Painting and coatings takeoff

Painting is labor driven. A painter still cuts in, masks, and edges around a small door or window, so the standards intentionally keep small openings inside the measured area. The size at which an opening is finally deducted is the most consequential decision in a painting takeoff, and the cut point changes by region.

In United States practice, Painting Contractors Association Standard P10 section 5.8 deducts an opening only if it is 100 square feet or larger, or if it runs floor to ceiling and exceeds 5 feet in width, so a normal door and window both stay in. Under RICS NRM2, measurement is net: any void over 1.00 square metre, about 10.76 square feet, is deducted, so a normal door is deducted but a small window is not. Australia and New Zealand follow the same void logic through the ANZSMM, with AS/NZS 2311 governing application rather than deduction, and other metric regions inherit the generic 1.00 square metre rule.

A third behavior, cover then deduct, subtracts every opening at full value. It belongs to cladding, siding, and drywall, where the same elevation also drives a board quantity, so the first question is which trade owns the elevation. Wall area behind cabinets, tubs, and showers is also not deducted under P10 section 5.9, because those items slow the painter; deduct the hidden area only when the scope stops paint at the fixture line.

Painting bills by surface area, so linear and shaped members convert to area through their wrapped perimeter, called the girth: area equals length times perimeter, and for a round pipe the perimeter is pi times the outside diameter.

The global default is the metric girth band method, with no minimum floor. Under RICS NRM2 section 29, surfaces of 300 mm girth or less are taken in linear metres, and under section 28 finishings of 600 mm wide or less are kept separate from the general area. The United States overrides this with a minimum floor: P10 sections 5.1 and 5.2 state that no object is considered less than one linear foot wide and is measured as one square foot per linear foot, so narrow trim, conduit, and rods are floored at that rate. A run that changes direction at a sharp angle is added at usually not less than half a square foot per linear foot under section 5.5.

Closely fabricated and open work, such as chain link fence, open web joists, and grating, is measured as a solid silhouette under P10 section 5.7, not by its net wire area, because the painter wraps every member. If both faces are finished, the silhouette area is doubled, and attached framework is measured separately. Net wire area would massively under bid the labor.

Doors and windows are enumerated as each, not folded into wall area, because the cut in, both faces, edges, and frame carry their own labor. Formal methods of measurement such as RICS NRM2 section 29 enumerate glazed and panelled doors and windows with a stated girth or pane size class, and United States practice likewise counts door leaves, often both faces, and frames as separate items. The exact pane size and girth classes vary between methods.

Ceilings are a separate area item from walls, because overhead work is slower and, above standard working reach, requires staging or scaffold that loads the labor. The height premium commonly applies once work exceeds roughly 8 to 10 feet, or about 2.4 to 3.0 metres, though the exact threshold is estimating practice. Trim such as baseboard, crown, and handrail is usually a linear item in linear feet or metres with its own rate, since metric methods take surfaces of 300 mm girth or less in linear metres; it can instead be converted to area through the girth conversion. The output unit is chosen by item type, while the girth rules supply the conversion math.

Coat count multiplies both labor and material, and it is set by the specification rather than by region. New architectural work is commonly primer plus two finish coats, for three coats in total, while high performance systems are primer, intermediate, and finish. Same color repaint over a sound finish may be one or two coats, and a dramatic color change needs an extra finish coat or a tinted blocking primer for hide. The one assumption to avoid is a single coat by default.

Theoretical coverage is fixed physics: a product's volume solids and the specified dry film thickness set how much area a unit of paint covers. In United States units, square feet per gallon equals 1604 times volume solids as a fraction divided by the dry film thickness in mils, the constant in Painting Contractors Association P13 section 5.2.2; in metric units, square metres per litre equals volume solids percent times 10 divided by the dry film thickness in microns. A loss factor then converts this to practical coverage, driven by application method: brush, roller, and airless spray lose roughly 10 to 15 percent, while conventional air spray loses roughly 40 to 50 percent. The paint volume is area times coats times dry film thickness, divided by volume solids times one minus the loss, and a procurement allowance then rounds the order up to whole containers and adds a small touch up reserve.

Porous substrates drink the first coat, dropping effective coverage below the spread rate sheet. Concrete masonry is the codified case: Painting Contractors Association P12 requires a block filler step before the finish system, with Level 2 standard fill the default when nothing is specified, under sections 5.3.2 and 5.4, and Level 3 premium fill one or multiple high build coats, backrolled, under section 5.3.3. For rough wood or fresh plaster the uplift is an extra prime or seal coat.

Surface preparation is one of the largest cost drivers after coat count. For steel, the SSPC and AMPP ladder runs from SP1 solvent cleaning, through SP2 and SP3 hand and power tool, to SP6 commercial blast and SP10 near white blast, mapping to ISO 8501-1 grades St2 and St3 and Sa2, Sa2.5, and Sa3 through ISO 12944-4. Preparation affects labor, and sometimes coat count, but not the painted area itself.

When dry film thickness governs acceptance, the work is partitioned into 100 square foot units. Painting Contractors Association P13 takes one spot, the average of three gage readings, per 100 square feet, with each spot at least 80 percent of specification, the average of all spots at least 95 percent, and no more than 105 percent where a maximum is set. SSPC-PA2, from AMPP, fixes the same 100 square foot, or 10 square metre, area unit, averaging 5 spot measurements over each 10 square metres with each spot between 80 and 120 percent. The two standards agree on the area size.

For protective coatings on steel, the service environment, not just hide, governs coat count and total dry film thickness. ISO 12944-2 classifies atmospheric corrosivity from C1 very low through C5 very high, plus CX extreme, and immersion as Im1 through Im4, and ISO 12944-5 then maps each category and durability class to a coating system with a set number of coats and total dry film thickness. The corrosivity category is a project input to capture, and C3, a medium urban or industrial environment, is the common general atmospheric assumption.

Intumescent fire protective coatings are not measured like decorative paint. The required dry film thickness is set by the specified fire resistance period, for example 30, 60, 90, or 120 minutes, the steel section factor, and the limiting steel temperature, read from the manufacturer's tested loading chart. That loading sets both the material volume and the number of build passes, and RICS NRM2 section 29 enumerates intumescent coatings as a distinct work category. Coatings also cannot be applied outside the product's environmental window: under SSPC-PA1 and ISO 12944-7 the surface must be at least 3 degrees Celsius, or 5 degrees Fahrenheit, above the dew point, with relative humidity near or below 85 percent and temperature within the product range, and where the product's technical data sheet is tighter or looser the data sheet governs.

Rounding follows the unit system. United States practice rounds each dimension up to the next whole foot, while metric standard method practice reports areas to two decimal places in square metres without dimensional round up. The same surface also yields different reportable quantities by purpose: a bid estimate, a progress billing, and cost control use the net measured area, while procurement converts the practical paint volume into whole containers and adds a touch up reserve, commonly around 5 percent for normal work and up to 10 percent for rough or complex work, so the ordered volume sits above the applied volume.

Exayard reads the drawings and applies these rules automatically, choosing the deduction threshold by trade and region, converting pipes, steel, trim, and open work into painted area through girth, and turning the net surface into coats and a paint order for the system and region in use.