Retaining Wall Block Calculator — Courses and Block Count

Blocks, caps and stone for one garden wall.

Showing US units

Block to buy EXAMPLE56 blocks of Belgard Diamond Pro Air Straight Faceplus 14 caps (18 in long each) of Diamond Pro Air Straight Face Cap, 2 cubic yards (loose) of 3/4-inch minus (with fines) and 3 cubic yards (loose) of 3/4-inch free-draining aggregate

An answer marked EXAMPLE is worked out from the page’s sample values. Type your own over the values marked SAMPLE to make it yours.

ftSAMPLE

Measured from one end of the run to the other, along the face of the wall, one straight run at a time. A wall that turns a corner is two runs; the special units that make the corner are a separate question this page does not answer.

inSAMPLE

Measured from the finished ground in front of the wall to the top of the last course of block, the cap not included. It is not the height the permit rule is measured over: that one runs from the bottom of the footing, here the leveling pad, to the top of the wall, the cap included where there is one, and the result works it out and shows it, because the two are further apart than almost anyone expects.

The permit exemption this page reports is void wherever the wall supports a surcharge, at any height, and a load beyond plain soil drops the engineering trigger lower again. So this is the first question, not a detail.

Every maker publishes its own coverage and its own course height, and they are not interchangeable. Pick what the yard near you actually stocks — the count changes by half again between these, and so does the number of courses a given wall takes.

States what its gravity-wall height figure is measured over, in the same breath as the figure: it includes the buried course.

Not only a finish. A cap sits on top of the wall, so it counts toward the height the permit rule is measured over — one maker prints that as a warning attached to its own estimating chart rather than as a dimension.

The publishers do not agree, and the difference is a third of the base material ordered. Both figures are somebody’s stated minimum, so this page applies the one picked here and names it in the note on the pad under the answer, rather than averaging two numbers neither publisher would sign. The pad is also inside the height the permit rule is measured over, so this is not only a question about how much base material to order.

Starts at 6 in — the minimum the Concrete Masonry & Hardscapes Association prints for a pad under any unit, and what each wall maker on the list prints for its own; Allan Block also allows 4 in under a wall under 4 ft, the other option, and the calculator starts at the larger. Source

Belgard’s installation guide and Allan Block’s residential guide each ask for at least 6 inches (152.4 mm) under their own units, VERSA-LOK about the same under its own, and the Concrete Masonry & Hardscapes Association’s tech note at least the same under any unit — measured after compaction.

Applies to Wall block and Capstones.

Starts at 0 spares — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a spare allowance for wall block or cap units, so the calculator adds none rather than invent one. Each step adds one block and one cap, for a unit broken on the pallet.

Applies to Leveling pad base and Free-draining aggregate.

Starts at 0 spares — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a margin for pad base or drainage stone, so the calculator adds none rather than invent one. Each step adds a whole cubic yard to both stone lines.

Applies to Leveling pad base and Free-draining aggregate.

0%

Starts at 0% — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a margin for pad base or drainage stone, so the calculator adds none rather than invent one. Change it to the share to buy ahead for a trench dug wider than planned.

Block to buy EXAMPLE56 blocks of Belgard Diamond Pro Air Straight Face

Height the permit rule is measured over — from the bottom of the footing, here the leveling pad, to the top of the wall, here the top of the cap Source 3 ft 6 in

Courses of block, the buried one included 4

Cap height, as published for this unit Source 4 in

Capstones 14 caps (18 in long each) of Diamond Pro Air Straight Face Cap

Leveling pad base 2 cubic yards (loose) of 3/4-inch minus (with fines)

for 0.73 cu yd (19.6 cu ft) of leveling pad, compacted; ordered at Caltrans’ “Compact cu. yds. = 1.5 X actual yardage”, read on this page as loose cubic yards Source

Free-draining aggregate 3 cubic yards (loose) of 3/4-inch free-draining aggregate

for 1.98 cu yd (53.3 cu ft) of stone behind the block, compacted; ordered at Caltrans’ “Compact cu. yds. = 1.5 X actual yardage”, read on this page as loose cubic yards Source

A 20 ft run showing 24 in of block above the ground, with the block, cap and pad chosen above.

Wall block — how the quantity was worked out
The job needs56 blocks
Buying 56 blocks of Belgard Diamond Pro Air Straight Face covers56 blocks
Left over0 blocks

Each line is worked out on its own, so each can be checked on its own; the notes further down name the figures behind them.

