Thread: Stucco coverage at corners

What are the specs for stucco coverage over lathing materials at corners? I have some exposed lathing materials in the corners and want to back up my call about substandard installation.

Any help would be greatly appreciated.

Mike

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Accessories shall be used, and accessories include corner beads or corner screeds.

From the ASTM standard for the installation of lath:

- 6.3.1 External Corner Reinforcement—Expanded lath, welded wire, or woven wire mesh bent to approximately 90° used to reinforce portland cement stucco at external corners. This accessory shall be fully embedded in the stucco.
- 7.11.1 General—All metal accessories shall be installed in such a manner than flanges and clips provided for their attachment are completely embedded in the plaster.
- 7.11.2.1 External Corner Reinforcement—External corner
reinforcement shall be installed to reinforce all external corners where corner bead is not used. Where no external corner reinforcement or corner bead is used, lath shall be furred out and carried around corners not less than one support on frame construction.

The last one probably covers what you need best: a) it says that corner bead is to be installed, but if one choses not to install corner bead, then external corner reinforcement is to be installed.

With corner bead, you would see the vertical corner (on vertical corners, horizontal on horizontal corners).

With external corner reinforcement you should not see it as it is required to be "This accessory shall be fully embedded in the stucco." - see 6.3.1.

Thank you Jerry

Originally Posted by Mike Inspector

What are the specs for stucco coverage over lathing materials at corners? I have some exposed lathing materials in the corners and want to back up my call about substandard installation.

Any help would be greatly appreciated.

Mike

Try this.



http://rds.yahoo.com/_ylt=A0oG7lC4v9...nts/Stucco.pdf

Originally Posted by Marcel Cyr

Try this.



http://rds.yahoo.com/_ylt=A0oG7lC4v9...nts/Stucco.pdf

Marcel,

There are some errors in that document - showing things which you are not supposed to, or allowed, to do.

Originally Posted by Jerry Peck

Marcel,

There are some errors in that document - showing things which you are not supposed to, or allowed, to do.

I did not pay to much attention to details Jerry, had lots of pictures of preformed and wraped corners.
It would be nice if you pointed out the errors so we can all learn.

No stucco in my area so this is a new territory for me.

I have an other link here that might be helpful to some.

Chapter 4, Lath for Stucco

Originally Posted by Marcel Cyr

It would be nice if you pointed out the errors so we can all learn.

Marcel,

I just skimmed through it the first time, and am just skimming through it again.

The drawing on page 3 does not show a bond breaker (the paper of paper backed metal lath) and a drainage plane (building felt or building wrap approved for this use), note that the text includes the two layers, it is the drawing which does not.

The left photo on page 8 does not show weep screed at the bottom of the metal lath, it just shows casing bead. The right photo is a poor photo to show that, but all it shows is (at best) a casing bead along the bottom and then a Z flashing under it and over the wood trim (that Z flashing is a good detail, but it needs a weep screed along the bottom of the stucco area to allow for weeping out the water migrating down the drainage plane). There is no need to install a drainage plane and then not install a proper accessory which will allow that drainage to weep out.

Also on page 8, and this is only true on some metal lath as some metal lath has the name both right side up and upside down, when you see the name of the lath manufacturer upside down - take a look at the metal lath and check to see that it was installed right side up. As the expanded metal lath is expanded the lath forms little cup edges at the bottom of the lath holes. The bottom cups should be up and these serve to help hold the stucco in place on the lath "cups up". When the cups are down they create little ski slopes which helps the stucco to slide off the lath - not good. Keep in mind that seeing the name upside down does NOT mean the lath is upside down, it just means you need to check it.

The meter can shown on page 9 is recessed back in the stucco and should have the stucco wall extend behind it, then the meter can installed, and when installed properly the meter can will have the required 1/4" air space behind it (between the back of the meter can and the stucco) and the top, bottom and sides will be open (not caulked) to allow air to flow in that 1/4" air space (that is why that 1/4" air space is there).

On page 11 it says "It shall also be permissible to follow the roof rake on gables with the top row of paper", that is not allowed in the ASTM standards or other standards (but I guess it is there) as those sheets of paper backed metal lath are also required to be installed horizontally just like all the rest of it is.

Thanks Jerry, good explanation. I had picked up the meter can. Even contractors around here don't float the meter can while doing the siding or re-siding. They just go around it. sloppy.

So the lath being up side down will some how make the house leak and rot?

The problem with them running the lath at the angle of a gable is that they end up with paper on metal instead of paper on paper and metal on metal.

Originally Posted by carl brown

So the lath being up side down will some how make the house leak and rot?

Not sure how you tied the lath being upside down to leading and rotting ... would you clue me in? Thanks.

The problem with them running the lath at the angle of a gable is that they end up with paper on metal instead of paper on paper and metal on metal.

AND that the laps are not correct, AND that the lath is not installed horizontally as required, AND that the "cups" in the lath are at an angle and not horizontal, AND ... (yes, the paper-metal-paper-metal aspect is a reason, but it is only ONE of the reasons) ...

Jerry,

I enjoy reading your post and I agree there are a lot of problems with the JOCO installation info.

Here are some pictures that were taken in JOCO a few years back!

Slide 1

I just do not agree with all that the experts say how to do things and what the real problems are with why a stucco job gets the blame for rotting houses.