Overview
Walk around most residential
neighborhoods and you'll find
concrete block retaining and garden
walls dotting the landscape. No longer
just holding back earth, stabilizing
slopes and preventing erosion, modern
concrete block walls define pathways,
create borders for outdoor “rooms” and
serve as focal points in featureless yards.
Building a block wall is a significant
investment of time (if you do it yourself)
and money (whether you do it
yourself or pay someone to do it).
Shopping for modular block can be
confusing because of the many colors,
textures, shapes, styles and stacking
systems available. This article will
help you sort through your options and
discuss what you need to know before
you shop so you can buy the right
block for your garden or retaining wall.
In a nutshell
- The more expensive the block, the more
it will look like natural stone.
- Each block system will accommodate
curves, steps, corners, caps and setbacks
differently. Your wall's requirements will
help narrow your options.
- When you shop, take along a sketch of
the wall's height, length, radius of inside
and outside curves, and specific features.
Then you'll have everything you
need to choose the material and narrow
down prices on one trip.
- Even if you plan to hire a pro, shop
around to see actual walls rather than
depending on contractors' pictures to
imagine how yours will look.
- Home centers carry some systems, but
you'll find the widest variety of options
at landscape suppliers.
Top of the line: $11 to $15 per sq. ft.
Photo courtesy of VERSA-LOKMid range: $9 to$10 per sq. ft.
Photo courtesy of KEYSTONELeast expensive: $4 to $8 per sq. ft.
What Kind of Wall Do You Get For Your Buck?
Top of the line: $11 to $15 per sq. ft.
The most expensive block offers the greatest flexibility in design potential, styles, colors
and wall size. Big “wow” factor.
Mid range: $9 to$10 per sq. ft.
Mid-priced block is good for highly visible
walls where function is still the primary
concern. It offers a high-end look and feel
and is available in many colors and styles.
Least expensive: $4 to $8 per sq. ft.
These easy-to-install blocks are often used
for garden walls. They're available in a limited
number of styles and colors.
What's the wall's purpose?
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Freestanding
Freestanding wall blocks are widely available at home
centers, nurseries and landscape suppliers.
Photo courtesy of Keystone
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Large retaining walls
Heavy-duty walls require full-size blocks, which are available
at landscape suppliers.
Photo courtesy of Rockwood
A freestanding garden wall 3 ft. or less in height that
serves a more decorative function gives you more flexibility
with the size, style and type of block you choose.
Most manufacturers offer a wide variety of styles in
two or three basic sizes. The garden wall size is the
most common. These relatively small blocks (about 12
in. long x 4 in. high) are lightweight (less than 25 lbs.)
and work best for accent walls around the yard and
garden up to about 30 in. high. All four sides are finished
and they have special blocks for columns, corners
and ends.
Retaining walls, because they're load-bearing and slope
into a hill slightly, require larger blocks and beefier connections.
These blocks are 16 to 18 in. long x 6 to 8 in.
high and weigh 50 to 75 lbs. Big walls usually entail
excavating and moving tons of soil and gravel as well as
the heavy block itself. These walls can be daunting to
do yourself, so think it through before you unknowingly
dedicate a whole summer to the task. Most systems
are engineered to handle heights up to 4 ft. Retaining
walls above that height must be designed or approved
by a licensed engineer.
What kind of look do you want?
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Three-way split
The corners are split off
the face of this block,
leaving a highly textured,
rounded surface. These
are usually the best choice
for tighter curves.
Photo courtesy of VERSA-LOK
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Straight face
When stacked, it has the
classic look of chiseled
stone. The uniform texture
is a good backdrop for a
garden or a good visual
base to a house. Its muted
appearance will look in
style for years. Block size
varies. In general, use small
block for smaller walls.
Photo courtesy of VERSA-LOK
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Tumbled or weathered
The edges are rounded
to soften its appearance
and make it look more
weathered and natural.
Different length blocks
can be mixed to further
vary the look.
Photo courtesy of VERSA-LOK
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Mosaics or ashlars
This combination of tumbled
and weathered block in different
sizes and colors gives a
wall a custom-fitted look.
Best used for straight walls;
curves require more building
experience and block cutting.
This type also requires
more expert advice for
curves, corners and stairs.
Do you want the block to blend with your property's existing features or to inject something new into the landscape? Although specific shapes, colors and textures vary by region, almost every manufacturer produces four main styles (see photos).
What are your wall's requirements?
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Solid and semi-solid blocks
Solid and semi-solid blocks
are heavy (up to 75 lbs.)
but are the most versatile.
You can simply split them
to form 90-degree corners
or any other angle, rather
than ordering special
blocks.
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Hollow-core blocks
Hollow-core blocks are
about half the weight of
their solid counterparts
and much easier on the
back. After you set each
course, you fill the cores
with gravel, making the
wall every bit as strong as a
solid block wall. You have
to order special blocks for
corners and caps.
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Lip systems (interlock or tongue-and-groove)
Lip systems (interlock or
tongue-and-groove) are
popular with DIYers since
they go together fast and
easy. However, they aren't
quite as versatile because
you can't vary the setback
(the amount each course
of wall steps back into the
slope). The typical setback
is 1-1/4 in. per row.
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A pin or a clip system
A pin or a clip system,
made from tough plastic
or fiberglass, anchors each
row of blocks to the ones
below. These systems are
fussier but will let you
slide the block forward
(no setback) if you need a
more vertical wall (such
as where a wall meets the
corner of a house).
The details of your project will help you decide on a block system. Different block systems are suited
to different project requirements. For example, all block systems have limits as to how tight a
curve they can form without being cut. Systems also vary in how they handle corners,
setbacks, cap blocks, columns and steps.
What's your budget?
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Add other costs
Although they can be expensive, a well-built wall will last as long as your house.
Photo courtesy of VERSA-LOK
The cost of block is only a piece of the total project budget. If you're using a contractor, you'll obviously pay labor
costs. A good rule of thumb for a contractor-built wall is to double the materials price—in other words, half labor,
half materials. Make sure to agree on the front end whether your contractor will provide final grading and resodding
(or will leave your yard a total disaster). Will the driveway be repaired? Wheel ruts fixed? Topsoil included?
These details often account for why one bid is significantly higher or lower than another.
If you plan to build your own wall, beware. There's
a lot of heavy work, including tons of fill and footing
material to get delivered and moved. Also consider
the tools you'll need to rent and other additional costs:
- Delivery charges for materials. Don't wreck your
back or your vehicle. Block is heavy, even the garden
wall variety. Pay the extra charge to place your
materials exactly where you want them.
- Skid steer rental ($200 per day). Keep in mind that
using heavy machinery will damage your yard, so
you need to add in the costs of grading and resodding
as well.
- A block splitter costs $90 per day. You can also
have the landscape yard split the blocks for you.
- Plate compactor rental ($50 per day). It's crucial to
compact your footing material or you'll have a sagging,
crooked wall in the future.
- Other materials such as “compactable gravel” for
the base, drainage layer material and drain tile.
