Best Methods of Taking Stucco Core Samples

I am wondering what you all use and how you go about taking core samples for Stucco on block and if you even do it to a section over wood and wire lath.

I will be doing this on freshly stuccoed homes and buildings and do not wish to reinvent the wheel. I have 3 or 4 ideas for block and methods I have used but none that will not damage the wall system over wood. I want the best and quickest method possible.

I would like to be able to easily photograph the results.

Thanks in advance for any help.

Why do you want to take core samples of a 3 coat hard stucco?
Are you trying to verify the 3 coats or density?
Sounds invasive in all respects to a Home Inspection.

What about something like this?



or this

You’ll likely need to play around with it to find which works best. I’m not sure how these will hold up once you hit the lathe. Your biggest issue is going to be the fact that no matter how precise you are, your core bit is likely gonna damage the housewrap and sheathing. You’re gonna have to find a way to not just core sample but make sure the damage you cause to it can be repaired as well.

It is to verify stucco thickness I will likely be observing how they apply it from the lath on.


Thanks I’ll check the links out. The screwing up of the housewrap and lath is the reason I will not likely be taking samples from there.

If you are just verifying thickness, just look for clues around vinyl window frames and soffit channel (non-invasive). For invasive measurements, a simple small hole with a masonry drill bit until you hit substrate will suffice. You will need these if you are also probing for moisture. For compression and density tests, you will need an actual core sample with a core drill bit. Best to use a dry bit so you are not adding water to the hole. As Glen said, make sure you are prepared to properly repair the hole before you leave.

They will be homes in progress or just done and I will bring my hawk and trowel from the old days :slight_smile: Plenty of already mixed mud should be all around. Thanks to everyone for all the help and keep it coming. I have a builder that actually wants the best possible job done.


Back when I checked concrete pavement thickness I placed thin steel plates down and referenced the location so I could go back and find the location for the core. As thin as stucco is you may get buy using a strong magnet to locate the plate.

That would be a great idea BUT they want it to be random. The guys see the plate then they just load it up. I guess I could slip some under the lath. Then I would not scew up the house wrap. Thanks for the advice and idea


To CYA you will need a testing plan and a quality control plan in the event you find thin stucco, which ever method you use. For example a testing plan could be taking one test every 500 square feet with locations determined with a random number table giving you the distance and offset from a base line for the sample location. If you find a thin sample taking the average of three random samples with in a two foot circle around the failed test could be used to offset the argument you picked the only thin spot on the wall. Your plan will need to be in writing so you, your employer and the stucco contractor are all on the same page. Without a plan you can be accused of testing only the spots you feel are too thin.


Thanks so much for the advice. I am way up in North Florida tonight waiting for a meeting tomorrow where we will figure out what we will do. Kind of made up a job that needs doing but have not yet started.

Core bit.

Thanks Roy :slight_smile:

Where are you at in N. Florida?

I was in Jacksonville :slight_smile: I got the gig and they do not want any written report or even core samples. Just watch and then call and talk with the big wigs. Thanks to all who helped.


I guess they had no idea you ran the family stucco business into the ground.:p:p

Must have a BS Degree Linas and now is a Clerk of the Works for Stucco installation. ;):slight_smile: