Detail for stone veneer
DexterBob
| Posted in Green Building Techniques on
I am looking for a wall framing detail that includes a stone veneer face over 1″ ridged insulation. It seems to me that after a rain screen detail over the rigid, the next surface would be OSB or plywood that metal lath would be adhered for applying the stone veneer? So the assembly would be 2×6 stud wall, OSB, WRB, 1″ ridged insulation, rain screen (lath, Coravent, etc), 1/2″ plywood, metal lath, stone veneer.
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Robert,
There are several ways to detail this type of wall. Stone veneer cladding over OSB sheathing is one of the riskiest wall assemblies ever invented -- so be forewarned. Many of these walls have failed; there are many ways to screw things up.
The GBA detail library includes several details of this type of wall; these GBA details avoid the use of OSB. Instead, rigid foam is used as the exterior sheathing, and alternate methods of wall bracing are used. If you are a GBA Pro member, you have full access to these details. Here is one of them:
https://www.greenbuildingadvisor.com/cad/detail/flanged-window-sill-exterior-foam-sheathing-stone-veneer-siding
Stone veneer shares some characteristics with stucco cladding -- including stucco's risks. For information on details for installing stucco with an air gap (to lower the risk) -- details that are applicable to your situation -- you should see To Install Stucco Right, Include an Air Gap.
Martin, I think Robert meant that he was considering OSB over furring as the substrate for the stone veneer. While this is far less risky to the structure itself than stone over OSB exterior sheathing, the OSB may deteriorate over time if it doesn't dry adequately. Why not use cement board instead as the substrate for the stone veneer?
Haile, I was thinking the same thing. But what would the make up of that assembly be? Do you think the cement board attached to rain screen strapping would be robust enough to attach lathe and rock to?
I like the cement board idea! Certainly more robust than an OSB detail. I'll see what the mason thinks of this...
Here's your options... http://www.nsvi.com/docs/NSVI_Installation_Guide.pdf
or contact Technical Support: 920 . 251 . 2434 before you proceed.
Stone veneer is much more complicated than meets the eye.
http://www.startribune.com/local/yourvoices/168582706.html
Richard, Your first link shows the standard detailing of mesh on sheathing only separated by a WRB. That's what has caused so many problems and what needs to be avoided.
Malcolm those details are used today. The problems are not the system. It's the lack of weep holes and installation errors.
If you think this system is bad and contributes to sheathing rot, just wait 5 to 10 years and watch what happens to all those buildings where guys are installing cavity fill insulation in between brick facade air gaps.
Richard, Stone veneer is a highly permeable cladding and subject to solar vapour drive. Just like brick it needs to be installed with a cavity or rain screen. The question is what material is best, not whether it needs one.
Malcolm this topic is inline with my business expertise. As I said above; "Stone veneer is much more complicated than meets the eye". Why your challenging me over a couple of posted articles is bewildering. Veneer applications are also based on geographical practices. The same can be said for building homes.
Richard, I'm not trying to be argumentative. The OP asked what material he should use for the backing of a rain-screened stone veneer. You sent him a link of how to detail it which showed he didn't need one. I think stone veneers are a very problematic cladding and always do need one. What would you have me do? Defer to you because you say you are an expert?
Malcolm,
There are many manufacturer's (shown below) and building scientist who claim to have the answer today and then rewrite the standards tomorrow after the failure. I also stated "contact Technical Support: 920 . 251 . 2434 before you proceed."
I apologize for overlooking that key detail. "Rain-screen"
I agree with you on the rain-screen issue when you live in a freeze thaw environment. Otherwise, I believe when the systems are installed within manufacturer and published regional industry standards your risks are minimal. I disagree with the use of rigid foam behind a rain-screen due to the potential of insect infestation over time.
When things go wrong as you know they do, it's always blamed on the installation of the product as the second article I posted above illustrates.
In my course of business when it involves a large project I do not proceed with anything until the manufacturer puts it all in writing. I never rely on a blog for answers, because these guys are not issuing the warranty even though there are some talented people here.
Below are manufacturer claims and industry claims made by building science.
From DuPont... Stone Veneer
The 2012 International Building Code (Section 1405.6) requires two layers of air and
water barrier behind stone veneers over wood frame construction. When used behind
stone veneer, DuPont™Tyvek® air and water barriers shall be installed in a similar
manner as they are installed behind stucco. DuPont™Tyvek® air and water barriers
should be separated from the stone and mortar by a second layer of DuPont™
Tyvek®air and water barrier, a layer of grade D building paper, felt, rigid foam board or the paper
backing of paper-backed lath. The first layer (directly over sheathing or studs) serves as
the wall system’s air and water barrier and shall be integrated with window and door flashings, the weep screed at the bottom of the wall and any through wall flashing or expansion joints. Lath shall be installed over the intervening layer (second layer) in accordance with ASTM C1063-03 Standard Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Plaster and applicable codes. DuPont self-adhered flashing products or recommended alternate may be required for high performance installations, contact your local DuPont™Tyvek® Specialist for more information.
