Acrylic EIFS Over EPS
Hi, doing some remodeling, changed windows, removed old 4mil poly on walls, (left the ceiling, but tightened it up) removed kraft faced r10 insulation in walls and replaced with Rockwool r14 (sealed every penetration, up and down every stud and but joints top and bottom plate, first) (WOW WHAT A DIFFERENCE, even without the new insulation, it was warmer)
New air sealed drywall, and still to come, vapor barrier paint.
2×4 construction.
Sheathing is 1/2″ fiber board w asphalt coating.
Question is
Im going to pull the old siding, then add new tyvek, properly flash windows and porch roof ect. , and then 3″ of eps
(not sur if it will be in 2 lifts or one)
Now,.. rather than adding strapping and new siding, would it be ok to just finish the eps with an acrylic finish, like Eifs, base coat, mesh and then finish. Will this hinder the dew point or dying of the wall. Im not worried about water infiltration, I will be doing all of the flashing myself.
Im trying to save on total thickness and cost. I know how to trowel and execute the Eifs.
Windows are bucked out to except eps with siding just incase.
Zone 5b
Thanks so much
LP
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Replies
Since you have more than enough insulation for condensation control in zone 5, having a vapor impermeable layer outboard of the foam will not be an issue. You can even skip the vapor barrier paint for your drywall, two coats of primer is all you need for vapor control.
There is a lot of EIFS around me (zone 5) and they seem to be holding up well. The key to this install being robust is attention to detail and using grooved foam against the WRB. Most EIFS manufactures offer a version of EPS that is grooved to allow for moisture to drain down (ie Durock Puccs).
Good stucco install takes a lot of experience, not sure if it is something I would take on as DIY. I have seen plenty of bad ones here where the installer didn't panelize enough or wasn't quick enough and there is discoloration.
Thanks Akos Toyh
Good to know about interior primer application, thanks.
I forgot to mention, In regards to drainage, yes there are manufacturers with drainage incorporated, BUT, I was thinking about using snow fence on top of the t tyvek, only because the eps I'll be using is recycled and not manufacturer specific.
Any thoughts to this approach.
Haven't done it for awhile, but did Eifs professionally for around 15 yrs.
The proper way to add drainage to flat EPS is by troweling on adhesive to the back side with a notched trowel. Most EIFS manufacturers have instruction on this.
Not building science related, but I've seen a fair bit of pretty ugly EIFS around here. Biggest offenders is too many moldings trying to make it look like stonework, screams fake from miles away. Besides looking like @#$ these trim pieces are also very expensive. I would select the exterior finish based on what works best on the house, doing siding or brick veneer for the street facing façade and EIFS only on the sides not visible is a good compromise.
Again haven't been in the field for a long time, but my recollection is that the method of notch toweling was used directly on the sheathing with no felt paper or tyvek ect. And along with poor window installation (and construction), missing kickout flashing, and and and, let alone training the installers the to do it this way, they got very good at doing wrong. This is why there were soooooo many failures.
I know for a fact, if you remove all of the eifs on a house (all 4 sides) that was applied directly to the sheathing with no drainage material, every penetration would be weeping, wet and rotted, under windows doors, kickout flshings, under deck attachments, even at a coaxial cable going through (if on the weather side). Very bad practice to install it like this.
I'll be mechanically fastening the eps, on top of tyvek (or similar)
Do you think the snow fence is too much, too thick, and maybe just sick with crinkly tyvek.
I agree about to much trim, I might mix it up with some shingle siding. Currently the house does have one area of the first floor with granite stone at the front.
As long as you don't think I'll have issues with dying, and dew point, because of the acrylic finish, I'll keep honing the final finishes.
Thanks for reading and responding.
Lp
I will add, maybe now that the industry has liquid applied materials that are compatible with Portland and glue, that this (notch and trowel) may be an appropriate method for comercial applications.
My understanding the EIFS issue was flashing and WRB related. How the rigid was adhered doesn't matter. No amount of venting would have kept that assembly out of trouble, amazing that nobody raised a red flag before it become a big issue.
I noticed that most of the EIFS in suburbia is installed over fluid applied WRB. I don't know if any of the fluid applied would be compatible with fiberboard sheathing, might be worth while to check into it as it would certainly help with air sealing.
I would be hesitant to use something like snowfence, it is pretty thin and mostly flat and I can't see it doing much, most drainage matts like Cedar Breather are a 3d mesh product. Textured house wrap is definitely an option.
The solvents in many coatings are a problem for EPS. Anything that reacts with PolyStyrene (the "P" and "S" in "EPS") is a problem here. I would probably not try to coat the EPS directly, and certaintly not without at least testing the coating on a sample of EPS first to make sure it didn't "melt" the EPS. You can't really rely on EPS for structure, either, so you'll need to add something to provide physical support to your exterior cladding materials.
Bill
Hey AKOS TOTH
Was just thinking "out of the box" with the snow fence, mostly because my upper windows are all above a porch/ deck roof. So distance from the window sill to roof is just over 24". The one 2 story gable wall has no penetrations. I was thinking that it (moisture) wouldn't fester, having such a short distance to escape and the wall being protected, just trying to save a bit. I'll look into stucco wrap or similar.
Thanks
Bill,
1. Are you concerned with a fluid applied going on top of the eps? Or
2. just the fact the back side might come in contact and melt.
Im thinking you mean the second one. I'll be sure to find and test this if I go that route, but honesty can't see using a fluid applied over fiber board. I will look into cedar breather, or stucco wrap.
Thanks for looking