Stucco scratch coat

10/8/2012 at 11:26:39 AM

You can cut some shallow grooves in the base coat with a circular saw and a diamond tip blade or masonry blade or use a grinder with a thin masonry blade. Just make sure the grooves are very shallow no more than about a 1/16 or 1/8 inch deep. This will give the final coat of stucco something to grab onto.

10/8/2012 at 2:14:58 PM

Just like when you key a footing before you pour your foundation...you need to create grooves in your base coat before applying the stucco. if you do not, in time it will crack off.

The same situation happened on one of our jobs a few years ago, the way we solved the problem was spreading thin set mortor with a 1/4" knotched trowel over the small area and applied our finish over that. To date it's still holding up.

Good luck, hope this helped.

10/8/2012 at 4:37:03 PM

In time the base coat will start to fall off or crack in places. Try adding concrete bonding additive to your mix on top of the scratch coat. it will hold up longer. remember to read additive instructions before use.

10/9/2012 at 4:23:12 PM

Stucco is typically applied as a three coat process: scratch, brown and finish. But it's not uncommon to use a two coat system, namely: scratch and finish. Given that your scratch coat has some "teeth" to it, as you indicated, you'll very likely be okay.