Stucco News

Question and answers on Stucco and Plastering-- August, 2011

                                Z furring for foam insulation

Mr Bullard-
I worked with you a number of years ago when I was a designer at a Washington DC design-build firm.  I thought that you did a really great job on the projects that you were involved in and I appreciated your expertise.
I have since moved to Dallas, TX and started my own architectural practice.
I am currently working on a project and was hoping to mine your expertise again.  I've heard other architects discuss using a hybrid stucco system that I can't seem to find much in the way of information on.  The system is standard 3-coat portland cement plaster over metal lath over (2) layers Grade D paper over EPS insulation over OSB wall sheathing and 2X6 studs at 16" OC.  I really like the idea of having the EPS insulation on the outside of the framing and I also like the idea of the standard 3-coat cement plaster.  Is this something that you have done before?  Do you have any thoughts on this or do you have a good resource where I might go to find the specifics on this exact system?
Garth M Russo, AIA
Live Oak Architecture

I have been wanting to use z furring for a long time. I finally got a small job where I could try it. I have recommended
this method to people before, but now I reallly have first hand experience.
This is an excellent method of stucco over foam board. It can be used for furring over block, concrete,  wood
 sheathing, or what have you. This eliminates the  need  for  hanging  the  lath  on nails,  and embedding  the  lath 
in the foam,  causing failure by not allowing the mortar to key behind the lath.

z furring for metal lath and stucco
 A view of the z furring. The center is only  the thickness
of the sheet metal allowing for a minimum of heat loss, as opposed to furring with furring strips, etc.                                                                               
I bought this in 10 foot lengths for $ 3 per length.
This is 1- 1/2" furring for 1-1/2" foam.
I got the foam board in 4 x 8 sheets from a drywall

The sheets are pre-scored for score and snap
for both 24" and 16" on center. The reason I haven't wanted  to use z furring before is I only have
seen 24" foam.  24" O.C. may be fine for drywall,
but  I really needed 16" for stucco.

You do want a neat cut for minimizing thermal
z furring for metal lath and stucco
z furring for metal lath and stucco
The procedure is nail, put, nail put. Pink panther indicates that this is made by Dow chemical company, another large corporate polluter, but probably not nearly as bad as Dupont.

We nailed the furring up to the old painted block using
 stub nails anda magnet. It can also be shot to block,
concrete and even steel.
The channels provided a very good, positive screw attachment for our self-furring metal lath.
As a warning, this used a lot more mortar
than we usually use for a scratch coat.  The foam is soft, and a lot of mortar squished behind the lath. This extra mortar does make for a better, more solid product.
z furring for metal lath and stucco