Trees that interfere with construction may need to be removed. Construction requires not only a place to put the building. It also requires underground trenching or tunneling for utilities, space for access by construction personnel, space for storing materials, space for mixing paint and mortar. Some of these activities are not compatible with maintaining strong, healthy trees. Trees whose roots are damaged during construction often die over the next several years. It is usually easier, cheaper, and safer to remove these trees before valuable structures are in place than after.
Protect selected trees by designating space for construction equipment and materials. Construction personnel can park vehicles offsite and/or store all construction equipment and materials in designated locations. That means more time and energy for them in getting tools to and from the job; it may mean more time and cost for you.
Designate tree root areas and keep construction equipment away. Most of the roots that trees depend on to absorb water and nutrients will be in the top foot of soil. They usually extend farther than the branches and often 2 to 3 times as far. Any damage to these roots compromises the tree's ability to support itself. Your minimum protection zone should extend at least as far as the branches; for more important trees, the protection zone should exceed the minimum. Construction personnel are seldom tree experts and may not understand your goals or methods; a physical barrier, fence, or even contract clauses may be used to insure protection.
Avoid grade changes that may damage tree roots. Your soil surface may need to be regraded to direct water movement. Heavy rainfall that once soaked into the soil or was slowed in its movement by vegetation may now fall on rooftops and driveways. It has to be channeled carefully to prevent erosion. Lowering the grade can damage tree roots. Brining in fill to raise the grade may prevent tree roots from getting oxygen. For some slopes, terracing to accommodate trees may be an option.
Reasons that trees die years after construction include: soil compaction from equipment driving through; one or more roots cut; excavation under the tree's canopy; trenching under trees to install utilities such as water, sewer, electricity, phone, TV; scarring or removal of bark; changing the original grade; landscape tillage and digging.
Some ways to prevent damage during construction: keep equipment and materials away from protected trees. For situations where equipment must enter, such as along a drive near trees, put down several inches of coarse gravel or mulch over which vehicles may drive. If necessary to cut large roots near the trunk of a tree, remove the tree instead; specify that all utilities use the same trench, route trenches away from trees, or tunnel two feet below the surface to go under rather than cutting the roots. Use visual or physical barriers to insure that equipment operators stay away from trees. Once the construction nears completion and landscaping begins, maintain your tree protection zones. Excavation or backfill in the root zone can be fatal regardless of your best intentions.
Summary: Select desirable trees, remove weak or unhealthy trees; protect the trees you select. Consider consulting a certified arborist before construction begins to assist with these decisions. Avoid excavation or backfilling in tree root zones. Discuss all the details with your general contractor and sub-contractors before site work begins. In some cases steep penalties have been included in contracts to impress on contractors the value you place on the tree. And remember that the inconvenience to them may cost you more. Only you can determine how much that tree is worth?
If you would like more information about protecting trees during construction, contact us by phone at 919.542.8202 or email Al Cooke.