Cedar shed treatments

Updated April 17, 2017

As well as being a durable material for constructing sheds, red cedar is free from pitch, easily cut and can be finished to a smooth finish. It is not subject to excess shrinkage or warping in extreme temperatures or humidity. Cedar is naturally resistant to attack by insects and vermin and unrivalled in its natural resistance to decay. Care should be taken with choice of additional treatments to avoid spoiling the appearance of the wood.


Over time, discolouration of cedar will occur. Scrubbing with diluted household detergent should remove dirt build-up. A solution of oxalic acid can aid removal of more stubborn water stains. If previous treatments have mildew showing through, then you can go clear back to the wood before cleaning and re-treating. Spray the wood with a solution of 3.42 litres (3 quarts) water, 1.14 litres (1 quart) of household bleach and 59 ml (1/4 cup) of ammonia-free liquid dishwasher detergent. Leave to soak for up to 15 minutes, then scrub with the same solution (or use a power wash).


The natural oils and preservatives present in cedar may cause discolouration of paint or solid-colour stains unless a suitable primer designed to control bleeding is used. Use an alkyd oil-based primer. Look for a label stating that that the product is suitable as a stainblocking primer for red cedar.

Solid colour

Water-, latex- and solvent-based paints are all suitable for use on red cedar sheds. They offer good protection against weathering and a wide range of colour. Use latex paint for the extremes of outdoor weather. For an opaque finish an alternative is a solid-colour stain, a thinner coating with fewer solids than paint, that allows some of the wood's natural characteristics to show through. They are available as latex- or oil-based products, and should always be used with a stain-blocking primer.

Transparent stains

To maintain and enhance the natural appearance of the wood, and offer enhanced protection against weathering, transparent or semi-transparent stains are available that contain fungicides to inhibit mildew growth. Solvent-borne oil-based products will penetrate beneath the surface, offering best protection against weathering.

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About the Author

Based in South Wales, John Birch has written about pet food and nutrition since 2000, and about Celtic spirituality since 2004. Author of "Heart2Heart" and "Footfall--Prayers for the Journey," he has also written for various U.K. magazines. A winner of NAWG national poetry prize (2005), Birch has diplomas in food technology and business IT from Glamorgan University.