I don't believe we have that here in California. Is that a snow thing? i.e. if you get 10" of snow, you obviously don't want the bottom exposed edge of your plywood soaking it all in. Thus the 12" up rule.

That would be my guess, and if you are in a snow zone it doesn't sound unreasonable.

-mike

Hi Mike,
Guess what? We're in California; SF Bay Area, to be precise. What I don't understand is why the waterproofing membrane has to be this Grace Ice and Wind Shield. The inspector says it's because it self-seals around nail holes. Doesn't felt paper do the same thing?
It just seems like the Ice and Wind Shield product is overkill. I read the product description and it's primarily used as a roofing membrane to prevent ice dams and wind-driven rain from penetrating thru to the sheathing.
Plus if we're going to be putting on stucco, we'll have 2 layers of Grade D paper.

"My questions are:
1. Does this sound reasonable, correct, and effective?"

Yes.
"2. What is the purpose of the sheet metal??"

The plywood extends beyond the walls original vertical plain leaving an exposed open grain and its another in the steps to seal the bottom of the plywood to prevent wicking.
However, what is interesting is that whether or not you are on a raised slab or on a floor joist system, the plywood is part of the shear element and will be securely nailed at the bottom, even with the bottom of the mud-sill at the intersection with the foundation, making it difficult to install a "J" metal.

"3. What kind of sheet metal should I use? Galvanized? Standard steel?
4. What kind of fasteners should I use to install the sheet metal and what kind of nailing schedule?"

A readily availabe galvanized metal attached with 1-1/4" roofing nails at 8" o,c,

This is what I've done; Looking at it in section, plywood, self-adhesive membrane, galv. "L" metal, galv. weep screed, 2 layers of plasterkraft and the stucco netting.

Seal the "L" metal/foundation joint with a urethane caulking.

Felt paper doesn't seal around nail holes, but the Grace product does. I sure wish my inspector had been like yours. The builder of our house didn't have to any of that and here is what it looked like 6 years later. When repairing the mess, we used Grace Vycor vs the Ice Shield as it was readily available.

Here is a link that might be useful: pics

No kidding! Patches said what I was going to say. Tar paper doesn't do what the grace stuff does. I'm about to redo my roof and I'm thinking of using the grace stuff under - it sounds awesome.

Stucco is horrible, horrible stuff (I've had to remove it) and more importantly, subject to all sorts of damage and leaks etc which can literally rot your house away from underneath....so all preventative measures are worth it. The metal's a good idea, when I see what you're doing. Use the best you can get which I guess is galvanised, which will be compatible with the no doubt galvanised nails contractor'll be using.

Where you are, you'll no doubt get a lot of rain. Prevention is GOOD.

Around the bottom is where your materials are going to fail. This is a GOOD idea.....you won't regret it.

Hi,
The inspector seems to be trying to make up for the fact that your grade is too close to wood structural elements. One of his suggestions seems off to me- having the bottom edge of the sheathing sitting in a trough. Maybe he misspoke, maybe you heard wrong, but that seems really dumb. A better detail would be a metal z-flashing applied to the framing before sheathing. Then the sticky ice & water shield on top of the sheathing. This should prevent moisture problems in either direction without forming a water trap, which a j-channel definitely is.
Casey

California UCB Code and soon to be adopted International Residential Code agrees that wood sheathing too close to grade must be protected from decay.

Won't repeat what others have stated but to say that the inspector made the right call...

Thanks everyone for your responses.
Patches, sorry to hear about your house. I'm also having a hard time finding the Grace Ice and Wind Shield product. I've even checked their website to find local distributors, one of which is Lowe's, but when I called Lowe's they said they didn't carry it.
Sombreuil, what I heard the inspector say was that the sheet metal should fold at the bottom and cover the plywood edge, so to me it sounds more like an "L" metal, rather than a "J" metal, if that makes a difference.
What do people think about changing the grade and removing the dirt around the foundation as another option?

pchow
"What I don't understand is why the waterproofing membrane has to be this Grace Ice and Wind Shield. The inspector says it's because it self-seals around nail holes. Doesn't felt paper do the same thing?"

There are a number of "self-adhesive" flashing products and they are available, in a variety of widths, designed to also be used for window installation as well, from the the big boxes and local lumber yards.

"Self adhesive" is the key.

You might call the distributor to find out what retail place close to you would have it. Grace Vycor is at many Home Depots if the inspector would allow a substitute.

I agree on the J-channel at the bottom... any water that does get behind the paper will have no way to drip out! It just makes a trough to soak the wood in. My shear inspection (same general area as pchow) will be next month, so we'll see what they want then.

