The Unit, Measured Cold
A brick is a module before it is a lump of fired clay. The number in the specification is nominal — it already contains the joint. A modular clay unit in North America is called 8 by 2-2/3 by 4 inches because the unit plus a 3/8-inch joint adds up that way, three courses to eight inches vertically, while the thing in your hand measures nearer 7-5/8 by 2-1/4 by 3-5/8. Metric standard format behaves identically: a 215 by 102.5 by 65 mm brick plus a 10 mm joint gives a 225 by 75 mm module, four courses to 300 mm. Every setting-out decision downstream comes from that arithmetic, and it collapses the moment the bed drifts a couple of millimetres a course.
Dimensional variation lives in the unit as much as in your trowel hand. ASTM C216 Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale) and ASTM C62 Standard Specification for Building Brick (Solid Masonry Units Made from Clay or Shale) sort clay units by permissible variation and by chippage; BS EN 771-1 Specification for Masonry Units — Clay Masonry Units does the same work through declared tolerance categories, and concrete units answer to ASTM C90 Standard Specification for Loadbearing Concrete Masonry Units. On the deck that means two packs from different firings can differ enough in size and shade to read as a stripe across a gable. Draw from three or four packs simultaneously, all day, every day, and never let a bricklayer work a pallet out before opening the next.
Suction decides whether bond forms at all. A dry, thirsty clay unit pulls water out of the bed before the cement has anything left to hydrate with, and the result is a joint that looks perfect and has almost no tensile bond across it. ASTM C67 Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile gives the initial rate of absorption test; the threshold above which units get wetted before laying is set by the project specification and by regional guidance, so read the spec rather than guessing from the last job. Wetting means docking — surface damp, no free water, the sheen gone off before the unit meets mortar. A saturated brick swims on the bed, bleeds fines down the face, and takes the whole lead out of plumb by the time you have laid six.
Suction is the only property in this heading a bricklayer can put a number to before laying, and the one-minute absorption test settles wetting policy before the gang forms an opinion about it.
The brick's weight before the absorption test.
The brick's weight after 1 minute of partial water immersion (per ASTM C67 procedure).
The actual bed surface area of the brick tested.
Initial Rate of Absorption
15 g/min/30in²
Within the typical range where pre-wetting usually isn't required, though local practice and mortar type can still call for it in some conditions.
- Mass absorbed
- 15 g
They open the calculator with your figures already in it
Brick Initial Rate of Absorption (IRA) Calculator: 15 g/min/30in² — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Add the equipment this sizes
This result is a specification — 15 g/min/30in² — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
What this calculation does not cover
- One specimen, one number. ASTM C67 works from a set of units and an average, and suction varies from brick to brick within a pallet and considerably more between deliveries — this result does not describe the rest of the load.
- The calculator sees two masses and an area and nothing else. It cannot tell whether the specimen was genuinely oven-dry and cooled, whether the water was held at the standard depth for the full minute, or whether the wet face was blotted before weighing, and each of those moves the mass gain.
- The test area is used exactly as typed. Nothing checks that it is the bed face you actually stood in the water, or that cores and frogs are treated the way your specification treats them — and leaving the field on the 30 in² (194 cm²) reference for a brick whose bed face is smaller than that understates the result.
- Only high suction is flagged. A very low IRA — dense engineering or glazed units that take up almost nothing — is its own problem: mortar that stays wet, stiffens slowly and lets the units float and bleed down the face. The calculator also does not say how long to dock a thirsty brick, and an over-wetted, streaming brick is worse on the bed than a dry one.
- IRA is a wetting-policy number, not a performance rating. It does not predict bond strength, and it says nothing about rain resistance, freeze-thaw durability, efflorescence or compressive strength — those are separate tests. The 30 g/min/30in² line is common practice rather than a code requirement, so where a project specification sets the threshold, that governs; a European specification written to BS EN 772-11 asks for a water absorption coefficient measured and reported differently, and this figure is not that value.
The Bed It Sits On
Mortar is neither glue nor concrete. Its job is to bed an irregular unit, seal the plane, and let the wall move a little without cracking the units. ASTM C270 Standard Specification for Mortar for Unit Masonry sets out Types M, S, N and O and permits specification either by proportion or by property — never both at once, because the two routes contradict one another on site and the supplier will pick whichever suits him. Reaching for a stronger mortar than the design calls for is the routine error: a hard mortar in a soft brick wall drives cracking through the units and into the face, and a spalled face cannot be repointed back.
