In order to calculate this, you need to input the length and width of your slab. Rebar steel will be calculated for the bending moments “Mx” and “My. a car weight about 5000lb. The floor system of the classroom shown in Figure 2. #5 rebar on a 6X6 grid, No cracks in that, poured the same time as the slab in the heated addition. Use of 5″ to 6″ (125mm to 150mm) is recommended if the concrete will receive occasional heavy loads. Minimum Top Rebar Spacing defined in the Slab Design Rules spreadsheet: Max Bot bar Spac: Maximum Bottom Rebar Spacing defined in the Slab Design Rules. Use 3/8 min repair frame in the footing. You can use the concrete Rebar calculations to find the amount of. Minimum clear cover to reinforcements in slab depends on the. 3. Use 2” rebar chairs to support the rebar in the center strata of the pad. 21 m 2. The tendency is to lay rebar the way one’s. INSTRUCTIONS: Choose units and enter the following: ( L) Length of the slab. 73 per square foot for concrete installation. ICF Foundation and One ICF Story – The sequencing here is to build the foundation walls first, place concrete, and then build the above-grade walls second. Two layers of steel bar reinforcement are needed for secondary containment floors because tank loads induce both positive and negative bending moments in the floor. Thickness of concrete slab depends on loads and size of the slab. The floor finishing is. Wet your concrete after the pour. Such applications usually involve the placement of large numbers of bars with close spacing. It says that floor slabs were patent designs back in the 1920's. Rebar. The movements of these structural elements are likely different than those of a slab-on-grade due toWhen operated by our highly trained Project Managers, GPR’s typical accuracy is +/- ¼” to the center of the object in concrete we locate: conduit, post tension cables, and rebar. 15 mm) polyethylene vapor retarder with joints lapped not less than 6 inches (152 mm) shall be placed between the base course or subgrade and the concrete. 5 inches of spacing (18" + 1/2" diameter of the rebar). In a typical reinforced concrete building, reinforcement bars arranged as mats are incorporated into a concrete plate of minimum thickness 125 mm to form a reinforced concrete solid slab. For example, a slab that is 6 inches thick might have rebar marked as size 6 or 3/4-inch. T F 8. 2. Minimum aging of new concrete slab: 28 days (cure time) Minimum width and length of slab: See new slab table & figures below MIN W L R S1 & S2 D I LIFT MODELS SLAB MIN. The main bars are usually positioned in the slab’s bottom layer, with a minimum cover distance of 20mm from the slab’s bottom. 2—Slabs-on-ground 5. In some cases, concrete needs reinforcement with steel mesh. Compressible floor-covering materials that compress more than 1 / 32 inch (0. Steel shall be located within 2” of the top or the upper 1/3 of the slab. Maximum spacing of bars for slabs • Main bars: 3h ≤ 400mm (in areas of concentrated loads 2h ≤ 250mm) • Secondary bars: 3. This how-to guide will show you how a. I'm in the process of designing a elevated composite concrete and metal deck floor slab for a warehouse. These beams are not fixed together with a slab as are superstructure beams; consequently concrete has to be poured down the beam’s narrow top opening and reach the bottom of the beam. Slab re i n - f o r cement and joint details for this type of court are shown in Fi g u r e 3; a cross section and other typical tennis court details are shown in Fi g u re 4. 2. The spacing of the rebar is also determined by the weight and size of the slab. 00 m 14 over 6. Ch. Map rebar and rebar patterns. Metallic and non-metallic pipes and conduits. In two-way construction,According to Clauses 8. Consider. Pour 6" fiber reinforced concrete over it. Five to six inches is recommended if the concrete will receive occasional heavy loads, such as motor homes or garbage. The provision of adequate reinforcement, slab thickness, and proper. In t e r p r etations of the ACI 318 code re q u i r ements (Ref. rebar strength is in tension, so by adding rebar to BOTTOM of foundation, it counter acts the load of compression. The commentary R26. The ACI 318-19 provides a number of requirements regarding slab thickness, concrete cover, and reinforcement ratio which facilitate the design process. This wood sheeting, which should also be stronger than average, will act as a subfloor. south d c rebar i 306" i #7,7/8" dia ---j r--rebar j. For live loads of about 50 psf (2. In a typical reinforced concrete building, reinforcement bars arranged as mats are incorporated into a concrete plate of minimum thickness 125 mm to form a reinforced concrete solid slab. Properly compacted sub-grades can reduce needs for reinforcement – as well. ACI 318-14. 