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Sidewalk Damage by Tree Roots
The problem of walkways and
other slabs being lifted or otherwise damaged has reached astronomical
proportions. Cities are spending millions of dollars on sidewalk
repairs each year. Complexes are perplexed by the costs of replacement
driveways and other cement.
The problem seems to only get worse
as time goes on. Replacement of cement is perpetuated by newly
encroaching roots. It seems that even if the roots are chopped
out, it is only a matter of time before they come back and start
the damage cycle all over again.
Some of the procedures to stop
this problem are so drastic that it seems almost criminal. Municipalities
are inundated with old beautiful trees that have out grown the
containment areas and in some cases are overlapping the concrete.
The shear mass of the trunk caliper is busting out all over
causing unbelievable damage.
The sad part of this story is that
someone planned this and chose these trees. Now that these trees
have created a pristine environment that makes a neighborhood
the beautiful shady place to live, the roots create havoc. Potential
liabilities spring up all over and not many organizations are
willing to live with the gamble. We live in a sue happy society
and the trees become the victims of precautionary measures.
I’ve seen whole trunks ground back on both sides to make room
for the "fix". Roots are treated with little respect and torn
out with heavy equipment. Special root cutting machinery is
designed to sever everything to make room for different types
of barriers. These barriers are designed to "redirect" the new
roots that develop after this devastating surgery. Chemical
barriers have also been developed to inhibit cell division when
new roots make contact.
Trees are tough right? They hardly
ever die when these drastic procedures are performed thus perpetuating
the concept that it is OK to do this. Similar to the misconception
that it OK to top trees because they come back, these practices
are ruining these specimens and creating future hazardous trees.
Trees can survive for a long time
on stored reserves. If the roots are cut, (even massive amounts
of roots), the tree generally survives. But this survival is
only temporary. As it takes a long time for a tree to develop
and grow large, it usually takes a long time for the tree to
die. Some of the potential liabilities created by massive root
destruction far outweigh the trip hazard problems. Large trees
can stand until the wind decides to get a little stronger than
the norm.
If the tree survives the current
seasons storms, it is still a candidate for toppling in the
future years because the open wounds are starting to rot.
In our efforts to solve the problems
of buckling cement we are inadvertently causing future problems
of equal or greater liability. If a large tree falls down, structures
and vehicles can be crushed. People can be seriously injured
or killed. And the turbulent upheaval of a falling tree can
lift up and damage the previously repaired side walk
Examples of large old trees with
drastic grinding performed many years ago are abundant. Just
because they are still standing, and look visually healthy,
does not mean that problems are not developing. At the very
least, drastic grinding shortens the life of the tree, which
In turn requires a removal that maybe should have been considered
in the first place. By now, the replacement tree could have
developed, and you would be better off. It seems that decisions
are often made for the here and now, with little thought of
the future. This statement pertains to the choice of new trees
as well as trying to get a few more years out of an older, damaged
tree. People also get personal attachments to a particular tree,
as I am attached to a few of my favorite trees. Common sense
should over power these feelings of sentiment when the tree
has been damaged by massive root severing.
Alternatives to such a destructive
measure need to be addressed. If a community is blessed with
beautiful established trees, every effort should be made to
try and live in a co-existence with these other living things.
All too often the personal feelings of an individual regarding
the mess or uplifting growth of roots, condemns the tree to
drastic measures or removal. There are better ways to accomplish
these same objectives with little damage to the tree. Re-routing
the side walk around the tree gives the tree more room to expand,
but unfortunately this procedure is not often done. Often because
of encroachment on private property, or hazardous traffic situations
with protruding curbs. Where possible, this approach should
be considered.
Another solution, though temporary,
is adding material to the raised edges, such as asphalt, to
lessen the trip hazards. Grinding down the raised edges is also
an inexpensive temporary fix. Another possibility is to add
fill, and re-pour in a way that develops a mounded walkway.
Once again, as the roots continue to grow larger in diameter,
the lifting problem will resume.
A suggestion that was recently
brought to my attention, that seems to make sense, is to pour
a smaller section, over the damaging roots, with separations
that limit the amount of damage for easier repairs. When a three
foot section is all that needs replacement, it is easier and
less costly to fix, than a larger continuous walk.
Careful selective removal of surface
roots with a sharp ax, after the cement has been removed, will
slow down the lifting problem with little damage to the tree.
Selective removal of the offending
roots is much more desirable than complete destruction to stop
all the roots. The roots that are six inches or more under the
slab, generally cause very little lifting, and should not be
eliminated. Even the roots that are closer to the slabs underside,
don’t necessarily need to be cut out. Loosening the soil above
the root before pouring, will allow more compression room before
causing lift.
Another great suggestion is adding
an underlayment of a compressible material such as a two part
pourable polyurethane foam. If one inch of foam is between the
roots and the slab, the roots will compress into the foam for
a longer period of time. This method has it’s limitations. If
heavy vehicular traffic is driving over the slab, the foam may
not be adequate support, but on walk ways, there should not
be a problem.
None of these suggestions is a
cure or a complete stop to the problem at hand. All of these
suggestions are keeping the needs of the tree in mind. I feel
that where large established trees are to be left in place,
an attitude adjustment is needed. There is no perfect answer
to a problem that was caused by improper planning in the first
place. You can’t expect a large variety of tree to conform to
an inadequate growing space. A decision must be made to either
live with the trees growth by careful co-existence, or start
over with proper varieties in the first place. Don’t destroy
the tree and hope for the best. Take a good hard look at the
benefits these trees give us, before you complain about the
problems these trees cause. You might find that the loss in
your own environment is greater than the problems caused by
the trees normal growth habits.
Proper planning is the only answer. Sadly, this
planning does not pertain to the pre—existing mistakes of past
tree choices. Future tree planting efforts are much more thought
out. We now know better varieties for tight planting areas.
Root barriers are being put in, as a preventative, rather than
a desperate effort after the fact. Common sense thinking about
growth patterns can help save money and needless repairs. Of
course, by the time these trees get big, they will be someone
else’s problem anyway. (OUCH)!
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