Counted for one straight run of a wall that stands on its own weight, on level ground. A wall standing in water or with groundwater behind it, a terraced set of walls, a wall near a property line and a wall the building department requires to be designed for earthquakes are not counted here: each changes the design rather than the quantity.

Not counted in these quantities: corner and step-down units; adhesive and pins; drain pipe, its fittings and filter fabric; stone placed inside the block cores; reinforcement buried behind the wall.

The pad and drainage stone are rounded up to the whole cubic yard — this calculator’s own choice, not a publisher’s: no wall maker or yard this calculator cites prints a minimum order or a step for them. The block is counted course by course, each course to whole units, with no offcut reused — this calculator’s own choice, not a publisher’s: a course that does not divide evenly into whole units ends in a cut unit, and the piece cut off is rarely the size the next course needs.

Height the model code exempts from a permit — from the bottom of the footing, here the leveling pad, to the top of the wall Source4 ft

Block finishing below the ground in front of the wall — from the finished ground down to the bottom of the lowest course8 in

Wall face the block has to cover, the buried course included53.3 sq ft

Leveling pad, compacted19.6 cu ft

Stone behind the block, compacted53.3 cu ft

  • The height above is not the height that shows. The code measures from the bottom of the footing to the top of the wall, so it takes in the 6 inch leveling pad, the block that finishes below the ground in front of the wall, and the cap where there is one — none of which shows once the job is done. That is why a wall that looks low can be over the line while a reader is still thinking about the part they can see. The exemption is also void, at any height, where the wall supports a surcharge, and an exemption is never permission: the code paragraph it sits in says in its own words that it does not authorize work that breaks any other rule of the jurisdiction. Source
  • Each course is counted to whole units: a 20 ft run is 13 1/3 of the 18 inch units, so a course takes 14, and 4 courses take 56. Dividing the wall face by one unit’s published coverage gives 54; the difference is the unit cut to finish each course. Source
  • The bottom of this wall is set 8 in into the ground. Belgard’s installation guide (Anchor Wall Systems’ text) asks for at least 6 inches of block below finished grade, and block is laid in whole courses, so what is buried is that or more. Source
  • A wall that stands on its own weight has a ceiling the maker publishes, and for this unit it is 40 inches. Belgard prints what that height is measured over in the same breath — including the buried course — and hedges it in its own words: gravity wall heights are based on project specific conditions and may be lower than this value. Past the ceiling the wall needs reinforcement buried in the ground behind it, which is a design and not a shopping list. No wall this page can answer carries more block than that figure allows, because the permit line refuses the next course first — but that is where the published numbers happen to land rather than a check this page makes. Nothing in it measures a wall against the maker’s ceiling. Source
  • The cap count is the run divided by the 18 inches of cap the maker publishes along the face of the wall, rounded up. This maker prints no cap rate of its own. Source
  • The pad is worked out 6 inches deep and 23.5 inches wide — the figures in Belgard’s installation guide (Anchor Wall Systems’ text): at least 6 inches deep after compaction, in a trench 12 inches wider than the 11.5-inch-deep block. The trade association’s figures, at least 6 inches thick and typically 6 inches past the front and the back of the bottom unit, agree. Source
  • The guide Belgard publishes names the pad material as compactable base material of three-quarter-inch minus with fines, which is what lets it lock up under load. It names no grading standard; the purchase line carries its words. Source
  • Belgard’s installation guide asks for 12 inches of 3/4-inch free-draining aggregate behind the wall, for every course, and the layer is worked out that far back for the full height of the block. The Concrete Masonry & Hardscapes Association asks for at least the same twelve inches behind any unit. The definition the association’s figure comes from adds that in units with open cores gravel can be used inside them to increase the weight and shear capacity; this page counts the layer behind the units and nothing inside them. It is a clean free-draining stone and it is NOT the same product as the base under the wall — one is chosen so water runs through it, the other so it locks up under load. A yard sells both and will not guess which is wanted. A perforated pipe usually runs at the bottom of this layer with an outlet through or around the wall; the pipe, its fittings and any filter fabric are not counted here. Source
