Hi there,

I'd like to use the cement/traditional stucco over our new Nudura walls. I prefer the cement stucco (over acrylic) for it being harder, easier to repair and not trapping water.

My handyman (which is very experienced with cement stucco over concrete/bricks) suggested to use Tyvek under the dimond metal lath. He wants to fix the screws in the concrete, every foot (or 1/2 foot, I can't remember exactly).

Our location: Ottawa, Canada.

I'd be happy to get the forum's feedback.

Many thanks,
Beno

Stucco to a large majority does not trap water. The mold trouble with wood framing and stucco is because of the tar paper under the stucco, if moisture gets behind it.

There is little benefit to using house wrap on an ICF house, the only advantage is it may benefit from above the openings to the soffit.

The lathe should be attached only to the ties in the ICFs.

And the water usually gets behind the tarpaper on the lower corner of nailer flange windows.

I remember reading that the tar paper is needed to create a separation area for moisture to travel.
My handyman said that the ICF ties are not strong enough, he wants to drill holes in concrete and use concrete screws for attaching the lathe.

check out the stucco topic below...
http://www.greenbuildingtalk.com/Forums/tabid/53/forumid/4/postid/61319/view/topic/Default.aspx

If he hits the webs it will hold the lath and the weight of the 3/4 inch conventional stucco. If he is not trying to charge you any more then let him go to the concrete if he is then tell him he needs to educate himself. I install ICF and before I became a home builder I was a Stucco man for 15 years. Done this many times  

If you first put the tar paper (Tyvek?) how will you know where the tie webs are? They will be already covered and you can't know where to put the screws.

Thanks,
Beno

If installed right your webs will all line up and you can just chalk you some lines. Or you can just free hand it ( you can tell if you are hitting them or not) Its just like hitting the studs on a stick house with Tar Paper or Tyvek. By code you have to hit the studs on stick frame when installing Wire Lath and the conventional system. So this is really not an issue 

I have a question that I hope is not too off topic. I live in Brazil and am renovating my home. In the part of Brazil I live it the temp. gets to the low 30's during the coldest part of the year, the building isnt insulation and has thin walls so indoor/outdoor temp are basically the same. My walls are made out of 3' X 1.5' concrete slabs that are about 1.5" thick and are held between two posts. (the house is 5 slabs tall, and 10 sections by 6 sections) The reason I am posting in this forum is because I would like to insulate the house by puting styrofoam sheets on the exterior, then chicken wire and just the scratch coat, smoothed down. (stucco finish is too expencive). From what I can tell the closest to this 'stystem' is ICF. (stucco on a styrofoam insulating concrete wall) I plan to glue the styrofoam onto the wall, attach the 1 inch chicken wire with fasteners to the concrete slabs, then apply the scratch coat - 3 to 1, sand to concrete mixture. I have never done anything like this before and would love feed back on whether my plan will work. Thanks, Jake

I guess I am confused on why you would use tar paper or Tyvek. The preferred substrate for stucco is EPS. Why would you cover it up? You need to talk to the distributor about it. He should be talking to the builder about all of this. Also, there is absolutely no reason to attach to the concrete. The stucco will adhere to the foam, so really there is no weight on the screws. Like I said, talk to your distributor/Technical Support.

dwangle: you are right, but only if you talk about artificial/acrylic stucco/TAFS.

In my case, I'd like to go with cement stucco, the paper will be to create a drainage plane and the metal lath + screws to support the increased weight of the concrete.

Beno, no tar paper or house wrap is needed. Wire lath of course. And you can get screw shear from NUDURA and calculate yourself if the stucco will hold (it will).

Jake, start a new thread, we will comment.

From what I've read on the internet, it's mandatory to use 2 layers of building paper to create a drainage plane. One question I have here is if the tar paper (or asphalt paper?) will not damage the foam from the ICF?

Brad or others, can you please point me to a resource that will describe the process of installing cement stucco over ICF? I am sure the building inspector will want to see something like this.

Thanks,
Beno

http://www.cement.org/Stucco/faq_icf.asp
Have you seen this? I am learning here. :)

As far as the Tar Paper goes it does not meet code for conventional Stucco. You can use a product that you can get from any Stucco manufacturer that they call pony rolls. It requires one layer and works great. Call Magna Wall or Dryvit they should be able to tell you all about it.