Mini Split Outdoor Unit Brackets on EIFS wall
I'm about to install my mini-split on an exterior EIFS (aka Dryvit) wall.
For those not familiar, EIFS is a system that consists of a plywood or OSB sheathing, covered with a foam layer then stucco over the foam.
As I was fastening my electrical conduit bracket, as I was tightening the screw, the bracket actually punctured the surface stucco coating (which was apparently really thin at that particular spot where the bracket was) impressing the bracket into the foam. I've fastened into other locations on the house without this happening, so I know it must be disproportionately thin at that spot - however, regardless it got me thinking of the load from the outdoor unit and how that would be applied - I clearly want to avoid this situation with the actual mini split brackets!!
So the way these mini-split brackets work, when loaded, is they obviously impart a horizontal moment of force against the bottom of the vertical legs into the stucco/foam (while the top horizontal bracket would have the cantilever force tending to pull away from the wall)
What do those of you who have installed on this medium typically do?
I will locate the studs for the horizontal bracket bolts, not just relying on the sheathing substrate for support. That shouldn't require any special treatment as the force will be acting outwards against the bolt head, which will be 'pulling' directly out from the stud. The bottom screws (and the vertical legs themselves) are my bigger concern to avoid the stucco cracking and foam collapsing under the load that is going to be pressing into it. The bolts there, although helping carry some vertical load, are really doing nothing to carry that horizontal component as the force of the bracket is inward, against the stucco/foam - not pulling against the bolt head. I was thinking to predrill a hole and insert a sleeve that fills the space between the stucco skin and the sheathing. This sleeve would then take the load from the bracket directly onto it, and in turn the stud, rather than onto the stucco/foam - could even use a fender washer on the outside bearing against the sleeve. Or perhaps a threaded rod with washer and double nut arrangement would be another possibility.
Thoughts or comments?
