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Modified vs unmodified thinset

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  • Modified vs unmodified thinset

    What is the difference? Are they for different applications?
    Tom
    Tom

    "Whoever ceases to be a student has never been a student." George Iles

  • #2
    Re: Modified vs unmodified thinset

    That's a big topic. I suppose to cover the basics you can say that modified is stickier and stronger, and it's what you want to use with porcelain tile.
    Bailer Hill Construction, Inc. - Friday Harbor, WA
    Website - Facebook

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    • #3
      Re: Modified vs unmodified thinset

      Ok, but my thought is then why do they manufacture unmodified? Are there applications where modified would be unsuitable, and you would need to use unmodified?
      Tom
      Tom

      "Whoever ceases to be a student has never been a student." George Iles

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      • #4
        Re: Modified vs unmodified thinset

        Unmodified is used in applications where there is the inability for the moisture to evaporate through the either the substrate or the tile above.

        For example....where tile is installed over Ditra. The thinset is sandwiched between the ditra (plastic) and tile and has little surface area for the moisture to escape and allow for curing, so an unmodified thinset is used because it will cure with minimal or no availability for the moisture to evaporate.

        This is what the representative from schluter explained to me at a show a few years back.

        Look at this diagram on page 12

        http://www.schluter.com/media/DitraH...9-2007-ENG.pdf
        Last edited by always-learning; 05-02-2008, 11:12 PM.
        Chuck

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        • #5
          Re: Modified vs unmodified thinset

          Sometimes it is just the expense. Why spend money on polymers which are not needed.
          When you are installing over concrete that is sound you do not need modified mortar as it will stick just fine and will not be subjected to flexing, but on plywood floors where movement is likely it is best to use a high grade thinset with lots of admix.

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          • #6
            Re: Modified vs unmodified thinset

            If you read discoloration in light grout you will learn from our mistake that unmodified thinset is suitable and unmodified not suitable for when using the Kerdi/Schluter system.

            Nicole

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            • #7
              Re: Modified vs unmodified thinset

              Originally posted by Nickymg View Post
              If you read discoloration in light grout you will learn from our mistake that unmodified thinset is suitable and unmodified not suitable for when using the Kerdi/Schluter system.

              Nicole
              I read this twice and can't understand it. Is there a typo or am I just tired?

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              • #8
                Re: Modified vs unmodified thinset

                I think I am tired - it does not make any sense at all! Sorry, do not worry about it. I am not tile expert.
                Nicole

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                • #9
                  Re: Modified vs unmodified thinset

                  Dry-set thinset mortar has no polymers and is basically sand, cement, and some retarder. It is the first thinset mortar developed (no, it was not engineered specifically for Schluter products). You can add a liquid latex or acrylic in place of water to make a modified thinset. Dry-set thinset mortar will not stick to wood after curing.

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                  • #10
                    Re: Modified vs unmodified thinset

                    Are you sure about those facts Mr. Byrne? I thought Herr Schluter invented unmodified after creating the Internet with Mr. Gore? :)

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                    • #11
                      Re: Modified vs unmodified thinset

                      Originally posted by mbyrne View Post
                      Dry-set thinset mortar will not stick to wood after curing.
                      Mike, could you explain this a bit more. I don't understand what you mean by "dry-set thinset mortar". But since I'm just a GC, not a tile setter, I think you will understand. Thank you.

                      Regards,

                      Tom

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                      • #12
                        Re: Modified vs unmodified thinset

                        Thinset morter, when "dry" will no longer adhere to plywood. That is why modified was created.

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                        • #13
                          Re: Modified vs unmodified thinset

                          Dryset mortar and unmodified is the same thing.

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                          • #14
                            Re: Modified vs unmodified thinset

                            Originally posted by scuttlebuttrp View Post
                            Dryset mortar and unmodified is the same thing.
                            Thank you! Now I understand.

                            Tom

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                            • #15
                              Re: Modified vs unmodified thinset

                              Originally posted by always-learning View Post
                              Unmodified is used in applications where there is the inability for the moisture to evaporate through the either the substrate or the tile above.

                              For example....where tile is installed over Ditra. The thinset is sandwiched between the ditra (plastic) and tile and has little surface area for the moisture to escape and allow for curing, so an unmodified thinset is used because it will cure with minimal or no availability for the moisture to evaporate.

                              This is what the representative from schluter explained to me at a show a few years back.
                              That's a good-sounding theory but it doesn't hold any water (pun intended).

                              Custom guarantees modified over Redgard. Actually they require it. From Redgard data sheet:
                              TILE INSTALLATION
                              Install tile or stone with a CustomĀ® polymer-modified mortar meeting ANSI A118.4 or A118.11 standards.

                              Schluter must know something we don't. Or they may be relying on technical advice from Mr. Gore :)

                              dg

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