5 kPa), column spacing typically ranges from 15 to 25 ft (4. Calculation Method For Find Out The Overlapping Length Of Beam, Column And Slab; Bar Bending Schedule For Slab And Estimation Of Steel Reinforcement In Slab; Calculation steps. and 6000 btu/hr heat loss in the second. 50 m span joist, beams, & girder soffit under 3. 5 rebar, then measure and mark for your dowels at a 18. 5h ≤ 450mm (in areas of concentrated loads 3h ≤ 400mm) Where h is the thickness of. , interior beam dimensions = 14 in. You'd really need to know how much steel was in it to get solid data. g. The minimum shrinkage and temperature reinforcement shall be as per Table 4. 8 mm) when subjected to 50 pounds (23 kg) applied over 1 inch square (645 mm) of material and are greater than 1/ 8 inch (3 mm) in thickness in the uncompressed state shall not extend beneath walls, partitions or columns, which are fastened to the floor. Type and spacing of the control and construction joints. of the most advantageous location for a floor opening depends on the type of two-way slab you’re designing or evaluating. 9836 – 18. , edge beam dimensions = 14 in. Exposed rebar will rust, compromising the concrete's strength. Add one more length to allow for that extra, giving you a total of 18. C. • Basement floor slabs with integral footings must provide for 5000 psi concrete in that portion of the slab acting as a footing. 9. D bar or 10 mm if you are using Plain bars. The type of rebar used in the construction of a given section of concrete will depend on several. 5 rebar, then measure and mark for your dowels at a 18. The simplest type of two-way slab to construct is known as a flat plate. The most common steel reinforcement or rebar sizes in residential construction are No. Welded wire fabric should be minimum WWF 6x6-10/10. Building Width for Use of Appen-dix B Tables. By Theodore Neff. 5 bars; There shall be a minimum clearance between parallel reinforcement bars of 2 1/2 inches; Bars larger then # 5 increase the chances of shadowing (voids behind rebar) Always use the larger of the two. 1 shows the design detail for a secondary containment floor slab with two layers of reinforcing. The procedure: Lay up the first 4-foot height of wall. Suspended slab/Two-way slab/One-way slabToday's video answers the questions I get asked most frequently: - How do you read or interpret slab reinforcement pl. The diameter of reinforcing bars shall not exceed one-eighth of the total thickness of the slab. 40ft x 15ft dumpster pad, 8" thick with double mat of #4 rebar 16" OC Each way. You cut as 4,000mm +760mm = 4,760mm. secondary containment floor slabs on grade. 40 (default) and 60 are common. Fabrication of rebars consists of cutting to length and required bending. Finite elements 1st example 2nd example 3rd example. 15% for mild steel bars. 87 d Spacing of bar = Design of Continuous Slab Suppose a slab is supported at the ends and also at intermediate points on beams, the maximum sagging and hogging moments to which the slab is subjected to due to uniformly distributed load, can be computed as follows: Let = intensity of dead load per square metre. get your rebar grid down, i would use 1/2" on 12" center. Figure 1a: Joint Spacing in Meters. I was thinking of the following: basement wall 8 inches thick 10 feet high backfilled up to 7 to 8 feet. The pri m a r y differe n c e s b e t w een each type are re i n f o rc e m e n t details and joint spacing. A good compacted base below the concrete is equally important. 4 × W1. A 4" slab should have joints 8-12 feet apart. Design Rules - Footing/Pile Cap Rebar. 1d is for every 45° bend. Contact*: Severity*: Description*:Problem #3 – Shrinkage cracks that allow moisture to reach the rebar. To define design strip rules, click the Slab Design Rules button on the Data Entry toolbar. 113. Locating conduits (plastic & metallic) and in-floor heating lines in concrete, or just below a slab-on-grade. The evaluation of rebar spacing results shows that the maximum standard deviation for rebar spacing is 0. For building footings I would use a #5 (5/8 inch) rebar. (b) A flat slab which is the same as a flat plate except the areas around the columns have. Grid length = Slab-length – (2 * edge-Rebar-spacing) The total length needed for Rebar is measured vertically and horizontally. ACI 332, Section 10. There are three (3) materials used in constructing a composite floor slab; steel decks, reinforcing bars and concrete. Narrow panels Fig. For this case, the lift should not be installed without written authorization from theIt has stood up to some really heavy equipment for 25 years. Larger diameter bar will allow a wider spacing of the bar, our designs went from 3/8 on 12 inches to 1/2 on 18 inch when we started to build pesticide storage facility's. For corrosion protection, however, most specifications require a minimum depth of concrete cover that usually ranges from 1 inch to 2 inches. 