{
 "page": "bathroom-floors-and-subfloors-central-ohio-by-era.html",
 "url": "https://www.openshowerco.com/bathroom-floors-and-subfloors-central-ohio-by-era.html",
 "title": "What is under a Central Ohio bathroom floor, by era, and what a tile floor asks of it",
 "record": "kb-wave-eight-2026-09",
 "generated": "2026-09-08",
 "how_to_read": "Every sentence on the page traces to one of these claims. status \"verified\" means two independent publishers state it; \"single\" means one named publisher, named in the page's sentence; \"conflict\" means the documents disagree and the page prints both.",
 "claims": [
  {
   "id": "C1",
   "claim": "The federal rehabilitation guide says that until the late 1930s and early 1940s the typical residential floor sheathing was boards of 1x6 and larger, straight-edged or tongue-and-grooved.",
   "status": "single",
   "quote": "the typical residential floor sheathing was 1x6 and larger, straight-edged or tongue-and-grooved wood boards",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C3",
   "claim": "The same guide dates the arrival of plywood floors to the early 1940s, when waterproof adhesives were introduced, and not to the 1950s.",
   "status": "single",
   "quote": "with the introduction of waterproof adhesives, plywood floors began to replace board sheathing",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C4",
   "claim": "Oriented strand board did not appear from nowhere: it grew out of waferboard, which came into use in the 1960s and did not hold up well where it got wet.",
   "status": "verified",
   "quote": "OSB technology and the raw material used originally evolved from waferboard technology",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    },
    {
     "publisher": "USDA Forest Service, Forest Products Laboratory",
     "title": "Wood-Based Composite Materials, chapter 11 of the Wood Handbook (General Technical Report FPL-GTR-282)",
     "url": "https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr282/chapter_11_fpl_gtr282.pdf",
     "published": "2021"
    }
   ]
  },
  {
   "id": "C5",
   "claim": "Both the Forest Products Laboratory and HUD record that oriented strand board went on to replace plywood in much of American construction.",
   "status": "verified",
   "quote": "OSB replaced softwood plywood in many construction applications",
   "sources": [
    {
     "publisher": "USDA Forest Service, Forest Products Laboratory",
     "title": "Wood-Based Composite Materials, chapter 11 of the Wood Handbook (General Technical Report FPL-GTR-282)",
     "url": "https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr282/chapter_11_fpl_gtr282.pdf",
     "published": "2021"
    },
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C6",
   "claim": "The Residential Code of Ohio still allows a floor with no subfloor at all, where the joists are no more than 16 inches apart and one-inch tongue-and-groove strip flooring runs across them.",
   "status": "single",
   "quote": "Subflooring shall be permitted to be omitted where joist spacing does not exceed",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-5-01, Floors (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-5-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    },
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-5-01 rule page (effective dates)",
     "url": "https://codes.ohio.gov/ohio-administrative-code/rule-4101:8-5-01",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C7",
   "claim": "HUD's guide says many houses built before 1920 have floor joists sized well below what the code now asks, and that 3x6 and 3x8 joists turn up in houses from before 1900.",
   "status": "single",
   "quote": "Many older houses built before 1920 have floor joists sized considerably below current requirements.",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C8",
   "claim": "HUD adds that because of the safety factor designed into newer floor systems, floors rarely fail structurally, but they can still bounce enough to feel unsafe.",
   "status": "single",
   "quote": "floors will rarely fail structurally, but they may have excessive bounce and feel unsafe",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C9",
   "claim": "The federal plywood standard, PS 1-66, took effect on November 1, 1966, and it was the first Voluntary Product Standard written under the Commerce Department's then-new procedures.",
   "status": "verified",
   "quote": "It was the first Voluntary Product Standard developed under new Department procedures",
   "sources": [
    {
     "publisher": "National Institute of Standards and Technology, U.S. Department of Commerce",
     "title": "Voluntary Product Standard PS 1-22, Structural Plywood (final draft)",
     "url": "https://www.nist.gov/system/files/documents/2023/08/24/PS%201%2022%20FINAL%20DRAFT%20-%20CLEAN%20-%208-7-2023%20-%20FINAL.pdf",
     "published": "2023"
    },
    {
     "publisher": "APA - The Engineered Wood Association",
