Start with the roots and work your way up to keep your trees safe
Trees aren’t generally harmed during construction.
If damage occurs, it can lead to a slow death.
Water and mulch can help reduce stress.
A fence or markers can provide a visual aid to limit foot traffic.
Trees add shade, privacy, natural beauty, and fresh oxygen to the area around your home. So while planning a building or renovation project is exciting, you'll want to consider tree protection during construction. Learn how to protect trees during construction and what you need to do once construction is finished to ensure your trees stay healthy.
Construction projects often expand buildings or landscapes, and the activity frequently happens near trees in your yard. Since construction involves heavy equipment, moving large supplies, and often excavating portions of the ground, it poses particular risks for living trees. Potential damage can include:
Soil compaction around the tree due to the weight of equipment, supplies, or foot traffic
Excavation that severs roots, wounding or killing trees
Trunk gashes and injuries from equipment or supplies that accidentally bang into the bark
Broken limbs from working too close to the tree
Toxic run-off from construction supplies like paints, sealants, mixes, and more
Changes to the soil conditions due to excavation and foundation work
Tree protection expenses depend on the extent, size, and type of protective measures. In most cases, simple fencing, tree guards, and a posted sign should cost less than $50 and may be significantly less if you find a deal on stakes and construction fencing.
However, saving trees close to construction work will cost more. Tree guards can cost up to $300, depending on the type, although it’s a more permanent solution if you want trees to stay near a new foundation. Renting an aerator to relieve soil compaction costs $50 to $80 per day. If you build a retaining wall to protect a tree, it will cost $40 to $200 per linear foot.
Before we jump into the steps below, keep in mind that you can follow this guide with both DIY construction projects, and projects involving professionals—with minor exceptions, protecting the tree works the same either way. Talk with your construction manager about preparations needed for tree protective measures.
The headline might read a tad bleak, but it’s the best prep step for even the most eco-conscious home and landowners among us. Everyone’s situation—and landscape—will look different, but knowing which trees to care for versus remove is helpful.
Here are some guidelines to consider:
Damaged or dead trees on a property that’s about to undergo construction are likely not worth saving. In fact, they may pose a fire or critter infestation risk down the road if left on the property.
You should inspect diseased trees carefully. A local arborist or tree specialist can tell you if the tree is salvageable or not.
Trees next to the construction zone may have to go, unless they are new or you can transplant them to a new area.
Trees in areas that are being regraded are less likely to survive. Taking protective measures before grading happens instead of after is key.
Certain kinds of trees (like fruit trees) are more resilient than others. Identify the types of trees in the construction area, and find out if fragile trees in or around the tree protection zone are worth saving.
Follow these guidelines for protecting trees located in a home construction zone.
It’s not very likely that a tree will get cut in half, have its bark torn off, or have its branches sheared while building a new structure. What’s more likely is subtle damage to the tree roots underneath, which slowly weakens the tree over the next one to five years. Eventually, it dies.
Roots not only anchor trees, but absorb nutrients and water that are key for tree preservation, and many of a tree's vital roots aren’t buried that deep. In fact, about 80% of its vital roots are 24 inches or less. Knowing the root zones of the trees you wish to protect, then, is key.
A good guideline measurement is for every inch of tree trunk, assuming a radius increase of 18 inches. If a tree has a circumference of 36 inches, its root zone is 54 inches. Simply multiply 1½ by its circumference to find an answer.
With the root zones in mind, mark—and perhaps fence off—all the trees that you think may be at risk of damage during construction. You can purchase a 100-foot spool of orange construction fence at home improvement stores for between $30 and $45.
If you’re adding a foundation, patio, pipes, or anything below the ground’s surface near a tree, it’s important to protect it from the tree’s root. As that tree continues to grow, roots can damage underground construction. If you can’t get rid of the tree entirely, consider installing a root barrier instead. These underground barriers block the tree’s roots and channel them in directions away from vulnerable foundations.
Root barriers vary, but they’re usually buried three feet deep in the ground in wedges that surround a tree or protect one specific side. It costs about $200 to $300 to install a root barrier, so this option is best reserved for trees you can’t lose.
The type of construction equipment can also make a difference for tree health. In addition to avoiding the ground around trees, you can choose equipment that will lessen the impact. When possible, use light equipment and hand tools for smaller projects. Look into options like underground excavation for pipes that keep the ground intact.
If you are planning construction in your yard, consider scheduling a lawn aeration before the work begins. Aeration cuts holes into the soil to better allow water and nutrients to seep down. Aeration also relieves soil compaction and helps reduce the risk that compaction will kill nearby tree roots, making it a great pre-construction step to help protect your trees.
