| Base
Preparation |
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As with pavers, base preparation is the most
vital part of the installation process. Begin laying out the trench
with a string line. Dig a trench 6” to 12” deep and about 4”
wider than the width of the style of blocks you intend to use. If
your property slopes, step the trench up or down allowing for at
least half the height of a block to buried. This saves time and
material.
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| A
Gravel base is required to place the retaining wall stone on, for long
term stability. |
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| Compact
the trench and fill it with 3” to 6” of gravel (see
“Base Thickness Chart”). Rake out, level, and compact the gravel.
A vibrating plate tamper is preferred to a hand tamper where possible. |
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| Laying
the First Row
Most retaining wall systems come pre-split, however some
Unilock® retaining wall products must be split. Use a 3lb. Mallet and a
3” – 4” chisel to split blocks along the center groove. This gives
each unit the natural split face appearance. |
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| If
your design has a corner, start by using a corner unit. Place each unit
directly on the compacted gravel base, leveling each one with a
carpenter’s level. |
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| Make
adjustments with small amounts of sand and a rubber mallet. Take your time
and do this properly. |
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| Laying
Additional Rows
Sweep debris off the top of the first row and place
your first block, starting at a corner if you have one, offsetting it by a
half a block. This will ensure your joints will be staggered, which is
necessary for proper stability of the wall. Cut a block in half to
complete the beginning of the row. Continue in this fashion until you
reach your previously determined height, backfilling every two rows. |
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| Backfilling
Gravel is used behind the wall as backfill to allow for
drainage. Be sure to backfill every two rows as you progress in height. A
filter fabric material is used to separate the native soil from the gravel
to ensure the gravel won’t become clogged and prevent proper drainage.
Make sure you allow enough fabric to cover the final height of the wall.
To ensure proper drainage behind the wall you should install a drainage
pipe. |
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| Coping
Coping units are used to finish off the top of the
wall. They are glued in place with Landscape Adhesive.
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| If
your wall is curved you may have to cut the coping units to fit. |
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| Finished
Step and Wall coping ready to fill with paving brick in front of door and
topsoil in planter box on right. |
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| Steps
Step creation is similar to installing a retaining
wall. The difference is that with steps you must compact the gravel behind
each row (or riser). Place the first row of wall units directly on to the
compacted base. Line up the area behind the row with the filter fabric;
fill with gravel and compact to the top of the blocks. Fit and glue the
coping units (or treads). Place the next row of blocks directly behind the
coping for your second tread and repeat these procedures for any
additional steps required. One attractive option is to create a longer
tread by installing pavers between the risers as shown here. |
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| Raised
Patio
To build a raised patio follow the same procedure as
for retaining walls. Backfill with gravel to within three inches of the
top of the final height of the patio. This allows for a bed of screeded
sand and the height of a paver.
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| Planters
The difference between constructing a planter and a
raised patio is that you backfill and compact the gravel to within 6
inches of the top of the coping. Place a filter fabric over the gravel
then fill with topsoil for planting.
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