Sand grading does more visible work than the cement does. ASTM C144 Standard Specification for Aggregate for Masonry Mortar covers it, and a poorly graded sand makes a harsh, unworkable mix that the gang fixes by adding water, then fixes again by adding cement, and the joint colour walks across the elevation from bay to bay. Batch by measured volume — gauge boxes, not shovel counts — and hold the same sand stockpile and the same water target from the first lift to the last.
Board life governs the pace of the day. Mortar is commonly required to be placed within roughly two and a half hours of initial mixing, with the exact window and the retempering rules coming from the governing specification; past that it is spoil, whatever it still looks like. Spread only the bed you can lay into before it stiffens — three or four units ahead in warm weather, more in cool — and furrow lightly if at all, because a deep furrow leaves a channel down the middle of the bed that fills with water and does its damage the first time the wall freezes.
The Perpend Nobody Sees
Head joints fail far more often than bed joints because gravity is working against you rather than for you. The unit gets buttered standing on end, pushed up tight, and the mortar has to hold its shape while the next one arrives. Full perpends are what the specification asks for, and slushing mortar down into the gap afterwards does not produce one — it produces a plug at the face with a void sitting behind it, which is worse than an honest open joint because nobody can see it.
Voids in perpends are a water path, an air path and a sound path at once. In a drained cavity they hand rain straight onto the back of the outer leaf and load the tray with more water than the weeps were sized for; in single-leaf work they explain why a nominally solid elevation wets through in a driving storm on one exposure only. Field testing to ASTM C1601 Standard Test Method for Field Determination of Water Penetration of Masonry Wall Surfaces very often traces leakage to head joints and to the interface between joint and unit rather than to the units themselves.
Tooling is compaction, not decoration. A concave iron run when the mortar is thumbprint hard presses the surface tight against the arris and closes the shrinkage gap that opens as the joint stiffens; too early and you smear laitance across the face, too late and you burnish a joint that has already begun to set, which then cracks along its edge. Raked and recessed profiles cut the effective cover over the bed and are a poor choice on an exposed elevation no matter how well they photographed on the sample panel.
Bond: What the Lap Actually Does
Lap is structure, not pattern. Half bond puts each perpend over the middle of the unit below, so a point load spreads sideways through the courses instead of running down a continuous vertical seam. Longer units take third bond for the same reason. Stack bond has no lap whatsoever, which is why the code treats it as a separate case and calls for continuous horizontal joint reinforcement — ASTM A951/A951M Standard Specification for Steel Wire for Masonry Joint Reinforcement covers the wire, with the requirement itself coming from TMS 402/602 Building Code Requirements and Specification for Masonry Structures or the local equivalent.
Set the course out dry before anything is bedded. Run the first course along the footing or the damp-proof course with the perpend gaps gauged, corner to corner and past every reveal, then shift the whole run if that kills a sliver cut at a window jamb. A wall that arrives at an opening needing a thirty-millimetre (1-1/4 in) slip of brick will display that slip for the life of the building, and it will be the first joint on the elevation to leak.
Traditional bonds change the count as much as the appearance. English and Flemish bond bring headers through the wall and demand closers at every quoin; a veneer imitating them uses snapped headers, which doubles the units cut and lifts breakage sharply. Decide bond before the take-off rather than after, because header courses, closers and returns are the whole difference between a comfortable waste allowance and running short on the last elevation with the scaffold already struck.
One Course, Multiplied
Corners come first and everything else obeys them. Build the leads racked back, plumbed on both faces, gauged off a storey rod that already carries the damp-proof course, sill, head, lintel bearing and eaves marks — then fill between them to the line. A lead built one course out of gauge multiplies that error into every unit between it and the next corner, and the fix is demolition rather than adjustment.
Line and pins hold the plane, provided the line itself is not sagging. Use a tingle plate at midspan on a long run, keep the line just clear of the face so units are laid to it rather than pressed against it, and check the middle of the run with a level instead of trusting the string. Plumb, level and alignment tolerances are tabulated in the governing specification — quarter-inch-in-ten-feet territory in the American documents, about 6 mm in 3 m — and a wall that genuinely meets them still reads straight in raking evening light, which is the test that matters to the client.
Quantities fall out of the same module the gauge came from. Face size plus joint thickness gives the units in a square metre or square foot; joint thickness and unit depth govern how much mortar a thousand units will drink. Cutting waste is pure geometry — openings, returns, rakes, and any bond that snaps headers — with breakage from handling and site cutting sitting on top of it. Take off elevation by elevation rather than as one lump, because that is how material actually gets ordered and how a shortfall on the last gable gets caught while there is still time to order in.
Work the unit count, joint allowance and mortar volume for each elevation from the face dimensions and joint thickness you have just set on the gauge rod.