  • The free-draining stone is a different product from the pad base. Wisconsin DOT gives its estimators a range of weights for its own open-graded base rather than one figure, and that base is graded to the state’s own specification and rolled in place. Nothing in the source list below ties the stone behind the wall to that grading, so this line is not weighed either; a cubic-yard order needs no weight, and it is given in cubic yards at Caltrans’ volume multiplier, as the pad is. Source
  • This page does not turn either aggregate line into tons. ConcreteTally’s paver base and driveway calculators do, at the weight Wisconsin DOT’s Standard Specifications use to convert their own dense-graded base, measured in place after compaction, into tons (section 305.4). Those two can use it because their own publishers send a builder to the base laid under local roads; the wall makers here name their stone by size and fines, or in their own words, and none of them points at that specification. A cubic-yard order needs no weight, so this page gives both lines in cubic yards only. A yard that sells either line by the ton weighs it on its own scale. Source
  • Both cubic-yard aggregate lines in this answer are loose cubic yards, which is this page’s reading of a road-building estimating table: each is the compacted layer worked out for this wall, times 1.5, from Caltrans’ “Compact cu. yds. = 1.5 X actual yardage”, published for road shoulder, base and surface material. None of the makers or the association in the source list below publishes a loose figure for its own pad stone or drainage stone, so applying Caltrans’ figure to them is this page’s choice, and one that buys more stone rather than less. Belgard’s guide compacts the pad and gives no step of its own for the stone behind the block; the association’s construction sequence compacts from the front of the wall back, so that stone is ordered the same way. Ask the yard whether its cubic yard is measured loose. Source
  • This is a material list, not a permit check, and it clears nobody. Every published figure behind it is in the source list below, with the body that published it; the ordering margins are not published figures, and the page says so where they are set. None of them is a statement about a particular address: the model code has no force anywhere until a jurisdiction adopts it, jurisdictions amend it, and at least one state requires a registered design professional for a wall crossing a property line whatever its height. Take the drawing to the local building department before anything is dug.
  • Reinforcement buried in the ground behind the wall is not sized here and never will be: it is designed from the soil and the geometry of the site, which is engineering and not estimating. Corner and step-down units are left out because the one estimating chart in the source list below gives those as a rule of thumb for a layout no calculator can see.
  • Caltrans’ Section 20 table does not agree with its own basis line. Its footnote says “1.5 tons = 1 cu. yd.”, “Compact tons = 2.0 X actual yardage.” and “Compact cu. yds. = 1.5 X actual yardage.”, but 1.5 cubic yards at 1.5 tons a cubic yard is 2.25 tons, not 2.0. Every row of the compact columns has the same gap: at 18 feet wide and 1 inch thick the table prints 439 compact cubic yards and 586 compact tons, where 439 cubic yards at 1.5 tons a cubic yard would be 658.5 tons. By weight, then, the table puts about 1.33 cubic yards of stone into each cubic yard of compacted layer; by volume, 1.5. ConcreteTally takes the volume figure, 1.5: it is stated in cubic yards, the unit a cubic-yard order is placed in, and it is the larger, so it cannot leave a base short of stone. The paver base, driveway asphalt and retaining wall block calculators use it for every cubic-yard order of compacted stone; ordered by weight, they use neither figure. Source

The printed list carries every quantity, the code-measured height, the number of courses and the conditions they were worked from.

Retaining Wall Block Calculator — Courses and Block Count

ConcreteTally

EXAMPLE — not a measured job. Every quantity below is worked out from this page’s sample measurements. Enter the real measurements and print it again before anyone orders from it.

Job / customer
Deliver to

Height the permit rule is measured over — from the bottom of the footing, here the leveling pad, to the top of the wall, here the top of the cap: 3 ft 6 in [19]

Courses of block, the buried one included: 4

Cap height, as published for this unit: 4 in [1]

