Setting the Blocks
Installing First Row
When you set your first row of block in, you're establishing the shape of the whole project, so you want to get it right.
It's real important to check the blocks for level as you set them down. If you need to make minor adjustments, you can use a little sand to raise the blocks. You don't want to use loose dirt because dirt will settle a little over time.
Make sure that the outside edges touch one another.
As you finish each row of a wall, you should backfill in behind, and in between the blocks. For a small wall you can just use dirt for the backfill.
For larger projects use crushed stone or river rock for the backfill.
Clean the tops of each row before you move on to the next row.
Installing Remaining Rows
All of the rows will need to somehow lock to the row underneath it. Some interlocking blocks have a flange on the bottom in back to lock on to the lower row. Some have holes in the top and bottom for pins to lock the rows in place.
If you've got a curved wall and are using the flange-type of block, you'll probably need to knock if off with a hammer. Otherwise, the flange will get in the way.
Most people set up a running bond pattern. This means that the joints between the blocks in the second row fall over the middle of the blocks in the first row.
After the second row of blocks is set, you follow the same procedure: fill around the blocks, compact the fill, clean off the tops of the blocks, and put on the next course. And this repeats all the way up the wall.
For large walls, some professionals use what's called a geogrid. This is a flexible plastic mesh that attaches to the back of the wall and anchors it to the hillside.
If you're using the pin-type of block, you'll need to use a special "cap" block for the top row. You don't want any holes for pins in the tops of these blocks.
We like to put some construction adhesive under this row to hold down the top blocks. This is just a little insurance.