Mature trees provide many benefits. One, they grace us with shade that helps lower our energy costs. And a large tree’s aspect can heighten land values. But if your building a house, you’ll need to plan ahead to protect these assets.
What can you do (or make your contractor do) to safeguard valuable existing trees? A proper mindset is essential. Your the project leader. If you’ve made a commitment to conservation, then take the lead in making sure your construction team understands your goals and shares your values. You can even set up formal training programs and manuals on tree care during construction for your team to emphasize this critical point. Your general contractor and his subs should understand they have to take your course as a prerequisite for getting the work. Make it a part of the contract.
Protects Trees with the Right Equipment
Installing a substantial tree protection fence made of heavy posts and large-gauge wire is good practice. Using barbed wire as part of the tree fence is even better. Place the tree fence outside the tree’s critical root zone (extending at least out to the canopy’s drip line). Hang colorful flagging from the fence, and have your contractor repair any damage promptly.
Wide-track dozers, utility tunneling devices, or smaller equipment with rubber wheels will let your contractor work with exacting care in tight places. This type of specialized equipment ensures minimum disturbance in designated tree-save areas.
Saving Mature Trees with Appropriate Construction Techniques
Does building your house require lowering grades around mature trees? You might need retaining walls (or, if on a slope, a combination retaining wall and tree well). Build the wall just outside the tree’s root zone, and just far enough away so that installing the wall’s back fill won’t impact delicate roots.
With a mature shade tree, the viable root zone may extend farther than the tree’s canopy. It may not be practical or financially feasible to build a wall out this far, but try to impact as little of the root zone as possible.
Trees hate it when excess earth fill is placed over their roots. If construction calls for raising grades, your contractor can use walls or tree wells to avoid root suffocation. The absolute minimum distance from a tree’s trunk that any construction should be allowed is three feet (3′).
Tree survival improves dramatically when construction is kept out of the drip line (feeder roots may extend well beyond this point). If filling around a specimen tree is unavoidable, use a tree well, and install perforated pipe or vertical shafts so the roots get adequate oxygen.
There’s a trade-off here – working further within the root zone may stress the tree, but extending retaining walls or earthwork farther out costs more and takes up more valuable space. The question you should ask – is the value of the impacted tree more important to your home-building project than the value of the impacted land?
Protecting Trees from Utility Construction
Utility lines can impact trees, too. Avoid laying utilities in critical root zones, if possible. If utility paths must go through root zones, tunneling under is better than trenching through, but it is more expensive. Use tunneling with significant trees, or where stands of large, established trees are to be saved. If several utilities can share a trench, it may reduce impact on root systems.
Significant trees can add real value to your home. Where saving mature trees is the goal, your contractor must plan before he allows anyone to dig. A little attention to detail before construction can head off problems at the pass, eliminate the need for removing dying trees at a later date, and ensure you wind up with the tree conservation benefits you envisioned.
References:
American Forests/National Association of Home Builders. Building Greener Neighborhoods: Trees as Part of the Plan. Published Jointly by American Forests and Home Builders Press, 1998.