Cypress Pine Posts
I have recently had to address a number of Cypress Pine Posts concerns from our builders. These have mostly all been related to surface checking appearing on the painted posts soon after installation. I want to outline some information on the properties of Cypress Pine for the end-user and homeowners for future awareness.
Cypress Pine from Bowens
Cypress Pine from Bowens is the particular specie White Cypress, it is mostly sourced from Central and Western Queensland. It is a highly durable softwood.
According to the Australian Standard AS 5604 -2005, it has a Class 2 durability in-ground and is Class 1 above ground. The creamy white sapwood of Cypress is easily distinguished from the heartwood and is not as durable at Class 4.
Decay and Rot
It is the natural oil/resins in the heartwood that make this timber durable from rot and decay as well as resistant to insect attack including termites. Due to the natural log taper, Cypress Pine will have less sapwood on the butt-end of the post. This is the end that should be selected for in-ground use.
The durability of Cypress Pine makes it a good choice for external applications. It has good stability with a low shrinkage rate at 2.5% radially and 3% tangential. Cypress Pine posts are structurally graded to F7 and are an economical option for external posts.
It is the natural oil/resins in the heartwood that make this timber durable from rot and decay as well as resistant to insect attack including termites
Surface checking is a natural characteristic of unseasoned Cypress Pine. It is more predominate on smooth dressed timber than sawn surfaces.
‘Checking’ is the separation of the wood ﬁbres along the grain forming ﬁssures (small cracks), they do not extend through the piece from surface to surface and do not affect the structural integrity of the post.
Once installed, the unseasoned posts begin to acclimatise to their environment, the result of moisture loss will show up as surface checking.
Protective Oil or Paint Coating
This is where a protective oil or paint coating will help to protect the post. A suitable external ﬂexible wood ﬁller can be used to ﬁll these ﬁne cracks to restore a smooth ﬁnish prior to coating.
The Australian Standard AS 2858 -2008, section 3, Grade Descriptions for Cypress, permits unlimited checks in the Grade F7. To further minimise surface checking as well as posts twisting our dressed all round posts are supplied fully wrapped in a plastic to help minimise the rapid loss of moisture.
This helps to seal in the moisture until the post is ready to be ﬁnished. Applying protective coatings either prior to installation or soon after is recommended.
When using any timber posts in-ground it is recommended that the in-ground end is coated with a bituminous paint or an alternative preservative. Bowens stocks Inground Wood Protecta for this purpose.