http://www.dupont.com/content/dam/assets/products-and-services/construction-materials/assets/K16279-Residential-OpenStudWRB_102811.pdf
Dri-Wall Rain-screen Installation Spec
http://www.keenebuilding.com/media/documents/driwall-rain-020-1/driwall-rainscreen-installation-instructions-2014-with-lh.pdf
MTI Rain-screen Youtube installation video
https://www.youtube.com/watch?v=wwKZ-z44Ysk
The Whole Building Design Guide - A program of the National Institute of Building Sciences
Building Envelope Design Guide - Thin Stone Wall Systems
http://www.wbdg.org/design/env_wall_thin_stone.php
Malcolm is right on this issue, and it sounds as if Richard is (mostly) conceding. I would go farther than Richard, however, and will say that the rainscreen gap is required in all climates -- not just a climate with freeze/thaw cycles. The most important risk factor is not cold temperatures -- it's high rainfall.
Plenty of manufacturers have recommended details that don't work. There are now tens of thousands of homes involved in construction defect litigation due to stucco or stone veneer installed over OSB. When a builder follows the manufacturer's recommendations, and the wall still rots, it takes years (sometimes decades) for the courts to sort out liability and for the manufacturers to (eventually and belatedly) come out with better details.
"The most important risk factor is not cold temperatures -- it's high rainfall."
Exactly. That's why our code here in BC mandates a rain screen gap.
I conceded on the fact I over looked the rain-screen data and failed to post about it. I agree a rain screen should be used as a matter of prevention, but I disagree it must be used in all environments and I disagree it will cure water infiltration problems. Proper Installation, design and geographical installation practices will always take precedence. What may work for New England does not mean it will work in Louisiana.
Richard, I don't mean to chew this to death, and I'm sure you are right that there are warm, dry climates where the absence of a drainage plane isn't an issue, but i can't think of an instance where the presence of a rain screen cavity wouldn't improve any stone veneer installation. So having said that, what is the best substrate? One of the proprietary plastic materials or cement board (or alternates) on strapping?
OP here! Maybe to get this centered on my original question: Location of my proposed structure is at an elevation of 4600ft in the Cascades of Oregon. The location sees 5294 heating degree days with annual rainfall of 12" and snowfall of 18". Temps range from -20 degrees in winter to over 100 in summer. What outer cladding substrate would be appropriate (over the rain screen) for my stone veneer. I see my options at this point: cement board (HardiBacker), OSB, PT 1/2" plywood.
Thanks for all your thoughts and an informative discussion!!
Robert,
I suggest you contact these 2 groups below. Request a complete systems warranty for their products recommendation in writing. In my opinion, 4-7-5 offer some of the best products industry has to offer.
http://foursevenfive.com/product-category/air-sealing-system/house-wraps-wrbs/
I also suggest for you to get in contact with the National Institute of Building Sciences (NIBS)
1090 Vermont Avenue NW, Suite 700
Washington, DC 20005
Tel 202-289-7800 . Fax 202-289-1092
http://www.wbdg.org/contact.php
Malcolm,
In my opinion, each project needs to be designed based on it's architecture and climate conditions. I do not believe there's a one size fits all specification. This is why we have architects, engineers and masonry designers. If your looking for a below head level installation the shoe may fit most. Once you exceed head elevation the dynamics change and the skeleton of the building become extremely important. The skill level of the installer's is of utmost importance.
Example of a residential failure at a friends home.... One cheapppp soul!
He hired a bunch of illegals to install his real stone veneer for $2500.00 cash (labor) around his $400,000 raised ranch. Within 10 month's all grout joints began to show micro cracks. Within 16 month's the micro's enlarged. Within 24 month's the stone was pulling off the house.
Why did this happen?
His cheap labor nailed the diamond lath in between the studs thru 1/2" plywood with 1 inch roofing nails. The weather barrier was one layer of 15 lb roofing paper. House is in zone 5. Need I say more? The replacement stone cost him big $$$. Fortunately he did not have enough time before the stone fell off to allow for water damage or this lesson could be really big money. I tried to tell him he refused to listen. Now he understands that making pizza is not the same as building homes.
Robert, As I see it you have two good choices: Cement backer-board on furring, or a proprietary plastic mat. Both can allow the wall to dry to the exterior if you decide to use a high perm foam. Both provide good capillary breaks.
However i do wish someone would weigh in on the possible inward solar vapour drive and whether a low perm foam would be a safer bet to avoid this potential problem - assuming your walls do have the ability to dry to the interior.
Robert and Malcolm,
Inward solar vapor drive usually doesn't lead to major problems as long as your interior layers are vapor-permeable -- in other words, you don't want interior polyethylene.
That said, I think that it makes sense to install a layer of rigid foam behind stucco, brick veneer, or stone veneer, to address inward solar vapor drive.
Robert, it sounds like you are contemplating a wall assembly with two layers of wall sheathing. If you are doing that, the very best system would:
1. Include bracing that does not depend on the wall sheathing (for example, diagonal metal strapping).
2. Have a layer of rigid foam as the first wall sheathing layer.
3. Then you want your rainscreen gap.
4. Your second (outer) layer of sheathing would be cement backerboard.
Needless to say, get these details approved by an engineer before proceeding.