Retaining walls, whether built out of rock, blocks,or timber's can be the back bone of the landscape. But if not constructed properly they can be the Achilles Heel.

There are three components to building a sturdy and sound retaining wall. They are compaction, foundation, and drainage. Compaction is important under and behind the wall. Settling soil under a wall will cause it to fail and cave in. Poor compaction behind the wall can result in sluping and settling which can also cause problems for the structure.

The foundation of the wall is partly compaction, but depending what the wall is built out of, is a lot more. A block wall is only as good as its first row of blocks. If that row is not straight or level, neither is any other row. With rock walls its important the rocks used in the bottom row are of substantial size and width. You can't stack rock four feet tall on top of a six inch thick rock at the bottom. The bottom rock should have a large foot print and fairly level top to build off of.

Drainage is probably the leading cause of a wall to fail, if it has been built right in the other aspects. A lot of people don't realize that a wasll is much like a dam. As water works its way through the soil and comes to the back of a wall it needs a place to escape. Usually drain pipe and drain rock are used to give the water and excape route. Some block walls are designed for water to weep right through them. Even these often need a pipe or very good grading to ensure water dosn't build up around the base of the wall.

Usually we recommend rock or block for retaining walls because they last the longest and most often look the best. But occasionaly timbers are the way to go. Due to high levels of toxins in creosote and pressure treated timbers, I would lean towards rock or block. There is more enviromentally friendly timber available these days but they don't last as long as the others and nothing last like rock does.