     "title": "Plywood (engineered wood products)",
     "url": "https://www.apawood.org/engineered-wood-products/plywood-osb/plywood/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C11",
   "claim": "The standard that covers oriented strand board, PS 2, was first approved on August 27, 1992, and APA calls it the first consensus-based performance standard for these panels.",
   "status": "verified",
   "quote": "Initially Approved as PS 2-92 August 27, 1992",
   "sources": [
    {
     "publisher": "National Institute of Standards and Technology, U.S. Department of Commerce",
     "title": "Voluntary Product Standard PS 2, Performance Standard for Wood-Based Structural-Use Panels (2018 revision draft)",
     "url": "https://www.nist.gov/system/files/documents/2018/09/18/ps_2_revisions_final_aug_2018.pdf",
     "published": "2018-08"
    },
    {
     "publisher": "APA - The Engineered Wood Association",
     "title": "OSB (Oriented Strand Board)",
     "url": "https://www.apawood.org/osb",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C12",
   "claim": "A span rating is the widest spacing of supports a panel is rated for; sheathing carries two numbers, roof over subfloor, while a single-floor panel carries one.",
   "status": "verified",
   "quote": "Span ratings denote the maximum recommended center-to-center spacing of supports in inches.",
   "sources": [
    {
     "publisher": "USDA Forest Service, Forest Products Laboratory",
     "title": "Wood-Based Composite Materials, chapter 11 of the Wood Handbook (General Technical Report FPL-GTR-282)",
     "url": "https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr282/chapter_11_fpl_gtr282.pdf",
     "published": "2021"
    },
    {
     "publisher": "APA - The Engineered Wood Association",
     "title": "OSB (Oriented Strand Board)",
     "url": "https://www.apawood.org/osb",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C13",
   "claim": "The thickness printed on a modern panel is a Performance Category, a designation tied to the nominal thickness the building codes use rather than a measured dimension.",
   "status": "verified",
   "quote": "A panel designation related to the panel thickness range",
   "sources": [
    {
     "publisher": "National Institute of Standards and Technology, U.S. Department of Commerce",
     "title": "Voluntary Product Standard PS 2, Performance Standard for Wood-Based Structural-Use Panels (2018 revision draft)",
     "url": "https://www.nist.gov/system/files/documents/2018/09/18/ps_2_revisions_final_aug_2018.pdf",
     "published": "2018-08"
    },
    {
     "publisher": "APA - The Engineered Wood Association",
     "title": "Plywood (engineered wood products)",
     "url": "https://www.apawood.org/engineered-wood-products/plywood-osb/plywood/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C14",
   "claim": "Ohio's code requires wood structural panel sheathing to meet one of the named standards, and says the Performance Category value is what the code means whenever it says panel thickness.",
   "status": "single",
   "quote": "shall conform to CSA O325, CSA O437, DOC PS 1 or DOC PS 2",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-5-01, Floors (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-5-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C15",
   "claim": "The Residential Code of Ohio sets the allowable deflection of a floor at the span divided by 360, in its Table 301.7.",
   "status": "single",
   "quote": "shall not exceed the values in Table 301.7",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-3-01, Building planning (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-3-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C16",
   "claim": "That limit is measured under the live load alone, not under everything the floor carries, which is a narrower test than it first sounds.",
   "status": "single",
   "quote": "The allowable deflection of any structural member under the live load listed",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-3-01, Building planning (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-3-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C17",
   "claim": "A bathroom is a room other than a sleeping room, so Ohio's minimum live load for it is 40 pounds per square foot, against 30 for a bedroom.",
   "status": "single",
   "quote": "The minimum uniformly distributed live load shall be as provided in Table 301.5.",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-3-01, Building planning (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-3-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C18",
   "claim": "For board subfloors Ohio still prints a table: 5/8 inch minimum net thickness at 16-inch joist spacing, and 11/16 inch laid across the joists or 3/4 inch laid diagonally at 24-inch spacing.",
   "status": "single",
   "quote": "MINIMUM THICKNESS OF LUMBER FLOOR SHEATHING",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-5-01, Floors (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-5-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C19",
