How to Build a Small Pad With Landscape Timbers

Purchase your landscape timbers, steel rod (rebar), and landscape spikes (giant nails). Landscape timbers come in 8' lengths, so to make things easy, with less cutting, try a pad that's in dimensions of 8' or 12', such as 8' x 8', 8' x 12', or 12' x 12'. The above pad is 12' x 12'. Anything much larger and you will need 'deadmen' laid into the pad for lateral stability.

Start with the lowest elevation for building your retaining wall. In a 12' x 12' pad, this wall will begin with one full timber and one half a timber laid in a line. Timbers can easily be cut with a handsaw. This bottom row can either be dug in and laid on grade, or propped up on solid rocks to keep moisture away. Landscape timbers are surface treated for outdoor use. Get the row level with a 4' to 6' level - pound it into position with a rubber mallet if necessary.

Anchor the row into the ground. For this drill a hole 6" from each end of the timber, and for the 8' piece, one in the center. Drill a hole 1/16" smaller than the diameter of your rod (1/2" rod is ideal, but it's harder to cut with bolt cutters - 3/8" rod will work also). This is so the rod will be snug in the timber. Cut your rod so that it will be driven at least 1' to 1 1/2' into the earth, plus the height of the timber (3"). Pound the rod down and through your timber until the top of the rod is flush with the top of the timber. The rod has no head on it, so it won't hold the timber down - but it will hold it laterally and keep the timber from moving side to side. This will keep pressure from fill from pushing the wall out.

Begin the edge walls. The retaining wall is designed like a giant 'U', with the edges of the 'U' keying in to the soil and holding the main wall upright. Take an 8' piece and start it above one corner of your bottom row, perpendicular to it, and run it until it terminates completely underground. Depending on your grade, 8' might be too long - a 4' piece might work better. Anchor the timber into the soil with rod, and where it rests above the corner of the bottom row, attach it with a landscape spike. Landscape spikes are heavy-duty nails - try to stay away from the edge of the timber and drive them slowly. A 2 lb sledge works well.

Start the other edge wall the same way, at the opposite corner of the bottom row.

Build up the main wall with another row of timbers, staggered over the joints - slightly less than 12' this time, because run between the ends of your edge rows. Attach the timbers to the timbers below with landscape spikes. Mark somewhere outside the wall where you drive spikes in, so as you work higher you don't end up trying to drive one spike into one below.

Run another row along the main wall above this, the full 12', overlapping your edge rows. Attach with landscape spikes.

Do more rows along the edges, again starting at the corner and running each timber until it terminates below grade. 6" back from where it terminates, drill a hole and drive rod in to hold it in place. Where the timber is on top of another timber, use a landscape spike. Spikes are $1 a piece, so use them sparingly. No more than every 4' is necessary. Be careful not to split the wood.

Build up this way until your retaining wall is as high as you need. Make sure each edge row overlaps the last and keys into the soil. When using landscape timbers as retaining walls, 6 timbers high is about all you can go without needing further lateral stability such as 'deadmen'.

Remove the sod from the pad area, and begin filling with dirt. Remove sod with a spading fork. Rake out each wheelbarrow-load of dirt flat, and then tamp:

Use the narrow edge of a board with a level on it to check your grade as you build up. It's easy to start mounding dirt in the middle - check for this as you go.

Allow the new fill exposure to the weather for a while, if possible. Several heavy rains will cause the dirt to settle. However it will remain sticky when it's wet, because of the clay content. If you're not putting down gravel or pavers above, use a few bags of sand or lime to counteract this.

Place your structure on the new grade. It can be anchored into the pad at the corners with rod. Drive the rod deep into the pad and attach this to the corners of your structure.

Put down a layer of pea gravel, and tamp it gently. Enough will form a cobblestone floor. With larger stones, such as river rock, you can sweep out a layer of cement into the cracks, and mist it with a hose until it hardens.