SettingsSettings for this calculation
The standard allowance most suppliers and estimating guides assume for ordinary work.
The length of the brick wall or veneer.
The height of the brick wall or veneer.
Extra bricks for cuts, breakage, and corners.
The actual (not nominal) length of your brick face, before adding the mortar joint.
The actual (not nominal) height of your brick face, before adding the mortar joint.
The thickness of the mortar joint between bricks, both horizontally and vertically.
The brick's depth, which becomes the wythe thickness for a single-wythe veneer wall.
Estimated brick needed
1,177 bricks
- Wall area
- 156 sq ft
- Coverage rate (from your dimensions)
- 6.86 bricks/sq ft
- Base brick count (no waste)
- 1,070 bricks
- Mortar mix needed
- 14 x 80 lb bags
They open the calculator with your figures already in it
Brick Calculator: 1,177 bricks — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
What this calculation does not cover
- Openings and returns are not in the geometry. The count treats the wall as one plain rectangle of face area, with nothing deducted for doors, windows, vents or reveals and nothing added for corners, returns or piers. Take openings out of the length and height you enter before you read the answer.
- It counts one wythe of brick laid flat, showing its long face. A second wythe or cavity leaf, header courses and rowlock bands, and any bond that turns bricks to show their end all put more units in the same area than this returns. Brick depth changes the mortar figure only, never the brick count.
- The mortar figure is joint geometry, not a mix design. It is the volume of the bed and head joints implied by your joint width and brick depth, converted at one premixed bag's published yield; it excludes the collar joint between wythes, droppings and board waste, and it assumes every joint is solidly filled. It does not proportion cement, sand, lime or water for a site-batched mix, and it does not pick a mortar type for your exposure.
- Nothing but brick and bagged mortar is counted. No wall ties, weep holes or vents, lintels, DPC, flashing, movement joints or reinforcement, and no bedding for sills and coping.
- This is a quantity take-off, not a structural design. It says nothing about wall thickness for the height, lateral restraint, wind or retained load, foundations, or the mortar strength the exposure demands. A freestanding, retaining or loadbearing wall needs those from the building code or an engineer.
The Hollow Unit's Arithmetic
Concrete block rewrites the rules of the bed. Standard practice beds the face shells only, so mortar sits on two narrow strips and the cells run continuous top to bottom — except at the starting course and wherever grout has to be contained, where the webs get bedded as well. Nominal 8 by 8 by 16 inch and 440 by 215 mm units both carry the joint inside the module exactly as brick does, and a block wall that wanders off gauge will fight every bond beam, every bearing and every opening head above it.
Cells only earn their keep if they line up. Reinforced cells have to stack cleanly from the dowel out of the footing to the top of the pour, and a course laid a half-unit out of bond puts a web precisely where the bar wants to be. Cleanouts at the base of grouted cells let you clear debris and dropped mortar before grouting begins; TMS 402/602 Building Code Requirements and Specification for Masonry Structures governs when they are required, along with pour and lift heights and the consolidation regime, and those limits vary with the grout space and the grout type rather than being one number you can memorise.
Grout is neither mortar nor a lean concrete. ASTM C476 Standard Specification for Grout for Masonry covers it, and it is deliberately fluid because it must flow into a narrow cell and fully around a bar — the units absorb the surplus water afterwards, which is why a high slump here is correct rather than sloppy. Consolidate each lift with a vibrator and reconsolidate after initial water loss, otherwise you leave voids exactly where the bar needs cover. Dam the cell beneath a bond beam with a grout stop or wire mesh so the pour does not run away down the wall, and count every knock-out and lintel block on the drawing, because bond beam volume is what a plain cell count always misses.
Count the block, then the cells that actually take grout — reinforced cells, bond beams and any solid-grouted zones — before the ready-mix order goes in.
SettingsSettings for this calculation
Waste is set to 5% by hand. Pick a tier above to replace it, or keep your own figure.
The length of the CMU wall.
The height of the CMU wall.
The actual (not nominal) face length of your CMU block.
The actual (not nominal) face height of your CMU block.
The mortar joint thickness between blocks.
Extra blocks for cuts and breakage.
The hollow cavity volume per block, from the manufacturer's spec sheet.
The percentage of cells that will be filled with grout.
Courses laid in bond-beam units and grouted solid, within the wall height above.
CMU blocks needed
185 blocks
Grout volume assumes uniform void geometry across all cells — face-shell-bedded (ungrouted) cells and webs reduce the actual grout consumption if only some cells are filled.