   "claim": "Ohio's panel table works from the span rating, not from the joist spacing: a panel rated 24/16 is 7/16 inch and spans 16 inches as a subfloor, and one rated 48/24 is 23/32 or 3/4 inch and spans 24.",
   "status": "single",
   "quote": "ALLOWABLE SPANS AND LOADS FOR WOOD STRUCTURAL PANELS",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-5-01, Floors (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-5-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C21",
   "claim": "Ohio limits what may be cut out of a joist: a notch may not exceed one sixth of the depth, may not be longer than a third of the depth, and may not fall in the middle third of the span.",
   "status": "single",
   "quote": "Notches in solid lumber joists, rafters and beams shall not exceed one-sixth",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-5-01, Floors (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-5-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C22",
   "claim": "In a house framed with trusses or wood I-joists, Ohio prohibits cuts, notches and bored holes outright unless the manufacturer allows them or a registered design professional has accounted for them.",
   "status": "single",
   "quote": "Cuts, notches and holes bored in trusses, structural composite lumber",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-5-01, Floors (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-5-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C24",
   "claim": "The National Park Service records the nineteenth-century method for a tile floor: a bed of concrete or of Portland cement and sharp sand laid first, as a solid foundation for the tile.",
   "status": "single",
   "quote": "bed of concrete of quicklime and gravel, or a mixture of Portland cement",
   "sources": [
    {
     "publisher": "National Park Service, U.S. Department of the Interior",
     "title": "Preservation Brief 40: Preserving Historic Ceramic Tile Floors, by Anne E. Grimmer and Kimberly A. Konrad",
     "url": "https://www.nps.gov/orgs/1739/upload/preservation-brief-40-ceramic-tile-floors.pdf",
     "published": "1996"
    }
   ]
  },
  {
   "id": "C25",
   "claim": "Where the tile went over an existing wood floor, the floorboards were pulled up, sawn into short lengths and dropped between the joists, and the Park Service says that trick has produced numerous cracked tiles and other failures.",
   "status": "single",
   "quote": "has resulted in numerous cracked tiles and other failures",
   "sources": [
    {
     "publisher": "National Park Service, U.S. Department of the Interior",
     "title": "Preservation Brief 40: Preserving Historic Ceramic Tile Floors, by Anne E. Grimmer and Kimberly A. Konrad",
     "url": "https://www.nps.gov/orgs/1739/upload/preservation-brief-40-ceramic-tile-floors.pdf",
     "published": "1996"
    }
   ]
  },
  {
   "id": "C27",
   "claim": "The Park Service records how far setting beds have thinned: from several inches to as little as three thirty-seconds of an inch.",
   "status": "verified",
   "quote": "Mortar beds are lighter, more flexible, and much thinner than they were previously",
   "sources": [
    {
     "publisher": "National Park Service, U.S. Department of the Interior",
     "title": "Preservation Brief 40: Preserving Historic Ceramic Tile Floors, by Anne E. Grimmer and Kimberly A. Konrad",
     "url": "https://www.nps.gov/orgs/1739/upload/preservation-brief-40-ceramic-tile-floors.pdf",
     "published": "1996"
    },
    {
     "publisher": "LATICRETE International",
     "title": "Requirements for the Thin Bed Method, TDS 105",
     "url": "https://cdn-global.laticrete.com/-/media/project/laticrete-international/shared/files/support-and-downloads/technical-datasheets/tds105.ashx",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C28",
   "claim": "The small white unglazed tiles in round, square, octagonal and hexagonal shapes that turn up in old bathrooms were sold on their sanitary qualities, and were aimed at bathroom floors specifically.",
   "status": "single",
   "quote": "were promoted for their sanitary qualities, particularly for bathroom floors",
   "sources": [
    {
     "publisher": "National Park Service, U.S. Department of the Interior",
     "title": "Preservation Brief 40: Preserving Historic Ceramic Tile Floors, by Anne E. Grimmer and Kimberly A. Konrad",
     "url": "https://www.nps.gov/orgs/1739/upload/preservation-brief-40-ceramic-tile-floors.pdf",
     "published": "1996"
    }
   ]
  },
  {
   "id": "C29",
   "claim": "A thick-bed installation is the traditional one: mortar packed over the surface before the tile goes down, either floating free of the substrate or bonded to it.",
   "status": "single",
   "quote": "packing a mortar bed over a surface before installing the tile",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Mortar bed",
