Floor Deflection

Discussion in 'Ceramic & Stone Sales and Installations' started by Bud Cline, Aug 29, 2007.

  1. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published


    Here’s something I thought I would point out to anyone interested and that maybe hasn’t seen it or been made aware of it thus far.

    If you have the latest TCNA Handbook For Ceramic Tile Installation 2007 you may have noticed that what has until this year been ongoing information about floor deflection is now printed in the handbook with a strikethrough. In years past the handbook has repeatedly made the statement: “deflection not to exceed 1/360 of the span – when measured under a concentrated 300 pound load”.

    Of course we tile guys have all embraced this information for some time now and some of us have used this information repeatedly in DIY Forums. We have beaten it over the heads of unsuspecting DIY’ers and even some adolescent installers. Though the rule still exists (and should in fact still be considered mandatory criteria) it seems the TCNA has finally decided to delete the information in their future publications.

    How would one test for this deflection minimum to begin with? I would have a tuff time carrying a 300-pound weight around with me. Oh sure, I could carry around three one hundred pound weights or six fifty pound weights but seriously folks. I have never ever tested a floor for deflection using this method. I don’t know anyone that has.

    Ms. Stephanie Samulski an instructor with the Ceramic Tile Education Foundation has written an article (DEFLECTION REFLECTION) that appears in the August/September 2007 edition of TILE MAGAZINE. Ms. Samulski does a good job of explaining the coming change so I’ll let her tell you about it in her article.

    Deflection Reflection: 2007 Handbook Language Simplifies Substrate Load Considerations - Columns - TILE Magazine:pdf:

    There are of course other means of determining the supposed deflection rating of a floor and this information I’m sure is all in books somewhere. Given the size and spacing of structural members used in a floor structure one can determine sufficiently enough the load factors and the deflection rating of the overall floor structure. It's not that difficult.

    A less scientific means of determination is the “John Bridge Jump Test”. Though not sanctioned by anyone but John I would support the method to a certain extent. At least with Johns method (and if one were to make an honest appraisal of the circumstances) after performing John’s Jump Test one would know readily if the structure was unsuitable for a tile installation.

    Check out the article in TILE MAGAZINE and make a mental note that nothing has changed when it comes to deflection criteria.
  2. Jerry Thomas

    Jerry Thomas Charter Member Senior Member

    I just got my book last week.... I ordered it months ago :) I will have to sit down and read through it.

    Thanks for pointing this out :)
  3. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

  4. Tileguytodd

    Tileguytodd Charter Member Published

    One of the largest Benefits to this is that Liability on new construction was Just SHIFTED from the Tile Contractor to the Design Firm/General Contractor.

    Changes Made by an Owner and brought to the General Contractor would have to be approved through the Design Firm (or architect) If it was not, Full liability would land squarely on the General Contractors shoulders NOT the tile contractors.
    It is No Longer Our Job on New construction Projects to Insure that Deflection has been Met or exceeded from a LEGAL standpoint (each of you can work out your own Moral Obligations).
    Our job is to Install tile as per the detail provided Period, THE END!!

    This of course does not apply to any REMODEL Project where a Homeowner is relying on your expertise which is why it is still Important to know when to and when not to Take a Project.
    Contrary to popular belief, when a Homeowner hires you direct, In most states he is NOT considered the General Contractor, YOU ARE!!!
    ( although in some states the GC license requirements may not apply, your liability will still be considered as if you were a General Contractor........this is a generalization...checking with your own attorney in your own area as to How These Changes effect you specifically is reccomended and ADVISED.........Alter any of your contracts accordingly)
  5. kwfloors

    kwfloors Fuzz on the brain Charter Member I Support TFP Senior Member

    Yes and then the GC comes down on you as you covered up a bad floor. If it was inspected who would get the blame?
  6. Tileguytodd

    Tileguytodd Charter Member Published

    Why would you do that? You certainly wouldnt cover a bad floor on Purpose, That would be Ludicrous for ANY mechanic, Akin to intentionally using an Improper product!!

    This is about the Unforseen.........These are the ones that End up in Court.......NOW when the court case comes up its not:
    Mr Tileguy, Did you do a Deflection test to determine the suitability of the structure for this type of installation..............

    Mr GC did you have design change approval from the architect to insure that When you scheduled the Tile Contractor to do this work it Met or exceeded requirements?


    Get out your checkbook :D :D :D

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.