Hello, I just went back from a building show and saw that a lot of sips company are now offering plywood sips instead of osb. I've never been really interested in osb sips because I'm not a fan of osb.

I've talked to another company that said that plywood sips aren't recommended because the eps is bonded only to a thin veneer instead of to a multitude of chips...

what are your tought on plywood sips?
thanks

I always wondered why plywood wasn't used myself. Must be a price issue? Ply does have a premium over OSB. Do you know what type of ply they were using? Seems a CDX ply skin would be the logical choice but is there any reason (other than price) that OSB is generally preferred over plywood?

I have never seen a 24ft. long piece of plywood

Higher likelyhood of the plywood veneers delaminating.

How do Steel sips maintain there adhesion? I would have thought they would be more likely to delaminate then plywood or OSB?

Actually, any material will stay laminated to any other material under load with the right adhesive and the right amount of adhesive. There's plywood and then there's plywood. Plywood design to be used in SIPs will and should be of a higher grade/quality/density (more glue) than off the shelf sheathing plywood. The same goes for OSB facings. Metal facings have a mill applied bonding primer applied to the lamination side to make sure the adhesive adheres properly.

"Higher likelyhood of the plywood veneers delaminating."

By this, is your concern the plywood to foam interface or the plywood layer to layer interface? I guess my question is if OSB is more likely to fail if exposed to moisture, wouldn't a plywood specifically designed to handle that type of environment (or at least perform better) be preferred all other things being equal?

Well, there is OSB specifically designed to handle moisture too. It probably has much more adhesive content and was pressed to a higher density. Theoretically and all things being equal, OSB and Plywood would bond equally well to the foam core, but the plywood would have more of a chance to have it's plys delaminate because of the particular forces 'long-spanning' SIP facings endure under load. SIPs are a different animal than 'short-spanning' sheathing loosely pinned to trusses. SIPs (stressed skin panels) are constantly under load even when not under an external load. This is just my opinion.

We at Eco-Panels have worked on several projects using AC grade plywood as a skin--floor, wall and roof panels. There is a premium price when using plywood in lieu of OSB. As others have mentioned, there are many different grades and options when considering plywood. Eco-Panels is an injected polyurethane panel that acts as the glue.

Seems that OSB handles moisture uniformaly where plywood could cup and promote delamination. especially if one facer got moisture and the other did not Thoughts ??

I have seen wet OSB SIP skins swell to nearly twice their thickness, but they did not seem to delaminate

It is my understanding that plywood has grain and will allow the water to spread out thus lowering the amount of water in an area.  OSB, not having grain, will hold a higher concentration of water in an area which will lead to the OSB rotting before plywood would.  If I remember correctly, I heard this in a lecture by Joseph Lstiburek, Building Scientist.  I know that plywood likes to delaminate but this can be somewhat controlled by purchasing the exterior type.  Dana1 might give some insight into this subject.

I like the Metal facer Chris , also we are in roofing and most of painted roof panels are Kynar or polyester but over galvalume as a base not just straight over galvanized although new G90 is quality stuff...Metal SIPS are???

Posted By Ray P. SIPLOCK Systems on 12 Mar 2012 08:02 PM
I like the Metal facer Chris , also we are in roofing and most of painted roof panels are Kynar or polyester but over galvalume as a base not just straight over galvanized although new G90 is quality stuff...Metal SIPS are???

Ray; we have both painted galvalume and painted G90 available