What to buy

MaterialBuyWhich isLeft over
Wall block56 blocks of Belgard Diamond Pro Air Straight Face56 blocks0 blocks
Capstones14 caps (18 in long each) of Diamond Pro Air Straight Face Cap14 caps0 caps
Leveling pad base2 cubic yards (loose) of 3/4-inch minus (with fines)54 cu ft0.9 cu yd
for 0.73 cu yd (19.6 cu ft) of leveling pad, compacted; ordered at Caltrans’ “Compact cu. yds. = 1.5 X actual yardage”, read on this page as loose cubic yards
Free-draining aggregate3 cubic yards (loose) of 3/4-inch free-draining aggregate81 cu ft0.0 cu yd
for 1.98 cu yd (53.3 cu ft) of stone behind the block, compacted; ordered at Caltrans’ “Compact cu. yds. = 1.5 X actual yardage”, read on this page as loose cubic yards
This calculator’s own choicesThe pad and drainage stone are rounded up to the whole cubic yard — this calculator’s own choice, not a publisher’s: no wall maker or yard this calculator cites prints a minimum order or a step for them. The block is counted course by course, each course to whole units, with no offcut reused — this calculator’s own choice, not a publisher’s: a course that does not divide evenly into whole units ends in a cut unit, and the piece cut off is rarely the size the next course needs.

Counted for one straight run of a wall that stands on its own weight, on level ground. A wall standing in water or with groundwater behind it, a terraced set of walls, a wall near a property line and a wall the building department requires to be designed for earthquakes are not counted here: each changes the design rather than the quantity.

Not counted in these quantities: corner and step-down units; adhesive and pins; drain pipe, its fittings and filter fabric; stone placed inside the block cores; reinforcement buried behind the wall.

Caltrans’ table gives 1.5 compact cubic yards for each cubic yard of finished layer, but its compact tons, 2.0 against its own 1.5 tons a cubic yard, come to about 1.33 cubic yards; this sheet orders by the 1.5.

This sheet clears nothing. It lists material; the source list at the end of it names the publisher of every published figure behind it. Whether a wall of this height needs a permit, and what has to be submitted with it, is a building department’s answer at the address the wall is going in. The pad and the drainage stone are loose cubic yards, this page’s reading of a road-building multiplier, and the sheet gives with each line the compacted layer it was worked out from. Ask the yard whether its cubic yard is measured loose.

Worked out from

Length of the wallMeasured from one end of the run to the other, along the face of the wall, one straight run at a time.20 ft (sample)
Height of wall showing above the finished groundMeasured from the finished ground in front of the wall to the top of the last course of block, the cap not included.24 in (sample)
What is above and behind the wall?Nothing above it — planting or level ground, nothing driven or built on
Which blockBelgard Diamond Pro Air — 1 sq ft of face, 8 in courses
Cap units on top?Yes — cap units along the top
Which published leveling pad depth6 in — each maker’s own minimum, and the trade association’s
Amount needed — Wall block56 blocks
Amount needed — Capstones14 caps
Amount needed, loose — Leveling pad base1.1 cu yd
Amount needed, loose — Free-draining aggregate3.0 cu yd
Whole units to take home over the count — Wall blocknone — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a spare allowance for wall block or cap units, so the calculator adds none rather than invent one.
Whole units to take home over the count — Capstonesnone — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a spare allowance for wall block or cap units, so the calculator adds none rather than invent one.
Whole cubic yards of pad base and drainage stone over the count — Leveling pad basenone — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a margin for pad base or drainage stone, so the calculator adds none rather than invent one.
Percentage on the pad base and drainage stone, for a trench that runs wide — Leveling pad basenone — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a margin for pad base or drainage stone, so the calculator adds none rather than invent one.
Whole cubic yards of pad base and drainage stone over the count — Free-draining aggregatenone — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a margin for pad base or drainage stone, so the calculator adds none rather than invent one.
Percentage on the pad base and drainage stone, for a trench that runs wide — Free-draining aggregatenone — this calculator’s own starting point, not a published figure. None of the wall makers or the trade association this calculator cites prints a margin for pad base or drainage stone, so the calculator adds none rather than invent one.

Estimates only — check quantities before you buy. Confirm with your hardscape supplier — or a structural engineer for a wall over four feet (1.2 m) (measured from the bottom of the leveling pad to the top of the cap, or of the last course where there is no cap, not from the ground) before ordering.

Where these figures come from

A number in brackets after a figure on this sheet is its entry in this list.

  1. Belgard Diamond Pro Air — published coverage, length and weight of one unit (Cut sheet, single page, right column — the FEATURES & BENEFITS bullet naming the weight and the square foot, read with the SHAPES & SIZES block, the title and the closing line of the left column.); Belgard Diamond Pro Air — published height of one course (inches) (Cut sheet, single page, right column, SHAPES & SIZES — the unit row, first figure of "8" x 18" x 11.5"".); Belgard Diamond Pro Air — published front-to-back depth of one unit (inches) (Cut sheet, single page, right column, SHAPES & SIZES — the unit row, third figure of "8" x 18" x 11.5"".); Belgard Diamond Pro Air — published cap height (inches) (Cut sheet, single page, right column, SHAPES & SIZES — the CAP row, first figure of "4" x 18" x 12"".) — Belgard (Oldcastle APG, A CRH Company), Manufacturer or grower specification. Effective from October 16, 2024. Retrieved October 11, 2026.
  2. VERSA-LOK Standard — published face area, wide face width and weight of one unit (Units section (id "units"), the "Standard Unit" specification table — rows Depth, Height, Face width (wide), Face width (narrow), Face area, Minimum radius, Maximum unreinforced height, Setback, Weight, and the page's opening paragraph.); VERSA-LOK Standard — published height of one course (inches) (Units section (id "units"), "Standard Unit" specification table — the Height (in) row.); VERSA-LOK Standard — published front-to-back depth of one unit (inches) (Units section (id "units"), "Standard Unit" specification table — the Depth (in) row.); VERSA-LOK Standard — published maximum unreinforced height (inches) (Units section (id "units"), "Standard Unit" specification table — the Maximum unreinforced height(ft.) row, read with the footnote sentence printed immediately below the tables.) — VERSA-LOK Retaining Wall Systems (Kiltie Corporation), Manufacturer or grower specification. The product page carries no publication or revision date; its footer reads "(c) 2026 Kiltie Corporation". Current as of the retrieved date. Retrieved October 11, 2026.
  3. Allan Block AB Classic — published coverage, length and weight of one unit (PDF page 4 of 68, which prints the folio 2 — the "AB Collection" unit table, columns Name / Setback / Coverage / Weight / Approx. Dimensions, the AB Classic row.); Allan Block AB Classic — published height of one course (inches) (PDF page 4 of 68 (printed folio 2), "AB Collection" unit table, AB Classic row, the Approx. Dimensions column — the H figure of "8 in. H x 12 in. D x 18 in. L".); Allan Block AB Classic — published front-to-back depth of one unit (inches) (PDF page 4 of 68 (printed folio 2), "AB Collection" unit table, AB Classic row, the Approx. Dimensions column — the D figure of "8 in. H x 12 in. D x 18 in. L".); Allan Block — base trench width and depth, and the narrower trench for a wall under 4 ft (PDF page 26 of 68, which prints the folio 24 — "Building a retaining wall", Base Preparation bullets 5 and 6, and the double-asterisk note under them.); Allan Block — at least 6 inches of wall rock in the base trench (PDF page 26 of 68, which prints the folio 24 — "Building a retaining wall", Base Material, bullet 2 (no double asterisk).); Allan Block — 12 inches of wall rock behind the block (PDF page 27 of 68, which prints the folio 25 — "Backfilling and Compaction", bullet 2.); Allan Block — capstones for each 10 ft of wall (PDF page 32 of 68, which prints the folio 30 — "Patterned Walls", the note under the pattern tables.) — Allan Block Corporation, Manufacturer or grower specification. Effective from March 2024. The document's own code is Doc. # L0631-0324, whose last four digits are March 2024; no day is printed anywhere in it. Retrieved October 11, 2026.
  4. Belgard Diamond Pro Air — straight-face cap, published size (Product page, the product-item list — the 'Diamond Pro® Air - Straight Face Cap 4 x 18 x 12"' entry) — Belgard (Oldcastle APG, A CRH Company), Manufacturer or grower specification. The product page carries no publication or revision date. Current as of the retrieved date. Retrieved October 11, 2026.
  5. VERSA-LOK A Cap — published face width and height (Units section (id "units"), the "A Cap" specification table — rows Depth, Height, Face width (wide), Face width (narrow), Face area, Weight; read with the introductory paragraph above it; and the "B Cap" table after it.); VERSA-LOK A Cap — published height (inches) (Units section (id "units"), the "A Cap" specification table — the Height (in) row, corroborated by the introductory paragraph's "3-5/8" tall".) — VERSA-LOK Retaining Wall Systems (Kiltie Corporation), Manufacturer or grower specification. The product page carries no publication or revision date; its footer reads "(c) 2026 Kiltie Corporation". Current as of the retrieved date. Retrieved October 11, 2026.
  6. Allan Block AB Capstone — published size (AB Collection product page, the AB Capstone panel — the bulleted size list under "Finishing block that provides a clean, polished look to the top of retaining walls.", and the feature list above it.) — Allan Block Corporation, Manufacturer or grower specification. The product page carries no publication or revision date. Current as of the retrieved date. Retrieved October 11, 2026.
  7. Allan Block — inches a capstone adds to total wall height (PDF page 61 of 68, which prints the folio 59 — "Estimating the Number of Blocks Needed", LEFT column, the note printed immediately below the full-size block chart.) — Allan Block Corporation, Estimating chart (approximate). Effective from March 2024. The document's own code is Doc. # L0631-0324, whose last four digits are March 2024; no day is printed anywhere in it. Retrieved September 13, 2026.
  8. Belgard Diamond Pro Air — published maximum gravity wall height, including the buried course (inches) (Cut sheet, single page, right column, FEATURES & BENEFITS — the gravity-wall bullet, read with the asterisk footnote printed below the list.) — Belgard (Oldcastle APG, A CRH Company), Manufacturer or grower specification. Effective from October 16, 2024. Retrieved September 13, 2026.
  9. Allan Block minimum base depth for a wall under 4 ft (inches) (PDF page 5 of 24, which prints the folio 3 — section "3.3 Base", item E.); Allan Block — the base must allow for at least one buried block (PDF page 5 of 24 (printed folio 3) — section "3.3 Base", item F.) — Allan Block Corporation, Manufacturer or grower specification. Effective from March 2024. The document's own code is DOC. #R0901-0324, whose last four digits are March 2024, and its last page reads "(c) 2024, 2019, 2015-2000 Allan Block Corporation, Bloomington, MN". Four of its twenty-four pages, this one among them, also carry the line asking the reader to consult the Allan Block Engineering Department to be sure of having the latest specification. Retrieved September 13, 2026.
  10. Allan Block — what the base under the units is made of (PDF page 5 of 24 (printed folio 3) — section "3.3 Base", items A and D.); Allan Block — wall rock, the stone behind and inside the units, and its grading (PDF page 4 of 24, which prints the folio 2 — section "2.2 Wall Rock", the heading and item A.) — Allan Block Corporation, Manufacturer or grower specification. Effective from March 2024. The document's own code is DOC. #R0901-0324, whose last four digits are March 2024, and its last page reads "(c) 2024, 2019, 2015-2000 Allan Block Corporation, Bloomington, MN". Four of its twenty-four pages, this one among them, also carry the line asking the reader to consult the Allan Block Engineering Department to be sure of having the latest specification. Retrieved October 11, 2026.
  11. CMHA minimum leveling pad thickness (inches) (Tech Note SRW-TEC-005-09, section SYSTEM COMPONENTS (heading id "mg-heading-7") — the "Leveling pad" definition.); CMHA typical leveling pad offset beyond the toe and heel of the lowermost unit, per side (inches) (Tech Note SRW-TEC-005-09, section SYSTEM COMPONENTS (heading id "mg-heading-7") — the "Leveling pad" definition, the extension clause.); CMHA minimum depth of free-draining fill behind the units (inches) (Tech Note SRW-TEC-005-09, section SYSTEM COMPONENTS (heading id "mg-heading-7") — the "Gravel fill" definition, its final sentence.) — Concrete Masonry & Hardscapes Association (CMHA), Trade association publication. The Tech Note prints no publication date; it is designated SRW-TEC-005-09 and its own reference list cites the association's Design Manual for Segmental Retaining Walls, Third Edition, 2009. Current as of the retrieved date. Retrieved September 13, 2026.
  12. CMHA — what the leveling pad is made of (Tech Note SRW-TEC-005-09, section SYSTEM COMPONENTS (heading id "mg-heading-7") — the "Leveling pad" definition, first sentence.) — Concrete Masonry & Hardscapes Association (CMHA), Trade association publication. The Tech Note prints no publication date; it is designated SRW-TEC-005-09 and its own reference list cites the association's Design Manual for Segmental Retaining Walls, Third Edition, 2009. Current as of the retrieved date. Retrieved October 10, 2026.
