ICF exposure, metal siding
Last Post 17 Jan 2012 02:15 AM by dmaceld. 14 Replies.
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jacktcaUser is Offline
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12 Jan 2012 02:16 PM
How much time do I have after I put my ICF walls up to cover them with roof and siding before damage can occur?   My environment is high desert.   Mostly sunshine but it can occasionally rain and rain hard especially in winter and spring. 

I'm thinking of installing metal siding on my ICF walls.   Is there any value added to covering the walls with black plastic 6mil moisture barrrier and shiny silver radiant barrier and 3/4" furring strips as well?   
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12 Jan 2012 06:56 PM
I have seen ICFs left exposed for over a year, with no lose of structural integrity. They willstart to break down because of the UV in sunlight. This is generally seen as discoloration of the foam and 'dusting'. I would suggest no more than 2-3 months exposure. Skip the 6 mil poly and radiant barrier. I personally would use a tyvek type housewrap, and furring strips for your metal siding. Neither is absolutely necessary, but I am a belt and suspenders kind of guy.
Wes Shelby<br>Design Systems Group<br>Murray KY<br>[email protected]
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15 Jan 2012 02:08 AM
So one can install Tyvex over the exterior ICF and then apply a stucco finish?
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15 Jan 2012 08:10 AM
Lbear,

I believe you plan to use some type of stucco.

I doubt that Tyvek would make a good base for any type of stucco.  That is, stucco would not likely stick to Tyvek.  My guess is that stucco on Tyvek would need a mechanically attached netting or mesh to hold the stucco. 

If I remember correctly from Joe Lstiburek's lectures, the best membrane to use behind real stucco is 2 thin layers of roofing felt which has the ability to vary the perm rating according to how much moisture it is exposed to.  The layer next to the stucco allows the stucco to move somewhat independently of the other layer.  The two layers create a thin rain screen.  As you know, real stucco is not waterproof.  According to Joe, the two layers are important.  My guess is that one layer of roofing felt covered with diamond mesh backed by black paper might work well in your arid climate.  Study Joe Lstiburek's writings on the internet about stucco.  Joe certainly does not like the new type of air barriers.  In fact, he says a lot of our current problems with trapped moisture started happening after we switched from felt.  He also mentions that the current felt is not quite the material that it used to be.  Now it is made with cheaper materials and thinner.  It may not work as well as it used to.

But if you build with ICFs, then I would not think you would need any barrier behind the stucco.  The most that I have seen stucco (real and synthetic) installers do is use a plastic or fiberglass mesh behind the stucco to give more puncture resistance.  This is ususally done for the first four feet up from the ground.  Even with this mesh, I would not weed eat against the stucco finish.  To avoid weed eating, avoid grass next to the house.  Use river rock, etc. instead.
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jonrUser is Offline
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15 Jan 2012 08:13 AM
Take a look at "Stucco Wrap" if you want anything at all.
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15 Jan 2012 01:45 PM
Out here in AZ, the way they do stucco is basically 1/2" - 1" of EPS that is attached to the homes framing/OSB. They then attach chicken wire/mesh to that foam. They then throw on the 1/4" - 1/2" of stucco.

Then as it rains, the stucco gets soaked and starts to let in water behind it. The EPS repels most of the water but where the staples are, water will trail in and get behind the EPS. The tar paper is the final barrier and if there are any rips in it, water will make its way into the wood framing.


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15 Jan 2012 02:48 PM
Lbear,

Do the staples have plastic caps to keep the water from following the staple.  I have never seen staples used to attach EPS.  I am familar with either nails or screws with the green plastic caps.  In fact, I have a cap nailer.
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ICF ConsultingUser is Offline
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15 Jan 2012 03:55 PM
Hello jacktca. The sun will eat your EPS, SLOWLY. Unless you are looking at a VERY LONG building period, 10 years+, don't worry at all. Metal siding is a great product, if you've installed your ICFs correctly, especially in high desert (where I live, western Colo.). Radiant barriers don't work unless there is an air space on the reflective side. So if you applied a reflective material of some sort, and then fastened furring strips across the forms (or vertically, depending on how your siding is oriented) I think you'd have an advantage. Whether advantage "dollars-out" is for you to determine. Keep well, ICFC
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15 Jan 2012 10:33 PM
Posted By Alton on 15 Jan 2012 02:48 PM
Lbear,

Do the staples have plastic caps to keep the water from following the staple.  I have never seen staples used to attach EPS.  I am familar with either nails or screws with the green plastic caps.  In fact, I have a cap nailer.

They do NOT have plastic caps. They sometimes run nails IF they are going through OSB but if no OSB, then they will run a staple. Here is a picture of what they do out here:




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16 Jan 2012 11:55 AM
My wife and I built a water well pumphouse which didn't receive siding for 9 months over a winter, spring, and summer.  You'll see some yellowing and a slight chalky dust,  A good rain will wash some of the dust off, but I don't think you lose much R value.

