Poured concrete vs block walls

01 / Understand the difference

What changes between poured concrete and block walls?

A concrete masonry unit, or CMU, is a manufactured concrete block. This guide compares mortared CMU construction with concrete poured into forms on site. It does not compare precast wall panels, insulating concrete forms, or dry-stacked landscape retaining blocks.

The CMHA guide to estimating concrete masonry materials treats units, mortar and grout as separate estimates. It also explains why unit configuration, corners and other details can change the quantities. A block count alone is not the complete masonry takeoff.

02 / Compare complete designs

Which is stronger, cheaper or better against moisture?

Those questions cannot be settled by a material name or a quantity calculator. A poured wall and a block wall with the same length and height are not automatically equivalent designs. Ask the designer to confirm the required wall thickness, materials, reinforcement, connections and foundation details for each option.

For moisture, ask what the proposed assembly includes: membranes or coatings, joints and penetrations, drainage, and the site conditions it is intended to address. Do not treat the absence of mortar joints as a promise that a poured wall will stay dry, or assume a block wall is unsuitable without reviewing its design.

For cost, compare quotations with matching inclusions. One offer may include forms, delivery and placement while another lists only the blocks. That is a difference in scope, not proof of which finished wall costs less.

03 / Compare the takeoffs

One wall face, two different material estimates

Use a simple wall that is 4 m long and 2.4 m high, with no openings. Its elevation area is 9.6 m². For arithmetic only, suppose the poured option is 0.20 m thick and the block option uses a 400 mm × 200 mm installed face module, including joints.

These are illustrative inputs, not recommended dimensions or structurally equivalent alternatives. The example excludes footings, reinforcement, special units and finishes.

The 120-block result is an area estimate, not a course-by-course bond or cutting schedule. Corners, openings, lintels and special units still need a detailed check. Do not add a mortar joint again when the entered module already includes it.

Keep allowance separate. An illustrative 5% allowance would add 0.096 m³ to the poured quantity, giving 2.016 m³ before supplier rounding. Applying 5% to the raw block count would give 126 blocks to order. The percentage is an example, not a recommendation. Spare blocks are not automatically laid or filled.

04 / Use the right calculation

Carry each quantity into the appropriate tool

For the poured option, enter the specified wall groups and openings in the Concrete Wall Calculator. Record its net volume separately from the ordering allowance, bag rounding and optional material cost.

For the masonry option, use the Concrete Block Calculator for the face-module count. It can also estimate mortar bags when you supply the manufacturer’s blocks-per-bag coverage. It does not lay out every corner or special unit.

If the drawings call for filled cells, use the installed count with the Concrete Block Fill Calculator. Supply the actual unit’s core volume and the specified fill share. Keep laying mortar and core fill separate, and check any bond beams or other grout spaces outside that simplified estimate.

For the poured wall’s forms, use the Concrete Formwork Calculator to count the faces, ends and opening deductions that apply. In the example, two faces plus two formed ends total 20.16 m² of contact area, excluding the top and base.

Contact area is not the whole forming system. The ACI 347R-14 Guide to Formwork for Concrete preview covers design, loads, accessories, bracing and construction responsibilities beyond this area calculation. An area result does not size forms, ties or supports.

Where either option has a separate concrete footing, calculate its specified dimensions with the Concrete Footing Calculator. Do not reuse one option’s footing dimensions for the other unless the design confirms them.

05 / Check the same price scope

Compare complete quotations, not concrete against blocks

Ask each contractor to identify what is included, excluded or provisional. Use current project quotations rather than a universal cost per square metre or linear foot.

• Main materials: concrete or masonry units, plus the specified mortar, grout and reinforcement.
• Construction work: forming, laying, concrete or grout placement, equipment, labor and curing work included in the quotation.
• Delivery and access: freight, unloading, pumping or other placement arrangements, and minimum-order charges.
• Supporting work: excavation, footings, connections and any specified backfill or drainage.
• Completed wall: required finishes, waterproofing, insulation, penetrations and attachments.
• Commercial scope: taxes, inspections, testing, exclusions, schedule and responsibility for changes.

The historical US HUD guide, Concrete Masonry Homes: Recommended Practices, addresses connections, finishes, insulation and utility placement as separate aspects of masonry construction. It illustrates why a completed wall involves more than units and mortar. It is not a current local design or code checklist.

The calculators’ optional amounts use the material rates you enter. They do not establish a full installed price or automatically include the work listed above.

06 / Prepare the next decision

What to confirm before choosing a wall system

1. Confirm the wall’s purpose and the requirements both options must satisfy.
2. Obtain the dimensions, reinforcement and other details for each proposed design.
3. Check supplier product data, crew availability, access and construction schedule.
4. Prepare separate material quantities and compare quotations with the same scope.
5. Resolve exclusions and design questions before ordering or starting work.

For foundation work, the footing and stem wall concrete guide explains how to keep the footing and poured-wall volumes separate without counting their shared section twice.