Guide to building a retaining wall with treated pine sleepers - ITW Proline


What is Treated Pine?

Treated Pine is a wood, such as radiata pine with is treated with CCA (copper, chromium and arsenic) to prolong its life.  CCA is used for the ‘control and prevention of damage to timber and timber structures by insect, wood rot, wood fungus and general timber decay’. Timber treatments can significantly enhance the lifespan of timber, particularly for in-ground applications.

Treated pine sleepers are commonly used for outdoor applications, such as building retaining walls, garden beds, steps and garden furniture.

Building a retaining wall

When building a retaining wall, sleepers must be supported at both ends and at 1200mm intervals (maximum) and posts should be placed in front of sleepers for the results.

Post holes should have 100mm of coarse gravel to manage drainage.

A drainage pipe should be installed at the base of retaining or garden wall and extend to a free draining outlet (not a storm water drain).

When using a screw to fasten treated pine, it is recommended the fixing embeds at least 60% of the secondary material (50mm Timber – 30mm embedment  minimum).

Please note that fasteners will vary depending on the size of your timber and the required strength of your fixing.