Why Contractors Don't Deduct Doors and Windows from Estimated Areas

Written by: Barry Affleck

When estimating Venetian plaster, it’s important to understand that plastering is very different from painting. Comparing Venetian plaster to rolling latex paint can be misleading. While they may both cover walls, the labour involved is completely different.

A Simple Wall Example

Let’s start with a straightforward wall:

Length: 40 ft.
Height: 8 ft.
Total area: 320 sq. ft.
Openings: No doors or windows
Condition: Surface primed and ready

A typical lime-based Venetian plaster finish may require:

1st Coat – Skim Coat: Approximately 4 hours
2nd Coat – Pattern Coat (Cross-Hatch): Approximately 6 hours
3rd Step – Polishing: Approximately 2–3 hours, depending on the desired sheen

Additionally, the job requires about 2 gallons (10 kg) of Venetian plaster. Consequently, the total production time is roughly two standard working days for a skilled applicator, though acrylic Venetian plasters may reduce this time slightly.

Now Add Doors and Windows

Next, consider adding:

Three doors
One window with a soffit

On paper, the wall area decreases because of the openings. However, the overall labour increases significantly. Although these openings remove approximately 95–100 sq. ft. of wall area, they simultaneously create additional edges, corners, returns, taping, detailing, and cleanup work.

Additional Labour Required

Typical increases include:

Skim coat: +30% more time
Pattern coat: +50% more time
Taping and protection: +10% more time

As a result, total labour can increase by as much as 90%.

Real-World Production Time

The same wall may now require:

Skim coat: approximately 8 hours
Pattern coat: approximately 10 hours
Taping and masking: approximately 1 hour
Cleanup and detailing: approximately 2 hours

Therefore, what appeared to be a reduction in wall area has actually added almost a full day of labour.

The Bottom Line

Simply deducting doors and windows from the wall area does not accurately reflect the true cost of Venetian plaster work. While openings reduce material consumption, they ultimately increase labour through additional masking, detailing, corner work, edge finishing, and cleanup.

In many cases, the extra labour far exceeds any savings in material. Years ago, contractors could absorb these differences because labour costs were lower and estimates allowed more flexibility. Today, however, labour is the largest part of the job, making accurate estimating more important than ever. Consequently, you should measure carefully, understand the complexity of the work, and price accordingly.

A Note on Ceilings

Ceilings have traditionally been priced higher than walls because they are more difficult to work on. For instance, in the painting industry, a ceiling might be priced 30% higher than a wall.

However, Venetian plaster is a different story entirely. Ceiling applications are often significantly slower and more demanding because:

Application and polishing require working overhead for extended periods.
Overhead rolling scaffolds or staging reduce productivity and require frequent repositioning.
Furthermore, material handling is less efficient than working on vertical surfaces.
Critical lighting conditions can affect the appearance of the finish, sometimes requiring colour adjustments or additional work to achieve the desired effect.

For these reasons, many experienced applicators price Venetian plaster ceilings at up to twice the wall rate. Whether the market supports that premium depends on the project, but ceilings should never be treated as standard wall work.

Conclusion

Ultimately, successful estimating is about understanding where time is spent. Doors, windows, soffits, returns, and ceilings may seem like minor details on paper, but they often account for a significant portion of the labour required to complete a project properly. Therefore, estimate with precision, protect your profitability, and respect the value of skilled craftsmanship.