Articles - Exteriors

Courier column June 18, 2010

I’ve had a couple questions recently about stucco, in particular about synthetic stucco or EIFS.  Here’s a quick summary of the different kinds of stucco.  I am not a stucco contractor, so this is from the home inspector’s perspective.  A stucco contractor can give you more detailed information. 

Traditional or three coat stucco is a masonry product.  As the name implies, it is applied in three coats.  The scratch coat is the bottom coat that is applied on the metal lath.  This is the thickest coat and, and is what adheres the stucco to the lath and building.  It’s called the scratch coat because this coat is ‘scratched’ to allow the next coat to bond to it.

The second coat is the brown coat.  This is usually not as thick as the scratch coat, and provides a smoother finish.  The top coat is called the finish coat.  This is the thinnest coat, sometimes not much thicker than a coat of paint.  Usually the finish coat is colored, so you don’t have to paint the stucco after the finish coat is applied.  
This stucco is very hard when finished and dry.  It can be damaged (ie from golf balls, Nissans, etc), but overall it is very resistive to minor damage and cracking.  I have seen 25 year old homes with traditional stucco and hardly a crack or dent to be found.  It is susceptible to cracking in the event of structural movement of the home. 

More common in newer homes is what home inspectors call “California One Coat”.  I don’t know why we call it that, because it’s usually installed in two coats.  The scratch and brown coats are combined into a single coat, but there is still a finish coat.  Home inspectors are not the only ones to call it ‘one coat’.  The manufacturers and installers also do.  In fact, there is a National One Coat Stucco Association. 

Traditional and one coat stucco is not completely waterproof, so they need a vapor barrier and weep screed when installed on wood frame walls.  I’ve talked about the weep screed in this column before.  It is a drain along the bottom of the frame wall, parallel to the ground or stem walls.  It appears as a ‘lip’ in the stucco walls.  Ideally it should be 6 inches above soil and 2 inches above hard surfaces.  
The vapor barrier (usually plastic nowadays) keeps water that penetrates the stucco off the wood sheathing and framing.  This water will either evaporate, or drain to the bottom of the wall (because of a secret ingredient called ‘gravity’).  The weep screed allows water/moisture that does not evaporate to drain out the bottom of the stucco walls. 

There is another type of stucco called EIFS or (less commonly) synthetic stucco.  This stands for Exterior Insulation and Finish System, and is called/pronounced “eeefs” (like the ‘eaves’ of a home, only with an F).  Like one coat stucco, EIFS has a base and finish coat.  EIFS also has a foam board that is glued or secured to the frame walls.  There is no wire lath (or ‘chicken wire’) in EIFS, rather there is a reinforcing mesh that is usually applied with the base coat. 

EIFS has been popular in Europe for decades.  It saw widespread use after World War Two to repair buildings that were damaged during the war.  Most of these buildings were masonry (block, stone, brick, etc.), and the EIFS worked very well.  In fact, properly installed EIFS is more ‘waterproof’ than one coat or traditional stucco. 

EIFS did not become popular in the United States until the 1980’s.  At first it was used primarily on commercial buildings in this country.  These were mostly masonry buildings, and the EIFS worked very well.  Eventually contractors started using EIFS on single family dwellings.  Most single family dwellings have wood frame walls rather than masonry walls.  We know that EIFS is actually very good at keeping moisture out of walls.  Unfortunately, this means EIFS is also very good at keeping moisture inside walls.  When water gets under EIFS, it cannot get out.  This caused moisture damage to the wall sheathing and framing, and mildew and mold in a lot of single family homes.  There have been several class action lawsuits against EIFS manufacturers or installers, and many private lawsuits.  Most of these were in the Southeast United States. 

It should be noted that in most of these cases the EIFS was not the culprit.  It was the installation, in particular the flashings, and especially the flashings around windows and doors.  There were also concerns at the wall/roof transitions (ie no ‘kick-out flashing’).  The EIFS itself performed admirably keeping moisture out of the walls.  And unfortunately keeping moisture inside the walls if the flashings were not properly installed. 

Newer EIFS is installed with a vapor barrier that allows water to drain from the wall.  When properly installed, there is nothing wrong with EIFS stucco.  In fact, recent long term studies have found EIFS with a vapor barrier is ‘better’ than traditional stucco.  By ‘better’, the studies show that EIFS is more water resistant and provides better insulation, which were always its strong points. 

I have not heard of any EIFS problems on single family homes in Prescott.  That’s not to say I have not found moisture damage in exterior walls in Prescott.  Improper window flashings and missing kick-out flashings are a concern with any exterior wall cladding, including one coat or traditional stucco or wood siding.  They’re just more of a concern with EIFS because the walls cannot ‘dry out’ as fast.