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Unread 06-07-2020, 09:15 PM   #31
jimmartz
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CX,

You make a very good point that I overlooked.
While plywood used as sheeting with the grain running perpendicular
to the supports has a Modulus of Elasticity comparable to that of
solid wood, because most of the force is on the outer layers.
When plywood is ripped and placed on its side the dynamics change,
and as you mentioned only those layers with the grain in the same direction
as the joist being sistered will have much contribution to the
Modulus of Elasticity, or strength.
Makes one wonder about the documents out there that show sistering with
plywood as an exceptionable option. Based on the above I would say that
sistering with solid 1x lumber would be better then 23/32 plywood. But putting
all them screws in 1x lumber would surly split it...

Also, I was only able to span about 1/3 of the length of the joist, net even 2/3.

It does seem to be in my nature to try to come up with a better wheel,
although keeping in mind what really works is good.
100 years ago they would not of thought we would be gluing wood chips
together press it flat and put it between two sticks and making it a joist.

Thanks,
Jim
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Unread 06-07-2020, 10:02 PM   #32
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Jim,

laminating 2x4 to the bottom of the joist would be a problem, little head room,
and pipes across the bottom of the joists. But with that in mind I thought of
using steel strapping a across the bottom. With steel having a far grater
Modulus of Elasticity a little goes a long way. I have seen where 1/4" steel
was used across to bottom of beams in a historic preservation.
Now I did not use 1/4" steel, the thickest bulk strapping I could find was
14 gauge. I am waiting for it to cure for a few days and hope that I can
see some good results.

Thanks,
Jim
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Unread 11-18-2020, 09:07 AM   #33
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Modified or not, between Planipatch and Ditra

Hi all,

I got 1/2 plywood over the sub-floor and plan to use Planipatch
to flatten low spots in the floor. After that I plan to use Ditra before
laying 6"x24" porcelain tile.

Normally one would use modified thin-set to attach the ditra to the
plywwod, but I will have Planipatch over much of the plywood.
Will a modified thin-set work between the Planipatch and Ditra?

I was thinking of using MAPEI Uncoupling Membrane mortar.
Between the Planipatch and Ditra I would use the MAPEI Polymer Additive.
And to lay the tile use only water with the Uncoupling Membrane mortar.
Does this sound like it would work good?

Thanks for any advice.
Jim
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Unread 11-18-2020, 09:14 AM   #34
cx
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I would recommend you use a modified thinset mortar meeting ANSI A118.11, the only mortar type suitable for bonding to plywood, for that installation.

My opinion; worth price charged.
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Unread 11-18-2020, 10:03 AM   #35
jimmartz
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CX,

Thanks for the reply.
Adding the MAPEI Polymer Additive to the MAPEI Uncoupling Membrane mortar
makes it ANSI A118.11 compliant.
My concern was that using it between the Planipatch and Ditra, that the
polymer additive may not dry correctly, like it don't dry between dita and
porcelain tile. Since both products would be MAPEI maybe I will send them a
message and see what or if they relay.

Thanks,
Jim
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Unread 11-19-2020, 12:58 PM   #36
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I did not hear back from MAPEI but reading the Ditra book I see these
two rules.
1. When putting Ditra over plywood use modified thinset or Schluter ALL-SET.
2. When putting Ditra over concrete(SLC and Planipatch would probably also fall under that), use unmodified thinset or Schluter ALL-SET.

Now since I got some of both, according to the Ditra book there is only one thing that works for both that is Schluter ALL-SET.
So, looks like I will be using Schluter ALL-SET, and unless I can find it local, it will be costing me $60 a bag off Amazon. At lest I should only need 2 bags, I can use the locally available unmodified thinset to lay the tile.

Thanks,
Jim
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Unread 11-19-2020, 01:51 PM   #37
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See post #34.

1. That's not quite complete. Should say a modified thinset mortar meeting the requirements of ANSI A118.11. No other thinset mortar type is suitable for bonding to plywood. Schluter knows that. Now you know that.

I would personally use Custom's VersaBond for all parts of your application, primarily because it is locally available, reasonably priced, and I know from personal experience that it will work just fine with all Schluter products. You won't get a Schluter warranty, but you don't need one. Anything that goes wrong with your installation will be an installer error. See my warranty information below.

And you surely don't need a 60-dollar-a-bag thinset mortar for any part of that project.

All entirely up to you, though.

