Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

2.5 paperback lath vs. 3.4 lath


kimski's Avatar
Member

Join Date: May 2006
Posts: 9

10-19-09, 02:07 PM   #1  
2.5 paperback lath vs. 3.4 lath

I am re-stuccoing my FL home. I am trying to compare two contractors and don't know the best route. My gables currently have wood planks so they will be removed beforehand.

One contractor would put up plywood with Tyvek and then 2.5 paperback lath. Another would use (2) 15# felt with Tyvek and then 3.4 lath. He said the plywood can expand so it's not ideal. He also said the 3.4 lath would told it's structure longer (not his exact words). He does have 35 yrs experience...

Is one better than the other?

 
Sponsored Links
tightcoat's Avatar
Member

Join Date: Jul 2003
Posts: 1,676
CAL

10-19-09, 03:52 PM   #2  
I like 3.4. If that contractor is going over open framing use nothing less. I still prefer 3.4 over plywood as well. And I don't know that it's necessary to remove the existing siding either, unless the stucco would make the wall assembly too thick. Over open framing over tyvek the paper backed lath should be good enough and over tyvek over open framing one layer of 15 paper should be fine. Codes may be different in CA and FL. Maybe there is a reason for two layers of paper. I suppose it won't hurt especially if they lap by 18". Make sure they include appropriate flashings and trim.

If the stucco will not project too far with the existing siding it can get two layer of paper and 3.4.

It has been my experience that 17-1.5-36 stucco wire cracks less than stucco over metal lath. It seems counter intuitive but that is my experience.

 
kimski's Avatar
Member

Join Date: May 2006
Posts: 9

10-20-09, 05:15 AM   #3  
Thanks tightcoat. I am removing the existing siding because they are wood planks that have warped in some areas. Since there is open framing behind it, I'm not comfortable that we can resecure it properly. I don't want to spend all this money and then the stucco cracks because the wood warps more.

The code says to use (2) sheets OR Tyvek. The second contractor is using both for better moisture control (according to him). The second contractor doesn't like plywood due to expansion but the first contractor said it's no different than frame houses that use plywood (my house is slab and frame). The second contractor also uses a sealant on top of existing painted stucco and then stuccos on top of that. He said the sealant gives the new stucco better adhesion. He seems to know a lot but I don't know if he's selling me stuff I don't need.

Thanks again.
Kim

 
tightcoat's Avatar
Member

Join Date: Jul 2003
Posts: 1,676
CAL

10-20-09, 06:56 AM   #4  
If you have painted stucco in addition to this new gable you should definitely use a bonding agent. What he and you are probably calling a sealant. Weld-Crete by Larsens Products is probably the best known. Anytime you stucco over paint the bond is only as good as the bond of the paint to the existing stucco. It is never recommended, we all do it. At least give the painted stucco a good pressure washing before the bonding agent you want to get off all loose paint, dirt, algae and anything else that will interfere with the bond of the bonding agent to the existing stucco. The new stucco will bond to the bonding agent just fine you want to make sure that the bonding agent bonds to the wall.

Now about the plywood. I tend to agree that it expands and can cause the stucco to crack. It is imperative that the required spacing of the plywood be observed. So does open framing without the additional stiffening. I would use 3.4 galvanized lath no matter what. If it were me and I was using two layers of #15 building paper I would cut the first piece down to 18" wide and put it at the bottom of the wall against whatever weep screed or flashing is used. Then I would take a full width piece and take it to the bottom as well. Then each successive layer overlaps the previous sheet by 18". This gives you two layers and good moisture resistance.

How large are the gables?

In these parts houses are sheathed with OSB in the living sections in order to give the walls shear strength. Gables are usually open framing and it works just fine. Over the OSB a layer of MR paper is installed then paper backed stucco mesh that is the equivalent of two layers of paper. Over open framing only one layer, the paper backed wire, is required. That seems counter intuitive but I'm sure there is a good reason for only one layer. Stucco is even more popular here than in Florida but our climate is different.

 
kimski's Avatar
Member

Join Date: May 2006
Posts: 9

10-20-09, 09:12 AM   #5  
Two of my gables are about 35 ft across and 10 ft high. A third is a little smaller.

Pressure washing will definitely be done but I do like the bonding agent application. It makes sense. We are also going with a colored stucco for the final layer and the "bonding" contractor has a better color selection so the job seems to be leaning in his favor.

Thanks again for your input.

 
Search this Thread