Painting and decorating calculators.Paint, primer, wallpaper, filler, coverage, drying and pricing.

Film thickness and spreading rate

Film thickness and spreading rateDry film thickness from wet film thickness and volume solids

DFT = \frac{WFT \times VS}{100}

Film thickness and spreading rateWet film thickness needed for a target dry film (with thinning)

{VS}_{t} = \frac{VS \times 100}{100 + th}

Film thickness and spreading rateTheoretical and practical spreading rate from volume solids

TSR = \frac{10 \times VS}{DFT}

Site conditions

Site conditionsDew point from air temperature and relative humidity (Magnus formula)

γ = \ln (\frac{RH}{100}) + \frac{17.625 T}{243.04 + T}

Site conditionsSurface temperature margin above dew point (3 °C rule)

γ = \ln (\frac{RH}{100}) + \frac{17.625 T}{243.04 + T}

Site conditionsMinimum application temperature and humidity check

T_{low} = \min (T_{a}, T_{s}, T_{n})

Site conditionsRecoat or drying time adjusted for temperature (10 °C rule)

f = 2^{\frac{T_{r} - T}{10}}

Products and spraying

Products and sprayingVOC released on a job and VOC content as applied

m = c V + c_{t} V_{t}

Products and sprayingThinning ratio: thinner volume and volume solids after thinning

V_{t} = \frac{V \times p}{q}

Products and sprayingSpray paint quantity allowing for transfer efficiency (overspray)

Q_{s} = \frac{Q_{n} \times 100}{TE} + V_{h}

Products and sprayingAirless spray tip code: fan width and orifice size

a = ⌊ \frac{N}{100} ⌋

Running the business

Running the businessLabour time from area, coats and productivity

T_{h} = \frac{A \times n_{c}}{P} + T_{p}

Running the businessJob price: labour plus marked-up materials plus VAT

N = H r + M_{c} (1 + \frac{μ}{100})

Running the businessDay rate to m² rate (and back)

r = \frac{D}{P_{d}}

Running the businessMarkup and margin

P_{r} = c (1 + \frac{μ}{100})

Running the businessHMRC simplified mileage allowance (cars and vans)

a = \frac{r_{1}}{100} \times \min (B, B_{1})

Running the businessCIS deduction on a subcontractor invoice

B_{n} = G - V_{t} - M_{t}

Running the businessVAT registration threshold headroom

H = T_{h} - T_{12}

Areas

AreasRoom wall and ceiling area less doors and windows

P = 2 (L + W)

Paint

PaintPaint quantity and cheapest combination of tins

V = \frac{A N}{S} (1 + \frac{w}{100})

PaintMist coat on new plaster: paint and water

M = \frac{A N}{S}

PaintPrimer or sealer quantity and tins

V = \frac{A N}{S} (1 + \frac{w}{100})

PaintFeature wall and main colour quantities

A_{f} = L_{f} H - O_{f}

Woodwork

WoodworkUndercoat and gloss for woodwork

V_{u} = \frac{A}{S_{u}} (1 + \frac{w}{100})

WoodworkDoor paintable area (leaf, edges and frame)

A_{f} = \frac{k H W}{10^{6}}

WoodworkSkirting and architrave paintable area

A_{s} = \frac{L_{s} g_{s}}{1000}

WoodworkWindow frame paintable area

A_{p} = W_{f} H_{f} - N_{p} p_{w} p_{h}

WoodworkRadiator and pipe paintable area

A_{r} = f L H

Exterior

ExteriorExterior masonry paint (smooth or textured surfaces)

V = \frac{A N}{S} (1 + \frac{w}{100})

ExteriorWood stain or varnish quantity

V = \frac{A N}{S} (1 + \frac{w}{100})

ExteriorFence panel and shed treatment

A = N_{p} W_{p} H_{p} s + A_{x}

Wallcoverings

WallcoveringsWallpaper rolls from height, perimeter, roll size and pattern repeat

D = ⌈ \frac{H + t}{R} ⌉ R + \frac{h R}{2}

WallcoveringsCeiling paper rolls

D = L_{s} + t

WallcoveringsLining paper rolls by area

A = (A_{w} + A_{c}) (1 + \frac{w}{100})

WallcoveringsWallpaper paste packets and mixing water

N_{p} = ⌈ \frac{N_{r}}{R_{p}} ⌉

Preparation

PreparationDecorator’s caulk or sealant cartridges per metre of joint

q = k b e

PreparationThinning and mixing ratio

V_{t} = \frac{V p}{100}

Painting and decorating calculators.Paint, primer, wallpaper, filler, coverage, drying and pricing.

Film thickness and spreading rate

Site conditions

Products and spraying

Running the business

Areas

Paint

Woodwork

Exterior

Wallcoverings

Preparation

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