Proper Stucco Application on your San Antonio area Home

  Having Stucco (Plaster) as your exterior cladding is required (by IRC code & ASTM standards) to be at least a 3 coat process with a minimum 7/8" thickness on typical wood frame construction. Unfortunetley Stucco applications aren't monitored as well as should be in our local areas. Many local builders get by with a 5/8", 2 step (coat) process- skipping the 1st coat, which should be the scratch coat. Actually as an inspector I have discovered that some builders claimed they were doing a 3 coat process when actually as I pointed out to them, it was a 2 coat their masons were doing. They didn't realize that their Stucco Subcontractors were only doing a 2 coat application. The 3 coats needed for a proper stucco installation includes, 1) The Scratch Coat (raked horizontally) with a minimum 3/8" thickness. 2) The Brown Coat also should have a minimum 3/8" thickness.   Photo shows the first 2 steps of the 3 coat process- Scratch Coat & Brown Coat. 3) The Finish Coat, also referred to as the Texture Coat should be a minimum 1/8" thick to complete the masonry part of the stucco process. The finish coat can include coloring in the texture coat or the finished stucco can be painted with an elastromeric paint to obtain the color desired. There are many different final coats (texture styles) available. Here are just a few samplings shown:
  

 
Images show a JWK Inspections masonry inspection in the San Antonio area. The Builder here was doing only a 2 coat, 5/8" thick Stucco process. They were skipping the Scratch Coat as verified at center photo which is a close up of photo at left. Photo at right shows a 5/8" weep screed that indicates it will be just a 5/8" stucco final thickness, not 7/8" as minimum code requirements call for. As per the International Residential Code (IRC), on stud frame w/ metal lath construction a minimum 7/8" thick, 3 coat stucco (plaster) process needs to be used. Also per IRC- 2 coats should only be used directly on concrete or masonry walls.

The IRC Code for Plaster, more commonly known as Stucco in our San Antonio and South Texas areas is shown here out of our JWK Inspections International Residential Code (IRC) 2015 Commentary (Interpretation) Edition. The numbered paragraph areas are the actual Code and the indented areas with the diamond symbols are the Commentary / Interpretations of that code.
         
Some of the more notable code requirements for Stucco are shown here (above & below) from the copy & paste of the IRC. Some noteables show: At R703.7.2 it does make clear that typical Stucco applications do need to be a minimum 3 coat process, however it can be only 2 coats when applied directly on Concrete, Masonry or approved bases (surfaces) other than with lath, which is used on a typical residencial wood frame that needs the 3 coats. At R703.7.2.1 it clarifies the bottom of stucco (weep screed) needs to be a minimum 4" above finished grade and at least 2" above impermiable hard surfaces such as concrete. That section also details the need for a proper weep screed system for needed drainage. In R703.7.3 it emphasises the need for 2 layers of building paper (moisture barrier), which can be felt paper, or other acceptable materials including house wrap such as Tyvek. The 2 seperate layers create a needed drainage plane between them.