Because the installation of concrete paving stones is a
complex and time consuming procedure many do it your
selfer's do not invest in the effort to do the job right –
the first time. If proper installation is not followed, the
paving stones will heave in some spots, settle in others and
spread out producing an unsightly outcome.
The following information is intended as an overview to the
proper installation of concrete paving stones. These are the
steps that would be taken by a reputable contractor who
would be providing a guarantee on the work done.
The first and a very important step is to have the property
surveyed for buried cables, power lines and gas pipes before
you start digging. Most utility companies provide location
services free of charge. All it takes is a phone call. If
you excavate without having the location services flag your
property, you will be held responsible for any damages and
subsequent repairs. Not to mention the fact that cutting
into a buried electrical service with a shovel could put you
out of commission for a very long time. As well, think of
the anguish you might create in the community by cutting off
utility services to your neighbours. The primary service
companies that should be called are gas, electric, cable TV,
and telephone.
Using stakes and string map out the area to be excavated.
The more intricate the area, the more complex the
installation and cutting of the concrete paving stones.
Remember that concrete paving stones are not flexible and
hence tight curves and arches can be difficult to fill.
Remove the existing pavement, sod, plants, and trees from
the area to be excavated.
Excavate the soil to the required depth. The depth needed is
the basic calculation derived from taking the finished
surface minus the thickness of the paver, the depth of the
setting bed and the depth of the base material. The required
thickness of the base material (commonly 4 to 8-inches for
patios and walkways and 6 to 12-inches for driveways and
roadways) is totally dependent on local soil conditions,
primarily the soils reaction to water. The city or county
soil engineer will be able to tell you the required
thickness of the base material for your area.
Prior to laying the base material, the sub-grade must be
compacted. With a clay sub-grade you will need to use a
powered roller or rammer. With a sandy soil the use of a
mechanical vibrator, should be adequate to provide proper
compaction.
After the sub-grade is compacted, place a layer of landscape
(geotextile) fabric on the sub-grade. It is important that
the base material be somewhat isolated from the natural
soil, especially in high moisture areas.
Use a granular base material that compacts easily on top of
the landscaping fabric. The material should be laid in 2 to
4-inch layers, or lifts as it they are called within the
industry, with each layer being individually compacted. It
is impossible to get proper compaction in a layer that is
thicker than 4-inches no matter what type of compacting
equipment is employed. The base material goes under numerous
names (“type 2 base”, “AB3”, “21A” or “3/4 minus”) depending
on where you are located. Your local concrete paver supplier
will know the material to be used as a base for installing
the pavers.
Once the granular base material has been compacted, install
edge restraints along the border, on top of the base
material using steel spikes to secure them in place. The
edge restraints are a key part of the potential longevity of
the paver installation as they provide lateral load
resistance and provide continuity to the interlocking
characteristics of the paving stones. Without the edge
restraints concrete paving stones will separate and spread
over time.
Lay the setting bed, to a depth of 1 to 1.5-inches, on top
of the compacted base material and spread it evenly across
the entire project area. The setting bed is usually a
material of washed coarse concrete sand or granite stone
dust.
You are now ready to install the pavers in your chosen
pattern. As a general statement, it is best to start at one
end of the project and in the middle of the area (there are
some exceptions with complex patterns. Do not place edge
pavers first as you cannot be sure of their precise
location. If it is a large project and you have several
skids, take pavers randomly from all skids to ensure that
any colour variations between the individual skids are
blended within the total project.
The paving stones are down, but you are not quite finished!
Sweep sand over the top of the pavers and fill the gaps
between the pavers. Use a vibrating compactor, over the
entire project, to force the sand to completely fill the
gaps between pavers (sweep additional sand as necessary).
The process of vibrating sand into the gaps creates an
amazingly solid and stable surface.
Last but not least, remove any excess sand that has
accumulated from the previous step and apply a protective
sealing finish to your project. A sealer will highlight the
paver colours and protect the stones from staining. The
sealer should be applied at regular intervals, follow the
manufacturer’s instructions.
Tip 1: If it rains during the compacting phases of the
sub-grade or the base material, make sure that the ground
has dried out completely before you continue.
Tip 2: Remember drainage when grading the soil. You should
allow for a slope of 0.25-inch per foot to allow water to
run off the finished project.
Tip 3: Don’t be afraid to use a level during all phases.
As with all home improvement and landscaping projects,
planning and knowledge are the keys to success.
For additional information on pavers, landscaping or other
home improvement projects, visit
Renovation Headquarters
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