26 Oct 2011. This method (F145-99) states the minimum subfloor is 3/4 exterior plywood over joists 16" oc. connecct2 - This is not a structural question. It is purely about constructability, and may involve architectural aesthetics. But there are very good reasons... Levelness of mortar bed joints. Quantity of cement required = 1/7 x 1440 kg/m 3 = 205.71 kg. Specified 3 dimensions of concrete masonry units are typically 3/8 in. Then, should concrete blocks be filled? Quantity of cement required in bags = 316.79/50 = 6.33 bags. Control of expansion joint shall be continuous through the mortar and masonry, at a … Apply a full bed of mortar onto the base, approximately ½ in to ¾ in (13 #2. Handling and Storage of AAC Blocks Making allowance for shrinkage between fresh and wet concrete = 1.54 x 205.71 = 316.79 kg. At the highest point (to line up with adjacent concrete) the required thickness of the mortar bed + paver is 70mm. 75mm of type1 is sufficent for foot traffic as long as the ground below is stable and wackered beforehand. 5. Minimum Thickness. Mortar joint thickness for load-bearing masonry shall be within the following tolerances from … The term thin set and dry set are used interchangeably. For optimal performance, the scratch coat should be ½ to ¾” thick. B. k thanks for the replies. While it does seem miniscule, +/- 3mm from a base line mortar depth of 10mm with the variation being checked within any... The finished mortar depth depends on the natural variances within the stones, but usually varies between a half inch and full inch of finish thickness. The mortar joint running along the top and bottom of the blocks is called the bed joint. Concrete Block Sizes. Besides its shape (truss or ladder), wire thickness is important in the placement process. course of block in a full mortar bed. A dry thin bedding mortar, comprises a mainly dense stone aggregate of maximum size equal to the joint thickness. You Must Provide = 9 x 2112 = 19004 kg of sharp sand + allowance for waste as appropriate. So you can order 20 tonnes of sharp sand and 57 bags of cement for this job. Now i am sure you understand How to estimate the amount of mortar Required To Lay Blocks (Cement and Sand) covering one square metre as well as make estimates for cement mortar. No. Next, calculate the number of blocks needed for the project by the number of blocks per square foot. 3.3.F Site tolerances indicates that the bed joints … Minimum Bond Strength: 200 kPa at 7 days for non -structural veneer. The thickness of mortar was probably more like 5/8". Mortar and Adhesive • Use ASTM C270, Type S, mortar applied to a thickness of ⅜ to 1¼ in. Lay out the block, making sure to leave a 3/8 inch gap between the blocks to allow for the vertical mortar joints (i.e., a typical 8x8x16 block is actually 15-5/8 inches long and 7-5/8 inches high to accommodate the mortar joint). The thickness of the mortar can vary in other types of structures from 1/8 inch to ¾ inch, according to the MC2 Estimator's Reference website. B. 500 kg/m2 is typical for office, storage space and similar. This guide specification is for concrete pavers mortared to a concrete base and grouted joints for exterior applications. Unless recommended otherwise by the brick manufacturer, the mixes in Table 6 should be used for clay bricks. In masonry constructions, bricks or blocks are laid in courses. Lay the First Course of Block. Quantity of cement required = 1/7 x 1440 kg/m3 = 205.71 kg. 'Mortar joint' is the term for the space of mortar between bricks. Allow adequate curing time for the mortar … Keeping the basement dry Brick elements shall be placed in a mortar setting bed within the hardened concrete block out. For instance, a 6" CMU is nominally 6" deep while a 10" CMU is nominally 10" deep. Step Two: Calculate the Number of Blocks. In general, masonry head and bed joints are required to be no more than 3/8 of an inch thick. Mortar was mixed with a ratio of 250ml of water to 1kg of dry mortar mix. This is known as the mortar joint, and is usually given in inches. New Zealand Concrete Masonry Association Inc. 1.4 Mortar and Mortar Joints Summary of Requirements Mortar Minimum Strength: 12.5 MPa at 28 days for structural masonry. (9.5 mm) less than nominal dimensions, so that a 4 or 8 in. Concrete Masonry Units (CMUs) are manufactured in a variety of sizes. Upgrade to Quora+ to access this answer Then, add more water and keep mixing. It is also the preferred mortar mix for soft stone masonry. Cement requirement. course of block in a full mortar bed. Fold the mortar mix from the bottom into the water, when mixing by hand. 6 gage or smaller wires may be laid in 3/8-in. I have 250 sq of old ceramic tile that I have removed in a kitchen and bath. (2 to 3 mm) thick. (12.7 mm) horizontal mortar joints. The terms thinset cement, thinset mortar, dryset mortar, and drybond mortar are synonymous. Four feet is the maximum bed width that can easily be accessed, including 8-inch-thick concrete walls, and 2 feet is the minimum path width that is comfortable to traverse. Choose the correct width of scoop to suit the blocks thickness. 