo blocks, the distributor offers nifty little mini-cranes that are easily operated to lift them into place.  I think the panels are typically moved by real cranes.  But my understanding is that the normal small blocks are quite doable as a DIY project.

I'm curious about the moisture problems you mention -- was this floor over an unsealed crawlspace?  Was the troweled on membrane placed on the underside of the AAC planks?  If that's the case, I would definitely think twice before using AAC for foundation walls.

Personally, I like the idea of AAC with external rigid foam insulation for above-grade walls, because AAC alone doesn't have great R-value.  But once you add the rigid foam, AAC is going to be more expensive than SIPs.  (Maybe still cheaper than ICFs, though.)

Floor was over vented crawlspace that averaged 6ft. in height easy to stand up and walk around, ground had excellent perc. and dirt was covered with 6 mil visqueen.
ACC was tested for moisture content and found to be OK, before Bostik MVP4 was troweled on the topside.
Foundation walls were 8" block with 1/2" stucco finish

If done properly wood sided SIP foundation panels can be a great addition to your structure and they have been done for many, many years in Canada with much success. Much less common in the US because of the favoring of cementous type foundation systems. It is funny how it is met with such derision in the "lower 48" yet concrete/cement foundations - which handle the "freeze-thaw" cycle horrendously and are conductors of thermal energy rather than insulators - are so well regarded. You do have to be careful to have "below grade" or "below ground" level of treatment of your plywood - note this is NOT the same as "ground contact" treating. Not many places provide this level of treated plywood. And you should use 5/8" ply instead of 7/16" OSB. Further, as with most any foundation system, you should wrap the foundation with a reliable water-proofing system and backfill with gravel for proper drainage. You're addressing three different issues - structure, insulation and moisture. A strong SIP panel, properly sheathed and covered, can address all three.

CHL;

30+ years ago we built wood foundations in Pennsylvania with success, the great deterent in the US is the further South you go, the greater chance for termite infestation (treated or not).
Steel SIP foundations have been successfully used in Calgary, but for anything going in the ground I still think concrete is the best

"done properly" is the key word

SIP Foundation Panels should not be a concern if properly installed. I have worked with wood foundations dating back to the late 1970's and have installed SIP foundations for the past 10 years. The biggest factors in any foundation are providing proper backfill and drainage. There is no reason not to expect an extremely long lasting foundation if these concerns are adressed. I do agree that SIP foundation panels should use treated plywood skins on the exterior and at least the lower portion of the interior where the wall panel meets the floor. Using OSB below grade is never a good idea.

Currently, all of the SIP foundations that we install now are built tall enough so that the floor system (trusses or I-joists) can be set in top mount hangers thereby eliminating the entire rim area of the structure. This leads to less pieces of material to assemble, less labor and a tighter, more energy efficeint structure.

If you are interested, contact me and I can provide referrals to past customers.

Thank you,

Curt Stendel
Panelworks Plus, Inc.
4861 Ambassador Blvd NW
St. Francis, MN  55070

Office:  763-213-8064
Cell:  763-360-3694
E-mail: curt@panelworksplus.com

Any issues with penetrations: water spigots; electrical; gas; furnace, intake, water heater vents? or can you just bore the holes through the panel? Any problems with flooring where it transitions from joist to top of panel?

I have build sip homes for 20 years I have used panels under ground for a long time with no problems, we have a new sip panel now that has mag board on one side, it has been tested under water for 13 years and never changed. We can put these under ground with a few restrictions, the panel has to be 8" wide and can only have up to 8' of dirt on them. Your can contact me at david@bridlewoodconstruction.com for me into

buggly;  could you please post the test, results, source, etc.

buggly,
any wood stored under water continuously will not rot. Consider the 200 year old logs being 'harvested' out of the rivers where they sank over 100 years ago. It only when moisture and oxygen are present that deterioration starts.