Poor Flashing Work on a Tile Deck Creates Thousands of $ In Hidden Damages

[Deck Expert]

Hello to All the HI's Out There...

How many times have you inspected a deck and noted some rust on the flashings?
The pics attached are of a job I started in Arroyo Grande CA. The complaint was the flashings were rusted, we demo'd the deck to the joists as the owner hated the slippery tiles. Even then there wasn't much indication of any problems until we pulled a joist from the corner and revealed the top of the 6"x14" x 22' beam.

Sh*t went downhill from there and you can see the extent of the hidden damage after the stucco was removed.

Turns out the flashing used was gravel stop nosing-the tile would run the water to the edge and the water ran down under the gravel stop and was trapped, with no outlet except down into the beams. Add a little summer heat and presto, dry-rot.
This job went from 12k in repairs to over 32K in repairs.

Do what you want, I would advise to call it out in very stern terms to warn your clients about potential for very expensive repairs to the hidden damage.

FYI- I do secondary inspections/DT and reports for HI's in California. We also fix decks...mostly.

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[Vern Heiler]

Bill do you have any pic's of properly flashed tiled deck. I don't see many tiled decks here and most have parapet walls with drains. How would I identify correct from incorrect on a normal inspection?

[Deck Expert]

Edge flashing detail on a tile deck Mer-Krete Systems

This drawing shows how we install a double drip edge flashing to eliminate water creeping back under the tile. I don't have any good pics as they never show the full detail...

Almost every open edged tile deck I see/work on has not been double flashed at the edge, and typically the contractor uses a single membrane without allowing for sub-surface moisture a way to escape except into the framing. Grout allows water under tile installation-water has no place to go/drain. It will find the weak link in the waterproofing/flashing chain and eventually cause major problems.

Here's some pics of a job I'm doing in Santa Barbara; the deck has parapet walls around it. We've installed a Thunderbird tile deck drain and overflow in the corner where sloping and a cricket will direct the water to. Note the weep holes on the bottom of the drain. Water that makes it past the tile/grout/expansion strips will be funneled to the weep holes on the drain.
We then flashed in the deck, waterproofed the whole thing like a bathtub, bringing Mer-Kote ARC waterproofing with polyester fabric reinforcement up to the top of the flashing where contiguous building materials will come down over the flashing. Then we installed expansion strips along the edges of the flashing, after which we poured a 3/4" underlayment mortar bed. The expansion strips will allow the bed/tile to expand and contract. We will, after the bed cures, put another application of ARC waterproofing on top. The tile can be thinset directly to our ARC waterproofing.

The tile installer will use single component urethane around the perimeter of the tile, allowing for expansion/contraction. Surface water will go to the drain grate on top, water making it past the grout will go under the tile/thinset and seep down to the weep holes on the floor as we leave pea gravel around the open neck of the drain grate to allow for moisture migration.

This system goes for around $20-$28 psf installed.

I hear crying all the time, oh my god thats so much...and I answer smugly, how much is your tile gonna cost? And what reaction will you have when your deck is failing in 5-8 years and all has to be pulled out? Most importantly, do you really think a system that sells for $6.00-$8.00 psf is equal to mine and will give you the same results?

[Eric Barker]

Whoa Bill, I'm glad you don't work around here. Part of the enjoyment in my job is seeing all the crap that is installed. If I kept coming across properly done work, things would get pretty boring. For me it's really interesting how people can screw things up. You wouldn't want to deprive me of that would you?

[Vern Heiler]

Thanks for the info. Please try to get some pic's of properly and improperly flashed open edge. Again I don't see a lot of these and would like to be able to identify good from bad, without tearing up the tile!