4.2.1 The nominal dimensions of concrete block shall be as follows: … For walls up to 5 metres long there should be no more than a maximum 10mm deviation. The maximum depth you would use a smoothing compound would generally be around out 10mm, you can add aggregates, to bulk up the screed going up to 30, 40, 50+mm. 519.2 Materials 519.2.1 Clay or Shale Brick (1) Conform to ASTM C32, grade MS. For intersecting bearing or shear walls carried up separately: a. I always use sharp sand and cement mix ratio of 5 to 1 cement for patios around 25/30mm. ... And regardless of thickness TCNA F112-15 for bonded mortar beds has a limitation- What … read more. pavers on a plastic, workable mortar bed, and (2) setting the pavers on a cured mortar bed with a thin-set latex-portland cement mortar. Greater of the two values shall be selected. Maximum Mortar Bed Thikness for Concrete Block. The most common mortar joint thickness specified is 3/8 inch. (10 to 32 mm) or one of the following with a minimum shear strength between the thin brick and substrate of 50 psi (345 kPa): - ASTM C270, Type S, mortar modified with latex or other suitable polymers - Modified mortar complying with ANSI A118.4, Latex- The maximum water content is 40 lb (18.1 kg) • 60 lb (27.2 kg) • 80 lb (36.2 kg) 1/2 • 30 kg (66.1 lb) YIELD Each 80 lb (36.2 kg) bag of QUIKRETE Mortar Mix will lay up to 37 standard bricks or 13 standard (8 in by 8 in by 16 in [200 mm by 200 mm by 405 mm]) blocks. When it comes to estimating the mortar needed, a good rule of thumb is that three standard bags will typically cover 100 blocks. The maximum bed joint thickness for reinforced masonry is of 20 mm. b. You can also use our block calculator to calculate other block sizes. Depending on the application requirements, it canbe greater than two and a half inches thick. Brick Most bricks will have anywhere from a quarter inch to a half inch of mortar on the base level that … Actual dimensions (length and depth only) shall be 10 mm short of the nominal dimensions. Supervisor. (203 mm) maximum offsets. So interested here to know what maximum bed joint thickness would be permitted before compressive strength of the mortar might be affected. Mortar Maintenance Issues to be taken into account include: joints. Please enter the dimensions of the wall. The thickness of mortar joints shall be The thickness of mortar joints between bricks is determined by the type of structure that is built. Expert advice on wet mortar will vary, but your full mortar bed should ideally be at a thickness of around 30mm to 40mm. Actual Size 3 5/8 x 7 5/8 x … Remark. The most commonly used concrete blocks are the stretcher blocks with a nominal length of 40 cm (half blocks: 20 cm) nominal height of 20 cm, and nominal widths of 8, 10, 15 and 20 cm. The maximum depth you would use a smoothing compound would generally be around out 10mm, you can add aggregates, to bulk up the screed going up to 30, 40, 50+mm. The building code for weight-bearing brick walls calls for mortar to be no more than 3/8 inch thick. The specially separated scoops ensure a mortar bed of 3 to 4 mm with minimum effort. According to NZS4210:2001 Section 2.7. The maximum mortar bed joint thickness is _____ inch(es). As a result, the maximum allowable thickness of mortar joints is defined in code Section 605.2.11 of the International One- and Two-Family Dwelling Code. the thickness of the wall they create. 85332. 