Interesting discussions on both SIP and ICF forums and one  particularly that focuses on our main concern. We are considering SIPS now for a larger (9800+ sq ft home) and have serious concerns about OSB, water etc.  I have a home with DryVit that has held up reasonably well.  We had some intrusion after 11 years in a couple of window areas and one valley with improper flashing.  I say reasonably well, it cost us about $45,000 to fix these problems as well as change a few others to avoid problems and re-paint (with DryVit paint) the entire home.

We found the Amvic system of ICFs particularly interesting but when searching for knowledgeable and reliable contractors in Indiana who could do more than a box have been disappointed so far.  Finding this we are back to considering either SIPS or conventional framing.

One thought on the SIPS was to use Avantech (sp? a water resistant plywood) instead of OSB. I was told that Insulspan would do so but the dimensions of the panels are limited to 4x8 because of the plywood. Any and all thoughts are appreciated.

Q. Am I overly concerned with OSB? (once wet ruined)
Q. Does the plywood solve any of this? i.e. if water intrusion monitored and stopped then plywood can return to close to its original dimensions
Q. There are limited resources in central Indiana for ICF construction. any answers or hlep on this one?
Q. What structural techniques would you use if you were building that "last home for retirement for the next 35 years or more.

Thanks

Several weeks ago there was an energetic discussion about plywood vs. OSB on the JLC Online forums. I would say the general agreement is OSB is crap for subfloor unless there is no or only a small amount of rain, snow, etc., during construction and it's going to be covered with carpet. For roof sheathing opinions were about split whether plywood is worth the cost. Again, if you can cover the roof quickly then OSB is OK. On walls, the risk of damage due to moisture during construction is minimal, so go with OSB. I would say on walls, plywood's ability to handle moisture on a short term basis isn't an advantage because with either material you have got to use a water barrier and proper door and window flashing to keep the wall dry for long term integrity. I think there was pretty much unanimous agreement that plywood is structurally a better product. It's stiffer & holds nails and screws better.

I considered SIP for the home I'm getting ready to build but opted to go with ICF. This was mostly because I can get in more sweat equity as a percentage of final cost with ICF than with SIP. The local SIP mfr admitted that material cost is 20% to 50% higher with SIP over conventional framing, but labor savings well offsets that. In my case I didn't want to exchange my labor to pay for mfr labor. I asked him a few weeks ago about using SIPs for floors. He admitted that's the one part of the house they are not competitive because of free span limitations.

My only concern, structurally, with SIP is its long term stability under column, or edge, loading. Will the SIP panels, by themselves, support the roof weight over the long term without tending to buckle? Some comments I've heard is that SIPs work great if installed using a post & beam structure  to carry the bulk of the weight from above.

As to the 4' x 8' limit on size if you use Advantech, that's right. The local guy said they regularly make the SIP up to 9' high by 24' long because they can get OSB sheets that size.

All of the above is subject to debate, I admit, but I offer it as something to think about.

I know very little about SIPS as I have never taken the time to really study the product so my opinion is very biased and I will keep it to myself. As for the ICF, I find it difficult to believe that you cannot find a competent installer in your area to do the project. Perhaps ask the distributor again or look at other ICF distributors in the area that could recommend the right contractor for your home. Surely there has to be someone qualified to do the project. I'd bet for the size of your new home someone on this site will travel to do the job.

Chris

Richardmack,

We are building with ICF wall and steel-concrete floor/roof systems in Southern Indiana, (Bloomington). While researching concrete homes, Indiana is not a leader! One of the reasons we are  going with ICF is because of the decay issues. The only wood we will use will be for inside walls, trim/doors and stairs. I agree with the previous poster, use your ICF dealer for builders reference. "Construction Resources" in bloomington may be interested as well.

Keep your eyes open to ICF.

Patrick T

Richard,
I have to disagree with some of the statements posted here. I have been in residential building for over 30 years, and I can not remember a single instance where plywood has outperformed OSB. I have not used plywood in a structural situation since OSB was know as blandex, and first came on the market. The idea that OSB is ruined because it gets wet one time is ridiculous. I once found a piece of 'blandex' laying in the side ditch of my driveway during early spring yardwork. It had been there since the previous fall, through a winter of rains, snow, and freezing temps. After several months of this 'mistreatment' the OSB was still structurally sound. I could never have said that about plywood. That was over 25 years ago. Since then I have used OSB on every project I build. I have never had a delamination problem, and I have had all types of water problems (rain, sleet, snow, broken water lines) to deal with.
In short, it has been my experience that OSB is far more stable and forgiving of water than plywood. And, yes, I will build my retirement home using OSB sheathed SIPS. Remember, water damage to any type of wood is caused by caused by continued exposure, not by getting rained on and then being allowed to dry out. Use proper flashing and rainscreen techniques and you will have no problems.

I agree with Wes, the new glues and better fabrication techniques make OSB products perform extremely well. I have used Advantech, which is an OSB product, on all my floors since 96. Sometimes it may be another brand, but it is still an OSB composite. Sometimes OSB on the roof, sometimes plywood!

Wes,

I am suprised that I have a complete 180 degree experience and opinion. I build in the Pacific NW where we get about 3 months of sun and 9 months of clouds, rain, and high humidity. I have found OSB to be dimentional unstable with moisture and evetually with just disitigrate in less than 6 months. I always have scraps of plywood and OSB hanging around in the bed of my truck for cleating purposes and I might get 1/2 season out of OSB but I get several seasons out of my plywood. This is of course not a scientific study but mearly anecdotal evidence of an observation in the bed of my truck. I personally stay away from OSB for anything outside my building envelope and even prefer plywood in my interiors too.

ICF Contractor

Richard,

   Where in IN are you? You might not be far from the contractor that is starting my project in a few weeks.

 

Brian

" Surely there has to be someone qualified "  If only that were the case.  Most users are very small or as I found out visiting one builder very bad.  Surprisingly this builder who uses ICF had installed an EFS system over the ICF.  Nothing wrong there except the job was the worst I've ever seen.  The home (about 6,000 sw ft) was one year old and the EFS was already failing and this over concrete.  The blue mesh was exposed in places and spongy in others.  I wondered if he had actually used ICF on this home but it appeared from looking in the basement and other areas that he had.  He also failed to acknowledge that anything was wrong with his work. 

My wife and I left as quickly as we could without being rude. If you or anyone else has recommendations for someone who cares about their work and can handle a complicated (somewhat anyway) design over 12,000 sq ft. I'd love to hear from them.

Thanks for the follow up. I am in Indianapolis.  I hope your contractor is not the one I've visited with recently. [email protected]