1 L from the center of the support at end support and 0. By: Olin Wade (Remodel or Move Stuff) The spacing of rebar in a slab depends on the purpose and size of the slab, as well as the climate in which it is being built. rt i 2nd layer walij-dwls longit #4@ 12" ole 11'9 "t_ "-1)_-item qty part or no. 3) Shrinkage cracks: As the concrete slab dries after placement, it shrinks. Slab may be supported on walls or beams or columns. These new concrete slabs do not account. Rebar comes in several types: Steel mesh, made up of steel wires that provide support to the concrete. For this case, the lift should not be installed without. 20 Plant-applied External Fusion Bond Epoxy Coating [Abrasion-Resistant Overcoat] for Steel Pipe (CSA Group, formerly the Canadian Standards1) Except as provided in Sentences (2) and (3) and in Articles 9. It may be desirable to tie and reinforce the new slab to the pre‐existing surrounding floor. The compaction UNDER the slab is more important than the thickness of the slab. The no. , the minimum footing width or area shall comply with Table 9. 1. Often it is necessary to cut holes in concrete floor slabs. However, this is the absolute minimum and applies only when there is no load on the concrete slab at all. 24-foot joint spacing. Since this is a patio, you could use 6x6 10/10 wire mesh instead of the rebar. Rebar Spacing. 2-way slab rebar arrangement method 1-way slab rebar arrangement method Slab main bar arrangement type classification Bent bar type. the slab joint spacing should be the same as for an un-reinforced slab. Standard concrete floor slab thickness in residential construction is 4 inches. Parking lots have most loads imposed on interior slabs sur-11. Two layers of steel bar reinforcement are needed for secondary containment floors because tank loads induce both positive and negative bending moments in the floor. The size of the rebar depends on the specific application, but typically #4, #5, #6, and #8 rebar are used. They want one expansion. If too much water was. Contractors sometimes use the “1/8 Rule,” meaning the size of the rebar is 1/8 the thickness of the slab. 1 Wall Reinforcements of SS and NS (a) Minimum Reinforcement in SS or NS walls - refer to TABLE 3. 3. less than around 0. This is illustrated in Figure 1, where #5 bars are used in both the top (T) and bottom (B) layers in T wo-way slabs are generally defined as suspended slabs where the ratio of the long to the short side of a slab panel is 2 or less. Clear span of the two way slab = 5000 mm. Step 1. The main reinforcement of the slab panel “A” is marked as (1). 00 m to 6. For example, if the first slab is at 12 inches and the second is spaced at 18 inches then measure and place your first mark at 9 inches and then continue spacing the marks at. However, if the concrete slab is meant to be the footing of a small structure, #4 rebar with a diameter of 1/2-inch should be used. Because of this, the Building Code places limitations on the size and spacing of rebar in gunite & shotcrete. Workmanship and jobsite conditions. cedures used to design and construct slab-on-grade such as streets, highways, and floors. Add the third side. Slab Design Rules - General. 6 Pedestrian Circulation--Stairs and. Place rebar in a grid pattern with a spacing between bars of approximately 12 inches. L is the effective length of the beam and slab. Thank ForSubscribeLikesShare. However, in some cases, 10mm dia bars are taken for the floor slab, when there is no extra external load other than reinforcement mesh load. b) Slab depth does not exceed 200 mm when the steel grade is 460. Free Reinforcement Calculator. Max Bending Check. 3%. This article presents steel quantity computation process for slabs, columns, and footings. #4 Rebar ; The #4 rebar is often used in residential and commercial projects to add strength in slabs and columns. Reading time: 4 minutes. 