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Interesting SIP alternative

wpoldake | Posted in Energy Efficiency and Durability on

Came across this site EZ Sip (

My original retirement house plan was the standard 2×6 wall framing, Roxul batt interior, with 1/2″ ply exterior wall then 2″ of Roxul then the furring strips with appropriate siding.

After seeing this concept and the associated savings in construction time, I am now in a bit of a quandary. Method does seem to meet interior and exterior insulation values, as well as issues of stud bleed through. Having ply on out side resolves potential accumulation of moisture due to dew point issues.

So what say others about this system?

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  1. GBA Editor
    Martin Holladay | | #1

    This system seems to be based on EPS panels with factory-made grooves to accommodate the studs. The web site does a poor job of describing the system, though, so I am left with questions. If I were considering the system, I would call up a company rep and ask about all of the steps needed to create a window rough opening with this system. Unless I'm missing something, it looks like every window rough opening requires a lot of custom work.

    And by the way, the exterior sheathing will be just as cold as it would with other wall systems. There doesn't appear to be any insulation on the exterior side of the sheathing.


  2. Benneaf | | #2

    William, In my opinion the whole issue of cold sheathing is overblown. Even the research often cited from Building Science Corporation found no discernible difference in the sheathing after three years. The SIPs do often have some thermal bridging where the studs are, but generally that is only every four feet. That's even less than an advanced framed 2x6 wall. The nature of SIPS is generally in line with building a tight envelope which is good as well. The trouble, as you read more on this site and others, will be finding HVAC contractors that actually know what to do with a well insulated tight house. Windows in SIP houses are generally precut out or cut out on site. Typically, a 2x frame is made around the window which is more thermal bridging, but that's the same as pretty much anything. Good luck.

  3. Yamayagi1 | | #3

    The EZ SIP system referred to in the link does not in any way remotely fit into the definitions or advantages of a true Structural Insulated Panel. The benefits of a true SIP are a result of the structural integrity of having the two sheets of OSB bonded to the EPS (or XPS or PU) foam substrate. The bonded assembly creates an incredibly strong monolithic structural composite that acts like an I beam in strength based on the "skin and web" bonding. The other advantage is the speed of assembly on site, with a material cost penalty disadvantage. The site speed of assembly might make up for some or most of the material cost disadvantage over stick frame systems... But- EZ SIPS are NOT SIPS. If you are in earthquake or hurricane areas, SIPS are well worth considering. The Kobe Japan earthquake of 1995 destroyed amost the entire city housing stock, but the few structural panel homes there were virtually undamaged...
    The other wall system you are proposing is covered in depth by the New Jersey architect Greg La Vardera. A search for "Swedish Wall Framing" will get you to his extensive detailing of his wall system that is based on advanced framing and mineral wool insulation. Worthwhile reading for your thoughts- Though I am planning on building with a system of 6 1/2" EPS SIPS walls with an interior furred out 1 1/2" utility chase insulated with 1 1/2" of mineral wool- a mix of the best of both systems? Wiring will be in ENT for future wiring changes and raceway access.

  4. jackofalltrades777 | | #4

    This wall system is NOT what I would define nor would SIPA define as "SIPs". It's basically a pseudo-hybrid type of system that offers none of the benefits of a true SIP but offers the negatives of typical wood frame construction.

    What makes a SIP a SIP and provides the strength is the I-Beam engineering that a SIP creates. The skins of a SIP are usually OSB and when laminated/glued to the foam core, offer the strength and a nailing/screwing base on both sides of the SIP. A true SIP has OSB sheathing on BOTH sides of the panel. A true SIP is also more airtight because the OSB skins are adhered to the foam core. The system you reference in assembled in the field and I can see air gaps all over the place. Not to mention the thermal bridging that is going on around door, window and corner areas. In the pics they have 3-5 studs sitting next to each other to provide strength. A SIP would not require that.

    SIPs are recognized by the International Building Codes but these panels are not SIPs. They are more of a prefabricated wall panel system. I don't see the advantages of using this system. Might as well utilize a real SIP at that point.

  5. Expert Member

    Lots of good reasons to consider Sips, but I'm not sure earthquakes are one of them. While SIPs offer a marked improvement over common Japanese construction techniques, the studies I've seen show their structural performance in a seismic event is no better than standard Western platform framing, and it is much harder to upgrade their connections to improve them than it is with common stick framed buildings.

