In this scenario, Jim and Rich install 1/2″ cementious backer unit (CBU) resulting in at least an 1-1/8″ thick subfloor. Therefore, whilst it is a conservative approach, Floors assumes that both ends of each beam are simply supported (see Fig 2). This calculator is designed to work with dimensional lumber only! John Bridge Forum also offers this helpful deflection calculator. Result will be displayed: Calculate Deflection for Solid Rectangular Beams Calculate Deflection for Hollow Rectangular Beams Calculate Deflection for Solid Round Beams Calculate Deflection for Round Tube Beams The guys advise against tiling right over linoleum because you don’t know the condition of the subfloor and a proud staple could cause tiles to crack. One edge was raised about 1/8 inch off the floor so I poured a self leveling underlayment at a thickness of 1/4 inch. The joists actual depth are 9 inches so I’m assuming they are 2X10. Jim and Rich often flash the floor to create a flat surface, and they always recommend installing an uncoupling membrane like DITRA overtop concrete. Let us say we have a 4-cm thick, 30-cm wide eastern white pine plank that act as the seat for this bench. This beam deflection calculator will help you determine the maximum beam deflection of simply-supported beams, and cantilever beams carrying simple load configurations. For instance, ceramic tile can withstand more deflection than natural stone. What’s the Difference Between Ditra and CBUs? If that same joist had gypsum ceiling (L/240), the allowable deflection is 0.6". The difficulty is that tile can be installed over a number of substrates, and each requires specific preparations to ensure a long-lasting tile floor. Having a solid floor system is key to limiting deflection within the limits of the material and style of tile your installing. A 1/4″ thick, 3 x 5-foot CBU panel costs about $11, or a little less than $0.75 per square foot. Hi, we're Ethan, Jocie, Kim and Fred. (6) Moisture, temperature, corrosive chemicals and gases expected to result in: While we're at it, here are some useful tools for finishing your house or apartment: the tile calculator; the paint calculator; the drywall calculator; and; the flooring calculator. To determine the requirements for a tile subfloor, I partnered with Jim and Rich from Diamond Tile located here in Maryland. Because ceramic floor tile is rigid and unforgiving, it needs a structurally sound, immobile base. Floors has no preferred units, you may use any units you wish but you must be consistent (p, F, E, etc.) I am experiencing an unbearable amount of noise from their footsteps including squeaking sounds and my whole place shakes. Good tutorial. For example, a floor with a span of 10 feet must deflect no more than 1/3 inch, or 120 inches/360 inches. Jim and Rich advise using a bond-promoting primer to enable the mortar to better adhere to the existing floor, and to set the floor with a specialty polymer modified mortar. Deflection, or bounciness, can cause tiles and grout to crack or come loose, and the tolerance depends on what type of tile is being installed. Can I lay tile over the underlayment without worry that my ceramic tile (wood plank style, 6″x20″) may crack due to deflection or “give” from the underlayment? The builder hired used 3/4” OSB for the flooring while the tile contractor used a 1/4” CBU under the tile, thus achieving 1” in total depth. That makes people think they can always skip over important details like thinsetting the cement board when that’s not the case. Sample beam deflection calculation. The engineer is saying the existing 1/2" plywood sub-floor is ok to put dittra and tile on top of(24"x24" glass 5/8" thick). You’d be surprised how many people will try to argue with me that it doesn’t matter which way you lay the grain of plywood. The floor calculator assumes all loads are applied normal to the floor surface, all beams are simply supported and the flooring material is fixed (to the beams) at all edges. There’s a lot of information (and mis-information) online about what constitutes a suitable subfloor for tile, and it’s tough to find a clear answer. Residential floors are typically sized for a … 0.001 means that the floor may deflect no more than 1 in 1000, tᴾ is the thickness of the unsupported section of floor material that will result in a deflection rate of no more than δy due to p, dᴸ & dᵀ are the spacings between the longitudinal and transverse beams respectively, which are defined by quantities; nᴸ, nᵀ, Iᴸ & Iᵀ are the second moments of area for the longitudinal and transverse beams respectively that will result in a deformation of no more than δy per unit length due to p, ωᴸ & ωᵀ are the loads per unit length supported by each longitudinal and