5 Slabs on Grade - “the purpose of isolation joints in slabs on grade is to allow horizontal and vertical movement between the slab and adjoining structures such as walls, columns, footings, or specially loaded areas (machinery bases). Joint spacing normally ranges between 12 to 18 feet depending on the amount of reinforcement the slab has. This guide identifies the various classes of floors based on use, construction design details, necessary site preparation, concrete type, and other related materials. The elevation to the top of the decking (bottom of the concrete waffle slab) for forming of the second floor above-grade slab is ___. So, there exist guidelines for spacing rebar inside a concrete slab. If the soil conditions on are not covered by this Part then additional guidance can be obtained from. Use f’c = 28 MPa and fy = 414 MPa for main rebars and fy = 276 MPa for shear reinforcement. I can't believe after being in this business for 12 years I've yet to pour a very long re-inforced concrete slab. The mesh reinforcement in the slab is placed in the top with 1" covers. Corner cracking and joint faulting are reduced by using these bars. How thick should rebar be? Common Rebar Sizes Rebar in patios, basement floors, footings and driveways may vary from size 3 to 6. Much of your need for reinforcement will be dictated by how well your site was prepared. UB 610 x 179_BP_Pinned. Level, straighten and brace the second form board. In two-way construction, According to Clauses 8. vapor retarders - some times referred to as vapor barriers, insulation, etc. Number of Main Bars = Ly / spacing + 1 = (4000/150) + 1 = 27 nos. But as the depth grows, so does the need for reinforcing the structure. Detail B: “Wrap and Snap Tie” (diagram upper right) is normally used when tying vertical wall reinforcement to hold the bars securely into. If the floor is. The thickened concrete slab. Figure 5. Where, d is the diameter of the bar. Our engineers wanted to make sure that big yellow boots fit between the rods so the workers did not stand on the rod and bend or. Local code authorities often specify the type and placement of the reinforcement in a monolithic slab. Concrete volume calculator plan view diagram. Figure 2 illustrates the typical locations of the top and bottom bars within the composite slab cross-section. Use wire mesh for driveways that are 4 to 5 inches thick, and rebar for those that are 5 inches or more. Selecting the correct type of rebar is as impor tant as the diamet er and grade. 2. Space joints (in feet) no more than 2-3 times the slab thickness (in inches). 1 of EC2, the recommended minimum spacing of reinforcing bars is 75 mm and 100 mm for laps. The minimum spacing between two reinforcement bars should be at least equal to the maximum coarse aggregate dimension plus a margin of 5 mm. Generally, for a standard residential foundation, the minimum spacing between rebar should be at least 4 inches. (Imagine you are walking around the slab) Hit Undo Last to Undo last side. I maintain a concrete cover of 40 MM. Functions of Distribution Bars In A SLAB: Distribution bar is to provide at the long span of the slab. Summarize and show schedule of the design outputs such as beam dimensions, main rebars diameter and quantity, and shear rebar diameter and spacing. 25" 3,000 PSI / 28 Day Aging #6 Rebar: 12 in: D2-10 Models: 4. Step-4: Rebar Calculation Process Of The Slab Panel-A 4. 4m x. Next, you put steel rebar every 2 feet to strengthen the bond between the foundation and the footings. Note: Cut the two side form boards 3 in. 1 of ACI 318-111 identifies a two-way slab as a slab system designed for flexure in more than one direction. ACI 302. Rebar being #4 grade 60. Matt, You need to tie the new footing and foundation wall into the existing structure's footing and foundation wall, so yes drill and epoxy the rebar in. The practice in which steel decks are used is known as composite floor decks. 4, and No. Besana. For slabs. First, Get The Number Of Required Bars. There are three different sizes of rebar typically used for home construction projects. The Building Structural Standard defines a two-way slab system as a concrete slab system in which two rebars are arranged in two directions regardless of the presence or absence of a beam that transmits a load to. 14 and No. Generally, rebar spacing in slab footings ranges from 12 to 24 inches, both for horizontal and vertical bars. 2: Repeat and continue to draw complete (closed) shape. Sub-slab details (i. Also, a small hole in the concrete will be totally fine, given the fact that there is a rebar grid. The support for reinforcing steel in floor slabs is shown in figure 7-24. Design beams B1, B2, B3, B4, and B5. diameter), spaced at a maximum of 24 in. f. For instance, the ACI 318-19 specifies minimum slab thickness that satisfies deflection. This is illustrated in Figure 1, where #5 bars are used in both the top (T) and bottom (B) layers in T wo-way slabs are generally defined as suspended slabs where the ratio of the long to the short side of a slab panel is 2 or less. However, some specific rules and requirements need to be met. Avoid using air contents over 3% for interior slabs. Once the concrete has gained strength to 2000 psi, typically within the 3 to 10 days recommended by PTI, the tendons are stressed. As a building material, concrete is very strong in compression but relatively weak in tension. 