     "url": "https://tcnatile.com/resource-center/faq/mortar-bed/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C30",
   "claim": "The sheet under a floating mortar bed, the cleavage membrane, exists to stop the bed bonding to what is beneath it, so the bed can slip if the substrate moves.",
   "status": "single",
   "quote": "This sheet prevents the mortar bed from bonding to the substrate",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Cleavage membrane",
     "url": "https://tcnatile.com/resource-center/faq/cleavage-membrane/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C31",
   "claim": "The Tile Council of North America calls the span divided by 360 the traditional accepted minimum for floor rigidity, and says it applies before the tile underlayment goes in.",
   "status": "single",
   "quote": "the accepted minimum requirement for floor rigidity is L/360",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Deflection",
     "url": "https://tcnatile.com/resource-center/faq/deflection/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C32",
   "claim": "HUD's guide says that limit came from plaster, not from tile: it is the deflection at which a plaster ceiling in the room below would crack.",
   "status": "single",
   "quote": "the deflection at which a plaster ceiling of the space below the floor",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C33",
   "claim": "The Tile Council warns that a floor built to the limit at 24-inch joist spacing often deflects more than the limit between the joists, where the tile is.",
   "status": "single",
   "quote": "these floors often have deflection between the joists exceeding L/360",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Deflection",
     "url": "https://tcnatile.com/resource-center/faq/deflection/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C34",
   "claim": "The same body says a stiffer floor is not automatically a safer one for tile: it reports failures at spans divided by 600.",
   "status": "single",
   "quote": "In fact, failures at L/600 have been observed.",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Deflection",
     "url": "https://tcnatile.com/resource-center/faq/deflection/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C35",
   "claim": "In 2007 the Tile Council struck the deflection language out of its individual floor methods and replaced it with a reference to the building codes and to the expected loads.",
   "status": "single",
   "quote": "Deflection language has been struck through in the 2007 TCA Handbook.",
   "sources": [
    {
     "publisher": "Tile Council of North America (article by Stephanie Samulski, published in TILE magazine and hosted by TCNA)",
     "title": "Deflection Reflection: 2007 Handbook Language Simplifies Substrate Load Considerations",
     "url": "https://tcnatile.com/wp-content/uploads/2022/08/Deflection-Reflection-2007-Handbook-Language-Simplifies-Substrate-Load-Considerations.pdf",
     "published": "2007-08"
    }
   ]
  },
  {
   "id": "C36",
   "claim": "The Tile Council's own explanation is that the tile trade's figure was measured under a 300-pound concentrated load, which is a different test from the uniform-load limit the building codes set.",
   "status": "single",
   "quote": "This deflection limitation differs from the L/360 deflection limit under uniform load",
   "sources": [
    {
     "publisher": "Tile Council of North America (article by Stephanie Samulski, published in TILE magazine and hosted by TCNA)",
     "title": "Deflection Reflection: 2007 Handbook Language Simplifies Substrate Load Considerations",
     "url": "https://tcnatile.com/wp-content/uploads/2022/08/Deflection-Reflection-2007-Handbook-Language-Simplifies-Substrate-Load-Considerations.pdf",
     "published": "2007-08"
    }
   ]
  },
  {
   "id": "C37",
   "claim": "Natural stone is held to twice the stiffness of ceramic tile: the span divided by 720 rather than by 360.",
   "status": "verified",
   "quote": "The maximum allowable floor member live load and concentrated load deflection is L/720.",
   "sources": [
    {
     "publisher": "Ceramic Tile Education Foundation",
     "title": "How to Install Floor Tile When It's Natural Stone Rather Than Ceramic",
     "url": "https://www.ceramictilefoundation.org/blog/caution-natural-stone-tile-installed-over-wood-framing",
     "published": "2017-04-11, updated 2026-09-01"
    },
    {
     "publisher": "TileLetter (National Tile Contractors Association), article by Mark Heinlein",
     "title": "Using L/620 and L/720 on stone floors",
     "url": "https://www.tileletter.com/using-l-620-and-l-720-on-stone-floors/",
     "published": "2023-04-03"
    }
   ]
  },
  {
   "id": "C38",
   "claim": "The Natural Stone Institute does not accept a single layer of wood panel under backer board for a stone floor, so a second layer of structural wood panel is required.",
   "status": "single",
   "quote": "two layers of structural wood panel are required on floors to receive stone tile",
