Drywall vs Block Walls: A Practical Comparison

Drywall partitions on light-gauge steel framing weigh roughly a fifth to an eighth of a plastered block wall, go up two to three times faster, and let services run inside the cavity instead of being chased in afterwards. Specified and built as a tested system, they match or beat block for sound insulation and fire rating at a smaller thickness. Block walls still win where a wall carries load, faces the weather, takes repeated hard impacts, stays permanently wet, or must hold heavy fixings that nobody planned for. The practical rule: default to drywall for every non-load-bearing interior partition, and reserve block for structural, external and heavy-duty service walls.

Weight and thickness

Weight is the first number a structural engineer asks for. A 150 mm hollow concrete block wall with 20 mm of plaster on both faces comes in at roughly 200 to 250 kg/m2, and a 200 mm block wall approaches 300 kg/m2. A drywall partition on 75 mm STUDS with one 12.5 mm board per side weighs 25 to 30 kg/m2, rising to 45 to 55 kg/m2 with two boards per side and mineral wool in the cavity.

That gap changes the slab and beam design. On a six-storey office building, moving the interior partitions from block to drywall cuts partition dead load by more than 80 percent, which either trims the frame or leaves generous reserve for tenants to re-plan layouts later without a structural check each time.

Overall thickness also matters for net lettable area: - 150 mm block plus two-sided plaster: about 190 mm. - 200 mm block plus two-sided plaster: about 240 mm. - 75 mm STUDS with one 12.5 mm board per side: 100 mm. - 100 mm STUDS with two 12.5 mm boards per side: 150 mm.

On an office floor with 200 linear metres of internal partitions, a 90 mm thickness saving returns about 18 m2 of net area per floor.

Programme and site logistics

A block wall passes through four sequential stages that cannot overlap: laying, at least a day of curing before rendering, two coats of plaster on each face, then 3 to 7 days of drying depending on temperature and humidity before skim and paint. A two-person crew typically lays 10 to 15 m2 of block a day, excluding plastering.

Drywall runs as a short parallel sequence: fix RUNNERS to floor and soffit, insert STUDS, run services, board the first face, place insulation, board the second face. A two-person crew completes 25 to 35 m2 of finished two-sided partition a day, and the wall is ready for jointing the same day. No construction moisture enters the building, which matters on projects where flooring and timber doors are installed early.

One practical caveat: drywall follows the levels it is fixed to. A 10 mm deviation in the slab or soffit shows up in the finished wall unless it is corrected before the RUNNERS go down.

Acoustic and fire performance

The assumption that block is always quieter does not hold. A plastered 150 mm hollow block wall typically achieves a weighted sound reduction index Rw of 45 to 48 dB. A drywall partition with one board per side and 50 mm mineral wool reaches 44 to 47 dB; with two boards per side it reaches 52 to 56 dB, outperforming block at a thinner section. Drywall works as a mass-air-mass system, while block relies on mass alone.

The result depends on building the tested system faithfully: seal the perimeter with acoustic sealant, avoid back-to-back electrical boxes in the same cavity, and carry the partition to the structural slab rather than stopping at the suspended ceiling.

For fire, 12.5 mm fire-rated gypsum board on each side typically gives a 60-minute rating, and two layers per side 120 minutes, according to the test report for that specific assembly. The Saudi Building Code (SBC) sets the required fire-resistance period for separations between units and along escape routes; meeting it means selecting an assembly tested to ASTM E119 or an equivalent standard, not estimating from board thickness alone.

Services, alterations and hanging loads

This is where the contractor feels the difference most. In block, every electrical or plumbing route means chasing, dust, mortar back-fill and the cracks that often follow in the plaster. In drywall, pipes and cables run in the 75 or 100 mm cavity before the second face is boarded, and access panels keep them reachable.

Post-handover changes decide the matter in offices, hospitals and government buildings. Removing a 10 m run of drywall partition takes hours and produces light, dry waste. The same length of block takes a full day and several cubic metres of rubble.

Hanging loads are where block is strongest. A single anchor in block comfortably carries 50 kg or more. In drywall, a toggle fixing in board alone holds 10 to 15 kg, and a screw into a STUD holds 25 to 40 kg depending on sheet thickness and screw type. Anything heavier, such as wall-hung kitchen cabinets, large displays or wall-mounted basins, needs a steel or timber backing plate fixed between STUDS during framing, not afterwards. Marking these positions on the partition drawing before boarding is what separates a successful drywall job from one that gets cut open later.

Where block remains the right answer

Drywall is not a universal substitute. Block remains the better choice for: - Load-bearing walls or walls contributing to lateral stability. - External walls exposed to rain and direct sun. - Pump rooms, plant rooms and stores subject to trolley and equipment impact. - Spaces where water sits against the wall continuously, such as industrial laundries or pool surrounds. - Walls expected to carry heavy loads that cannot be planned in advance.

Residential and commercial bathrooms and kitchens work well in drywall provided moisture-resistant boards, a liquid-applied waterproofing membrane behind the tiles and adequate ventilation are used. EN 520 classifies these boards as Type H according to their water absorption.

The steel framing decides drywall performance

Boards alone do not define a drywall partition; the framing behind them governs flatness, stiffness and permissible height. ASTM C754 covers the installation of steel framing members that receive screw-attached gypsum panel products, and ASTM C645 covers the framing members themselves.

Points a site engineer should check: - STUD spacing: 600 mm for standard heights, 400 mm for taller walls, tiled finishes or fixing loads. - RUNNERS fixed to floor and soffit at 600 mm maximum centres, with a fixing near each end. - A 15 to 20 mm deflection gap at the head where slab movement is expected, using a slotted or deep-leg head detail. - Sheet thickness: lighter gauges for low, unloaded partitions; heavier gauges for tall walls and tiled areas.

Baghdadi Factory produces RUNNERS in three sizes, 5, 7.5 and 10 cm, and STUDS in 4.8, 7.5 and 10 cm, with sheet thickness from 0.35 to 1.0 mm and thicker on request; lengths are cut to order, so contact the factory to specify. Choosing among the three widths follows wall height and the services inside: 48 mm for light, low partitions; 75 mm for general use; 100 mm for tall walls and plumbing runs.

Practical summary

• If the wall is interior and non-load-bearing, start from drywall and ask for justification where block is proposed.
• Fix the acoustic and fire targets as numbers first, then pick the tested system that meets them at the smallest thickness.
• Mark hanging-load positions on the partition plan before the first face is boarded.
• Match STUD width to wall height and pipe diameters, and confirm sheet thickness in the purchase order.
• Keep block for external, structural, permanently wet and heavy-impact walls.

The useful question is not which system is better, but which wall in the building needs which system. Most projects end up with both.