36,621. Masonry blocks 390 x 190 x 190mm. sive strength between the thin Iayer mortar and the unit. Mix the appropriate mortar in a mortar box, then lay a 1-inch thick layer of mortar onto the foundation inside the outline. Most bricklayers comply with the 3/8-inch determination for uniformity of appearance. Then, should concrete blocks be filled? (102 3 or 203 mm) module is maintained with 3/8 in. For a mortarbed, this is not always practical as the typical mortarbed and tile in the minimum thicknessmeasures more than one inch. Those that use cinders (fly ash or bottom ash) as an aggregate material are called cinder blocks in the United States, breeze … Access Can version here. The thickness of the mortar can vary in other types of structures from 1/8 inch to ¾ inch. A typical 30Mpa pre-batched mortar costs £1,000 (€1,100) per tonne at 2017 prices - that's 50 quid (60 Euro) per square metre for the bedding, if you use 50mm thickness. (203 x 203 x 406 mm) concrete masonry unit. (9.5 mm) mortar joints. In this case, mortar joint thickness could be varied from 6.4 to 19 mm to make rooms for the variations of the top of the footing. Minimum thickness of mortar or grout between brick and reinforcement: 1/4 in. b. (25 mm) to accommodate for elevation differences. With tensiIe stressin2 perpendicular to the bed joints, faiIure is generally caused by stresses exceeding the comparatively low tensile bond strength between the bed joint mortar and the unit. To require a mortar with a compressive strength of 30Mpa for a patio, is, quite frankly, taking a break from reality! D&k Building Services. Using a self-furred or lath furring fastener, center the lath near the middle of the mortar thickness. Brickwork and blockwork can be formed as: I am planning to use 20mm thick bluestone pavers. Click to see full answer. Brick and blockwork are materials used in masonry construction, which also include concrete, stone, manufactured stone, timbercrete and glass. Likewise, people ask, how thick should mortar be? Not to be confused with the un-bonded minimum thickness of 1 1/4 inches with reinforcing mesh in the center. Step 2: Dimensions of wall. The mass of the total scratch coat along with setting bed mortar and the faux stone units provides water management through both absorption and evaporation. The up-and -down, vertical joints are sometimes called “perpends” by tradesmen. Return to Guide specifications. 250 mm; twice the maximum projection from the face of the wall. Keep mixing until the water is mixed in. Mortar shall be of the mix proportions necessary to achieve adequate strength and durability and be suitable for the type of masonry. As you can see, there should be a maximum deviation of 10mm in any length of wall up to five metres. Then you need to calculate your concrete block costs; just multiply the number of cinder blocks by the price per single block: concrete block costs = price per block * number of blocks. The code specifies the maximum allowable tolerances for mortar joints in Section 05.2.1.1[i] for load bearing masonry as follows: Bed Joints +/- 1/8 inch (or: 1/4 inch to 1/2 inch) Head Joints -1/4 to +3/8 inches (or: 1/8 inch to 3/4 inch) It is important to note that the code only specifies mortar joint tolerances for load bearing masonry. Thin-bed mortar will arrive onsite with the Shaft Block. Connect2: Use Type M or Type S mortar (ASTM C 270). Corner blocks are laid first and the first course should be completed before second course installation. 1/2 inch. The maximum wire diameter allowed by the masonry code would be one-half of the 3/8-inch mortar joint thickness, or 3/16 inch [TMS 2011 Code: Section 1.16.2.3]. When it comes to estimating the mortar needed, a good rule of thumb is that three standard bags will typically cover 100 blocks. ... (2 Core Concrete Block Units, Full Mortar Bedding) Net Section in. If your floor is level and small you can use 3/4 but if there are high spots that would … Masons rarely use micrometers or a machinist calipers to measure mortar joints. Who, on the job site can actually measure the differen... Walsall • Member since 24 Sep 2018 • 30 jobs, 97% positive feedback. AAC blocks can be laid with conventional thick-bed mortar (approximately 10mm), however the manufacturer’s approved option is a proprietary thin-bed mortar. I've made up a couple of pads to support a old concrete laundry tub. For 9m3 of Mortar; You Must Provide = 9 x 6.33 = 57 bags of cement + allowance for waste as appropriate. You can also purchase pre-mixed bags of mortar, which generally yield around 12 blocks per 80-pound bag. For wider blocks, two or more lines of mortar may need to be applied using a narrow scoop. 