Concrete Hollow Block (CHB) Wall Takeoff — Blocks, Mortar, Rebar
CHB is the default wall system in Philippine construction. The takeoff is quick once you have the per-square-metre factors.
Block count
A standard 400 × 200 mm face block covers 0.08 m². With 10 mm joints, the effective coverage is ~0.086 m²:
Deduct openings over ~0.5 m² (doors, windows).
Mortar
Class B mortar (1:3 or 1:4 cement:sand) for bedding and for filling reinforced cells:
| Item | Approx. per m² of wall |
|---|---|
| Bedding mortar (100 mm CHB) | ~0.006 m³ |
| Bedding mortar (150 mm CHB) | ~0.009 m³ |
| Cell grout (cells reinforced @ 600 mm) | ~0.008 m³ |
Convert mortar volume to cement bags and sand using the mix-ratio method.
Reinforcement
- Vertical bars: 10 mm at 600–800 mm c/c, plus one each side of every opening and at wall ends and corners. Length = wall height + dowel/lap into slab.
- Horizontal bars: 10 mm every 3rd course (~600 mm), or ladder-type joint reinforcement every 2nd course.
- Lintel bars over openings.
Plaster finish
Cement plaster ~16 mm thick → ~0.4 bag cement + 0.03 m³ sand per m² per face (1:3)
Add a scratch coat allowance for exterior walls and skim/putty for painted interiors.
EngEst Pro’s Structural Calculator takes off CHB walls from wall area and height — blocks, bedding mortar, cell grout, vertical and horizontal rebar, and two-face plaster — all as priced BOM lines.
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