  

 I toyed with the idea of applying cheap "oops" latex paint from the big box stores to protect the foam.  I may do this after we build our house if it will take some time for the stone exterior.  How about a Picasso like exterior using the variety of custom colors available on the oops paint shelf!  Would most likely freak out the neighbors!
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16 Jan 2012 01:54 PM
I purchased a trailer load of furring strips on craigslist for $80.   Enough to cover the roof and side of the house.    I will install reflective barrier and furring strips.    So yes, there will be a 3/4"-1" air pocket in between the house and the metal. 

My jury is still out on the moisture barrier (6 mil plastic).   Tyvek is too rich for my blood.    Do I need it in the high desert (Southern California)?   It rains occasionally but moisture is not a problem.     It's an extra $60 and a little bit of work/hassle to put it on.   The money is not a problem but the work/hassle is.  


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16 Jan 2012 02:30 PM
Jack, I wouldn't bother with a moisture barrier in your climate.   Looks like you can get over 3 months of temps over 90F so a radiant barrier might be useful.   Pretty good map of SW climate zones below.


http://www.sunset.com/garden/climat...000067305/     Dave



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16 Jan 2012 06:39 PM
Posted By jacktca on 16 Jan 2012 01:54 PM
My jury is still out on the moisture barrier (6 mil plastic).   Tyvek is too rich for my blood.    Do I need it in the high desert (Southern California)?   It rains occasionally but moisture is not a problem.     It's an extra $60 and a little bit of work/hassle to put it on.   The money is not a problem but the work/hassle is.  



I say no, no, no, no, to the plastic. The ICF is plenty adequate as a moisture barrier. Plus, you don't want a vapor barrier anywhere except in the super cold regions of the northern US and Canada. You need for water vapor to be able to travel through the wall, and it won't do that very fast through ICF. When I built my ICF house I did a test to see how much water styrofoam would soak up. In about ten days time submerged in the tub it took on zero water.

Tyvek is a moisture barrier but not a vapor barrier. Poly is both.

In fact, if you do use a radiant barrier make sure it is one that water vapor can travel through. If you can't find a vapor permeable barrier, then don't use it. Think real hard about using a radiant barrier. As has been said you must have air space above it for it to work at all. But, if your climate is cold in the winter you may want the heat that the metal siding absorbs to help in the heating of your house. It's a trade off between reducing cooling load in summer and increasing heat load in the winter. The siding itself will reflect a lot of the sun. I see frost on my roof get melted by the sun reflecting off an adjacent wall.





Even a retired engineer can build a house successfully w/ GBT help!
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16 Jan 2012 10:31 PM
I say no, no, no, no, to the plastic. The ICF is plenty adequate as a moisture barrier. Plus, you don't want a vapor barrier anywhere except in the super cold regions of the northern US and Canada. You need for water vapor to be able to travel through the wall, and it won't do that very fast through ICF. When I built my ICF house I did a test to see how much water styrofoam would soak up. In about ten days time submerged in the tub it took on zero water.

Tyvek is a moisture barrier but not a vapor barrier. Poly is both.

In fact, if you do use a radiant barrier make sure it is one that water vapor can travel through. If you can't find a vapor permeable barrier, then don't use it. Think real hard about using a radiant barrier. As has been said you must have air space above it for it to work at all. But, if your climate is cold in the winter you may want the heat that the metal siding absorbs to help in the heating of your house. It's a trade off between reducing cooling load in summer and increasing heat load in the winter. The siding itself will reflect a lot of the sun. I see frost on my roof get melted by the sun reflecting off an adjacent wall.


So do most ICF homes just leave the exterior EPS alone and then just put the finishing product (siding, stucco) on?

With a stucco finish, in heavy rain events, water will saturate the stucco and then water will begin to flow behind it. Even then, the EPS should stop the water from reaching the concrete wall.

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17 Jan 2012 02:15 AM
Posted By Lbear on 16 Jan 2012 10:31 PM
So do most ICF homes just leave the exterior EPS alone and then just put the finishing product (siding, stucco) on?

With a stucco finish, in heavy rain events, water will saturate the stucco and then water will begin to flow behind it. Even then, the EPS should stop the water from reaching the concrete wall.


In my research before building my house the only barrier that was advocated across the board is flashing around doors and windows to prevent water from getting into the area between the blocks and the door or window.

As far as water behind stucco I don't see how that can be an issue because the stucco surely must be in solid contact with the ICF. But I'm not acquainted with the ins and outs of stucco application so someone who has used it will need to give you a more definitive answer.

Even a retired engineer can build a house successfully w/ GBT help!
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