2019-06-08T12:30:02+01:00. And maintain a stan-dard 3/8-inch-thick joint. Divide the number of blocks being installed by 33.3 to calculate how many bags are needed. Thin Joint mortar is widely available in the form of 25kg bags of dry, pre-mixed powder. STONE INSTALLATION INSTRUCTIONS 3 SURFACE PREPARATION TABLE 1 And maintain a stan-dard 3/8-inch-thick joint. It makes for dropping the blocks in place and leveling them a bit difficult. The term “thin set” is used to describe the method of installing pavers or slabs with a bonding material that is 1/16 to 1/8 in. ... you need to know the distance between each concrete block. This will make sure that your flag settles at 10mm high (maximum). Reinforced concrete … minimum to 3/4 in. The building code for weight-bearing brick walls calls for mortar to be no more than 3/8 inch thick. After joints are thumbprint firm, they shall be tooled to a tight, smooth concave surface with an approved tool. As a general rule, we use mortar between bricks, stones, blocks etc. I noticed that the original had some pretty wide mortar beds in some places as well. Regarding head joints, variations from +9.5 mm to -6.4 mm are permitted for instance the designated thickness of 9.5 mm can be varied from maximum of 19 mm to minimum thickness of 3.2 mm. Joint width shall be 3/8″ inch, 1/2″ for slump block. The thickness of the mortar can vary in other types of structures from 1/8 inch to ¾ inch. Standard mortar requires a 1:3 cement to sand mix, which amounts to 1 yd 3 of sand for every seven bags of cement. My concern is that the mortar bed is too "thick" and won't be as strong as a thinner … The structural element is the wall panel. That element has been tested for decades and the mortar bed is just a small element for myopic analysis.... (6.4 mm) bars may be laid in 1/2-in. 1/4 - in. 1/16" bed of water-repellent mortar. If necessary, set the first post block on a mortar bed at a maximum thickness of 1 in. 519 Brick Masonry and Concrete Brick or Block Masonry 519.1 Description (1) This section describes furnishing and laying brick or concrete brick or blocks in cement mortar beds to construct manholes, inlets, or other similar drainage structures, or parts thereof. Minimum width of collar Joints containing both horizontal and vertical reinforcement: A dry thin bedding mortar comprises a dense stone aggregate and a porous water-absorbent light aggregate, the maximum aggregate particle size corresponding to the joint thickness and the dense stone making up \-85 vol.% of the total aggregate. 200 mm, or twice the maximum offset in a stepped footing. Stop mixing when the mortar is wet enough to slip easily off the shovel but holds its shape if you make a hollow in the mix. While I am happy to use builders glue on the pads which I made up using 2 old concrete besser blocks and a cheap paver top and bottom I want a weak mortar to level them out as the concrete driveway isn't perfectly flat. Keep adding water until the mortar attains a smooth consistency. After the poured foundation has fully cured and hardened, mark an outline for the cement block wall onto the surface of the foundation, using a chalk line. It is considered to be a general-purpose mix, useful for above grade, exterior, and interior load-bearing installations. Mortar should extend fully across bedding surfaces of hollow units for the thickness of the face shell, so that joints will be completely filled. In my 40 years experience in masonry, I have never seen the need for a mason to cut down a block or two.... They are identified by their depth – i.e. The [IS 2185 (Part 1) :2005 term nominal means that the dimension includes the thickness of the mortar joint. Traditionally mortar joints are 10-12mm but ive seen upto 20mm but would never recommend that thick.. more modern building practices can achieve 2-3mm thin joints but uses a special mix.. Anyways how old is the house? The base is the concrete foundation on which the house is built on. A list of the standard size of CMUs can be helpful if you have any questions about the project or the mortar joint. (6.4 mm), except: a. Interlocking Concrete Pavements Guest User May 12, 2020. Divide the number of blocks being installed by 33.3 to calculate how many bags are needed. They are held together with mortar as the bed and binding material. Unless otherwise required or indicated on the project drawings, head and bed joints shall be 3 / 8 inch (9.5 mm) thick, except that the thickness of the bed joint of the starting course placed over foundations shall be not less than 1 / 4 inch (6.4 mm) and not more than 3 / 4 inch (19.1 mm). 1.3 the thickness of a mortar bed, cross or perpend joint should be 10mm +/- 3mm. You can also purchase pre-mixed bags of mortar, which generally yield around 12 blocks per 80-pound bag. Installing 18" x 18" Tavertine over previously used back board. The consistency of the mixed thin-bed mortar should be such that it flows easily through the teeth of the notched trowel leaving the shape of the teeth in the mortar bed. Bricks and blocks (CMU) are designed to have a 3/8″ mortar bed between units. Actual thickness may vary due to Mason’s quality or “stretching” to meet a non-modular dimension. . 