Once aerating is done, set a watering schedule for your lawn and nearby trees. For many extended construction projects, you must turn off the sprinklers and nearby irrigation, which means you’ll have to take care of watering manually so that the trees get the moisture they need. Young trees will benefit from a good soaking about once every week or two.
Trees near the path to a construction site can get dinged, bashed, and gouged during busy work hours. If that bark damage is more of a danger than crushed roots, we suggest wrapping the trunk with a plastic tree protector wrap or a guard for the duration of the construction. This method will prevent you from having to repair a tree trunk retroactively.
Even with the best set of plans in place, surrounding trees may still receive some impact during construction. Limiting foot traffic helps prevent additional trauma or stress to the area. If walking in these areas is unavailable, especially for construction workers who must load heavy objects across the area, lay down planks or plywood to help reduce the impact.
Mulch does an amazing job of insulating and maintaining moisture around the base of a tree. Both of these things are advantageous during construction and in the months that follow, especially if you live in a drier area where not as much rain falls.
For younger trees, sticking to an annual mulching schedule is a good idea. After a year three, biannual mulching is usually plenty.
Even if you take all the precautions, there’s still a chance some trees will wind up damaged during construction. You can root out these issues by keeping a close eye for dead sections or branches of an otherwise healthy tree cropping up.
This is a sign that roots were damaged, and you’ll need to prune these areas—tree care during the winter is a good time—to prevent further decay.
New constructions often alter the surrounding ground’s elevation and soil. That can spell trouble for trees, especially those that rely on shallow roots for nutrients. If you want to preserve a nearby tree, such as a beautiful ornamental, then consider upgrading from root guards to a retaining wall around that portion of the tree.
You can build a retaining wall with basic concrete blocks, more aesthetically pleasing brick, or pavers to match a nearby patio. Usually, only a foot or two is high enough to create a barrier. This type of wall protects roots and allows the tree to keep the soil composition that it’s used to while foundation work can proceed close by.
What do you do when the worst happens and a tree does get damaged during construction work? Some damage is hard to notice: One of the reasons that soil compaction is dangerous is that it’s not obvious that roots have damage and the tree may live for several more years before dying (although wilting leaves and dying needles are often signs). But if you notice damage quickly, you can take action to help the tree:
If branches are broken, prune them back to the main branch or trunk (coating the scar isn’t usually necessary).
If excavation has severed tree roots, clear the root and cleanly cut it so the wound closes fast. Keep the tree well-watered: Trees can lose around 20% of their roots and survive largely unharmed if well-cared for.
If you believe soil compact occurred, arrange for soil aeration ASAP to give roots the best chance to survive. Water thoroughly afterward.
If bark is gouged or damaged, cut away the damaged section cleanly and let it scab naturally. If the tree is in danger of fungal infection, consider spraying the wound with a fungicide.
For the simpler tree protection steps above, stick to a DIY project to save money. There’s no need to hire a tree maintenance pro if you’re only staking out some plastic fencing around a root system or wrapping a trunk in a tree guard.
However, installing root barriers or retaining walls takes more work, and hiring a local tree maintenance professional can help you protect your trees efficiently before the start of your construction project. While you’ll pay more for professional help to protect your trees, it’s worth the investment to preserve old or ornamental trees.
The best way to protect tree roots is to avoid the roots entirely by excavating outside the root radius of the tree. For nearby projects, it’s a good idea to construct a temporary retaining wall. But that’s not always possible, depending on the project and the root system. In these cases, consider using alternative equipment like an auger to tunnel under the ground.
Remember, tree roots can damage nearby cement foundations as they grow. If a tree is close enough to interfere with large excavations, it may be better to remove the tree than risk future problems.
As a general rule, the protected area should be about 1½ times as wide as the canopy of the tree’s leaves. This digging measurement can vary by tree species and the age of the tree. Of course, that can be a lot of fencing for larger trees, which is why our first step is about making difficult decisions on which trees to save.
It may be possible, but transplanting a large, mature tree can be a tricky project, and some trees handle it better than others. If you have a tree you need to save and are considering transplanting it elsewhere, we highly suggest calling a tree removal service and arranging a consultation to see what they say (and how much a full transplant would cost).
Any type of construction that damages a tree’s roots via soil compaction can be dangerous, and is one of the primary causes of mature tree death in residential areas. Simply putting lots of weight on the ground around the tree, like construction supplies, trailers, and equipment, can kill roots near the surface. Of course, installing new foundations, patios, or utility lines can cut through nearby tree roots. Accidentally striking a tree with equipment or supplies is rarely a problem, but can cause damage of its own, too.
This is fairly rare, but sometimes the local government or a group like a historical society will label a tree as a landmark, or historical item. These designations almost always come with a small, on-site plaque for identification, but you should also be able to look up protected trees in your area on a city website or similar list. If the tree in question is a landmark, call your local government and ask how to proceed before making any plans.