- Wall area
- 156 sq ft
- Coverage rate (from your dimensions)
- 1.12 blocks/sq ft
- Grout volume needed
- 394.87 gal
- Mortar volume (face-shell bedding, joints only, no waste)
- 16.83 gal
They open the calculator with your figures already in it
Concrete CMU Block Counter & Grout Infill Calculator: 185 blocks — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
What this calculation does not cover
- Block count is gross wall area divided by one block's nominal face. Openings are not deducted, and nothing is set aside for the half, corner, lintel or sash units a real course layout needs. Bond-beam courses you enter are named inside the count, not added to it, and cut to the whole courses the wall height holds: a 2.4 m (7 ft 10½ in) wall of 8 in (203 mm) courses holds 11. Every other block is a plain stretcher.
- The grout figure is the theoretical void volume with no waste allowance of any kind. Mortar squeezing into the cells reduces it; spillage, overpour, cleanout blocks and lintel courses filled solid increase it. The waste factor you enter moves the block count only, never the grout.
- Grouted cell fraction is applied as a flat percentage of the void volume of every block that is not in a bond-beam course. It does not know which cells your drawings call for or where the vertical bars land — a 50% entry is an average, not a layout. Bond-beam courses are grouted solid only if you enter them; at 0 a partially grouted wall's bond beams are grouted at the same fraction as everything else.
- One void volume is applied to every block in the wall, bond-beam units included. A knock-out bond-beam unit holds more than a stretcher's cores, because the webs are cut down to form the channel: NCMA's preblended-grout yield for an 8 in (203 mm) bond beam, 2.0 ft (0.61 m) of beam per 80 lb (36.3 kg) bag of about 0.66 ft³ (19 L), is about 12.5 L (0.44 ft³) a unit against the 8.5 L (0.30 ft³) default, so the bond-beam share is a floor. Mixed units in the same wall — a thicker base course, half-high or solid bottom units, two-core against three-core block — are not handled; run those areas separately.
- The mortar row is the joint volume only: bed and head joints on the two face shells, at the joint width you enter and a fixed face shell of 32 mm (1¼ in), for the blocks before waste. It is not an order. Beds spread wider than the shell, mortar lost into the cores, droppings and mixer tails all come on top. NCMA TEK 4-2A's site-mixed rules of thumb, 4¼ to 4½ ft³ (0.12 to 0.13 m³) of sand for 46 to 62 units and a ton (907 kg) of sand for 240, come to about 2 to 3 L (0.07 to 0.1 ft³) of sand a block, and a batch yields roughly its sand volume in mortar: about five to eight times this row at the default joint. Its preblended rule, one 80 lb (36.3 kg) bag for about 16 units, is given in bags, not volume. A first course in full bedding, and any wall laid with the webs mortared, take more again.
- This is a quantity take-off, not a masonry design. Which cells must be grouted, the grout strength and lift height, the reinforcement, and whether the wall carries its load all come from the structural drawings and the governing masonry code. Nothing here checks any of them.
Water, Ties and the Right to Move
A cavity wall works by draining, not by resisting. Flashing at the base of the cavity and at every interruption — sills, heads, shelf angles — collects water and discharges it through weeps whose spacing and form come from the governing building code rather than from habit carried off the last job. Mortar droppings on that flashing dam it, and a dammed tray means a wet inner leaf. Bevel the bed away from the cavity, run a cavity batten or a mortar collection device, and clear the tray before the scaffold lift rises past it, because afterwards it is inaccessible.
Ties carry the leaves together and carry water apart, and they do neither if they are installed carelessly. Full embedment into both beds, the correct fall to the outer leaf where the tie type calls for it, no mortar bridging along the wire, and spacing and type per code — BS EN 845-1 Specification for Ancillary Components for Masonry covers the components in the European system, TMS 402/602 in the American. Ties pushed in after the bed has stiffened, bent up over a course, or resting on a dry joint are worth nothing structurally and are entirely invisible once the wall is closed.
Clay and concrete move in opposite directions, which is the single most useful fact to carry onto a long elevation. Fired clay takes up moisture after it leaves the kiln and grows, permanently and slowly; concrete block cures and shrinks. Clay brickwork therefore takes expansion joints and concrete masonry takes control joints, the two are not interchangeable, and their positions — at offsets, at changes of height, near corners, at large openings — belong on the setting-out before the first course goes down. Nothing done at day thirty inserts a joint that was needed on day one.
