"Thin" SIPS for stick-frame retrofit?

[think-it-through]

Hello All,

I've been a JLC subscriber for a few years, new to the online forums, I'm a homeowner interested in data-driven value & quality workmanship.

Forgive me in advance for my ignorance, but can anyone point me to JLC articles or forum discussions or product info related to the application of "thin" (i.e. maybe 1-1/2" overall thickness) SIPs to the exterior of existing 2x4 stick-frame home?

House is in southern California, built in 1960, single story, 2x4 stick frame, stucco exterior, button-board+plaster interior, plank & beam flooring on raised foundation, with no insulation in the walls.

Want to replace the original single-pane aluminum-frame slider windows with dual-pane windows. Because the place is going on 53 years old, with no insulation in the walls, and the tar-paper exterior wrap under the stucco crumbles every time my contractor touches it (had to recently replace the patio sliding door and one exterior man-door), and also because we live in earthquake country, I am leaning toward tearing off the exterior stucco down to the studs, inspecting the electrical wiring for any issues and the framing for termites, installing the new windows, adding insulation in the walls, and re-stuccoing the exterior. My initial thought was to use one of the new blown-in fiberglass products in the exterior stud-bays (because it's economical and proven), then sheath over the studs using "thin" SIPs (for both increased R-value and simultaneously adding earthquake-resistance).

I know this not the most economical option, but I can afford it, and to my layman's mind, it meets my criteria for creating a much higher-quality home while I am (actually my contractor is) at it. So I'm trying to educate myself enough to determine if my initial plan is bogus (either because it will cause more problems than it solves, or maybe because such a product ["thin SIPs"] is not actually available). My contractor is not aware of any "thin SIP" products, and such a project would be a learning experience for him. He's sharp, willing, and trustworthy, but because this was my idea I want to run it to ground technically myself before I insist that he do it this way.

Any feedback appreciated, and I thank you in advance, even if your feedback is just pointing me to an existing discussion you might already know of (I did search the website, couldn't find a match for a situation similar to the plan I'm proposing).

[Lavrans]

The only thin SIP type materials I know of that sound like what you are talking about are insulated siding panels. Generally foam sandwiched in a sheet-metal. You'll see them on commercial buildings, etc., but they are a type of siding (this month's EDC has a advert/article about a system that integrates with their series of windows...). They might be a good choice though, especially if you happen to like a fairly modern look.

I'm doubtful you could get a wood product that would work very well for the application you are talking about (1-1/2" thick doesn't leave much for insulation). There are a number of metal clad SIP roofing systems, too. Again, I'm not sure how "structural" they would be for your application, and they are thicker than 1-1/2" or so.

[Martin Holladay]

Think It Through,
Here are two articles for you. One retrofit used nailbase:
http://www.greenbuildingadvisor.com/...ulation-panels

Another retrofit used SIPs:
http://www.greenbuildingadvisor.com/...-zero-showcase

[Lavrans]

Those are all pretty standard size SIP's. I guess you lose 1/2" with the nail base, but still 6" rather than 1-1/2" or so. Does the nail base provide any structural reinforcement?

[keithwins]

Have you talked with any SIP companies? They'd be the ones to tell you if they will make up some 1 1/2" SIPS for you. I suspect they will, but they might be disproportionately expensive.

I'm not sure if there's any off-the-shelf analysis of how much they'd contribute structurally, since what you're doing is neither a SIP building now solid sheathing on stick-frame. So that would depend heavily (as always) on the details of implementation.

[clydewater]

HI
I was at a lumber yard show and saw ZIP has a new wall product with about 1" super dense foam laminated to their panel. This is thin, can then be taped up to make it air and WRB.

[Mark Parlee]

Getting in here way late
Been gone doing level II at EDI

LAV, can you link me to the article you mentioned in post 2

Clyde, did they give you any kind of idea of the insulation value?

[Lavrans]

LAV, can you link me to the article you mentioned in post 2

Here you go Mark.

The mag is fairly light on information, but touches on a lot of things. I like the green roof problems- hadn't really thought about a green roof in a tornado zone and the problems that can create...

[clydewater]

Hi
Here is a link to the specs. Check the right side of the page for the spec sheet

http://www.zipsystem.com/zip-system/rsheat.aspx

They claim R 3.6 for a 1" panel and 6.6 for a 1 1/2" thick panel.
Not great, but better than nothing.

I just used some of the roof sheathing and tape system to replace part of a slate roof with asphalt roofing shingles on an old Victorian house. I was working alone, so I liked the fact that I could get the roof watertight in one day. The tape really holds well once it is rolled in

Thanks
Rich

[Mark Parlee]

Thanks Lav

Thanks Rich,
I see the insulated panel as additive in the right place as far as insulation goes.
Any insulation over the face of the framing members reduces thermal transmission via conduction.

[clydewater]

You are welcome Mark.
I was impressed as to how dense the foam was. There were some bracing rquirements that may be needed to suppliment the sheathing, but overall I was impressed by the product.
I may use it on my own house as a retrofit since I have 1 X 6" plank sheathing and needless to say, it is not very air tight.
Will add some insulation, make it air tight, adds the WRB, etc and not have to do too much to pack out the windows etc
Rich

[Ted S.]

I'd be interested in the additional bracing requirements required for this product in new construction.

I can't see how you can meet the wind loading requirements of the I Codes with the foam between the sheathing and studs?

Otherwise, I like the concept, foam over sheathing as it is more widely done is problematic in several ways, albeit perfect on paper and theory.

[think-it-through]

Hello All,

Sorry for my delayed response after initiating this thread - had to replace the old computer and it took awhile...

Thank you all for the insights and the links to articles & product info, I greatly appreciate them and I will print them out to discuss with my contractor.

Thanks again, best wishes to all.

—think-it-through