   "sources": [
    {
     "publisher": "Ceramic Tile Education Foundation",
     "title": "How to Install Floor Tile When It's Natural Stone Rather Than Ceramic",
     "url": "https://www.ceramictilefoundation.org/blog/caution-natural-stone-tile-installed-over-wood-framing",
     "published": "2017-04-11, updated 2026-09-01"
    }
   ]
  },
  {
   "id": "C39",
   "claim": "The Tile Council states that the current tile installation standards specifically exclude oriented strand board, and that thin-set makers do not recommend bonding ceramic tile straight to it.",
   "status": "verified",
   "quote": "The most current ANSI standards for tile installation (A108 - 1999) specifically exclude OSB.",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: OSB",
     "url": "https://tcnatile.com/resource-center/faq/osb/",
     "published": "undated"
    },
    {
     "publisher": "National Park Service, U.S. Department of the Interior",
     "title": "Preservation Brief 40: Preserving Historic Ceramic Tile Floors, by Anne E. Grimmer and Kimberly A. Konrad",
     "url": "https://www.nps.gov/orgs/1739/upload/preservation-brief-40-ceramic-tile-floors.pdf",
     "published": "1996"
    }
   ]
  },
  {
   "id": "C40",
   "claim": "Where tile is bonded to concrete, a crack in the concrete can travel up into the tile; the Tile Council calls this reflective cracking.",
   "status": "single",
   "quote": "cracks occurring in the concrete can cause cracks in the tile layer",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Cracked tile",
     "url": "https://tcnatile.com/resource-center/faq/cracked-tile/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C41",
   "claim": "The Tile Council of North America lists what breaks the bond between tile and floor: excessive deflection, moisture-induced deterioration of the subfloor, delamination of the subfloor, and thin-set spread in dabs.",
   "status": "single",
   "quote": "Moisture induced deterioration of the subfloor.",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Hollow, loose tile",
     "url": "https://tcnatile.com/resource-center/faq/hollow-loose-tile/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C42",
   "claim": "A crack isolation membrane does not remove the need for movement joints; the Tile Council calls that a frequent misconception and says there must always be soft joints in the tilework.",
   "status": "single",
   "quote": "It is a frequent misconception that anti-fracture membranes allow you to eliminate expansion joints",
   "sources": [
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Crack isolation, suppression, anti-fracture membrane",
     "url": "https://tcnatile.com/resource-center/faq/crack-isolation-suppression-anti-fracture-membrane/",
     "published": "undated"
    },
    {
     "publisher": "Tile Council of North America",
     "title": "FAQ: Tenting",
     "url": "https://tcnatile.com/resource-center/faq/tenting/",
     "published": "undated"
    }
   ]
  },
  {
   "id": "C43",
   "claim": "The Handbook's movement joint guideline, as quoted by a tile trade publication, is a maximum of 25 feet in each direction indoors, and 12 feet where the tile takes direct sunlight or moisture.",
   "status": "single",
   "quote": "Interior - maximum of 25' in each direction",
   "sources": [
    {
     "publisher": "TileLetter (National Tile Contractors Association), article by Scott Carothers",
     "title": "The critical importance of movement joints in tile work",
     "url": "https://www.tileletter.com/the-critical-importance-of-movement-joints-in-tile-work/",
     "published": "2023-05-01"
    }
   ]
  },
  {
   "id": "C44",
   "claim": "The Forest Products Laboratory states that serious decay happens only when the wood's moisture content is above the fiber saturation point, which it averages at thirty percent.",
   "status": "single",
   "quote": "Serious decay occurs only when the moisture content of the wood is above",
   "sources": [
    {
     "publisher": "USDA Forest Service, Forest Products Laboratory",
     "title": "Biodeterioration of Wood, chapter 14 of the Wood Handbook (General Technical Report FPL-GTR-282)",
     "url": "https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr282/chapter_14_fpl_gtr282.pdf",
     "published": "2021"
    }
   ]
  },
  {
   "id": "C45",
   "claim": "The same chapter says fully air-dried wood usually sits at or under twenty percent moisture content, that it will not decay while it is kept air dry, and that existing decay will not progress.",
   "status": "single",
   "quote": "wood will not decay if it is kept air dry",
   "sources": [
    {
     "publisher": "USDA Forest Service, Forest Products Laboratory",
     "title": "Biodeterioration of Wood, chapter 14 of the Wood Handbook (General Technical Report FPL-GTR-282)",
     "url": "https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr282/chapter_14_fpl_gtr282.pdf",
     "published": "2021"
    }
   ]
  },
  {
   "id": "C46",
