Our SLC & Radiant Heat Flooring Project

Discussion in 'Ceramic and Stone Q&A' started by Camille, Jul 27, 2007.

  1. Camille

    Camille New Member

    Re: SLC & Radiant Heat Flooring by Todd Groettum

    Ok, so my husband and I are DIY wannabes...that is we have a list a mile long of things we plan to do ourselves on our house, but have yet to really attack any of the big ones. At the top of the list is our kitchen floor.

    Todd - let me just say that after weeks of research this article is the first I've seen to touch on all the aspects of what we need all in one place, so thank you for that!

    We currently have a kitchen/small dining space that is currently ceramic tile/rug respectively. We found an amazing deal on some gorgeous marble tiles about 8 months ago and bought them for the whole space. We plan to rip up the existing tile and rug in this area (and disgusting linoleum we found underneath it while moving an island) all the way down to the plywood subfloor. The current tile is clearly not flat or level, which I know would be a big problem for marble. In all my reading, this is our basic plan:

    1. make sure the joists aren't too far apart for structural soundness
    2. lay down cement board (would there ever be any reason for a new layer of ply first?)
    3. install radiant heat mats (we're looking at suntouch from HD)
    4. Use SLC over the mats to be sure the marble tile gets laid completely flat and level
    5. Install tile with white thinset and 1/8" joints
    6. seal tile to avoid scratching and grout with unsanded grout

    So as you can imagine, your article is EXACTLY what I need to be sure we don't screw this one up. I only have a few questions after reading this article.

    1. Do we actually need the cement board if we're going to use SLC over the mats?
    2. If so, would we need to fill and sand the seams/screws before priming?
    3. Forgive my ignorance, but this is the first I've read about Dam Blocks. Does this mean I will have a 1" gap between the SLC and doorways, and where it will meet the rug in the livingroom? And are these used in place of the foam strip for expansion or in addition to? I guess this step went right over my head.

  2. stullis

    stullis Charter Member Senior Member

    Re: SLC & Radiant Heat Flooring by Todd Groettum

    Skip the cement board if using SLC.

    You do need to add more plywood when using marble and while SLC manufacturers claim you can go over a single layer of plywood a second layer is preferable.

    Personally not impressed with Suntouch.

    Not sure what tiles and grout you are using but you might not have to seal them.

    The dam blocks just keep the SLC from flowing into areas you don't want it.

    Transition heights to other flooring may be a problem as well as clearance heights for appliances might be an issue when adding plywood and using SLC.

    Good luck but you are probably biting off more than you can handle with this flooring project.
  3. Camille

    Camille New Member

    Re: SLC & Radiant Heat Flooring by Todd Groettum

    Thanks for the reply! I'm beginning to worry that we are in over our heads, but I'm not giving up yet!

    Do you have any recommendations otherwise?

    So, if we put dam blocks next to the existing carpet that will stay in place, do we need to fill that space in with something after we remove them? or just lay the tile with no worries?
  4. Tileguytodd

    Tileguytodd Charter Member Published

    Re: SLC & Radiant Heat Flooring by Todd Groettum

    Thank you for your kind words.......It appears scotts covered your questions and I have to agree with him on his final comment also.

    I would love to be able to encourage you to Go Forth and conquor, but I'm a bit hesitent to do so and while I do not want to discourage you from doing a tile job, here is why I am Concerned.

    Doing a Marble or granite job as a first time DIY project is near Insanity (its ok, ive been accused of worse and I do like to share ;) ).

    Stone installations DONE RIGHT - (this means Dont listen to 1 word a retail salesperson tells you, trust me, theyve NEVER done stone but they LOVE to sell it!!) are difficult.........No, they are worse than that they are extremely and intensly difficult to do well, EVEN for a Professional who sets tile day in and day out!!!

    I would hate to see you exchange a Poorly done ceramic floor for a poorly done Stone floor.......I'm not kidding here, Its THAT HARD and I do not want for you to get frustrated with your first experience.

    If you were doing a tile floor with ceramic or porcelain i'd be in your corner cheering you on............But STONE...........I can not in good conscience tell you this is going to go well............Because ITS NOT!!!
    You can get it in sure.......but CAN you get it in without needing it to be ground and repolished is the question........And the odds are about 50 - 1 against you........perhaps higher. Grinding and repolishing the floor will cost almost as much as the entire installation IF ( a big IF ) You can find someone to do it!!

    Please reconsider your choice of material for this area OR if you really must have Marble, Have a professional install it for you.

    I am sincerely only trying to look out for you here and save you from a decision that you may truly regret.

    One final item that you need to know is 2 layers of PLYWOOD Flooring is MANDATORY for ANY stone installation that is Not set on Dry pack 1 1/4" of hand screeded cement/sand.. You must attain a Load = to or higher than L/720 (twice as stiff as needed for a ceramic tile floor) Then you must consider your traffic.......do you have large gatherings in this room where you may have a very high concentrated load......example 5 aunt Martha's and 6 Uncle eddies each weighing 250 Lbs each around a dining table is equivelent to 1 Barnum & Bailey elephant.....In this case an Even Higher Load range would be reccomended to insure damage does not occur......Yes, this is EXTREME but some folks have LARGE families (in more ways than 1) and this is a very serious consideration to insure a lifetime of service from your floor!!

    If I can be of any further assistance please feel free to email me and I will get back to you as soon as is convenient.
    Best Wishes
  5. Jerry Thomas

    Jerry Thomas Charter Member Senior Member

    Re: SLC & Radiant Heat Flooring by Todd Groettum

    Camille... just some advice about the grout. I use a sanded grout on all 1/8 grout joints, because where all 4 tiles intersect there is a sizable space there and sanded grout won't crack, I have seen non-sanded grout crack or pinhole where the tiles intersect.
  6. stullis

    stullis Charter Member Senior Member

    Re: SLC & Radiant Heat Flooring by Todd Groettum

    Generally 1/8" joint on the floor I would agree with you Jerry, only problem in this case is they want to use marble tiles which could possibly result in scratches depending on the marble.

    Perhaps TFP admin wants to move the appropriate parts of this thread to the DIY section.

    Joist structure also needs to more than likely be beefed up as well as the extra layer of plywood.

    What size is the area Camille? Nuheat or one of the cable type systems for the infloor heat would be better.
  7. Jerry Thomas

    Jerry Thomas Charter Member Senior Member

    Sorry Camille, I missed the marble part. :zzz: Carry on :)
  8. Tileguytodd

    Tileguytodd Charter Member Published

    Once again I am going to agree with Scott that sanded grouts and Polished stones do not mix!! I would also ADD this:

    Marble/Granite has a Chamfered edge and Some reveal should be left but depending on the amount of chamfer, leaving all unfilled may not be preferred.

    A 1/16" space is what I generally use when setting GOOD QUALITY stone. If the stone has a lg chamfer I may fill a portion which will then appear as an 1/8" joint.
    If the chamfer is minimal (basically an Eased edge) I will keep the joint at the 1/16" mark leaving the eased edge unfilled.

    Much depends on the stone itself and only the Installer can make the decision as to wether a 1/16" joint is even possible. This takes an excellent quality stone, the type you will NOT find at a large home improvement store.
  9. Tileguytodd

    Tileguytodd Charter Member Published

    So, its been a bit over 6 weeks and we have Not heard back from Camille...........Camille.............Are you Out there??
    Whats The Buzz!!!!!!!!!!!!!!! ;)
  10. William Mear

    William Mear Charter Member

    she heard something she didnt want to.

    hope she took the right path.:brick::(

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