AZ has some pretty lenient building codes. Here is a typical build in Phx, AZ. I found over 50+ spots on this ranch home where they tore through the tar paper & styrofoam and left a gaping hole for water intrusion. They DO NOT OSB shear the homes in Phx, only in a few spots here and there. What you see here is the final framed product before they start putting the tar paper and styrofoam as seen in the picture.

As you know stucco is NOT waterproof, once it is water soaked, water will flow behind it. The 1/2" styrofoam that they use is also NOT 100% waterproof as it has gaps, tears and rips in it from all the nails and staples they use. So you are left with the tar paper as your final water barrier. If that is in any way ripped or compromised, water will find its way in and soak the fiberglass insulation, the studs and then your drywall. This is the way that tract homes are built in Phx.

Imagine the air& water infiltration in a home like this! Not to mention the amount of bugs that find their way into the walls.

They attach tar paper right to the open studs?

Foam, taped house wrap, stucco wrap, mesh, stucco makes more sense to me.

Posted By jonr on 11 Dec 2011 04:48 PM
They attach tar paper right to the open studs?

Foam, double layer taped stucco wrap, mesh, stucco makes more sense to me.

YEP!

They attach the tar paper & styrofoam directly to the open studs by running a staple (as seen in the photo) through the tar paper and into the stud (that is if they don't miss the stud as shown in the picture).

As can be seen, in OVER 50+ instances, they missed the studs and the staple went into the void between the studs and ripped the tar paper and crumbled the styrofoam. Remember, the DO NOT install OSB sheathing on the entire home. Therefore the paper rips very easily as there is nothing solid behind it.

I GUARANTEE YOU that a home built like this in a rainy climate would experience mold, rot and failure within 2-3 years. Since it is AZ, you are OK when it doesn't rain but when it does, get ready for interior leaks. I personally spoke to numerous Phx homeowners that got water leaks coming out of the drywall during wind driven rain or in a long duration soaking rain. The water will literally come right through the drywall and weep. Of course the entire fiberglass bat is soaked, and the studs are soaked behind the drywall.

Welcome to Phx AZ home building! They use this practice even on million dollar homes. Unless you custom build, this is what you get.

Here are 2 more images but of a 2-story home. This home is 100% done being framed. I kid you not. They will start installing the paper wrap and styrofoam this week, then stucco it. The areas of missing OSB will remain that way, missing. They only shear certain areas.

I also guarantee you that the tar paper will get ripped during install in the areas where it spans in-between the stud frames, with the result being water/air intrusion.




    

I'd say some more OSB to prevent racking. But no need to cover it all (foam over studs is legitimate if you aren't suspending tar paper).

How is that rigid enough to apply stucco mud, without sheathing? I must end up thicker in-between the studs.

Posted By ICFconstruction on 11 Dec 2011 10:29 PM
How is that rigid enough to apply stucco mud, without sheathing? I must end up thicker in-between the studs.

They use 1/2" to 1" styrofoam/EPS across the studs and the just staple the EPS to the stud. They then run mesh/chicken wire on top and then apply a VERY thin layer of stucco, probably 1/2".

They alternate styrofoam thickness to compensate for the areas that do not have OSB.

As I mentioned, rips will form on the tar paper, that is guaranteed. Even the installers know it. All they do is go back and run some caulk on the rips from the inside of the home before they fiberglass insulate and drywall. Mind you they never get all the rips and even the ones they do get, they are very sloppy and quick with the caulk gun.

I suppose if I were forced to live in one of these, I would keep the house slightly pressurized during wet/warm weather to help keep moisture out. Those small roof overhangs certainly don't help either.

So the window flashing is set up to dump water behind the foam?

no voids or honeycombs in that construction

Posted By jonr on 12 Dec 2011 09:20 PM
So the window flashing is set up to dump water behind the foam?

Yep.

They don't consider/use the foam as a "water barrier", it is thought of as a substance to attach the stucco to and for insulation value. It is not considered a water barrier.

Posted By guest on 12 Dec 2011 10:09 PM
no voids or honeycombs in that construction

Apparently not.

They need to go to full OSB and drain wrap.

How would a home like this perform during high winds?

I would believe not too well. These homes rack quite a bit during 40MPH+ winds. Without the OSB sheathing there is quite a bit of movement .

Lbear,

What would happen to this house during a downburst?  A downburst would make a 40MPH wind insignificant.  The dimensional lumber would be splinters.  Other new and stronger technologies should do better although they might lose most of their shingles.  I seem to remember reading about downbursts in that part of AZ.  I believe it was associated with the SABS house.

I'm going to guess that racking + stucco = more cracks and cracks mean even more leaks.

Posted By jonr on 14 Dec 2011 11:17 AM
I'm going to guess that racking + stucco = cracks and cracks mean even more leaks.

Cracks in the stucco are considered "normal" out here. Unless they are greater than 1/4" wide, they will leave them be.

Stucco/concrete is NOT waterproof, water will soak the concrete and then go behind it, the EPS is also NOT 100% waterproof. The tar paper is the true water barrier. Unfortunately when they rip and tear it in over 100+ places in a 2story home, you will get water intrusion.

Stucco will crack, preferably on expansion/controll joints, but if you have cracking as much as 1/4" there is a structural problem

EPS actually is 100% waterproof if you detail the seams properly, but it'd not as easy to do that with EPS as it is with XPS.

SFAIK there are no generally accepted methods of using EPS as the weather resistant barrier (WRB), but there is with XPS. But the cost of doing a separate "tried & true" WRB is pretty cheap.