Western Red Cedar
Botanical name
Thuja plicata
Origin
Western Red Cedar grows in North America.
Trading names
Western Red Cedar
Appearance
Heartwoodvery pale brown to very dark brown.
Sapwoodyellowish white.
Texturefine but uneven.
Grainstraight.
Growth ringsprominent.
General comment
Easy to dry.

Easy to work but the sanding dust can be very irritating to the breathing passages, so a well-ventilated workshop is essential.

It is rather brittle, so care is needed in working end grain.

Since it is very soft there is a risk when dressing it that the cutters may compress the softer earlywood, which will later recover to produce a ridged surface.

Glues well and is a good base for coatings.

The damp wood is corrosive to iron, resulting in a black discolouration of the surrounding wood, so hot-dipped galvanised nails are commonly used in areas likely to experience any dampness.

A yellowish colouring readily leaches from the wood, so white-painted woodwork at a lower level can be stained if storm rains penetrate, say, to the unprotected rear surface of cladding.

Not resinous.
Common uses
Cladding, external joinery, garden furniture, window sashes and frames, greenhouses, roofing shingles and shakes.

If damp conditions are common the shingles and shakes may be subject to soft rot attack and some form of fungicidal treatment may be needed. A steep roof slope will be helpful by ensuring rapid drainage of rain and dew.
Properties
(See notes below)
Hardness rating
Average Hardness Rating - Dry: Soft

Lyctid Susceptibility of Sapwood
Not susceptible
(source AS 5604)

Termite Resistance of Heartwood (inside above ground)
Resistant
(source AS 5604)

Natural Durability Rating of Heartwood Above Ground
Class 2
(source AS 5604)

Natural Durability Rating of Heartwood In-Ground Contact
Class 3
(source AS 5604)


Notes
Density: 'Green Density' (GD) is the density of the wood at the time the living tree is felled. It varies considerably with the season, weather conditions, the age of the tree and so on; the quoted figure must therefore be accepted as a guideline only and when accurate green density figures are required for, say, assessment of transport costs, it is advisable to carry out accurate determinations on the materials involved.

'Dry Density' or 'Air Dry Density' (ADD) is the average density of the wood at 12 per cent moisture content. It too varies with conditions of growth, climate and maturity of wood.

There are published figures for both Green Density and Air Dry Density of most commercial species.

The figures given above have been rounded to the nearest 50.

Hardness rating: the hardness rating of a timber species is measured by the Janka Test. This is a standard test which measures the penetration into the timber of a common load and projectile. The results relate to a hardness capacity of the material and are expressed in kN. This information is useful where the timber may be subject to potential damage from impacts e.g. a dance floor. There are 2 sets of published figures; one for 'Green' or freshly felled timber and one for seasoned timber - i.e. timber with a moisture content of 12%.

The ratings given here are:
  Soft - less than 5.5
  Moderate - 5.5 to 7.0
  Hard - 7.1 to 10.0
  Very Hard - greater than 10.0.

Lyctid susceptible sapwood: Only the sapwood of some hardwoods is susceptible to lyctid borer attack. No softwoods are susceptible to attack.

Natural durability ratings: The natural durability rating of a timber species is a rating of the timber's resistance to attack by wood destroying fungi and wood destroying insects. The sapwood of all timber species has poor resistance and so the natural durability rating applies only to the heartwood of a timber species. The rating is based on the testing of stakes and poles embedded in the ground and on expert opinion of historical performance. There are 2 sets of ratings: one for above ground use and one for in-ground contact use. The lower the number the higher the performance in terms of durability. This information is useful for specifying material for external or exposed applications.
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