Pre slope under shower pan liner


Old 11-19-11, 11:13 AM
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Pre slope under shower pan liner

i have a 30' x 60" shower bottom that needs to be presloped under the pan liner. I have done this pre slope using deck mud in the past
I have a friend who is a tile layer that has the carpenter create the
pre slope using plywood. First the 3/4" plywood subfloor is installed with cutout for the drain at the center. He sets 3/4" float strips around
the perimeter. He then takes another sheet of plywood cuts out the hole for the drain. Then he cuts appproximately half way through the plywood diagonally from corner to corner. He flips the sheet over so cuts are down and jumps on it causing the plywood tofold at these cut lines creating the pre slope. Then the pan liner is installed.

Has anyone done the preslope this way? seems like an easier way to get the 1/4" per foot minimum required pre slope.
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Old 11-20-11, 02:59 PM
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Others may agree with your carpenter's method, but I can't think of a more difficult method of achieving a pan slope. Seems to me a dry pack using levels would achieve a much more consistent floor. Just an opinion, so wait on others to chime in.
Old 11-24-11, 04:42 PM
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i would never use plywood as the pre-slope unless it's fully supported on the joists to the drain, and the way you describe it, only the perimeter and the center is supported. I prefer the pre=slope with deck mud, it solid under foot and no bounce / deflection what so ever
Old 11-27-11, 08:02 AM
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Dry packing the mud is easy!

The plywood deal is a disaster waiting to happen down the road, if this is over a concrete foundation!

Just level off your finished drain height and then measure out to your longest wall from the drain, and then calculate the slope rise. Mark and then make a level line all the way around.

Pack & screed mud, using various lengths of 2x4's

Or the better solution would be A Schluter shower kit system!
Old 11-27-11, 09:15 PM
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Shower pan liner preslope

Thank you for the input. The fact that the plywood isn't supported was a concern of mine as well. i guess the "old school" ways are sometimes still the best option.

I have also heard of a product by Noble (the Chloroloy peope) called Nople ProSlope that creates the preslope. Looks interesting. Has anyone used it?
Old 11-28-11, 11:20 AM
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Noble's pro slope and kerdi shower tray are really only options if your shower will be one of the pre fab sizes they make. Ive built several kerdi showers, but have never used their tray. Making a preslope with deck mud is easy, and cheaper than most other options, and it will stand the test of time.

That idea with the plywood is actually pretty funny. I'd not try it, as there is no way it would provide adequate support as you describe it.

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