My opinion; worth price charged.
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Unread 12-30-2020, 10:52 PM   #38
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Self Leveler over Plywood

Just now getting back to this project.
So I got 1/2" plywood down over the plank subfloor.
Originally I thought my biggest dip would be from the
sagging of the 2x8 joist and the outside edge would be
flat as it is on the foundation. The most the joist are
sagging in the middle is 3/8"

Unfortunately now that I got a 10ft straight edge and
am checking all around the floor I found that perpendicular
to the joist I got a 1" dip in the middle of a 10ft span in the floor.
So the area with the 1" dip is about 9'x10'.

I was originally going to use PlaniPatch, but that list a maximum
of 1/2" thick and it is much more expensive. So now I am thinking
about using a self-leveler for this area that has a 1" dip.

I do have some questions though.
Here is the list of self-levelers I found in my area:
MAPEI Self Leveler Plus
Sakrete Fastset Self Leveling Resurfacer
Custom LevelQuik RS

All of these list using a mesh over plywood, I see
many people online not using mesh and pouring directly over
primed plywood. Is the mesh really needed?

I plan to take this to a feather edge. Is taking self-leveler
to a feather edge over plywood a problem?

Would it be ok to add more 1/2" plywood in the dip in
the floor to help fill it in and use less self-leveler?
What about using cement board to help fill in the hole?

Any different recommendation on how to fill in the dip?

Thanks,
Jim
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Unread 12-30-2020, 11:24 PM   #39
smifwal
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Ardex K 15 is good from a 1/8"-1 1/2" of you can source it
Combined with Ardex feather finish will get you where you need to be
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Unread 12-31-2020, 01:15 AM   #40
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The Ardex K 15 has about the same requirements.
Per the instruction, list mesh over plywood.
Also, it is not found in my area.
Jim
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Unread 12-31-2020, 08:13 AM   #41
smifwal
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Quote:
Originally Posted by jimmartz
Per the instruction, list mesh over plywood.
where are you seeing this?
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Unread 12-31-2020, 05:40 PM   #42
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This is off the Ardex 15 page in the downloads, specification:
https://www.ardexamericas.com/wp-con...cification.pdf

Under section 3.2 E. 3.
"Wood subfloors require the use of the mesh-reinforced ARDEX K15® + E25™ Resilient Emulsion Underlayment System. After priming, install 3.4 galvanized diamond metal lath by stapling to the wooden subfloor approximately every 6 inches to center."

I think this requirement may be from TCNA method F185.

This only leave me more unsure what I am going to do.
Looking for some guidance from someone with real life experience
on how to fill in a 1" deep dip.

Thanks,
Jim
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Unread 12-31-2020, 06:48 PM   #43
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Quote:
Originally Posted by Jim
I think this requirement may be from TCNA method F185.
Not the way it works, Jim. The Methods published in the TCNA Handbook are methods that have been submitted by product manufacturers and accepted by the Handbook committee.

In Method F-185, under Requirements, you'll find: "Use lath designed for this purpose, nailed or stapled in accordance with the underlaymet manufacturer's instructions."

The product manufacturer's instructions always trump any other industry requirements. You'll note that in the section you quoted it says to use "3.4 galvanized diamond metal lath" (should read 3.4lb. metal lath). I've rarely noted a requirement for lath of that weight specified for ceramic tile work and you'll note that F-185 makes no such specification.

And I'm sure that doesn't help at all with your decision.

My opinion; worth price charged.
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Unread 12-31-2020, 08:32 PM   #44
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What product are available in your area?

If it we me I would use Planipatch in the inch area in 2 lifts and the self level the rest unless it was a small section then I would use Ardex feather finish. Feather finish cost more than planipatch
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Unread 12-31-2020, 11:58 PM   #45
jimmartz
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The more I look into this and the more I think about it,
I think I should avoid self-leveler. I don't have any helpers
and I am more of a slow methodical person. All the self-levelers
I see available to me and fast stetting.

I am not sure if 2 layers 1/2" thick is acceptable for Planipatch.
And Planipatch is expensive to fill in a 1" deep valley.
So I am thinking of filling in the valley with 1/2" and/or 3/8" BC plywood.
Then use Planipatch over that to give a flat surface.
Per unit of volume plywood is much cheaper then Planipatch.
Anyone have experience in doing this, what is your thoughts on
this method?

Thanks,
Jim
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