   "claim": "HUD's guide says deterioration of floor sheathing is often moisture-related and can be rot from roof or plumbing leaks, and that no repair should start until the cause is understood and corrected.",
   "status": "single",
   "quote": "Corrective work should not be initiated until the cause of the deterioration is understood",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
     "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C47",
   "claim": "HUD's kitchens and baths volume states plainly that tile work cannot be made permanently waterproof, and that whatever water gets past it has to be able to dry before it saturates.",
   "status": "single",
   "quote": "Recognizes that tile work cannot be made permanently waterproof",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 6: Kitchens and Baths",
     "url": "https://www.huduser.gov/portal/Publications/PDF/kitchen.pdf",
     "published": "1999-11"
    }
   ]
  },
  {
   "id": "C49",
   "claim": "Ohio's residential energy rule reaches heated floors only where the floor is a slab: it requires R-5 insulation under the whole slab area, on top of the slab-edge insulation.",
   "status": "single",
   "quote": "R-5 insulation shall be provided under the full slab area of a heated slab",
   "sources": [
    {
     "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
     "title": "Rule 4101:8-11-01, Energy efficiency (Residential Code of Ohio)",
     "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-11-01_eff_7_1_19.pdf",
     "published": "2019-07-01"
    }
   ]
  },
  {
   "id": "C50",
   "claim": "An uncoupling membrane works by putting an air space between the tile and what is under it, so the two can move independently, and the Handbook methods that use one can carry electric heating wire.",
   "status": "verified",
   "quote": "provide air space between the tile and the substrate to allow independent movement",
   "sources": [
    {
     "publisher": "TileLetter (National Tile Contractors Association), article by Dale Kempster",
     "title": "Uncoupling membranes methods and standards: a timeline",
     "url": "https://www.tileletter.com/uncoupling-membranes-methods-and-standards-a-timeline/",
     "published": "2019-07-01"
    },
    {
     "publisher": "Ceramic Tile Education Foundation",
     "title": "How to Install Tile with Electrical Radiant Heating",
     "url": "https://www.ceramictilefoundation.org/blog/how-to-install-tile-electrical-radiant-heating",
     "published": "2018-12-04, updated 2023-07-04"
    }
   ]
  },
  {
   "id": "C52",
   "claim": "For a shower with no threshold, HUD's guide says the floor is set in mud rather than thin-set and grout, and that the framing has to be planned for the thickness of that mud.",
   "status": "single",
   "quote": "the floor should be planned to accommodate the thickness of the mud underlayment",
   "sources": [
    {
     "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
     "title": "The Rehab Guide, Volume 6: Kitchens and Baths",
     "url": "https://www.huduser.gov/portal/Publications/PDF/kitchen.pdf",
     "published": "1999-11"
    }
   ]
  }
 ],
 "conflicts": [
  {
   "claim_id": "C31",
   "a": "L/360 is the accepted minimum requirement for floor rigidity under tile",
   "a_source": "S14 (Tile Council FAQ, undated)",
   "b": "The 2007 Handbook struck the L/360 language out of its floor methods and pointed instead at the building codes and the expected loads",
   "b_source": "S23 (Tile Council, 2007)",
   "printed": "print both, in that order. The FAQ says Traditionally and the 2007 article explains what replaced it. Presenting only the first would print a rule the body itself withdrew; presenting only the second would leave the reader with no number at all."
  },
  {
   "claim_id": "C39",
   "a": "The tile installation standards specifically exclude OSB, and thin-set makers do not recommend bonding tile straight to it",
   "a_source": "S15 (Tile Council FAQ)",
   "b": "Tile can be installed reliably over an OSB subfloor in Handbook systems that include OSB",
   "b_source": "S15 (same page, next paragraph)",
   "printed": "print both. The page holds both statements and the distinction is direct bonding versus a system with a separating layer. Printing only the exclusion would read as a ban on tile in every house built since the 1980s."
  },
  {
   "claim_id": "C52",
   "a": "A no-threshold shower floor is sloped a quarter inch per foot maximum toward the drain",
   "a_source": "S7 (HUD Rehab Guide Volume 6, 1999)",
   "b": "The site's own curbless page describes roughly a quarter to a half inch per foot",
   "b_source": "walk-in-curbless-shower-columbus.html (the site's existing page; an internal consistency reference, not a source)",
   "printed": "print A only, attributed to HUD, and say nothing that contradicts the site. A quarter inch per foot sits inside the site's range, so both can stand; HUD's maximum is specific to a no-threshold base and is not a general shower rule."
