Originally published as a Guest Opinion in Boulder Colorado's Daily Camera on Sunday, April 27, 2008.
It has been interesting to follow the current house size debate in Boulder. This debate is frequently framed as a contest between property rights advocates and meddling neighbors.
However, the issue is somewhat more complicated, due to a very real and different property rights consideration that doesn’t seem to be receiving much attention: when a property owner expands the housing footprint on an old lot, he frequently destroys some of his next-door neighbor’s property, by damaging old established trees.
Such destruction can take two forms. First, trees depend on their roots for survival: they supply water, oxygen and other essential elements to their living cells. The removal of roots results in an immediate reduction of a tree’s capacity to absorb these substances and leads to stress. Stress, in turn, frequently results in disease, infestation and death. If neighbor A kills neighbor B’s tree, she has effectively taken that neighbor’s property away.
The other possible negative consequence is the creation of a serious physical hazard, since root removal often results in trees toppling over. Depending on the arrangement of their stems and limbs, falling trees sometimes behave like gigantic hammers, and pose serious risks to, yes, property (not to mention people and pets.)
This second scenario is possibly presenting itself right now on my block in Old Town Louisville: my next door neighbors recently found that their new “neighbor”, (a developer), had cut almost half the roots off two old Green Ash trees whose trunks are located just inside my neighbor’s fence. There were no stakes to mark the proposed dig, so they had no way of knowing that this developer would be digging, in places, to within a foot of the fence. When the builder proceeds, in the near future, to remove large sections of the crowns of these trees (to make room for the second story), the danger will increase, because the trees will thereby become unbalanced in the same direction in which the severing of their roots has predisposed them to fall. As a safety precaution, these trees may well have to be removed.
Incidentally, the developer also removed the large, historic trees on his lot, so, if and when the two compromised ones go as well, there will suddenly be a glaring hole in a piece of Louisville’s urban forest that multiple generations of residents worked hard to grow and nurture. What kind of “neighbor” would do something like that, right off the bat? But this developer will not only have single-handedly ruined a good part of my neighborhood’s environment: if the two other trees fall or are removed, he will also have caused a loss of cherished property on the part of my neighbors.
Unfortunately, a site plan and house design can be extremely sensitive to the neighbor’s trees’ roots, yet still endanger that neighbor’s property. This is because the trees on the construction side of the boundary can also fall on the neighbor’s property, if certain roots are cut. Such events occur all the time, and not only from cutting of roots within a few feet of the trunk: since trees often fall over without the “aid” of humans, those that are predisposed to do so, (say when a good old Boulder 100 + mph wind event strikes during full leaf-out), are more likely to fail when any roots are cut, even if the roots that are cut are relatively minor, and even if they are cut at a fair distance from the trunk.
Tree roots gravitate toward foundations (they find oxygen and frequently, water, where the soil meets the concrete.) It is important to note: even maintaining the exact footprint of the previous houseusually results in cutting of roots, since excavations almost always require an “over dig”, to allow the setting of forms for the pouring of the stem walls. But most new construction in this market involves digging well outside of the old foundation.
Another of my neighbors dealt with this potential problem by actually narrowing the footprint of his new house in one direction, to protect two old Maple trees: the above-ground part of the house rests on beams that allow it to cantilever out over and beyond its foundation. The first floor of the new house is, nonetheless, much wider than that of the previous house. Similarly, a client is designing an addition to rest on piers, instead of footers, to avoid damaging a beloved tree. In both cases, the extra cost involved may well be offset by the value of the trees they are saving. Both houses are large by almost any standard.
But the easiest way to avoid cutting tree roots, whether they originate from your tree or your neighbor’s, is simply this: build up and shrink the footprint, and/or site the house somewhere on the property away from any trees you intend to keep. Presumably, among this group of trees, you’ll include those that have grown up on the neighbor’s side of the fence. After all, her trees are her property.