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Block wall materials for 44 ft at 11 courses, rebar every 24″

Blocks needed
3828×8×16 blocks
44 ft long × 11 courses (7.33 ft) — 323 ft² of wall, 5% breakage included
Elevation44 ft11 courses · 7.33 ft382 blocks · 11 bags mortar · 23 vertical bars
Blocks (with 5% breakage)382blocks
Blocks (exact)1.125 per ft² including joints363blocks
Wall area44 ft × 7.33 ft323ft²
Wall height11 courses at 8″7.33ft
Mortar (Type S, 70 lb)3 bags per 100 blocks at ⅜″ joints11bags
Masonry sandif mixing from bagged cement and lime instead1.47yd³
Vertical rebar (#4 @ 24″)203 linear ft including 18″ into the footing23bars
Grout for filled cells110 × 80 lb bags — only the cells with steel in them65.8ft³
Footing16″ × 8″ × 44 ft — twice the wall thickness1.45yd³
Engineering7.33 ft is over the 4 ft thresholdRequired

Notes

  • 1.125 blocks per square foot is the number, and it already includes the ⅜″ mortar joints. A "8×8×16" block is 7⅝ × 7⅝ × 15⅝ actual — the missing ⅜″ is the joint, which is why nominal dimensions divide so cleanly into wall areas.
  • Grout goes only in the cells that have steel in them — 23 cells here, 65.8 ft³. Solid-grouting the whole wall is a different job with several times the material and a footing sized for several times the load.
  • At 7.33 ft this is past the point where most jurisdictions want an engineered design and a permit — universally so if it retains soil. Soil pushes sideways with a force that grows with the square of the height, and a wall sized by rule of thumb fails by overturning, not by crushing.
  • The footing decides whether the wall lasts. 16″ × 8″ is the usual rule of twice the wall thickness, below the frost line, on undisturbed soil. Block laid on a footing that heaves cracks along the mortar joints, and there is no repair short of rebuilding.
  • Drainage behind any wall holding back soil is not optional: gravel backfill, a perforated pipe at the base and weep holes. Water pressure behind a wall is a larger force than the soil itself, and it is what actually pushes walls over.

Blocks

44 ft × 11 courses is 7.33 ft high and 323 ft² of wall — 382 blocks with 5% for breakage and cuts.

The number to remember is 1.125 blocks per square foot, and it already includes the ⅜″ mortar joints. A block sold as 8×8×16 actually measures 7⅝ × 7⅝ × 15⅝; the missing ⅜″ is the joint, which is why nominal sizes divide so neatly into wall areas.

Mortar

11 bags of Type S at ⅜″ joints, or 1.47 yd³ of masonry sand if you are mixing from cement and lime instead.

Steel and grout

23 vertical bars, 203 linear ft including 18″ of anchorage into the footing, and 65.8 ft³ of grout — 110 bags.

Grout goes only in the cells that have steel in them. Solid-grouting the whole wall is a different job with several times the material and a footing sized for several times the load.

The footing decides whether it lasts

1.45 yd³ at 16″ × 8″, below the frost line, on undisturbed soil. Block laid on a footing that heaves cracks along the mortar joints, and there is no repair short of taking it down.

Before you start

Anything over 4 ft, and anything at all that retains soil, needs an engineered design and a permit almost everywhere. Soil pushes sideways with a force that grows with the square of the height, and walls sized by rule of thumb fail by tipping over rather than by crushing.

Drainage behind a retaining wall is not optional either: gravel backfill, perforated pipe at the base, weep holes. Water pressure behind a wall is a bigger force than the soil, and it is what actually pushes walls over.

Nearby sizes

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