  13. Belgard — at least 6 inches of the block buried below finished grade (PDF page 2 of 4 (printed folio 8) — the BASE COURSE block, first bullet; restated in the EXCAVATION block above it.); Belgard — how much wider than the block the pad trench is dug (inches) (PDF page 2 of 4 (printed folio 8) — the EXCAVATION block, second bullet, which is the sentence above the LEVELING PAD block.); Belgard — leveling pad at least 6 inches deep after compaction (PDF page 2 of 4, which prints the folio 8 — the LEVELING PAD block, first and second bullets.); Belgard — 12 inches of free-draining aggregate behind the wall (PDF page 3 of 4, which prints the folio 9 — CONSTRUCTION OF SUBSEQUENT COURSES, fifth bullet.) — Anchor Wall Systems, Inc., reprinted by Belgard as its Quick Reference Guide: Standard Wall Installation Guide, Manufacturer or grower specification. The guide carries no printed publication or revision date; it is posted under a 2023/10 path on the publisher's site. Current as of the retrieved date. Retrieved October 11, 2026.
  14. VERSA-LOK — buried below grade, at least a tenth of the height that shows (Homeowner Glossary, entry "Embedment" (letter E)) — VERSA-LOK Retaining Wall Systems (Kiltie Corporation), Manufacturer or grower specification. The glossary carries no publication or revision date; its footer reads "(c) 2026 Kiltie Corporation". Current as of the retrieved date. Retrieved October 11, 2026.
  15. VERSA-LOK — leveling pad about 24 inches wide, and the first course buried about a tenth of the height, for a homeowner wall (Homeowner Installation Tips, Step By Step Installation, Step 1: Leveling Pad Preparation, first and second sentences); VERSA-LOK — leveling pad about 6 inches thick, for a homeowner wall (Homeowner Installation Tips, Step By Step Installation, Step 1: Leveling Pad Preparation, first sentence); VERSA-LOK — 12 inches of drainage aggregate behind the units, placed and compacted (Homeowner Installation Tips, Step By Step Installation — Step 3: Backfill Your Wall, second sentence; Step 4: Install Successive Retaining Wall Courses, last sentence); VERSA-LOK — the leveling pad material, and that it is compacted (Homeowner Installation Tips, Step By Step Installation, Step 1: Leveling Pad Preparation, first and fourth sentences) — VERSA-LOK Retaining Wall Systems (Kiltie Corporation), Manufacturer or grower specification. The page carries no date. Current as of the retrieved date. Retrieved October 11, 2026.
  16. VERSA-LOK guide specification — drainage aggregate and its grading (Specification for Segmental Retaining Wall Systems (VERSA-LOK Standard unit), Part 2, section 2.05 Drainage Aggregate, item A and the gradation table under it); VERSA-LOK guide specification — leveling pad material for the Standard unit (Specification for Segmental Retaining Wall Systems (VERSA-LOK Standard unit), Part 2, section 2.04 Leveling Pad, item A, first sentence) — VERSA-LOK Retaining Wall Systems (Kiltie Corporation), Manufacturer or grower specification. The specification prints no date; it cites the NCMA Design Manual for Segmental Retaining Walls, 3rd Edition, 2009. Current as of the retrieved date. Retrieved October 11, 2026.
  17. Allan Block — twelve inches of wall rock behind the block, compacted within the consolidation zone (PDF page 5 of 24 (printed folio 3) — section 3.4 Unit Installation, item D (one sentence) and item F (first three sentences).) — Allan Block Corporation, Manufacturer or grower specification. Effective from March 2024. The document’s own code is DOC. #R0901-0324, whose last four digits are March 2024, and its last page reads "(c) 2024, 2019, 2015-2000 Allan Block Corporation, Bloomington, MN". Retrieved October 11, 2026.
  18. CMHA — the construction sequence behind a segmental retaining wall (Tech Note SRW-TEC-005-09, section CONSTRUCTION (heading id "mg-heading-10") — the list after "Construction occurs in the following sequence:", its third, fourth and fifth items) — Concrete Masonry & Hardscapes Association (CMHA), Trade association publication. The Tech Note prints no publication date; it is designated SRW-TEC-005-09 and its own reference list cites the association's Design Manual for Segmental Retaining Walls, Third Edition, 2009. Current as of the retrieved date. Retrieved October 11, 2026.
  19. Retaining wall height exempted from a permit by 2021 IRC R105.2 item 3, as republished by Grant County, Washington, measured from the bottom of the footing to the top of the wall (feet) (Page 1 of 2, under the heading "R105.2 Work exempt from permit.", sub-heading "Building:", numbered item 3.) — Grant County, Washington, Government publication. The handout prints no publication or revision date; its own header names the code edition it reproduces as the 2021 International Residential Code. Current as of the retrieved date. Retrieved September 13, 2026.