transverse beam respectively as a result of p, yᶠ & σᵖ are the maximum deflection and maximum stress (respectively) that will be seen in the floor material due to F (Fig 4), A design pressure of 100N/m² and a point load of 1000N are to be applied to a 10m x 8m rectangular floor of 1 longitudinal beam and 5 transverse beams. All too often, tile flooring is installed by the builder without prior consultation with architect to ensure that floor framing has been designed for weight of tile, using industry deflection limits. Ditra is waterproof, while cement board lets water through but won’t be damaged by it. CBUs need screws and joint tape. How to Fix Floor Deflection for Ceramic Tile. (ii) Any dead load, live load, and in-service creep deflection criteria for floor Trusses supporting stone or ceramic tile finishes. To calculate a specific value, the Tile Council of North America (TCNA) offers a standard formula. Learn more about it here. L/360 vs L/720 These come from another post. Can you tell me if there is any city code or ordinance that requires the subfloor to be at least 1-1/4” in depth? The name of the game is a rock solid floor system and sub-floor. For a standard-size tile job, the difference in cost shouldn’t be a deal-breaker. The Tile Council of America (TCA) recommends a max. δy = 0.001m (1 ÷ 1000), Enter the above data as shown in Floors (Fig 4). I use the Jolly line on all shower alcoves instead of using bullnose tiles. I assume defection is not an issue there. http://www.prolabinc.com/asbestos-test-kits.asp. I built a home about 7 years ago that is having all kinds of problems with the tile flooring (cracked tile, displaced grout, creaky flooring, 1/2”+ deflection in some areas). Tensile moduli; Eᴾ, Eᴸ, Eᵀ define the resistance to bending for the floor, longitudinal and transverse materials respectively, Deflection:
I would be truly grateful. Which one would make more sense? All calculations are as accurate as can be expected using classical (Castigliano) theory upon which they are based. Basic Lumber Design Values are F =2000 psi F =1100 psi F =2000 psi E=1,800,000 psi Duration Of Load = 1.00. Make sure the floor is solid enough if your going with a large format tile or natural stone. Recent research has shown tile to fail, under some conditions, when the floor is more rigid than L/360. Any help would be welcomed. Beam Deflection Calculators - Solid Rectangular Beams, Hollow Rectangular Beams, Solid Round Beams Enter value and click on calculate. 23 of DITRA Handbook). If they install a second layer of wood underlayment (3/8″ plywood or thicker), the guys would use 1/4″ CBU on top. in the centre of a bay (Fig 1), Dimensions:
Ditra can also be laid directly on a flat plywood subfloor using a latex modified mortar; especially for tiles that only require L/360 deflection standards. I would rip out everything and add another layer of 3/4 plywood. Maximum deflection is limited by L/360 or L/480 under live load. For instance, ceramic tile can withstand more deflection than natural stone. So I have a dead line in a week and a half and I quickly decided to use cement boards to get level. See the table below. Enter your floor joist information and then hit 'Calculate deflection' to find out your floor rating. So the house dimensions will now be 24' X 13'. I said I wanted to add an additional layer of ply and his response was "it would do nothing but add weight to the floor." The joists are spaced on 16 inch centers and have a span of 14 feet. Ditra is a decoupler, meaning (in this case) there’s no chemical bond between the tile and the subfloor. Codes also specify how much floors are allowed to bend under load, a measurement called a deflection limit. Thanks. This may make Ditra a better choice if moisture from below is a concern, such as with some outdoor applications or installations over concrete. I have witnessed numerous discussions in the field about proper ways of laying plywood… and it never takes long for somewhat to point out the span rating stamped on the wood and sometimes with an arrow facing in strong axis (the 8′ length). And, while this is a cement construction building, I’m afraid of this being a safety issue if the floor can’t support the load/weight of these double stacked hard flooring surfaces. I only want to do this once. I hope this is a good place to ask this question, but from an engineering perspective is there any way to reduce deflection in wood floor joist without adding additional support beams? Plywood and OSB are the two most common materials used for floor decking, and typically they are 5/8″ or 3/4″ thick. Pics of : Tile Floor Joist Span Calculator. Schluter recommends using ring shank nails or screws, turning panels perpendicular to joists and not