-mike

Hi Mike,
Can't wait to hear what your inspector says! We actually already had our exterior sheathing/shear wall inspection and passed that without any problems.

If I used the "L" sheet metal rather than the "J", would that solve the "soaking trough" problem?

Also, I found a substitute product for the Ice and Water Shield. Same brand, Grace, but their Vycor V40. Here's a description:

"Grace Vycor® V40 Self-Adhered Flashing
Provides superior protection against water, air and moisture infiltration in window and door openings, corner boards, under stucco finishes, masonry walls and other flashing areas. The product is 40 mil thick and is designed to meet the requirements for weather resistive barriers as defined by Federal Specification UU-B-790a, Grade A. It is designed to work in severe winter climates, milder climates, and in coastal areas where wind driven rain is common. It should not be used on roofs. Grace Vycor® V40 is compatible with wood, plywood, oriented strand board, concrete and masonry and fully adheres to the substrate to prevent water from passing through and into the substrate. Available in a range of widths: 6", 9" and 12", to accommodate a variety of job requirements."

It is the same thickness as the Ice and Water Shield, seems to perform the same function but for non-roof applications, which is my situation. Hopefully, it's OK with the inspector.

Hi, the flashing detail I was trying to get across would roughly be a z- or zigzag shape; it would begin directly on the studs, go down to the foundation level, jog outward horizontally 1/2 inch (under the bottom of the plywood) and then have a drip edge that pointed down again at least 1/2 inch. Its function would be to keep water off the principal structural elements, namely, the studs. then, the sticky, self-healing membrane would prevent any water from soaking the sheathing.
If at all possible, it's always best to have that 12 inches of vertical space from grade to framing...

Casey

"If I used the "L" sheet metal rather than the "J", would that solve the "soaking trough" problem?"

Yes, also there is a suggested application of a wood preservative such as "Green Wood".

This is a wood prservative and moisture inhibitor. He may have suggested the green as it will leave a teltale stain, however, JASCO offers there product in a green and clear formulation.

Thanks everyone, you've been so helpful with your comments and responses.
I have one more question:
Is this "L" or "Z" sheet metal readily available thru supply stores or is it something that will need to be custom fabricated?
The 75 ft roll of Grace Vycor was only $35, but I shudder to think what it might cost for a custom order on the sheet metal!

Both "Z" bar and "L" metal are readily available in galv. as well as bonderized.

pchow asked:

"What do people think about changing the grade and removing the dirt around the foundation as another option?"

THAT is the correct option in this case.

If you can get your final soil grade at 8" below the wood siding or more, you don't have to do anything else to the siding.

Grading is CHEAP.

Flashing and treating the wood is expensive.

Go with the grading....that's what the smart money would do.

Vycor V40 is just Ice & Water Shield without the non-slip surface (so it can't be used on a roof). The thinner versions are intended for wall and deck flashing and are called Vycor Plus and Deck Protector (same but with non-slip surface). they will will work fine and are available in narrower rolls. I would not use another brand or butyl based flashing.

The plywood should be clean and free of contaminants like the preservative suggested by the inspector. For greater adherence brush on WR Grace's WB Primer (water based) and let it get tacky before applying the Vycor and rolling it with a small metal roller (very important step). The flashing will adhere so well that the poly surface will separate from the bitumen if you try to remove it. There is a solvent based primer available if you want to get crazy about this. There is also a vapor permeable liquid flashing called Perm-A-Barrier VP (unless they've changed the name again).

The shape of the metal counter-flashing is not important since all it can do is protect the Vycor from UV exposure (and possibly trap water behind it if the bottom is bent inward or sealed).

There is no reason to carry any of this additional waterproofing much above the bottom of the stucco but the Vycor could be carried below grade if the primer is used. Of course any of it that is exposed should be covered with something.

Any metal counter flashing will eventually corrode and have to be replaced if it is not stainless steel or copper. If the stucco is too close to the ground you should be thinking about how to protect it as well.

I would say that the inspector's detail is so expensive and poorly conceived that unless you are allowed to modify it as described above, your only reasonable choice is to lower the grade.

Here is a link that might be useful: liquid air/water barrier

This is a typical stucco base detail with the exception that the self-adhering flashing is set in WB Primer, It should be acceptable for a clearance of 4" above soil and 2" above paving.

If the sheathing overhangs the foundation the Vycor could be covered with copper or aluminum z-flashing free to drain downward.

For a better drainage underlayment I would recommend Tyvek StuccoWrap (DrainWrap is the same thing) installed with capped nails and taped at ALL joints with a second layer of cheap micro-perforated lumberyard wrap for the stucco to adhere to.