60 per square foot. 15 feet x 12 inches per foot = 180 inches. This new slab design does not account for second floor installations or installations in a. The concrete floor will be reinforced according to WAC 246-359-430. It follows that the design yield strength of reinforcing steel that may be used in a slab designed in accordance with AS 3600-2000 is 400, 450 or 500 MPa. ) is going to be 5'-6' for 4 ksi concrete anyways. Top Bars for Slab Continuity Properly designed top reinforcing bars installed above. Nail one end to the braced form and use the calculated length of the diagonal to set the form at 90 degrees. These slabs are supported directly by the columns and have a completely flat soffit. Rebar should be minimum Grade 40 reinforcing steel. If your two slabs have different spacing for their rebar mats, measure and mark so your dowels fall in the middle of the spacing of the second slab. 5 round bars, respectively, while. According to Indian standard rcc concrete roof slab thickness in residential building construction is 4 inches (100mm). Rebar Development Length Calculator is a web application that supports the design of post-installed rebar in concrete applications by calculating the necessary tension and compression development lengths required in accordance with ACI 318-19 / ACI 318-14. 15m and then Sand level is rammed. Fill in the price and single rebar length that you will buy at your supplier: rebar price = €2/m single rebar length = 6 m. I have 10 in. 3 Storey Building: Larger diameter rebars, such as 16mm and 20mm, may be used to accommodate the. All floor elements were brought in as DECK elements. (a) A flat plate which is a two-way slab supported on a column grid without the use of beams. Because of this, the Building Code places limitations on the size and spacing of rebar in gunite & shotcrete. For live loads of about 50 psf (2. The maximum spacing of temperature steel is the smaller of 5 times the slab thickness or 18 in. 0 pounds per cubic yard (0. Essentially a early age concrete shrinkage problem (cement paste not reaching full strength/bond with aggregate and restraint on the concrete member due to rebar. This design is particularly effective for structures with consistent loads. x 27 in. Stainless steel rebar. * BEAMS SHEAR CONNECTORS (IF PRESENT) For M15 concrete, lever arm = 0. Column spacings are 48 feet center to center. com Ezekiel Enterprises, LLC 301 Mission Dr. 5. With some limitations, reinforcement for slabs can be sized using the Subgrade Drag Theory in order to increase the spacing of control or construction joints. Round up the value of n to the next whole number to find the nominal rebar size required for that spacing. FLOOR SLABS M. 3. Rebar is recommended on concrete measuring 5 – 6 inches thick. The specified compressive strength of concrete shall be as set forth in Section R402. -l. Easiest way to go. In addition, the spacing of the bars will also vary by the project. 30% carbon cont ent and only. A rebar slab calculator is a tool used to determine the quantity and spacing of reinforcing bars (rebars) needed in a concrete slab. In either case, blocks should be used under the. Rebar Spacing for Concrete Slab. Then use USDA NRCS Standard Drawing ES-46 to select ( ) There's no generally-accepted rule of thumb as to how to space rebar in a concrete slab. 76 Slab designation: CS1 Check if one-way or two-way slab 1 Slab is one way since it is catilever slab Minimum slab thickness min t = 69. The rating your floor can withstand is also factored in. R403. , where a T-beam girder is supporting T-beams that in turn are supporting slabs, as shown in Figure 8. The suspended reinforced concrete slab is tied into the external capping beam. Clear cover of the slab = 25-mm. Provide the required spacing and diameter of the rebar. Advertise Here. (1) ε = θ (h b + h s) L-L 1. 7. I generally use a minimum of 4 bars, with 2 bars of 12 MM thickness in the bottom of the beam, and 2 bars of 10 MM at the top of the beam. 7. 