Joint and tie requirements quoted from IRC R606.3.1 and R606.13.2
Nearly a fifth of a brick wall is mortar, by the area you are looking at. And the tie rule in IRC R606.13 contradicts itself: the spacing maximum printed beside the area requirement can never be reached.
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Brick dimensions are yours, off the brick, because ASTM C216 is not free to read. The joint and the tie rules are quoted from IRC Chapter 6 as printed in the 2018 Seattle Residential Code.
Specification summary
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Reopen that address to reproduce these figures exactly.
Entered
Result
The grid the area rule gives, and the one the spacing maxima allow
Worked example
A 40 ft by 9 ft wall in 7-5/8 by 2-1/4 in brick with the code 3/8 in joint, one door and four windows.
The module is brick plus joint in both directions. 7.625 + 0.375 is exactly 8.00 in along the wall. Up the wall, 2.25 + 0.375 is 2.63, so three courses measure 7.88 in, not eight. The horizontal direction is modular on this brick and the vertical one is not, which is worth knowing before anybody counts courses off a drawing.
6.86 bricks per square foot, which is 144 divided by 8.00 times 2.63. On 279 sq ft of net wall that is 1,914 bricks, or 2,009 with 5% waste, or five pallets.
18.3% of what you are looking at is mortar. The brick face is 7.625 by 2.25 and the cell it sits in is 8.00 by 2.63, so nearly a fifth of the finished wall is joint. Anybody choosing a mortar colour is choosing a fifth of the wall colour.
62 ties for the field, at one per 4.5 sq ft. Switch to adjustable ties and the same wall needs 105, which is 69% more, because R606.13.2.2 requires one per 2.67 sq ft.
And 31 more ties around the openings, at 3 ft around each perimeter, additional to the field count. Half again on top of the field, from five openings.
The brick count is the number people ask for. The tie count is the number that stops the job when it runs out, and the opening ties are the half of it nobody orders.
The formula
One division, and the denominator is the cell rather than the brick:
bricks per sq ft = 144 / [(l + j) × (h + j)]
l, h
the brick's own length and height, measured, because ASTM C216 is not free to read
j
the mortar joint, which R606.3.1 sets at 3/8 in
(l + j) × (h + j)
the cell one brick occupies, which is what the wall is actually made of
The mortar share falls straight out of the same two numbers: one minus the brick face over the cell. On a standard brick with a code joint that is 18.3%, which is why changing the joint by a sixteenth changes the brick count by about 3% and changes the look of the wall considerably more.
Why there are no brick dimensions on this site
ASTM C216 and C652 set brick sizes, and neither is free to read. So this page will not print a modular figure it cannot cite. It takes the length and height off the brick you are buying, which is a tape measure and ten seconds.
That is not fussiness. Brick sizes vary by manufacturer and by region more than people expect, and a calculator that assumes a nominal module gives a confidently wrong answer on any brick that is not that module, with nothing on screen to say so.
The worked example above shows why it matters. On a 7-5/8 by 2-1/4 brick with the code joint, the horizontal module is exactly 8 inches and the vertical one is 2.63, so three courses are 7-7/8 rather than the 8 that gets quoted. Whether that is true of your brick depends on your brick.
What this page does quote is the code, which is free to read in the form a city publishes it: the joint from R606.3.1, the tie requirements from R606.13.2.1 and R606.13.2.2, and the opening ties from the same section. All of it is here verbatim.
Prices for masonry units and mortar
The published figures for masonry units and mortar are on the block calculator, with the byline, the publication date and the caveats that go with them. They are not repeated here, because the same table on two pages is worth less than one table you can find.
The joint is a code dimension, and the first one is not
Brick coursing is brick plus mortar, and the mortar half is not a matter of taste.
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). Mortar joint thickness for load-bearing masonry shall be within the following tolerances from the specified dimensions: 1. Bed joint: + 1/8 inch (3.2 mm). 2. Head joint: - 1/4 inch (6.4 mm), + 3/8 inch (9.5 mm).