2 /' in. Type N mortar mix has a medium compressive strength and it is composed of 1 part Portland cement, 1 part lime, and 6 parts sand. Masonry. 6 5 4 3 1 2. In this case, mortar joint thickness could be varied from 6.4 to 19 mm to make rooms for the variations of the top of the footing. Regarding head joints, variations from +9.5 mm to -6.4 mm are permitted for instance the designated thickness of 9.5 mm can be varied from maximum of 19 mm to minimum thickness of 3.2 mm. Standard mortar requires a 1:3 cement to sand mix, which amounts to 1 yd 3 of sand for every seven bags of cement. Lay out the block, making sure to leave a 3/8 inch gap between the blocks to allow for the vertical mortar joints (i.e., a typical 8x8x16 block is actually 15-5/8 inches long and 7-5/8 inches high to accommodate the mortar joint). Airtec Aerated block walls can be constructed using either conventional 10mm mortar joints with mixes as shown in the table above or using 2mm Thin Joint mortar. Actual Size 3 5/8 x 7 5/8 x 7 5/8 Nominal Size 4 x 8 x 8. Head and bed joints are typically ⅜ in. The rest of the wall can be laid with face-shell bedding only, except where cores will be grouted solid. There is a 10% allowance for wastage of both bricks/blocks and mortar included in this calculation. Concrete Block (CMU) Sizes. It is definitely an aesthetic question. Use Type M or Type S mortar (ASTM C 270). For example, 3/4-inch-wide mortar bed joints produce only half the flexural strength and compressive strength of 3/8-inch-wide mortar joints, according to … Cancel Next Note: The standard thickness of a mortar joint is 10mm. After joints are thumbprint firm, they shall be tooled to a tight, smooth concave surface with an approved tool. Mortar should be discarded if it shows signs of hardening or if 2 ½ hours have passed since the original mixing. Durability: M4 Exposed/Coastal Cement 1 part : Lime 0 -0.25 part : Sand 3 parts M3 Exterior/Inland Cement 1 part : Lime 0.50 … Mix approved AAC thin-bed mortar in a clean mixing container (5-gallon bucket or pail) per manufacturer's directions. Making allowance for shrinkage between fresh and wet concrete = 1.54 x 205.71 = 316.79 kg. maximum is achieved for Post block must be placed level and plumb in all directions. MMinimum External plaster thickness 12 to 15mm. Dimensions and Mix Proportions: 625 x 200/100 x 250 (L X B X H) mm thick Autoclaved Aerated Block masonry with cement mortar 1:6 / Adhesive (jointing mortar) as prescribed as per Manufacture specification. For good construction, the the mortar bed thickness is not critical, since the intent is to be a structural element (a wall) that is... Access US version here. Some of them have a face that is 7 13/16 and a back side of slightly less than 7 5/8, while others are 7 5/8 on both sides. Use our concrete block calculator to work out the total wall area, number of blocks required and total cost of the project. Provisions for the mortar joint thickness, t j, in masonry walls can be found in structural codes, see Table 1.Some codes, e.g., the Swiss Masonry Code SIA 266 and the European Masonry Code EN 1996-1-1 , only give an allowable range for the joint thickness.However, the Building Code Requirements and Specifications for Masonry … Bonded Screed Maximum Depth. Reading time: 1 minuteMinimum thickness of concrete slab, beam, column, foundation and other structural members is selected to meet the design requirements as per standard codes. ... and solid lightweight aggregate concrete blocks (LAC). I recommend width of head joints be a minimum 1/4 inch to permit proper tooling and a maximum 3/4 inch to limit shrinkage cracking.The width of bed joints does have a significant effect on wall strength. UNIT MASONRY/CONCRETE In sequence: (1) mortar applied directly to untreated, unpainted masonry, concrete or stucco, (2) Cultured Stone manufactured stone ... mortar setting bed, (5) Cultured Stone manufactured stone veneer, (6) mortar joint. The rest of the wall can be laid with face-shell bedding only, except where cores will be grouted solid. Then you need to calculate your concrete block costs; just multiply the number of cinder blocks by the price per single block: concrete block costs = price per block * number of blocks. This thick mortar bed will level in-corrections of the sub foundation. Regularly block vertical joint with 8-in. The maximum misalignment of bed joints is 1.25 inch, the clearance between the connecting parts cannot exceed 1/16 inch and the pintle ties must be 3/16 inch diameter. Keeping the basement dry in. Tile set by the thinset method is adhered to the substrate with a thin layer of "thinset" cement. With this method, the procedure of laying the blocks is more like gluing than conventional brickwork construction. 