Hi! I'm a renovator looking for a solution to the exterior stucco of my house. I'm a young guy and love renovating old (100+ y/o) homes. I live in Montgomery, AL and have done several homes in my spare time over the past few years in our historic district. I do almost all of the work myself (tile, electrical, flooring, trim, etc..).

My most recent project is a 2500 sq ft "villa" on piers (~5' of crawlspace) with a Mediterranean feel. It is a stucco clad house which is rather rare for this area. The stucco is over wood lath, not chicken wire. I have several problems with it. Additionally, because of the rarity of stucco in this areas, we have no good stucco contractors to get contractors / quotes / information from. There is one guy who gave me a quote and told me how he wanted the area prepped before he started, but he hasn't showed in months and is unreachable.

1. In some areas near the foundation, rot and termite damage has ruined the lath, causing it to crumble and the stucco that is applied to it to crack and break. For these areas, I used a concrete saw to cut out the affected areas- going up until I reached lath with no termite damage. I then screwed some OSB to the studs to cover up the area and have a backing to attach the new chicken wire to. This was per that no-show contractor's instructions. The need here is to apply a stucco mix to these areas and blend them in with the surrounding stucco.

2. In other areas, I have had to tear down entire exterior walls which I have clad in OSB currently. I just need brand new stucco here and it will just blend in with the old where the corners meet.

3. The entire house looks like it has a "block" exterior. But if you look closer, you will realize that whomever installed the stucco used some sort of a tool to "press" lines into the stucco, presumably when it was still wet, to create this block look. I am looking to get rid of that and just have a smooth surface for several reasons. First, I don't like the look. Second, the tool and the way the pattern was applied wasn't the sharpest, an many lines are overlapping or crooked. Third, many of these impressions have led to cracks, because the stucco is thinner in those areas and are the weakest point of the wall. I'm not sure why they did this, but that's neither here nor there. I was planning on finding a contractor who could "skim" the entire surface after installing the new stucco in the areas described above.

The old stucco had several layers of paint which i ground off with a diamond cup wheel on a grinder. (Don't ask how long that took- it was brutal). I knew that to apply a new scratch coat or color coat, I had to get the old flaking paint off otherwise it would not adhere properly.

So here I am- my contractor has dipped out on me and I don't know if I'll be able to find another one which means doing this myself...I need to know and understand better how to apply a stucco surface to the areas that are covered in OSB (new wall and the sections of the old walls that were rotted- both of these areas are recessed ~ 1/2" to leave room for building up stucco to the older stucco). I also need to understand how to "skim" an old stucco wall to fill in these block lines (almost look like expansion joints) and create a smooth surface for the entire wall

Any and all help / pointers would be appreciated!

 

Some photos showing us your present conditions with the OSB installed would be helpful. I see some potential problems. the OSB in close proximity to the ground will deteriorate a whole lot faster than the wood lath. This is not to say don't use it but leave it clear of the ground and seal it against water coming up from the ground. I fear you might have left the stucco pretty smooth when you ground it off. New stucco does not bond well to a smooth surface. There are a couple solutions: one is paint it with bonding agent and then go over it with new mortar. Another is to mix up some really rich mix and dash it hard against the smooth surface and then apply another coat of regular mix. A half inch of stucco is too thin to get good strength, though it happens. By the time you get paper and lath or woven wire over it it is even thinner. Can you live with a little hump at the transition? And as a matter of curiosity, do the wood lath run horizontally or diagonally? In old houses I've seen both. I can't see much difference in how the stucco lasted. Is there backing behind the lath or is it open framing? Again, I've seen both but open framing allows better keys of the stucco into the lath.
Other than learning a new skill and using muscles differently than you ever have before the stucco process is not to difficult. We can help you through it.

 

Thank you so much!

1. The house sits on a brick foundation that is ~4' at the front and ~7' at the back. The chipboard (as you can prolly see in the pics) shouldn't ever get too close to actual dirt.
2. I did smooth out the stucco by grinding it, but there's still some texture...maybe like 100 grit sandpaper rough
3. As you can prolly see from the pics- a transition won't do well in areas where the chipboard replaced the old stucco like patchwork. That being said, in order to get rid of those block lines, I have to skim the rest of the surface anyways, raising the profile of that too, so I was hoping that that might accomplish the task of hiding that transition from old to new stucco
4. The lath runs horizontal. And if it would work better, I'm not opposed to just taking the chipboard down and nailing up wood lath. It's open framing behind it

 

Hey @tightcoat, just wanted to see if you had any thoughts on the pics I posted? Any help would be much appreciated!

 

How hard is the stucco? By that I mean can you drive a galvanized roofing nail into and through it?
The only thing that bothers me about your plan is the thinness of the stucco over the OSB. The way I see it, removing it and adding wood lath would not help much. What might help is taking the OSB off and using woven wire lath over the open framing, either paper backed woven wire mesh or woven wire over water resistant paper. The way that was done in the old days was 20 or 18 ga wire was strung around the studs about every 8 inches and a nail driven in from time to time to stretch the wire up or down to get it very taut then nailed into every stud then the paper and wire installed. Paper backed woven wire has that line wire installed in the wire.
This might make your new stucco thicker than you wish but you can add an extra scratch coat of necessarry to build up thickness. You would only do this over where you have OSB

OR you could use this procedure over the open framing and wire over the existing stucco. Putting on a 1/2" coat over the stucco and as much as needed to make it even over the OSB.

I am thinking out loud here. There are fiberglass reinforced stucco materials that you can put on thinner than conventional three coat stucco, Maybe you can use that. And maybe you could add a coat of that over the existing stucco, too to get a flush surface. This would mean less stuccoing and save the labor of taking the OSB off. I think I like this idea better.
If you go the route of the fiber reinforced stucco then carry the wire only and not the paper back over one stud bay's width onto the existing stucco. Leave enough paper backing to lap onto the existing, but not all the way to the end of the wire. The idea is to get water resistance where the different material abut but still get some bond onto the old stucco through the wire. This assumes you can get a nail into it and into the stud, which actually is doubtful. I suppose you could drill pilot holes and then drive the nails or use masonry screws. You don't want to bang on this too much for fear of loosening the existing stucco.
You can always just infill where the OSB is but then you will get a crack and a potential leak where the two different substrates meet.

 

Have you made progress? How is it going? What did you settle on?