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1(viii) Surface area calculations

From the Resene One-Line Specification Manual

Corrugated iron

Add 10.5% to the initial surface area calculation. For example, a corrugated iron structure 200m2 will actually have a surface area of 200m2 x 1.105 = 221m2.

Surface area calculations for corrugated iron

Fences – posts and battens

A two metre high solid fence has an extra 45% surface area on the post and batten side. For example, if the front face of the fence is 2 metres high by 10 metres long then the surface area is 2 x 10 = 20m2. The post and batten side would therefore have a surface area of 20 x 1.45 = 29m2.

Surface area calculations for fences - posts and battens


For older buildings and houses, take the floor area and add 40% – allows for soffits, roof pitch, corrugations and overhangs. For newer homes with small soffits allow floor area plus 25%.

Surface area calculations
for Roofs

Rough sawn timber

For the given surface area, allow up to twice the amount of paint or stain for the first coat.

Surface area calculations for rough sawn timber

Stucco textures

Based on a model of 1cm high pyramids with a 1cm base (coarse texture), the surface area is two times greater than the base area. If the height of the pyramids is 0.5cm (representing a medium texture) the increase in surface area is about 40%.

Surface area calculations
for stucco textures

Trough section

Add 50% to the flat surface area.

Surface area calculations
for trough section

Unprimed weatherboard

Unprimed weatherboards require priming back and front. Stained weatherboards require the first coat also to go all around. The total area of a (rusticated) weatherboard is 21/2 times the area that is shown when it is fixed.

Surface area calculations
for unprimed weatherboard

Resene One-Line Specifications and Data Sheets
Resene offers clear and simple paint specification guidelines, designed to make specifying the right paint system easier. If in doubt about any aspect of your specification please contact Resene.

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