A chimney brick order turns a measured net count into whole packs a supplier can deliver. The measurement guide owns the net count, and the brick and mortar guide owns the product choice. This page does the last step: one order line per wythe and size, a stated waste basis, and a pack count that matches the delivery.
How do you order chimney brick?
Start from the measured net face area, apply the coverage rate of the brick actually being used, add waste on a stated basis, round up to whole bricks, and round up to whole packs. Keep each wythe on its own line through every step, because each wythe has its own perimeter and its own count.
Net bricks = net face area x bricks per ft2
Order bricks = net bricks x (1 + waste / 100)
Packs = order bricks / bricks per pack, rounded up
The Brick Industry Association wall-area method works this way. Its Table 4 gives 675 modular bricks per 100 ft2 at a 3/8 in joint, which is 6.75 bricks per ft2, and 655 standard bricks per 100 ft2, which is 6.55 bricks per ft2. Those table values exclude waste and assume running or stack bond, so the waste step still has to follow. The Association states a general rule of at least 5 percent added to net brick quantities for breakage and waste.
A single combined total hides which wythe ran short. A delivery check needs the net count, the waste basis, the order count, and the pack count as separate figures on each line.
What must the order record state before you buy?
Write every field below before placing the order. A missing field becomes a guess at delivery, and a guess cannot be verified.
| Field | What to record | Why it matters |
|---|---|---|
| Product | Clay facing brick, ASTM C216 grade and type, colour, and sample reference | Colour alone does not tell the supplier which grade or type to supply |
| Size, joint, and bond | Specified brick dimensions, joint width, and bond basis | These three set the coverage rate |
| Coverage basis | Bricks per ft2, with its source | A rate without a source cannot be checked |
| Net area and net count | Measured net face area per band, and the net brick count per wythe | Every figure below starts from these counts |
| Waste basis | Waste percentage and what it covers: cuts, breakage, or both | An unstated percentage cannot be audited later |
| Packs | Bricks per pack from the supplier, split-pack policy, and returns terms | Pack rounding creates surplus that must be accepted or refused |
| Lot | Single-lot order where the supplier can supply it | A second lot can shift colour visibly |
Confirm the product before running the order math. The coverage rate belongs to one brick size, and the pack size belongs to one supplier listing. A rate or a pack size carried from another product makes the whole order wrong.
Worked example: the fixture stack at the 5 percent rule
The fixture stack from the measurement guide is 2 ft by 2.5 ft in plan and 7 ft high above the roofline, with a corbelled cap band 2.5 ft by 3 ft in plan and 1 ft high. The main stack gives 63 ft2 and the cap band gives 11 ft2, for a total net face area of 74 ft2. The brick is modular, at 6.75 bricks per ft2.
- Net bricks: 74 x 6.75 = 499.5 bricks, rounded up to 500 bricks.
- Order bricks at 5 percent: 499.5 x 1.05 = 524.475 bricks, rounded up to 525 bricks.
- Pack rounding: the example supplier states 500 bricks per pack. 525 / 500 = 1.05, rounded up to 2 packs.
Result: the order is 2 packs, or 1000 bricks, for a 525-brick need. The surplus is 475 bricks over the order need. That surplus is the cost of whole-pack rounding on a small job, and it belongs on the record before the order is placed, so it is not mistaken for a counting error at delivery.
| Line | Net area | Rate | Net bricks | Waste | Order bricks | Buy |
|---|---|---|---|---|---|---|
| Outer wythe, modular brick | 74 ft2 | 6.75 per ft2 | 500 | 5% | 525 | 2 packs |
The 500 bricks per pack figure is an example supplier figure for this calculation only. It is not a standard. The supplier quote sets the real figure for a real order. Where the supplier splits packs, the same order need buys 525 bricks exactly, with no pack surplus. Ask about the split-pack policy before rounding, because it changes the delivered quantity on a small stack.
The metric check matches. 74 ft2 converts to 6.8748 m2, and 6.75 bricks per ft2 converts to 72.66 bricks per m2, which returns the same 499.5 bricks before rounding.
What if the stack has two wythes?
Give each wythe its own line, with its own perimeter, area, net count, waste, and pack count. A wythe is one brick thickness of the stack wall. The inner wythe has a smaller perimeter than the outer wythe, because it sits inside the outer wall thickness. Doubling the outer wythe order count overstates the inner wythe, and ordering only the outer count leaves the inner wythe short.
Run the same three steps for the inner wythe: measure its faces, multiply by the rate for the brick size used in that wythe, add waste on the same stated basis, and round up to whole packs. The two lines may share a product and a waste basis, and they still stay separate, because their areas differ. Where the inner wythe uses a different brick, its rate line changes too, and the size on each line has to be the size the measurement used.