  }
 ],
 "sources": [
  {
   "id": "S1",
   "publisher": "USDA Forest Service, Forest Products Laboratory",
   "title": "Wood-Based Composite Materials, chapter 11 of the Wood Handbook (General Technical Report FPL-GTR-282)",
   "url": "https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr282/chapter_11_fpl_gtr282.pdf",
   "published": "2021"
  },
  {
   "id": "S2",
   "publisher": "USDA Forest Service, Forest Products Laboratory",
   "title": "Biodeterioration of Wood, chapter 14 of the Wood Handbook (General Technical Report FPL-GTR-282)",
   "url": "https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr282/chapter_14_fpl_gtr282.pdf",
   "published": "2021"
  },
  {
   "id": "S3",
   "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
   "title": "Rule 4101:8-5-01, Floors (Residential Code of Ohio)",
   "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-5-01_eff_7_1_19.pdf",
   "published": "2019-07-01"
  },
  {
   "id": "S4",
   "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
   "title": "Rule 4101:8-3-01, Building planning (Residential Code of Ohio)",
   "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-3-01_eff_7_1_19.pdf",
   "published": "2019-07-01"
  },
  {
   "id": "S5",
   "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
   "title": "Rule 4101:8-11-01, Energy efficiency (Residential Code of Ohio)",
   "url": "https://codes.ohio.gov/assets/laws/administrative-code/rules/4101/8/4101$8-11-01_eff_7_1_19.pdf",
   "published": "2019-07-01"
  },
  {
   "id": "S6",
   "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
   "title": "The Rehab Guide, Volume 5: Partitions, Ceilings, Floors and Stairs",
   "url": "https://www.huduser.gov/portal/Publications/PDF/part.pdf",
   "published": "1999-11"
  },
  {
   "id": "S7",
   "publisher": "U.S. Department of Housing and Urban Development, Office of Policy Development and Research",
   "title": "The Rehab Guide, Volume 6: Kitchens and Baths",
   "url": "https://www.huduser.gov/portal/Publications/PDF/kitchen.pdf",
   "published": "1999-11"
  },
  {
   "id": "S8",
   "publisher": "National Park Service, U.S. Department of the Interior",
   "title": "Preservation Brief 40: Preserving Historic Ceramic Tile Floors, by Anne E. Grimmer and Kimberly A. Konrad",
   "url": "https://www.nps.gov/orgs/1739/upload/preservation-brief-40-ceramic-tile-floors.pdf",
   "published": "1996"
  },
  {
   "id": "S9",
   "publisher": "National Institute of Standards and Technology, U.S. Department of Commerce",
   "title": "Voluntary Product Standard PS 1-22, Structural Plywood (final draft)",
   "url": "https://www.nist.gov/system/files/documents/2023/08/24/PS%201%2022%20FINAL%20DRAFT%20-%20CLEAN%20-%208-7-2023%20-%20FINAL.pdf",
   "published": "2023"
  },
  {
   "id": "S10",
   "publisher": "National Institute of Standards and Technology, U.S. Department of Commerce",
   "title": "Voluntary Product Standard PS 2, Performance Standard for Wood-Based Structural-Use Panels (2018 revision draft)",
   "url": "https://www.nist.gov/system/files/documents/2018/09/18/ps_2_revisions_final_aug_2018.pdf",
   "published": "2018-08"
  },
  {
   "id": "S11",
   "publisher": "APA - The Engineered Wood Association",
   "title": "Plywood (engineered wood products)",
   "url": "https://www.apawood.org/engineered-wood-products/plywood-osb/plywood/",
   "published": "undated"
  },
  {
   "id": "S12",
   "publisher": "APA - The Engineered Wood Association",
   "title": "OSB (Oriented Strand Board)",
   "url": "https://www.apawood.org/osb",
   "published": "undated"
  },
  {
   "id": "S14",
   "publisher": "Tile Council of North America",
   "title": "FAQ: Deflection",
   "url": "https://tcnatile.com/resource-center/faq/deflection/",
   "published": "undated"
  },
  {
   "id": "S15",
   "publisher": "Tile Council of North America",
   "title": "FAQ: OSB",
