Wood that is durable underground

Woods with natural resistance to rot

On the Library of Congress American Memory website, I found some old magazine reports of studies done in the 1800s on the durability of wood . It's interesting, but not surprising, to see that those researchers discovered what every fence builder knows -- red cedar and black locust are naturally rot-resistant woods. (Their studies didn't include redwood or bald-cypress, two other woods with excellent resistance to decay.)

If you need modern research on the durability of various wood when used as fence posts, a good study to read is Service life of treated and untreated fence posts. But, just because they're interesting, here are the old studies of rot-resistance that I found in Manufacturer and Builder, a magazine from the late 1800s.

In some tests made with small squares of various woods buried an inch in the ground, the following results, says the Garden, were noted:

-- Birch and aspen decayed in 3 years
-- Willow and horse chestnut in 4 years
-- Maple and red beech in 5 years
-- Elm, ash, hornbeam and Lombardy poplar in 7 years
-- Oak, Scotch fir, Weymouth pine and silver fir decayed to a depth of half an inch in 7 years
-- Larch, juniper and arborvitae were uninjured at the expiration of the 7 years.

Source: Durability of Woods. [Manufacturer and builder / Volume 17, Issue 11, p.242, November 1885]

Here's a five-year wood-durability study that involved wood stakes placed six inches in the ground:

Durability of Various Kinds of Wood.

ACCORDING to the Nautical Magazine, the following are the particulars of experiments made on several kinds of wood, 1-1/2 inches square and 2 feet long, placed vertically in the ground, and about 1 foot 6 inches exposed to the atmosphere, January 1st, 1831; examined at two different times, namely, May 8th, 1833, and February 24th, 1836:

Leaf or live-oak
-- Very good, 1833
-- Three much decayed, the rest tolerable, 1836

Canada white-oak
-- Very much decayed, 1833
-- Very bad, and rotten, 1836

Memel oak
-- Very much decayed, 1833
-- Verybad, and rotten, 1836

Dantzic oak
-- Very much decayed, 1833
-- Exceedingly bad, 1836

Mahogany, hard
-- Good, 1833
-- Tolerably good, 1836

Mahogany, soft
-- Much decayed, 1833
-- Very bad, totally decayed, 1836

Lebanon cedar
-- Good, 1833
-- Tolerably good, 1836

Pencil cedar
-- Very good, 1833
-- All very good, as put in the ground, 1836

Teak, heavy
-- Very good, 1833
-- Rather soft, but good, 1836

Fir, red pine
-- Much decayed, 1833
-- Very rotten, 1836

Fir, yellow pine
-- Very much decayed, 1833
-- Very rotten, 1836

Fir, Virginia pine
-- Decayed, 1833
-- Very rotten, 1836

Fir, pitch pine, hea-
-- Decayed 1/(?) of an inch, the rest good, 1833
-- Decayed 1/4 of an inch, the rest tolerably good, 1836

Fir. pitch pine, light.
-- Very rotten, 1833
-- Very rotten, 1836

Polish larch
-- Decayed 1/4 in the surface, and lost in weight, 1833
-- Decayed 1/4, the rest a little decayed, 1836

English elm
-- Very rotten, 1833
-- All rotten, 1836

Canada rock-elm....
-- Very rotten, 1833
-- Rotten, 1836

American ash
-- Very rotten, 1833
-- Rotten, 1836

Locust tree-nails....
-- Good, and retained their weight, 1833
-- 1/8 inch rottem. time rest, the rest as solid as when put into the ground, 1836

Source: Durability of Various Kinds of Wood. [Manufacturer and builder / Volume 3, Issue 4, p. 74, April 1871]

And yet another report on the durability of various wood stakes when almost completely buried in the ground...

EXPERIMENTS have been lately made by driving sticks, made of different woods, each 2 feet long and 1-1/2 inch square, into the ground, only 1/2 inch projecting outward. It was found that in five years:

-- All those made of oak, elm, aspin, fir, soft mahogany, and nearly every variety of pine, were totally rotten.
-- Larch, hard pine, and teak-wood were decayed on the outside only.
-- Acacia, with the exception of being also slightly attacked on the exterior, was otherwise sound.
-- Hard mahogany and cedar of Lebanon were in tolerably good condition.
-- Only Virginia cedar was found as good as when put in the ground.

This is of some importance to builders, showing what woods should be avoided, and what others used by preference in underground work.

Source: Durability of Different Woods. [Manufacturer and builder / Volume 3, Issue 12, p. 278, December 1871]