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Walk out deck


Charles
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Greetings.

Multi-million dollar ocean front estate. Has multiple walk out roof decks. Some with living space below.

Problem. Bulk water appears to be soaking through the concrete tile decking and into the mortar bed and seeping out at the membrane flashing. The amount of efflorescence concerns me as it appears to be excessive and appears to indicate failure of the tile bonding agents and possible the roof membrane.

Pictures show the tile, lack of tile adhesion, wet mortar, wet adhesive, and the efflorecsence.

Opinions please.

Charles

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Hi Charles,

I think you need to go into your computer files and rename your second picture and remove the space between F (2) if you want that photo to display.

Did you take pictures looking up from underneath and were there signs of leakage and efflorescence there?

Are you sure that's meant to be an adhered tile roof and that is tile adhesive and not a sand bed beneath the a paver surface?

I've seen a few rootop paver decks here. They are usually designed with a heavy modbit membrane, followed by a layer of 2 inch styrofoam as a protective buffer, followed by a layer of either washed stone or sand and finally a layer of pavers. They weigh a lot. Looked at one on a 15 story condo building one time that had a leak and was opened up for repair with construction barriers around the area they were repairing. The gravel barrier was about 6 inches thick before one even reached the styrofoam.

ONE TEAM - ONE FIGHT!!!

Mike

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The efflorescence appears to be from water draining OVER the drip edge, which is likely to happen on any flat roof, unless there's a gutter. I'm not sure the efflorescence stains correlate with any flat roof problems per se.

Look at other flat roofs in the area. Do they also show the efflorescence?

Regarding the tile being properly bonded, it's hard to say from looking at the pictures. I'd talk with local tile setters for their opinion.

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There are so many ways this installation could be messed up, it is impossible to comment from just the pics provided. I see way too many messed up (simple) shower pans to have confidence in someone constructing something of this magnitude successfully.

First, the concrete substrate is really stupid; it should be an aggregate (draining) bed. Second, the lack of directed drainage tends to make me suspicious of the design path; having all the that moisture drain out right over decorative elements doesn't promote confidence.

This one requires a lot of additional looking & analysis, review w/the architect, installer, code officials, or anyone who managed to see the installation in process.

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I guess my primary concern is design related. There are no stains on the ceilings below.

We do not do a good job on walk out decks in our area, period (North Florida). The list of typical errors is long, from improper membranes, poor design, to weight of flooring materials exceeding design limits (a possible concern here when you consider the weight of the bulk water after soaking into the finished flooring and mortar bed beneath). And yes, this is a mortar bed that is soft and failing. Multiple loose tiles were observed.

I would suppose that a properly designed deck would include surface drainage for most if not all of the liquid and if "some water" gets through, the roof membrane would take care of the rest. In this case it appears that most of the water is soaking into the stone and mortar bed and then draining to the membrane and weeping out at the edge/drip flashing.

In this case it just felt wrong, looked wrong and in the end, we have recommend design review with the architect and builder.

On a recent multi-million dollar home we inspected that had decks over living spaces the architectural details did not include a roof membrane but specified two layers of “Durockâ€

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