Leaking Deck Over Garage

[lockhart76]

Homeowner has a 30x30 walkout deck over his finished attached garage. Deck is on I-beam joists with 5/8" plywood glued and screwed. Previous contractor then added 3/8" osb and covered it in LinX truck box liner spray (or Rhino spray or a similar brand). It leaked. COntractor came back and rolled on an armourthane product. It leaked. (that is all I know about the second product) Contractor has not returned. Homeowner has tarred down tarpaper and other sheet prodcuts over leaky spots and has redone his garage ceiling (interior) twice now. Wants to replace the deck surface with a long lasting product that doesn't leak.
Challenges:
-Home is stucco with a flashing ledge on which the base of the stucco sits over the deck. This height cannot be adjusted. It is currently 3/4"-1" above the deck.
-Around the deck are 6- 10x10 stuccoed posts with no base flashing!?!
-There are three separate doors leading onto the deck and as of now the deck height is level with the TOP of the aluminum threshholds on them so it cannot go higher. If it wasn't stucco I would consider moving the doors up.
-Can't build a roof b/c i dont feel comfortable doing it w/o engineered drawings and he wont get them. (I do think a deck surface product will work.)

I will remove the existing roll on prodcut and the 3/8 OSB. Then, I am thinking of applying a rolled vinyl product like Duradek or Dek-master. However, the triangle shaped cantstrip flashing will not fit under the stucco drip sill so how to flash the vinyl to the home and posts? ANd how to flash it to the door threshholds? I don't like the idea of a bead of silicone being the only barrier to water. Any comments on the longevity of these vinyl products?

Or, perhaps I could apply a roll on product like this

http://www.ducan.com/rd_overview.php or another brand like this

http://www.homehardware.ca/en/exclusive-to-home_99.htm

I am not as familiar with these but I do like the idea of a roll on product b/c then I can roll under the existing stucco drip sill on the bottom of the wall and roll right up to and even right up the posts an inch or so b/c they have no drip flashing or bottom bead to roll under.

OR, perhaps I could put down Commercial Ice and Water on the original 5/8" (or some other product) then use 1/2" furring strips and lay a deck surface over the deck with 5/4 x5" pt bullnosed decking?? (or some other surface) Height would be a concern, esp. around the door threshholds and i am not sure how to ensure the screws that hold the decking down and the screws/nails that hold the furring strips down will be sealed. ??

I am open to other suggestions. I can post pics if someone suggests how to do this and feels that it would help them to formulate a solution or suggestion.

What do you think would work best? I operate under a "meticulous workmanship" motto. I want to do this the best way possible. (I also want to help the poor fellow out. =) He has had a leaking deck on and off for 15 years now and water leaks are so insidious. =(

Any comments are appreciated.
Thanks.

[BeachBoy]

You aren't going to like any of the answers you're going to get.....

After 15 years of the deck leaking there is likely to be plenty of rot and other damage to the deck and I-joists. You'll need to uncover, remove and replace whatever is damaged.

I like the Mer-Krete 747 Exterior Dual Membrane System
http://www.merkote.com/merkrete/dual747-1.htm
which I had installed on two decks recently. Use stainless steel flashing, especially over the door threshold, and around the posts, and appropriate stucco flashing. The posts must be completely flashed so they are waterproofed. You'll have to redo the stucco to get the stucco flashing at the right height. You'll also need to raise the doors an inch or two so the threshold is high enough. See the MerKrete technical info for details. (There are other systems that will work, some better than others). The amount of work to fix it right will be extensive.

[NW Architect]

AND if you aren't permitted to get into the stucco and door sills to detail the job out right, the job won't work and you'll be the one hearing from the lawyers. WALK AWAY!

[lockhart76]

I am in Canada. Can I even get merkrete here?

[Dick Seibert]

WALK AWAY!

Ditto.....

[lockhart76]

No more "dittos" permitted. =)

I realize the general consensus is to walk away, but this job presents unique challenges. I thought someone might have a creative way of solving them while leaving the stucco intact.

[DonMirabito]

Lockhart,
I thought I'd offer a slightly different take on the walk away approach. If you are going to take on the job you must be aware of not only the proper method of repair both in craftsmanship and building code requirements, but the liability which you take on for it. I don't know what the law is like in Canada, but in the USA contractors are perceived as evil. If we do something it is expected to be right whether you put in warranty exclusions or not. Local building officials will inspect to make sure we didn't do anything illegal from a code perspective. Usually, the law will protect the homeowner while hammering you with the phrase you are the professional contractor you knew or should have known how to do this right and didn't. Therefore you are guilty! Think mold and mildew and major liability. That substructure is probably junk and needs to be replaced. If the homeowner can't afford to do it right don't do it at all. Remember no good deed will go unpunished no matter your intentions.

Good Luck.

[tinner666]

This deck is suspended over a roof, correct? Fix the roof and re-attach the deck.

If the deck is the roof, oops! Remove it and use smaller framing, IF it won't create something 'less than code'.

I guess you could google Tom Hay and ask him. He invented the Poly roofs and SprayMax.

[Kgphoto]

Code is the MINIMUM requirement and what you are proposing(op) won't even meet that.

Therefore, either do it right or don't do it.

Sorry for the customer's bad fortune, don't make it yours.

[Unforgiven]

Reglet flashings are a pretty effective way of flashing to stucco walls, and can work on the posts, too. I'd check into replacing the plywood and rotted joists, and using an EPDM system or torch-down system. Don't rely on rolled or sprayed on "waterproofing coatings." They fail in short order. And don't use OSB. Get some real plywood.

[lockhart76]

From what i know of reglet flashings, they need to be installed and then stuccoed over? To attach them in a renovation scenario you would need to cut out stucco, attach, and then stucco over the flange?

[lockhart76]

Is it possible to cut out the stucco and then place the upper edge of the flashing under the stucco or under the stucco, mesh and paper?

[NW Architect]

Extremely difficult to do:
1. You must cut away some stucco without nicking the building paper
2. You must have sound building paper at the bottom of the wall (where pooling and leeking has probably been occuring
3. You must cut some lath staples up behind in-place stucco
4. You must slip a new flashing up under that sound, in-place, building paper that remains behind the existing stucco
5. You must patch back a small strip of stucco and hope it matches the existing stucco well enough to make your client happy

[Bill Robinson]

No more "dittos" permitted. =)

I realize the general consensus is to walk away, but this job presents unique challenges. I thought someone might have a creative way of solving them while leaving the stucco intact.

Creative yes, effective no

This is a good one to begin practcing not taking short cuts, or not being being creative, whichever you want to call it.
Bill R

[No faux zone]

5. You must patch back a small strip of stucco and hope it matches the existing stucco well enough to make your client happy

You could always go with a different color and texture in this area and make it a feature strip. Make a "V" groove at the seam. Better to make it look intentional than to make it look like a patch. (Just a thought)