I mounted some brackets to stucco last summer to hold up a 8k BTU Air Conditioner. Although it worked last summer, when I put the AC away for the season, I noticed that the anchor and screw were coming loose.

I think mounting against stucco would be a bad choice. Therefore, I am planning to mount the brackets to a stud.

I am planning to use this to find the stud (very good tool):
Precision Sensors Professional Stud Finder

AC is probably about 40lbs, at least the half that is sticking out of the window.

Questions:
What is between the stud and stucco? Do I just use a masonry drill bit and drill until I hit the stud? What type of screw and how long should I use?

Thanks

 

There are about three ways stucco could have been done n CA. Briefly there could be 3/4" applied directly over the studs. There could be 3/4" over OSB or plywood. There could be 1/4" - 3/8" of stucco over usually 1" of EPS foam over OSB or rarely over e studs. You could
D have a synthetic stucco system ( EIFS) which is a thin coat f stuff over some kind of sheathing.

How old is the house?

You are right about needing to anchor to studs.

 

Thanks for replying.

The house was built in the early 70's. With the information that you provided, would 2.5 inches exterior screws do the job? Do I just use a masonry drill bit and drill until I hit the stud?

 

I always get the joy of mounting to the stucco. I have to mount electrical boxes and cameras.

What I do is use a sharp probe.... like an ice pic.... to see how far the sheathing is behind the stucco. Here, in NJ, I find anywhere from 3/4" to over an inch of foam. I don't usually require my device to hit the studs but I do need to catch the sheathing so I use spacers the thickness of the stucco. I'll drill a hole thru the stucco to the wood the outside diameter of the spacer and then run my mounting screws thru the spacer. The spacer keeps the stucco from crushing.

 

I have never seen those before.

Help me understand the design Pete. So when you stick it through, do the screws go through them and also mount into the wood on the other end? It has to or otherwise it will come loose. If that is the case, what if it goes through the inside wall? How strong is it compared to mounting against a stud?

Thanks

 

Why not just use one of these?
No drilling required into the wall.
https://www.google.com/search?q=air+...w=1366&bih=657

 

Joe,

I bought those last year and returned them for several reasons:

Mainly because they don't work with retrofit windows. They would destroy the lining over time.

Also, if you have seen it, I just have a scary feeling of using it since they are not as wide as in the pictures.

I am using something similar to this:
Air Conditioners Bracket - CAD$24.00 : Warehouse Sale, Furniture,Mattress,Air Conditioner...wholesale and online retail.

 

From inside to outside, does it go like this:

Drywall
Stud
Plywood(or Sheath)
Vapor Barrier
then Stucco

Am I missing anything? How thick is the sheathing and is it about 4 inches from the drywall since the stud is a 2x4?