Three eighths of an inch, head and bed. That figure is doing more work than it looks: on a brick two and a quarter inches tall it is 14% of the course height, so roughly one course in seven of a brick wall is mortar rather than brick, before the head joints are counted at all.
The starting course is the exception, and it is a wide one. Not less than 0.25 in and not more than 0.75, which is three times the range of every other joint in the wall. That is deliberate. The foundation is not level, the brick has to be, and the first bed joint is where the difference goes.
The tolerances are asymmetric, which is worth reading twice. A bed joint may be up to an eighth thicker than specified and the code states no minus tolerance at all. A head joint may be a quarter thinner or three eighths thicker. Bed joints carry load and head joints do not, which is the whole of the reason.
Ties are required by area, and the spacing maxima can never bind
Where the facing and backing (adjacent wythes) of masonry walls are bonded with 3/16-inch-diameter (5 mm) wall ties embedded in the horizontal mortar joints, there shall be not less than one metal tie for each 4-1/2 square feet (0.418 m2) of wall area. Ties in alternate courses shall be staggered. The maximum vertical distance between ties shall not exceed 24 inches (610 mm), and the maximum horizontal distance shall not exceed 36 inches (914 mm). Additional bonding ties shall be provided at all openings, spaced not more than 3 feet (914 mm) apart around the perimeter and within 12 inches (305 mm) of the opening.
Where the facing and backing (adjacent wythes) of masonry are bonded with adjustable wall ties, there shall be not less than one tie for each 2.67 square feet (0.248 m2) of wall area. Neither the vertical nor the horizontal spacing of the adjustable wall ties shall exceed 24 inches (610 mm). The maximum vertical offset of bed joints from one wythe to the other shall be 1.25 inches (32 mm).
What each sentence requires, and what its own spacing maxima would allow
Tie
Section
Area rule
Spacing maxima
Which allows
Actual grid
Plain 3/16 in wall ties
R606.13.2.1
4.5 sq ft
24 x 36 in
6.00 sq ft
24 x 27 in
Adjustable wall ties
R606.13.2.2
2.67 sq ft
24 x 24 in
4.00 sq ft
24 x 16 in
The two tie types are not close. A plain tie is required every 4.5 square feet and an adjustable one every 2.67, so the adjustable tie needs 69% more of them. Adjustable ties are the ones that let the bricklayer work independently of the backing, and that convenience is priced in tie count.
And each sentence contradicts itself, mildly. The plain-tie spacing maxima, 24 inches vertical by 36 horizontal, work out at 6.0 square feet per tie. The area rule in the same sentence demands one per 4.5. So the 36 inch horizontal maximum is unreachable: hold the vertical at 24 and the area rule puts the horizontal at 27 inches. The adjustable sentence does the same thing, 4.0 square feet against a required 2.67.
Which means the spacing figures are a ceiling on the grid shape rather than a description of it. Lay ties out on the area and the spacing takes care of itself; lay them out on the spacing and you will be short.
The ties nobody counts are the ones around the openings
The area rule gives a number for the field. R606.13.2.1 then adds a separate requirement that is not proportional to anything:
Additional bonding ties shall be provided at all openings, spaced not more than 3 feet apart around the perimeter and within 12 inches of the opening.
Around the perimeter of every opening, at three feet. A single 3 ft by 5 ft window has a 16 ft perimeter, so it is another six or seven ties on its own, and they are additional to whatever the area rule already asked for over that stretch of wall.
On a house with a dozen openings that is a hundred extra ties, which is not a cost but is very much a delivery: running out of ties at the third window stops the job.
The reason is structural rather than bureaucratic. An opening is a discontinuity, the veneer around it is unsupported on one side, and the wind load that the field sheds into a grid of ties has to go somewhere else at the jamb.
Why there are no brick dimensions on this page
Because they are set by ASTM C216 and C652, and neither is free to read. So the calculator takes the length, height and width off the brick you are actually buying rather than publishing a modular figure it cannot cite. Measure one, or read the box.
