| Dear Ms. Builder: We are planning to make a major several-room
addition to our house. We have a beautiful wooded lot and we want to protect
the trees. Since there will be some grading, how do we protect the trees? -
Mike H.
Dear Mike: When you consider the cost to replace a large tree and
reduction in resale value of your house, the death of a tree is a large
financial loss. There is also the cost of removing a dead tree. I recently had
to pay about $800 to have a large ash tree taken down near my house.
Often the damage done to trees during construction can take four years or
more to become apparent. Gradually one tree after another begins to die. Since
much of this damage is "invisible" during the construction phase,
neither you nor the contractor relates it to the construction done years
before.
If your wooded lot is important to you, definitely hire an arborist (tree
expert) even before the building plans are complete. The arborist can advise
you as to which trees and areas around them that need the most gentle care. For
example, this can impact
where a trench is run or where heavy equipment is used and cleaned.
Once your arborist has analyzed your lot, schedule a meeting with your
contractor to discuss his report. Also include a clause in the contract to
cover any future loss of trees should your contractor not follow the
recommendations of your arborist.
Other than a bulldozer smashing into a tree trunk, which is pretty difficult
not to notice, the primary indirect damage to trees results from: 1) compacting
on the soil, 2) chemicals from construction materials and 3) damage to roots
during trenching. Even with no obvious damage, a tree may eventually die from
this indirect damage because it is weakened. During a drought or other severe
weather, insect infestations, etc., the weakened tree cannot survive as a
healthy one would.
As a brief background, good top soil is full of tiny air pockets. Tree roots
require these air pockets for oxygen and to provide a holding area for water
after a rain. Backing a dump truck or just repeated passes by a pickup truck
can compact the soil and destroy these air pockets.
Heavy equipment should avoid any area inside the radius of the drip line of
the trees. Your arborist can tell which trees are most sensitive and where your
soil is most susceptible to compaction. Mark these areas with some cheap orange
plastic fencing available at most home center stores.
Depending on where you live, the soil acidity can range from very acidic to
alkaline and various trees prefer various levels of acidity. Many common
building material that may end up in the soil, like concrete and brick mortar,
are highly alkaline and can affect the soil.
For example, whenever a truck delivers a load of concrete, the chute is
hosed down at the end of the job. Mortar mixers are also cleaned out at the end
of each work day. Have your arborist discuss this with the contractor to
determine a safe location to clean off the equipment with a high alkaline
level.
When doing any major room addition, there is going to be some trenching for
gas and water lines that may damage roots. Plan the location of these
underground lines based on the tree species.
Some trees, like oaks, can handle a substantial amount of root damage (up to
40%). Others, like a beech tree, are much more sensitive to their roots being
disturbed.
Here are some sources for arborists and information - American Forests (202)
667-3300, National Arbor Day Foundation (402) 474-5655, World Forestry Center
(503) 228-1867, Scenic America (202) 888-4300, International Society of
Aboriculture (217) 355-9411.
Send your questions to Ms. Builder, 6906 Royalgreen Dr., Cincinnati, OH 45244 or
visit www.dulley.com/msbuilder.
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