Replies

1. 
   Texfan | Aug 12, 2003 05:15am | #1

   Use metal lath over tarpaper. You need a moisture barrier between the wood and cement.nail the lath down good. Thats what hold your stucco on the wall.

   "I am not young enough to know everything."

   - Oscar Wilde (1854-1900)
1. 
   Boxduh | Aug 12, 2003 05:43am | #2

   I second the felt and lath method.  Who is this stucco guy anyhow, telling you he wants to put it directly onto the plywood?  Are we really talking about a portland cement stucco job here, or an EIFS synthetic?

   Real stucco needs diamond lath mesh, goes on in three coats, and builds out to a little under 1" total thickness.  When done right, it goes on over felt, so as to be isolated from the sheathing.

2. 
   Turtleneck | Aug 12, 2003 06:16am | #3

   If you are in some insanely dry end of the continent... why not?

    Turtleneck

   the only miracles I've ever produced are waiting for me at home

1. 
   Petey | Aug 13, 2003 12:51am | #4

   Yes this is a real stucco job (with portland cement) , It is in the Chicago suburbs. One other note; the house that is going to be torn down to make way for this new one is about 75 to 80 years old. It has cypress 1x4 sheathing with dovetailed grooves to hold the plaster, no felt or mesh!

1. 
   Bigslice | Aug 13, 2003 01:02am | #5

   Tyvek has a product called stucco wrap, and all tyvek thak I know of goes outside of the plywood. Stucco wrap is textured, so I imagine it holds the stucco better. However, the idea behind the tyvek is that it repels moisuture from penetrating the wood sheathing from the outside but it allows moisture to escape from the inside to the outside, should there be condensation behind the plywood.

   For traditional stucco applications, see your stucco supplier. I went to Durock and they had technical papers available that show how to do the job. The felt and lathe method is commonly used, though they also have Tyvek in place of the felt. The metal lathe needs to be applied using furring nails, which keep the lathe slightly away from the paper (I can't remember the gap required. Also, pay attention to the metal lathe:  you will notice the pattern has an angle to it. That angle should be sloped upward from the back to the front so that when stucco is applied, it "drops into" the lathe rather than fall away from it.

   I'm not a stucco guy and this is based on my recent research as I considered stucco on two gables that I have. Advice came from Durock makers of stucco products, and two independant contractors. I have also been told that nailing the stuff on tight reduces cracking, though I don't know for sure.

1. 
   Scooter1 | Aug 13, 2003 01:07am | #6

   Out here in California, we have stucco lathe, which is a two part sandwich made of felt and chicken wire in 8x4 sheets which replaces house wrap and gets nailed to the plywood. It even has weep holes. The stucco sticks to the wire. You could put housewrap under it, and stucco would never touch it. I don't get the question, really. Use the stucco wrap.

   Regards,

   Boris

   "Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934

1. 
   Petey | Aug 13, 2003 06:36am | #8

   I guess the question was if anyone had ever heard of putting tyvek under the sheathing. Thats how the plasterer (?  spelling) wanted his surface for the stucco application. I am just doing the carpentry and my concern was being responsible for any complications due to lack of moisture barrier. thanks for the info 

2. 
   Turtleneck | Aug 13, 2003 05:19am | #7

   My first thought on the subject was no way. Stucco wicks water. Maybe those solid boards would stand up to some moisture but I thought  plywood will eventually fail and separate. With Tyvek behind the plywood it can only dry from one side. But then again, maybe your stucco guy knows what he is talking about and we'll both be dead and long gone before there is a problem. 

   Trying to get  dried concrete off of a sheet of pl;ywood is next to impossible and mabe the rough surface would double the surface area and speed drying.

   I guess you have to look at things from all sides.

   I still prefer tarpaper to Tyvek for breathability

    Turtleneck

   the only miracles I've ever produced are waiting for me at home

1. 
   Petey | Aug 13, 2003 06:39am | #9

   I feel the same way about the tarpaper and isn't it organic? thanks for the feedback

1. 
   Turtleneck | Aug 13, 2003 07:04am | #10

   I hope this doesn't get out, but

   I think alot of suspect products

   [ (like Tyvek) ]

   have been successfully marketed.

   (right click space above) Turtleneck

   the only miracles I've ever produced are waiting for me at home

3. 
   sungod | Aug 13, 2003 07:59am | #11

   I have seen old houses with stucco over wood lath.  It held up with no visible problems, but it was one story with 4' eaves too.

1. 
   AndyEngel | Aug 13, 2003 05:09pm | #12

   As I understand it, stucco should never actually contact the housewrap or tarpaper. That includes Tyvek Stucco wrap. Contact can allow water to pass through the housewrap or tarpaper by capillary action.

   BTW, seems to me that stuccoing right over plywood is inviting rot. I'd sheathe, then do a double layer of tarpaper applied shingle style, #30 is better, then wood lath covered by expanded metal lath followed by stucco. The reason for the double layer is that if the top layer is compromised by stucco contact, the bottom layer should still keep moisture away from the sheathing. Next best would be to skip the wood lath, but I wouldn't leave out anything else. I might use housewrap instead of tarpaper, but only if the 9 ft. rolls saved enough labor to justify the extra cost. And if I used housewrap, I don't think I'd skip the wood lath, because I'd be too concerned about stucco contacting the housewrap.

   Check our http://www.buildingscience.com for more on this topic. Andy Engel, The Former Accidental Moderator