2. Why Does Concrete Require Rebar? Most concrete requires some type of reinforcement. Crack Control – when crack widths are not checked by calculations No Further Checked Required. Subject: Re: Rebar in shop floor? Kingston,Mi. 3. The installation of the rebar is critical for the success of the overall project. It also provides worked examples,. Sudip Shrestha. If the slab is more than 24 inches thick, #5 (#5/8 inch diameter) rebar may be required. Annex. Generally, #4 rebar (1/2 inch in diameter) is the most common size used for slab on grade applications. Typically, once the concrete in the foundation wall has set, install the floor system. Vertical rebar every 16 inches. worked on the rebar behavior inspection of a sustainable RC slab. Rebar should be placed evenly throughout the project. Minimum thickness of concrete structural elements based on ACI 318-14, IRC 2009, IS 456 2000, and UBC. The steel rods help reinforce the strength of the concrete slabs giving the structure a strong form. E. Size and spacing of rebar;secondary containment floor slabs on grade. 4 bar at the top and the bottom of the footing or one No. Carbon steel. Draw also the typical beam detail showing the main. 006 inch; 0. SCI P300 is a comprehensive guide for the design and construction of composite slabs and beams using steel decking. 6. 15. REBAR SPACING: GP‐7 SERIES MODELS: 4‐1/​4" 3000 PSI / 28 Day Aging #6 Rebar:. In the case of the RCC slab, the maximum spacing between two secondary parallel wires should be 5D or 450 mm or whatever. Most residential slabs contain. Install tie down 'J' bolts into the slab using a template of the base of the. (as in example diagram) Multiply the 2. The maximum weight of fly ash, other pozzolans, silica fume, slag or blended cements that is included in concrete mixtures for garage floor slabs and for exterior porches, carport slabs and steps that will be exposed to deicing chemicals shall not exceed the percentages of the total weight of cementitious materials specified in Section 19. 006 inch; 0. 12mm. MINIMUM VERTICAL REINFORCEMENT AND SPACING (INCHES) b, c: Soil classes and later soil load d (psf per foot below grade) GW, GP, SW and SP soils 30: GM, GC, SM, SM-SC and ML soils 45:Concrete Floor Slabs On Grade Course# ST-702 EZ-pdh. Dynamic and/or oscillatory. Pool construction crews must place each steel bar and drop of concrete with precision to avoid future structural problems. And the rebar details of (1) is 10mmØ @ 8″ c/c. 83-6. 5, which correspond to diameters of 3/8-inch, 1/2-inch, and 5/8-inch, respectively. However, we want to use slabs for the floor elements in this model. The performance of the paving joint is enhanced by these bars. 4 rebar in the lower part of the foundation. Heavy Loads. That has held up great over the last 8 years, no cracks at all. 9mm deformed rebar for walls instead of 10mm. 1. 5 m. The floor has been designed with two mats of steel, 7 1/2" total concrete thickness and 50 ksi steel beams with a single row of shear studs on the beams. ACI 330R-08, Guide for the Design and Construction of Concrete Parking Lots is. The top surface needs to remain wet while the curing process takes place. normal rebar sizes (e. Maximum spacing of bars for slabs • Main bars: 3h ≤ 400mm. Detail A: “Snap Tie” (diagram upper left) is the simplest and is usually used for rebar in a flat horizontal position. Minimum. The main reinforcement of the slab panel “A” is marked as (1). x 20 in. The typical depth for rebar placement for slabs is 2-4 inches. e. STRENGTH REINFORCEMENT REBAR SPACING GP‐7 SERIES MODELS 4‐1/4” 3000 PSI / 28 Day Aging #6 Rebar 12 In. HOUSE BUILDING IN THE PHILIPPINES - EPISODE 56: REBAR LAYOUT FOR C-JOIST SLAB Message us:Facebook: retir. The formula is, Number of bars = (length ÷ spacing) + 1. If you are using rebar under the weight room, raise it on stools, tie it off in a 12" grid. Number of Main Bars = Ly / spacing + 1 = (4000/150) + 1 = 27 nos. 2. 3% (100As/bd < 0. 3. It simply means it contains steel. AI Homework Help. g. Floor slab of bottom-most SS or NS and floor slab of NS located above an SS: (i) Slab reinforcements at both external face and internal face shall be H13-. To reinforce a 4” concrete slab or driveway with steel rebar, determine the grid spacing and rebar size – #3 or #4 in a 12” to 18” grid. A 4-inch-thick slab cast on the ground and in permanent contact with it will float and rebar is not required. Floors shall be a minimum 3 1 / 2 inches (89 mm) thick (for expansive soils, see Section R403. Some brands of forms have preformed chases that run the length of each. The compaction UNDER the slab is more important than the thickness of the slab. Place these positioners at a spacing that will not allow the rebar to bend or deflect enough to reduce the coverage you wish to obtain with the concrete you place in you forms. 2 – Contraction joints, states the following: “ (d) Joint depth shall be a minimum of ¼ the slab thickness for formed or tooled joints, or dry-cut sawed joints in hardened concrete (e) Joint depth shall be a minimum of 1 in. 375 inches, which is equivalent to 9. 5% of the cross sectional area of a slab. vided in the slab under the net.