  6. jackofalltrades777 | | #6

    University Of Berkeley & Federation of Scientist study on SIPs and earthquakes:

  7. user-4310370 | | #7

    You may as well use the zip system + interior insulation over this, its an inch of foam adhered to OSB with a WRB adhered to that - seems simpler and the interior insulation can be whatever you prefer. I can't say anything as to a cost difference though.

  8. 39Chev | | #8

    It seems that most people are wanting to talk about why a regular SIP is stronger. I don't know where William lives, but I live in North Central MN and we don't have earthquakes. Normal stick-building works fine here (as far as strength), and virtually NO builders are using actual SIP's around here.

    I asked about these back a few months ago and really did not get many opinions regarding their energy efficiency, long term durability, etc. They sure seem to be an intriguing way to insulate. I can see where they would be quick to frame...just lay the styrofoam down and drop the studs into the slots? As Martin mentioned above, the window framing might be a little more complicated.

    I have my house listed for sale right now and if it sells, I might try these on the workshop (I build the workshop first with 3/4 bath etc. and live in that while my house is being built). I talked to a couple of carpenters, and though they have never used these, they were also intrigued.

    If I end up using them, I'll be sure to report back on how they work.

  9. Expert Member

    Brad, SIPs Achilles heal is the joints between panels. That's where the failures have occurred. Find out about best practices for sealing them before you build.

  10. 39Chev | | #10

    I won't be using SIP's, but these EZ Sips are intriguing. Click on the link in William's original post to see what I am talking about. These are 4x8 EPS panels with cut-outs for the studs and removable channels for the wiring, etc. I have no interest in actual SIP's.

  11. Benneaf | | #11

    I hadn't looked at the link provided in my initial reply, but as several have mentioned these are not actual SIPs. It really doesnt even look like a time saver to me as even being slightly off with a framing member will give you fits getting it to fit into the pre-cut chase. True SIPs have been around a long time and are a proven technology even if they are not widely used. I am building in TN and though I used SIPs on my last house this one will be framed. I will be using a 2x8 top and bottom plate with two 2x4 walls staggered every 8 inches to minimize thermal bridging. There are a million ways to build and build energy efficiently, you just have to decide what is most cost effective in your local, for your weather, with your subs, that gets you to the level of insulation you want. No small task, but the wall system is really one of the easier decisions. The execution of your air sealing strategy, how you insulate your foundation/crawlspace, and your HVAC design are all just as inf not more important. Just think of it all as a system, not just isolated parts.

  12. Expert Member
    MALCOLM TAYLOR | | #12

    I had the same thought about the stud spacing. When I look at the walls on the house I'm framing up right now, a run of 16" oc is the exception, not the norm. Built up posts, backing for interior walls, double studs at openings. Maybe there is some way to easily modify the foam, but it looks like you would spend a lot of time with a utility knife hogging out chases for anything not at 16".

  13. [email protected] | | #13

    Hi. I am the president of EZ SIPS. Thank you all for finding my website and EZ SIPS.

    For areas with king studs, posts and doubled up studs you simply cut off the panel at the edge and continue on the other side. We supply sheets of foam to build out the thermal break layer to the same thickness. While there is some labor to cut and mount the foam, many people are using EZ SIPS as a cost effective and convenient product for building the maximum quantity of high efficiency EPS foam insulation into their project.

    Our vertical wiring chases are on both sides of each stud slot. They are cut so the mouth of the stud slot opens a little more than 1.5". Unless your 16" or 24" on center is very very sloppy you will not have a problem sliding the panels down over your framing.

    The advantage of EZ SIPS over standard sandwich SIP panels:

    1. Hybrid combining the benefits of SIPs at 50% less cost than pre-cut SIP panel systems

    2. Any carpenter can work with EZ SIPS

    3. Exposed inner wall face with snap-away vertical & horizontal wiring / plumbing channels

    4. Thicker actual EPS insulation

    Please feel free to inquire with me directly toll free at 1-888-747-7488

  14. [email protected] | | #14

    [Post deleted by GBA editor]

  15. GBA Editor
    Martin Holladay | | #15

    Richard Lewin,
    It's OK to answer technical questions on this Q&A site. But this is not a good place to promote your products.

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