Does a higher allowance change the order?
Sometimes it changes the count, and sometimes it changes nothing. Check the allowance against the pack size before buying, so a change at the supplier does not surprise you.
| Waste basis | Order bricks | Packs at 500 per pack |
|---|---|---|
| 5%, the Association general rule | 525 | 2 |
| 10%, a buyer-chosen figure | 550 | 2 |
At 10 percent, 499.5 x 1.10 gives 549.45 bricks, rounded up to 550 bricks. That is 25 more bricks than the 5 percent order, and still 2 packs at the example pack size. The allowance changes the count here, and the pack count stays the same. The 10 percent figure is a buyer-chosen margin for this check only. No source in this pack sets 10 percent as a chimney rule, and the Association figure used for the order is at least 5 percent.
The same 74 ft2 at the standard brick rate of 6.55 bricks per ft2 gives 484.7 bricks, so 485 bricks net, and 509 bricks at 5 percent. Record the brick size before applying any rate, because the rate follows the size.
Worked example: the sloped-roof stack
The sloped-roof fixture from the measurement guide has a net face area of 58.5 ft2, measured face by face. The brick is modular, at 6.75 bricks per ft2.
- Net bricks: 58.5 x 6.75 = 394.875 bricks, rounded up to 395 bricks.
- Order bricks at 5 percent: 394.875 x 1.05 = 414.61875 bricks, rounded up to 415 bricks.
- Pack rounding: 415 / 500 = 0.83, rounded up to 1 pack.
Result: the order is 1 pack, or 500 bricks, for a 415-brick need. The surplus is 85 bricks. The smaller stack rounds to a single pack, while the taller fixture stack rounds to two. The pack count follows the order need and the supplier pack size, and it cannot be guessed from the stack height alone.
Chimney brick ordering mistakes
- Ordering the net count with no waste, then running short on cuts and breakage.
- Applying waste before the net count is checked, so the waste covers a wrong figure.
- Doubling the outer wythe count for a two-wythe stack instead of measuring the inner wythe.
- Changing the brick size after the stack has been measured, so the rate no longer holds.
- Ordering by colour alone, with no grade, type, or size on the order.
- Carrying a rate or a pack size from another product or supplier.
- Rounding the combined total instead of rounding each wythe line up separately.
- Accepting a pack surplus without recording it, then disputing it at delivery.
- Ordering a second lot for the shortfall, and getting a visible colour shift.
- Counting mortar, the flue liner, or the crown in the brick pack count.
What this order does not cover
The brick order covers facing brick for the outer stack only. Mortar follows its own specification and supplier quantity, the flue liner follows its own specification, and the crown or cap slab follows its own specification. None of those quantities appears in the brick pack count, and no mortar bag count is given here, because no source in this pack publishes one for this stack.
Safety and professional scope
Ordering brick plans materials only. It does not design the chimney, size the flue, set the chimney height, or approve a rebuild or repair. Those decisions rest with the project's design team and owner, under the governing code and the project specification.
Work on a chimney stack needs safe access and fall protection. Do not climb onto a roof or lean over an edge to check a stack without the access and protection the job requires.
Sources and scope
- Brick Industry Association, Technical Note 10, Dimensioning and Estimating Brick Masonry, February 2009: modular brick nominal 4 by 2-2/3 by 8 in, 3/8 in joint, 675 brick per 100 ft2; standard brick 3-5/8 by 2-1/4 by 8 in, 3/8 in joint, 655 per 100 ft2; Table 4 values exclude waste and assume running or stack bond; brick breakage and waste, as a general rule at least 5 percent added to net brick quantities. Accessed 2026-10-26.
- NIST Handbook 44, 2026, Appendix C: square-foot to square-metre relationship for the worked-example conversion. Accessed 2026-10-26.
Scope: the Association record supports the stated coverage rates and the at-least-5-percent waste rule. The worked examples use calculation fixtures, not project quantities. The 500 bricks per pack figure is an example supplier figure, and the 10 percent allowance is a buyer-chosen figure for the sensitivity check; neither is a standard. No universal waste factor above the Association minimum, pack size, price, mortar quantity, flue size, or chimney-height figure is given, because no source in this pack publishes one for this job. No rate or pack size is carried to another product.
Review responsibility: Saleem Sial owns the published calculation, source, and editorial checks. Waseem Sial, External Reviewer and Engineer, remains listed for ongoing external review; no completed external-review date is claimed.
Next, measure the job with How to Measure for Chimney Brick: Stack Faces, Bands, and Net Area, choose the brick and mortar with Choosing Brick and Mortar for a Chimney Stack, check sizes and rates with Brick Sizes and Coverage, or run the count with the Brick Calculator.
