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eddy_mollison

Cantilevered Porch Rebuild - Need Direction on Flooring Solutions

21 days ago
last modified: 20 days ago

Hi, I'm currently rebuilding a ~67.5 sq ft cantilevered second-floor porch on a 1920s brick duplex in Detroit, MI. The porch sits directly above the main entry door. I've rebuilt the frame of the porch with new pressure-treated LVL framing is complete with 7 joists, rim board across the front, with the original corbels below. I'm a little stuck with identifying the best path forward for the flooring of the porch moving forward, knowing that it is an unprotected surface, susceptible to Michigan freeze / thaw cycles, UV, etc.


What I have currently planned:

  • Tapered PT 2x4 installed on top of joists to create slope toward the front (approx. 1/8" per foot)
  • ¾" PT plywood subfloor on top of tapered PT 2x4
  • K-style aluminum gutters on all three open sides feeding into one downspout on the driveway
  • Fascia-mounted aluminum picket railing (Century or similar)

What I need direction on:

  1. Flooring system — Is tile viable here, and if so, what does the correct assembly look like over a wood subfloor that is fully exposed to Michigan weather? Does tile require a roofing-grade primary membrane below it (like a PVC membrane), with tile serving only as the traffic surface above? Or is a liquid-applied membrane like RedGard with Schluter Ditra sufficient for this application? Any guidance on the general sequencing is appreciated.
  2. PVC membrane as standalone finish — If tile isn't practical, is a single-sheet PVC membrane (Duradek or similar) the correct primary waterproofing solution for this application? Any product recommendations suitable for DIY installation? Open to any other ideas someone may have as far as flooring solutions go.
  3. Drip edge — What is the correct perimeter drip edge detail for either system where the floor terminates at the fascia and drains into gutters? Is BARA-RAK from Schluter the right product, or is a standard aluminum roofing drip edge acceptable for a tiled deck?

Traditional decking is not an option — everything must shed water into gutters and keep the entry below completely dry. Happy to provide photos or additional detail. Thanks in advance.





Comments (10)

  • 20 days ago

    Using a PVC membrane beneath tile seems pretty logical, though I'm not really sure that I understand how you're suggesting BARA-RAK would work with PVC. BARA-RAK / drip edge seems like something that should be installed when the cement is set with the uncoupling membrane, not beneath the PVC membrane:



    My only other concern with BARA-RAK is that I have some potential connectivity issues that would probably be more manageable with modifying a standard aluminum drip edge - because of the slope I am adding with the subfloor, I'm not certain these pieces will connect like they would on a totally flat surface. Maybe a better question for Shluter Rep.


    Not sure if this is just a bunch of AI-jargon, but I'm also not understanding your comment on the gutters at all, nor is your link working. A drip edge that terminates into a gutter system seems pretty straightforward ... and has been used successfully millions of times before ...

  • 20 days ago

    I get this when I go to that web site - I'd beware!

    Website blocked

  • 20 days ago

    LF Builders is always AI slop to get their link in on every post whether Ontario or not. Slop always just repeats keywords in your OP.

    Outdoor mortared tile is never a good choice in freeze/thaw climates. You will have a lot of movement, especially deflection in such a long cantilever. That eliminates the uncoupling talk.

    The dimension of the step down once sleepers are in, and the preferred detail of flashing to the brick (assuming a kerf for termination bar) is important in deciding the membrane. Typically fiberglass (with each manuf. proprietary drip edge) is good when you have no step down, but I believe that is not a DIY-sourced product.

    I believe Duradek has a minimum dimension to flash at the wall. I also believe it must go through an installer, not sure.

    All of those adhered membranes detail the same at the edge, in that they are welded to the drip edge.

    You may have to DIY an off-brand membrane if you can't source Duradek.



  • 20 days ago

    I assume outdoor tile is more acceptable when it sits under a covered area, granted I'm a little confused why there would be so many "frost resistant" tiles out there... unless they are typically placed under covered areas.


    That being said, I'm not married to anything - my main goals are a) waterproofing and b) something that won't be slick but still comfortable if you don't want to wear shoes, nor get super hot in sunny conditions.


    Re: drip edge - I don't have any major aesthetic requirements. When you say "no step down" there is a threshold (that will need to be modestly moved up do to upsizing the new lumber / LVL from 2x8 to 2x10, and I expect there to still be a small step down (1 - 2") from the threshold to the porch itself, even after slope is added.


    You are correct that Duradek requires an installer, I think TufDek is something you can source on your own.

  • 20 days ago

    Duradeck is only supposed to be installed by a network of trained and authorized applicators. I assume that you're aware of that requirement. Obviously, you are not a DIYer (at least not the typical DIY person).


    Requirements for substrate for Duradeck:


    https://duradek.com/Downloads/PDF/Techtalk-126-USA-Plywood.pdf


    The Duradeck PDF contains a section re: deflection of L/360 minimum.


    They sell Tiledek specifically for underneath tile installation. For tile to be installed, you need to make sure the deflection is correct - I think natural stone is L/720 minimum. Tiledek is also required to be installed by an authorized applicator.


    I imagine that there are other similar products. I hope your project turns out well - I love cantilevered second-floor porches! I'm commenting in order to bump this back up to the top - hopefully, you'll receive more advice/suggestions in addition to what you've received already.

  • 20 days ago

    Tile itself in freezing is not the problem per se, but grout cracks, it also absorbs moisture, that moisture gets under the tile and pops it off or cracks it when freezes. Beyond deflection from dead load, you also have live load to contend with, not that you'll have more than prescriptive psf for the members unless you host a balcony kegger.

  • 20 days ago

    Ha - to your point, I excpect to occasionally have 2 - 3 people, or at MOST, 4 on the deck at a time, which as far as I'm concerned is still well below the prescriptive PSF. For what it is worth I tried to overbuild the deck as much as possible - it's significantly stronger now than the original design (not that it says much, but still). Do you have any ideas other than PVC membrane?


    Looks like there's a TufDek installer in Detroit, not sure about DuraDek.


    This is the most DIY-friendly / no installer necessary line I have found: https://econodek.com/

  • 11 days ago

    @dani_m08 thanks for the encouragement!


    @dan1888 would love if this and things like it had more track record...

  • 11 days ago

    Contact them for customer contacts.