A cavity wall, taken apart
- Outer clay leaf — the rain screen, not the waterproof layer; unit count and mortar volume both come off the module of face size plus joint Brick Calculator
- Drained cavity — kept clear so water reaching the back of the outer leaf runs down onto a tray and leaves through weeps spaced to the governing code Cavity Wall Weep Hole Spacing Calculator
- Wall ties — bedded in both leaves and useless if pushed into stiffened mortar; quantity follows wall area against the coverage the code permits Brick Veneer Wall Tie Density Calculator
- Cavity insulation — boards held tight to the inner leaf so the residual cavity in front of them stays open and drainable, ordered by area and board thickness Foam Board Insulation Calculator
- Blockwork inner leaf — carries the load and the airtightness line; block count and any grouted cells are a separate take-off from the brickwork in front Concrete CMU Block Counter & Grout Infill Calculator
Tie quantity comes off wall area against the code's coverage limit, and settling it before the leaves rise matters because a tie remembered afterwards gets pushed into a joint that has already stiffened.
The total brick veneer or cavity wall area.
Whether the site is in Seismic Design Category D or higher, or subject to wind pressure over 30 psf.
Wall ties needed
83 ties
This gives total tie count based on area coverage — additional ties are required within 12 in (305 mm) of openings and other discontinuities, and around every 3 ft (0.91 m) along their perimeter, beyond the uniform-field count calculated here.
- Wall area
- 220 sq ft
They open the calculator with your figures already in it
Brick Veneer Wall Tie Density Calculator: 83 ties — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
What this calculation does not cover
- This is a uniform-field count taken from the gross area you type. It does not deduct window and door openings, and it does not add the extra ties required around opening perimeters or at other discontinuities — those are additional to the figure shown.
- The 2.67 sq ft (0.25 m²) and 2 sq ft (0.19 m²) coverage limits are US IRC/IBC figures. UK, European and Australian masonry standards set tie density on a different basis, so this count does not stand in for a design to those documents.
- It counts ties by area coverage only. It is not a structural design and does not check tie type, embedment, cavity width, the backup wall, or the fixings holding the tie to it. Where an engineer has specified a tie schedule, that schedule governs, not this number.
- The seismic/wind switch is a two-state choice you make. The calculation does not read your site's seismic design category or design wind pressure, and there is no band between the two coverage limits.
- It returns a total, not a layout. Setting the ties out on a grid that satisfies the coverage limit and the separate maximum horizontal and vertical spacings is a further step, and the figure carries no allowance for spares or ties lost during the lift.
What the Wall Remembers
Weather bounds the working day at both ends. Cold-weather provisions in the governing specification take effect below a stated ambient temperature and require heated materials, protection, and in the harder cases heated enclosures; hot-weather provisions address the opposite failure, where the bed stiffens before the unit lands and no bond ever develops. Cover the top of unfinished work at every break, not merely overnight — rain entering open cells and unfilled cavities is the origin of most efflorescence that later gets blamed on the sand.
Cleaning down belongs to the build, not to goodwill at handover. Leave droppings until they are hard enough to come away with a trowel and stiff brush instead of smearing, prewet the wall thoroughly so cleaner cannot soak into dry units, follow the unit manufacturer's own cleaning guidance for that product, and rinse properly afterwards. Acid applied to an unwetted wall burns the face, strips cement from the joint surface and can draw metallic staining out of the units themselves — damage no amount of repointing corrects.
Everything about masonry stays legible afterwards, which is the trade's peculiar exposure. A joint tooled too early reads as a grey smear at ten years; a lead built out of gauge reads as a converging line under the eaves; a hollow perpend reads as a damp patch on the inside face of a wall two rooms away from where the water entered. One course laid properly — units blended, bed full and workable, perpend solid, lap honest — is the entire wall, because a wall has never been anything else.
Taking Off One Course at a Time
Fix the module first — unit face size plus joint thickness — then let every quantity on the job fall out of it, elevation by elevation rather than as a single lump sum.
- Unit count per elevation, with cutting waste separated out — Openings, returns, rakes and snapped headers are geometry you can count; handling breakage is an allowance on top and belongs in its own line.
- Mortar volume against the specified joint thickness — Joint thickness and unit depth drive it. If the gang is laying a fatter joint than specified, both the mortar figure and the gauge are already wrong.
- Grouted cells, bond beams and lintel blocks counted separately — A plain cell count misses bond beam and knock-out volume every time; list them off the reinforcement drawing rather than the block schedule.
- Ties, joint reinforcement and movement joint positions marked before the first course — Spacing and type come from the governing code. Positions marked on the setting-out cost nothing; positions discovered at first floor cost a rebuild.
- Unit suction checked against the specification before wetting policy is set — High-suction clay laid dry gives a joint with no tensile bond. Test result and spec threshold decide whether units are docked, not the weather that morning.
Opens the calculators above on one screen with the dimensions from this article already filled in. Quantities only — this site publishes no price list, because local prices vary too much to publish honestly.