The fence post is the most abused element in exterior construction. It sits in the ground, where moisture is constant. It sits at grade, where freeze-thaw cycles are most severe. It carries the fence load. And it is almost always specified incorrectly, which is why most wood fences fail at the post long before the rails and pickets show any distress. The post is the specification. Get the post right and the fence stands for a generation.
Cedar fence posts are not the dressed lumber posts from a chain yard. They are round or square, from the heartwood of western red cedar or northern white cedar, with the red-brown to golden heartwood visible at the cross-section. The heartwood is the durable part. The sapwood — the pale outer ring — is not durable in ground contact and should be absent or minimal.
The correct fence post for New England conditions is 4x4 or 4x6 stock in all-heart western red cedar, or a round post from northern white cedar, minimum 3.5 inches in diameter at the ground line. All-heart means the heartwood extends to the full face of the post with no sapwood. The standard post depth in New England is one-third the post height plus 6 inches, with a minimum depth of 24 inches.
All-heart cedar in ground contact will last 20 to 30 years in New England conditions. The heartwood of western red cedar contains natural preservatives — thujaplicins — that inhibit rot and insect attack. Mixed heartwood and sapwood material will fail at the sapwood zones first, typically at or just above grade where moisture cycling is most severe.
Pressure-treated pine is the default post material and it works. But it arrives on site wet with chemical preservative, it shrinks and checks as it dries, and it requires disposal considerations at end of life. All-heart cedar arrives dry, is stable, and is the historically correct post material for traditional New England fence work.
Specify "all-heart western red cedar 4x4 fence posts" from a lumber yard that stocks cedar. Not all yards carry all-heart stock — call ahead. If all-heart is unavailable, round northern white cedar posts from a regional supplier are the alternative. Do not substitute standard cedar 4x4 dimensional lumber, which contains significant sapwood and will rot at grade.
All-heart western red cedar, 4x4 minimum, for fence posts on traditional New England residential properties. Set minimum 24 inches below grade in compacted crusher run with positive drainage away from the post. No concrete collar at grade — concrete traps moisture at the most vulnerable point of the post. This is the post that does not rot on the maintenance cycle of the fence itself.
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