  20. Unbalanced fill above which the 2015 IRC requires an engineered design (inches) (Single-page excerpt, the block headed "CHANGE SIGNIFICANCE:" — the paragraph beginning "Section R404.4 also has a new trigger height". The operative provision itself, with its revision marks, is in the block headed "2015 CODE:" above it.); Wall height above which the 2015 IRC requires an engineered design where the wall resists lateral loads in addition to soil (inches) (Single-page excerpt, the CHANGE SIGNIFICANCE block — the sentence naming vehicles parked above and fences built on top.); Safety factor the 2015 IRC requires of an engineered retaining wall design (Single-page excerpt, the block headed "2015 CODE:" — the sentence following the list of stability requirements.) — International Code Council, Trade association publication. Effective from 2015. The excerpt names its own source as Significant Changes to the International Residential Code, 2015 Edition; no month or day is printed. Retrieved September 13, 2026.
  21. County of Los Angeles — a retaining wall requiring a building permit must be designed by a registered design professional (Residential Code Manual No. 1014, R404.4 Article 1, "DESIGN OF RETAINING WALLS" — page 1 of 9, under the heading ISSUE.) — County of Los Angeles, Department of Public Works — Building and Safety Division, Government publication. Effective from July 12, 2017. Retrieved September 13, 2026.
  22. North Carolina's own amendments to R404.4 — triggers unrelated to a single wall's height (Page 1, "2018 NC Residential Code / R404.4 Retaining Walls (210914 Item B-1)", numbered items 1 and 2 of four; the item's closing lines run on to page 2.) — North Carolina Office of State Fire Marshal, Government publication. Effective from January 1, 2025. The item's own closing line, at the top of page 2, reads "The delayed effective date of this Rule is January 1, 2025." Retrieved September 13, 2026.
  23. Allan Block's published estimating chart — approximate blocks and capstones by courses and wall length (PDF page 61 of 68, which prints the folio 59 — "Estimating the Number of Blocks Needed", LEFT column, the chart headed "Approx. number of full-size blocks needed".) — Allan Block Corporation, Estimating chart (approximate). Effective from March 2024. The document's own code is Doc. # L0631-0324, whose last four digits are March 2024; no day is printed anywhere in it. Retrieved October 11, 2026.
  24. Wisconsin DOT volume-to-weight conversion factor for in-place dense-graded aggregate base (Standard Specifications section 305 Dense-Graded Base, subsection 305.4 Measurement, paragraph (2)) — Wisconsin Department of Transportation, Government publication. Effective from November 2024. The specification is headed 'Effective with the November 2024 Letting' and '2025 Standard Specifications'; no calendar day is published. Retrieved October 10, 2026.
  25. Wisconsin DOT statewide estimating range for compacted open-graded base aggregate (Facilities Development Manual, Chapter 19 Section 5 Estimates, FDM 19-5-3 Bid Item Guidance — the paragraph 'Base Aggregate Dense, Breaker Run, Select Crushed Material, Pit Run and Backfill Granular Conversions' (PDF page 2, continuing on page 3) and Table 3.1 'Compacted Aggregate Conversion Factors', row 310.0110 Base Aggregate Open Graded (PDF page 3).) — Wisconsin Department of Transportation, Government publication. Effective from May 15, 2025. FDM 19-5-3 is dated May 15, 2025 in its own heading. Retrieved October 11, 2026.
  26. Caltrans estimating multipliers for aggregate surfacing, loose versus compact (Appendix, Section 20 'Aggregate per Mile - Aggregate for One Mile Surfacing, For Estimating Shoulder, Base or Surface Material', basis footnote below the table (Page Appen-28)) — California Department of Transportation (Caltrans), Division of Maintenance, Government publication. Effective from July 2014. The document is dated July 2014 on its face; no day of month is printed. Retrieved October 11, 2026.

This list, with a link to each document: concretetally.com/retaining-wall-block-calculator/#sources-heading

Every table ConcreteTally reads, with its dates: concretetally.com/sources

Local rules differ — ask your building department.

Where these figures come from

Every table ConcreteTally reads, with its dates: all sources.