aligning joints with joists (pg. Jim and Rich don’t advise tiling over resilient flooring. I was installing Dri core planks as a sub floor. In other words, you can’t rely on either material to make a spongy or bouncy subfloor more suitable for tile; you have to add rigidity first, using plywood or other structural panel materials. I have visited several tile stores and received conflicting subfloor thickness requirements. The floor calculator determines the stress in the floor material as a result of the design load per unit area and the maximum expected point load applied to the centre of a bay, but not for the support beams because their depths are unknown. (on center). The subfloor is 5/8 T&G. I’m planning on tiling our kitchen. δy specifies the rate of deflection permitted per unit length of floor; e.g. Schluter Systems (the makers of Ditra) have a lot of pretty good misc metal products for doing tile transitions. Moving into a house where the current kitchen floor is linoleum with likely asbestos. Should I put down 1/4 inch durock or densShield and should I put thinset under the cement board? You will find further reading on this subject in reference publications(2 & 3). deflection of L/360 for ceramic tile and L/720 for natural stone tiles. Reducing Deflection Calculating Deflection Many tile contractors can judge a floor’s deflection by walking around. Nice write-up Ethan. Design substrate for total load deflection not exceeding L/360, as measured between control or expansion joints. 9×9 tiles were the ones usually made with Asbestos. For example, while joist manufacturers regularly meet the standard L/360 criteria for code construction with 24" o.c. Where do you see that advice? p is the design or specified maximum pressure that the floor can support over its entire surface without exceeding the deflection criteria; δy
Still worth testing a piece. In fact, failures at L/600 have been observed. Whether you are installing stone or ceramic tile over floors and walls there's one thing to consider; deflection. 6000mm in any direction the floor shall deflect no more than 5mm. Floor Truss Span Tables Alpine Engineered Products 17 These allowable spans are based on NDS 91. Best practices? installing an uncoupling membrane like DITRA, http://www.prolabinc.com/asbestos-test-kits.asp, Home Depot Coupons, Coupon Codes, 10% Off Sales – FALL/WINTER 2020-2021, AJ Madison Coupons, Sales, Coupon Codes, 40+% Off – FALL/WINTER 2020-2021, Lowes Coupons, Sales, Coupon Codes, 10% Off, Target Coupons, Sales, Coupon Codes, 10%-60% Off – FALL/WINTER 2020-2021, Sears Coupons, Sales, Coupon Codes, 10% Off – FALL 2020/WINTER 2021. If the floor is uneven, it can be flattened just like a wood or concrete subfloor. In this case, the guys usually install 1/2″ plywood overtop and 1/4″ CBU or DITRA. The floor calculator can also be used to calculate the material properties of a non-rectangular floor by breaking the overall shape up into regular rectangles and calculating each rectangle individually (Fig 3). In real terms, a concentrated weight of 200 lbs (91 kg) over a 3" (75 mm) wide area, is not all that difficult to attain in a situation such as a fridge or a stove being brought across a floor on a dolly. The deflection calculator provides several engineering specifications such as the moment of inertia and yield strength to determine deflection. As a fabric-like material, it’s obvious that Ditra offers no additional rigidity to make a floor “stiffer” for tile. Many tile contractors can judge a floor’s deflection by walking around. 2. Top Chord 3.8.2 Cast-in-Place Concrete Floors. Do I place a cement board over this underlayment….Do I place ditra over it….or do I proceed directly to tile? The floor calculator is applicable to all floors manufactured with any material assuming that the longitudinal and transverse beams are equally spaced and the flooring material is all-covering. Using CalQlata's Area Moments calculator, a beam of 0.2m x 0.4m has a second moment of area of 0.001067m⁴ (Fig 5) which is greater than 0.000801m⁴ and therefore will result in a smaller deflection than the design requirement. The bathroom currently has linoleum as the flooring surface, a good subfloor under that. Better safe than sorry. Its almost impossible to remove and it’s throughout the house. The deflection for the entire floor shall not exceed 1:1000, i.e. 3. You can send in a sample of your floor to an asbestos testing lab. All materials (beams and floor) will be manufactured from the same material, which has a tensile modulus of 1.3E+10N/m². I just purchased a condominium unit in a 7 story building in downtown Chicago. If not, it’s probably worth hiring a knowledgable contractor. 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