How much faster is machine plaster than hand application?

Machine (spray) plaster is typically 2-3 times faster than hand application. A 2-person team (one spraying, one flattening) can cover 80-120 m² per day with a PFT G4 or G5 pump, compared to 30-40 m² per day by hand. The time saving comes from the spraying speed — the flatten, float, and trowel stages take roughly the same time as hand application.

What plastering machine do I need?

The most common machine plaster pumps in the UK are the PFT G4 and PFT G5 (also known as the Knauf PFT range). The G4 is a continuous mixer/pump suitable for most interior plastering jobs with an output of 6-22 L/min. The G5 is a larger version for high-volume commercial work. You also need a compressor, spray gun, and supply hoses. Machines can be hired from most plant hire companies for £100-£200/day.

Is machine plaster the same product as hand plaster?

No — machine plasters are specifically formulated for spray application. They have a different particle size, longer working time (90-120 minutes vs 60-90 for hand plaster), and optimised flow properties for the pump. Knauf MP75 is the most popular UK machine plaster. You cannot put standard hand-mix plaster through a spraying machine — it will clog the pump and give a poor finish.

How much water does machine plaster need?

Machine plasters typically require 14-15 litres of water per 25kg bag (compared to 10-11 litres for hand plaster). The machine mixes the plaster and water continuously as it pumps. You need a clean mains water supply with adequate pressure (minimum 2 bar) and flow rate (minimum 15 L/min) connected directly to the machine. A 1,000L IBC tank with a pump is a good backup.

What are the disadvantages of machine plastering?

Machine plastering requires: (1) significant floor and window protection due to overspray, (2) expensive equipment (hire or purchase), (3) a reliable water and power supply, (4) minimum job size to be economical (typically 100+ m²), and (5) trained operatives. For small rooms or patch repairs, hand application is more practical. The equipment setup and cleaning takes 30-60 minutes each end of the day.

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Machine Plaster Calculator — Spray Plaster Coverage & Productivity

Calculate spray plaster quantities, pump output rates, material per hour, and team productivity for machine-applied plaster.

Wall/Ceiling Area

Total area to be sprayed

Machine Plaster Product

Select your spray plaster product

Team Size

Standard: 1 sprayer + 1 flattener

Price Per 25kg Bag (optional)

Enter your supplier price per bag

How We Calculate This

This calculator estimates material quantities and job duration for machine-applied (spray) plaster. Machine plaster has different coverage rates to hand-applied plaster due to the consistent application thickness and overspray factor.

The formula

Bags = (Wall area ÷ Coverage per bag) × Wastage factor

Spray time is calculated from the total mix volume divided by pump output rate. A 25kg bag mixes to approximately 19 litres. At a typical pump output of 15 L/min, one bag is sprayed in about 1.3 minutes. Total job time accounts for all stages: spray, flatten, rule, float, and trowel finish.

Coverage rates (per 25kg bag)

Knauf MP75: 1.8 m²/bag at 8mm
Knauf Goldband: 1.5 m²/bag at 10mm
ThistlePro Spray Finish: 1.4 m²/bag at 13mm
ThistlePro Spray Coat: 1.6 m²/bag at 10mm

Wastage for machine plaster is typically 12% (higher than hand application) due to overspray, material left in hoses, and the initial setup/purge cycle.

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.