Durable Residential EIFS System
Last Post 01 Sep 2014 11:28 AM by Bryan1978. 13 Replies.
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ricky_005User is Offline
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29 Aug 2014 01:23 PM
Residential EIFS systems of the past have a bad reputation of rotting out wood stick framing and sheathing. The cause of failure was always blamed on the contractor for not following the critical details around openings etc...

I'm going to use the revised EIFS residential systems by STO for example.
http://www.stocorp.com/index.php/en...egory.html


 
As you can see the plywood seams are meshed and filler applied. You can also assume that nail holes and imperfections in the plywood would also need to have the filler applyed before the final liquid barrier is applied. Once the liquid barrier is complete you should have a perfectly air tight water barrier which you should be able to get with semi skilled labors. The results, No holes/Staples in your air water barrier.

Next the EPS is attached with an synthetic mortar forming a rain screen between the AWB and EPS ...... again no nails or screws penetrating your air water barrier.

Than of course the mesh, base coat, and finish.

It seems like a decent method of setting up a durable EIFS system on wood framing?


I'm a bit concerned about the cost of the system. Anyone know roughly what the cost per S.F. for materials, and the labor cost for installation for such a system?
jonrUser is Offline
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29 Aug 2014 05:11 PM
You might consider DensGlass at about the same price as plywood.
JellyUser is Offline
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29 Aug 2014 10:27 PM
Ricky, you're in Atlanta right? There's probably a STO dealer within 10 miles of you. Price it out and post the results. EIFS doesn't get the love that it should.

But I would like the assembly better with steel framing and DensGlass.
ricky_005User is Offline
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30 Aug 2014 12:40 AM
Yes in the Atlanta area... As you know EIFS systems have the best Thermal performance of all the common claddings. Many home owners had their hearts ripped out in the 90's so many are scared of the system built on wood sheathing.

I would think steel framing would put me even closer to the cost of ICF.

Lets say I built a one story home 9' ceilings hip roof all sides with a 2'-4" soffit over hang. With such a wide soffit it should eliminate any rain hitting the exterior walls except during wind driven rain events which will happen occasionally. So with a wide over hang I'm thinking it should increase the durability to a certain degree....you still have to do your do diligence on water sealing the windows and doors and penetrations but I was thinking being just a one story home maybe tyvek commercial stucco wrap would be adequate .... not as air tight as the liquid applied barrier but would be cheaper than the liquid.
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30 Aug 2014 12:50 AM
I do have some concerns about the liquid applied AWB splitting/opening up at the plywood joints over time as the home settles, wood shrinkage or high winds. But there again, house wrap with mechanically attached EPS is full of holes from the nails and staples.

You have to use diagonal bracing if you use Densglass right?
JellyUser is Offline
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30 Aug 2014 07:21 PM
Well it depends on your construction drawings whether the sheathing is structural or not. Steel framing would not put you anywhere near ICF. It is probably a little more than wood framing at the moment, but the peace of mind would be worth the small escalation of cost. And if you need diagonal bracing then steel strapping is cheap.

The problems with EIFS were indeed due to the failure of proper installation. EIFS are used extensively across Europe with great results. One thing you have to be careful with though is vandalism. If your house is in an urban area, with foot traffic directly adjacent to your house, the cosmetic finish can be vulnerable to blows.
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31 Aug 2014 11:35 AM
After speaking with a distributor, pricing for the STOTherm NExT system materials and labor is roughly in the $6 to 7$ per S.F. with 3" of EPS

Note:
Materials for Openings, penetrations, corners, starter strip etc are not included in the price.
JellyUser is Offline
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31 Aug 2014 12:24 PM
You would probably need twice that thickness to meet R requirements, or you would have to add some sort of insulation on the inside. Is your project a 1-story or two?
jonrUser is Offline
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31 Aug 2014 01:55 PM
It would be interesting to see more discussion of designs with no sheathing other than rigid foam (staggered layers plus diagonal steel strapping and/or other techniques). I know someone who did this and it seems to work fine. Some say "you could kick your way through the wall", but then it would be much easier to "kick your way through a window".
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31 Aug 2014 03:07 PM
Actually it might not be so easy to kick through layers of polymer modified stucco, mesh, foam, et cetera, but you could easily get through it with a Sawzall. Then again you can easily get through OSB with a Sawzall, too.
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31 Aug 2014 04:26 PM
Posted By Jelly on 31 Aug 2014 12:24 PM
You would probably need twice that thickness to meet R requirements, or you would have to add some sort of insulation on the inside. Is your project a 1-story or two?

Here is the exterior wall stack out ....

Wood Framing..............................................................
1/2" to 5/8" interior drywall
2x6 wall studs 16" O.C. with cellulose or blown fiberglass insulation
1/2" 4 ply Plywood sheathing
STOTherm NExT System..............................................
StoGuard Mesh and Sto Gold filler
Sto Gold Coat
Sto Adhesive
3" of EPS
Sto Base Coat
Sto Mesh
Sto Finish
.......................................................................................


jonrUser is Offline
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31 Aug 2014 04:31 PM
Jelly: I agree. So why plywood or OSB when you have rigid foam and are either going to glue on EIFs or add furring strips (preferably glued and screwed) for other types of siding? You get a layer that reduces drying and could rot.

Possible answers: X cross steel strapping isn't approved or isn't as strong (even if it meets specs). But that also leaves options like plywood at the corners and additional foam elsewhere. Less expensive, less heat loss and more breathable over most of the house.
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01 Sep 2014 12:19 AM
if strapping isn't enough then U-channels with clips are available
Bryan1978User is Offline
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01 Sep 2014 11:28 AM
I'm wondering if this system would be better if the foam panels were fastened to the framing members over 2 layers of 60 minute paper. An example of what I'd do would be as follows: inside 1/2" drywall, 2x6 framing on 24" center's, 7/16 osb sheathing, liquid applied wrb, 2 layers of 60 minute paper, foam panels mechanically attached, then the stucco finish. This I feel would be the best for drainage but I'm no expert and may want to talk to one before you install system. Their warranty may not cover your home installed this way. I'd add some kind of sealant to the screws prior to installation to help eliminate chances of water migration to the frame members.

Just my 2 cents as I'm looking for same info.
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