   "url": "https://tcnatile.com/resource-center/faq/osb/",
   "published": "undated"
  },
  {
   "id": "S16",
   "publisher": "Tile Council of North America",
   "title": "FAQ: Mortar bed",
   "url": "https://tcnatile.com/resource-center/faq/mortar-bed/",
   "published": "undated"
  },
  {
   "id": "S17",
   "publisher": "Tile Council of North America",
   "title": "FAQ: Cracked tile",
   "url": "https://tcnatile.com/resource-center/faq/cracked-tile/",
   "published": "undated"
  },
  {
   "id": "S18",
   "publisher": "Tile Council of North America",
   "title": "FAQ: Crack isolation, suppression, anti-fracture membrane",
   "url": "https://tcnatile.com/resource-center/faq/crack-isolation-suppression-anti-fracture-membrane/",
   "published": "undated"
  },
  {
   "id": "S19",
   "publisher": "Tile Council of North America",
   "title": "FAQ: Cleavage membrane",
   "url": "https://tcnatile.com/resource-center/faq/cleavage-membrane/",
   "published": "undated"
  },
  {
   "id": "S20",
   "publisher": "Tile Council of North America",
   "title": "FAQ: Hollow, loose tile",
   "url": "https://tcnatile.com/resource-center/faq/hollow-loose-tile/",
   "published": "undated"
  },
  {
   "id": "S21",
   "publisher": "Tile Council of North America",
   "title": "FAQ: Tenting",
   "url": "https://tcnatile.com/resource-center/faq/tenting/",
   "published": "undated"
  },
  {
   "id": "S23",
   "publisher": "Tile Council of North America (article by Stephanie Samulski, published in TILE magazine and hosted by TCNA)",
   "title": "Deflection Reflection: 2007 Handbook Language Simplifies Substrate Load Considerations",
   "url": "https://tcnatile.com/wp-content/uploads/2022/08/Deflection-Reflection-2007-Handbook-Language-Simplifies-Substrate-Load-Considerations.pdf",
   "published": "2007-08"
  },
  {
   "id": "S25",
   "publisher": "Ceramic Tile Education Foundation",
   "title": "How to Install Floor Tile When It's Natural Stone Rather Than Ceramic",
   "url": "https://www.ceramictilefoundation.org/blog/caution-natural-stone-tile-installed-over-wood-framing",
   "published": "2017-04-11, updated 2026-09-01"
  },
  {
   "id": "S26",
   "publisher": "TileLetter (National Tile Contractors Association), article by Mark Heinlein",
   "title": "Using L/620 and L/720 on stone floors",
   "url": "https://www.tileletter.com/using-l-620-and-l-720-on-stone-floors/",
   "published": "2023-04-03"
  },
  {
   "id": "S27",
   "publisher": "TileLetter (National Tile Contractors Association), article by Scott Carothers",
   "title": "The critical importance of movement joints in tile work",
   "url": "https://www.tileletter.com/the-critical-importance-of-movement-joints-in-tile-work/",
   "published": "2023-05-01"
  },
  {
   "id": "S28",
   "publisher": "TileLetter (National Tile Contractors Association), article by Dale Kempster",
   "title": "Uncoupling membranes methods and standards: a timeline",
   "url": "https://www.tileletter.com/uncoupling-membranes-methods-and-standards-a-timeline/",
   "published": "2019-07-01"
  },
  {
   "id": "S29",
   "publisher": "Ceramic Tile Education Foundation",
   "title": "How to Install Tile with Electrical Radiant Heating",
   "url": "https://www.ceramictilefoundation.org/blog/how-to-install-tile-electrical-radiant-heating",
   "published": "2018-12-04, updated 2023-07-04"
  },
  {
   "id": "S30",
   "publisher": "Ohio Administrative Code, Ohio Laws (codes.ohio.gov)",
   "title": "Rule 4101:8-5-01 rule page (effective dates)",
   "url": "https://codes.ohio.gov/ohio-administrative-code/rule-4101:8-5-01",
   "published": "2019-07-01"
  },
  {
   "id": "S31",
   "publisher": "LATICRETE International",
   "title": "Requirements for the Thin Bed Method, TDS 105",
   "url": "https://cdn-global.laticrete.com/-/media/project/laticrete-international/shared/files/support-and-downloads/technical-datasheets/tds105.ashx",
   "published": "undated"
  }
 ]
}