That is not a limitation worth apologising for. Brick sizes vary by manufacturer and by region more than most people expect, and a calculator that assumes a nominal module will be wrong on any brick that is not that module, silently.
Read 2026-09-09. 2018 Seattle Residential Code, Chapter 6 Wall Construction, Seattle Department of Construction and Inspections. Prints IRC Chapter 6 in full, including Sections R606.3.1 for mortar joints and R606.13.2.1 through R606.13.2.2 for wall ties. Used because codes.iccsafe.org returns HTTP 403 to any automated request.
Also absent: the air space, the flashing and the weep holes. Anchored masonry veneer has its own section, R703.8, and a veneer wall is a drained cavity rather than a solid one. That detail is what keeps the wall dry and it is not a quantity, so it is not on a calculator page. It is the first thing to ask a bricklayer about.
Frequently asked questions
How many bricks per square foot?
It depends on your brick and your joint, and the honest answer is 144 divided by (brick length plus joint) times (brick height plus joint). On a 7-5/8 by 2-1/4 in brick with the 3/8 in joint R606.3.1 requires, that is 6.86 per square foot. A different brick gives a different number and there is no universal figure.
How thick should a mortar joint be?
Three eighths of an inch, head and bed, per IRC R606.3.1. The exception is the bed joint of the starting course over the foundation, which may run from 1/4 to 3/4 in. That first joint has three times the range of every other one because it is where the foundation's error gets taken up.
How much of a brick wall is mortar?
About 18% of the face on a standard brick with a code joint, and it is worth working out for your own brick because the calculation is two multiplications. It is also why mortar colour is not a detail: a fifth of what you are looking at is mortar.
How many wall ties do I need for brick veneer?
One per 4.5 square feet of wall for plain 3/16 in ties, or one per 2.67 square feet for adjustable ties, per IRC R606.13.2.1 and R606.13.2.2. Adjustable ties need 69% more. Then add ties around every opening at 3 ft spacing, within 12 in of the opening, which are additional to the field count.
What is the maximum spacing for brick ties?
The code prints 24 in vertical and 36 in horizontal for plain ties, but that spacing can never be used: 24 by 36 inches is 6 square feet per tie, and the area rule in the same sentence demands one per 4.5. Satisfy the area and the horizontal spacing lands at 27 in. The spacing figures are a ceiling on the grid shape, not a description of it.
Do I need extra ties around windows?
Yes, and they are additional rather than included. R606.13.2.1 requires bonding ties around the full perimeter of every opening at not more than 3 ft apart and within 12 in of the opening. A single 3 by 5 ft window is another six or seven ties on its own.
Does this calculator cover the air space and weep holes?
No. Anchored masonry veneer has its own section, R703.8, and a veneer wall is a drained cavity rather than a solid one. The air space, the flashing and the weep holes are what keep it dry, and none of them is a quantity, so none is on this page. Ask a bricklayer about them first.
Check these numbers yourself
2018 Seattle Residential Code, Chapter 6 Wall ConstructionSeattle Department of Construction and Inspections. Read 2026-09-09. Prints IRC Chapter 6 in full, including Sections R606.3.1 for mortar joints and R606.13.2.1 through R606.13.2.2 for wall ties. Used because codes.iccsafe.org returns HTTP 403 to any automated request.
How every figure here is verified: Sources & Method. Who builds this: About. Found something wrong? Tell us and it gets fixed or removed.
Figures on this page last checked against the source documents on 2026-09-09. Codes are amended locally; confirm against the edition your jurisdiction enforces.
Brick dimensions are yours, not this site's. ASTM C216 and C652 set them and neither is free to read, so the calculator measures rather than assumes. The code figures quoted here are from one city's adopted IRC and your jurisdiction may have amended them. Air space, flashing and weep holes are in R703.8, are what actually keep a veneer wall dry, and are not quantities, so they are not on this page.