2. Control of expansion joint shall be continuous through the mortar and masonry, at a … 4. A joint thickness of up to 20mm may be accepted on the bottom course to accommodate any slab level issues. SUPPORT There are 2 solutions : • Pour a concrete strip footing for the new wall • Use ready made concrete strip footing blocks INTERIOR Existing wall Existing foundation HempBLOCK wall Min. When you start any wall-tiling project, the thickness of the cement board really does matter. In masonry with greater tensiIe bond strength between the bed joint Jointing Mortar: Mortar application as per manufacturer recommendation. Minimum mortar thickness for levelling? (10 mm) thick, except at foundations. Bonded Screed Maximum Depth. The building code for weight-bearing brick walls calls for mortar to be no more than 3/8 inch thick. Though, a pro rata tolerance is applicable for walls less than 5m long. The depth of the block out shall be such that a mortar bed thickness of 3/8 in. Load capacity of simply supported concrete slabs. The concrete blocks that are used to build block foundations are hollow. The concrete base of the block out shall have a rough textured finish, such as would be produced by a screed or wood float. Quantity of cement required in bags = 316.79/50 = 6.33 bags. The concrete blocks that are used to build block foundations are hollow. Placing Mortar. This type of cement is designed to adhere well in a thin layer - typically not greater than 3/16th thick. TMS 602-13/ACI 530.1-13 3.3.B Placing mortar and units indicates that a 3/8" (9.5mm)thick bed is anticipated/typical. Figure 1 illustrates nominal and specified dimensions for a nominal 8 x 8 x 16 in. 4-inch CMU . What’s the Maximum Mortar Bed Thickness for Paving Slabs? Table 8-2.-Nominal Lengths of Concrete Masonry Walls in Stretchers Table 8-3.-Nominal Heights of Modular Concrete Masonry Walls in Courses Table 8-4.-Average Concrete Masonry Units and Mortar per 100 sq. Design process includes proper assumption of structural … Plaster. At these locations, mortar the cross-webs too. At these locations, mortar the cross-webs too. Plain concrete. Ready made jointing chemical with 3 to 4 mm thickness or with conventional cement mortar (1:6) ... Lintels should be placed on mortar bed. Tool all the joints concave. I. Imposed loads varies from approximately 1.5 kN/m2 (153 kg/m2) in domestic buildings to approximately 1 0 kN/m2 (1053 kg/m2) in heavy industrial areas. Most bricklayers comply with the 3/8-inch determination for uniformity of appearance. The Tile Council of America Handbook states the thickness of the mortar can be 3/4 if the area is smaller than 100 sf and that the mortar thickness should be 1 1/4 for areas larger than 100 sf. Tool all the joints concave. Joint width shall be 3/8″ inch, 1/2″ for slump block. The thickness of mortar joints is critical to the overall structural integrity of the dwelling. All fi nished joints should be 8–10mm thick. Concrete and masonry chimneys shall be lined with an approved medium-duty refractory brick not less than 4 1 / 2 inches (114 mm) thick laid on the 4 1 / 2-inch bed (114 mm) in an approved medium-duty refractory mortar. Mortar calculator for laying bricks or blocks. c. Keep space free of mortar or other rigid material to permit differential movement between concrete and masonry . The actual ANSI recommendation for a mortar bed bonded to concrete SOG is for a "nominal 1 1/4 inch" thickness, Davy. The lining shall start 2 feet (610 mm) or more below the lowest chimney connector entrance. Minimum thickness of concrete structural elements based on ACI 318-14, IRC 2009, IS 456 2000, and UBC 1997 is presented. Typical mix ratio for mortar (laying of blocks) is 1:6. You’ll need roughly 1 1 / 8 standard blocks per square foot, so multiply the square footage by 1.125 to estimate the total needed. The volume of mortar required = 0.03 x 150 = 4.5 m 3. Installing 18" x 18" Tavertine over previously used back board. 6.1.14 Mortar. (9.5 mm) mortar joints. A108.1A, 5.2.3. A concrete masonry unit (CMU) is a standard-size rectangular block used in building construction.CMUs are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them. This means I will need a 50mm thick mortar bed.