I have an exterior wall which is 10" thick, it is a composite wall in that from the inside to the outside are:

(1) 1/2" drywall
(2) 3-1/2" 2X4 wood studded wall
(3) 3/4" wood sheathing
(4) thick felt paper
(5) 4" concrete block
(6) 1" of stucco

Recently I cut and chiseled a trench horizontally along the wall to facilitate an exterior kitchen bar sink from the outside to the inside. The trench is about 24" long and 3" thick.



Then I test fitted the pipe fittings.



Then I made the connections and used some foam sealant in the back and around the hole leading to the inside.



Now I am trying to figure out the best way to patch this back up.

I have done some exterior stucco patch before by first using a bonding agent on the exterior concrete then apply a layer of stucco. But this is different with the pipe and some spongy foam in there.

Specifically,

(1) What should I do with the space around the pipe? Should I spray more foam to fill them up until they are more or less flush with the outside of the pipe, or should I pack some concrete products around the pipe?

(2) Should I use regular concrete or hydraulic cement until about say 1/2" from the finished wall then top coat with stucco? Or can I use stucco all the way?

(3) Should I mix it on the dry side to prevent it from "slumping"? Should I consider using hydraulic cement so it will set superfast?

(4) Before the concrete patching, would it be helpful to cut a piece of wire cloth and secure to the front of the pipe to act as the key for the mix?

 

Not my area of expertise but if I had to make that repair I think I'd embed some wire lath in the void, apply a scratch coat and then try to match the stucco.

 

I would also use wire lath, the knuckle grater type. First though I would fill in the deeper areas. Then I would drill and screw lath to the existing structure to anchor it in place.

 

What would you use to fill in the deeper areas?

I thought about injecting more foam, then I thought about packing in mortar or concrete, then I thought may be I need hydraulic cement, then I was wondering if I should just leave it kind of hollow LOL.

I can certainly cut in a piece of wire lath which I guess can be used as key for the stucco, but because of the smaller area and top and bottom being somewhat flushed I doubt I will have issue with the stucco sticking. I was thinking if I pack the deeper areas with mortar I might as well build the whole thing up in one shot

 

I think the texture is called orange peel right? I have done knock down textures with joint compound which is much finer and smooth. How would you do the same with stucco mix? Is it the same - apply the material then use a sponge or anything to "stick and pull" the material at random spots then wait 30 minutes to come back with a flat trowel to run over the top gently while hoping it matches?

 

I doubt it's called orange peel. I've painted miles of stucco with that texture. Basically the stucco is troweled on [somewhat smooth] and then a small amount of stucco is added on top in a skipping motion.

 

You've already foamed the really deep pockets. I would wet the old stucco then fill the deeper sections with mortar. A patch like this is no place for concrete. Then attach wire lath and proceed with the repair.