Most homeowners who call us about a wooded lot in Downers Grove open with the same worry. They have a big oak in the backyard, they want a deck near it, and they are convinced the Village is going to stop them.
Almost always, it will not.
The tree Downers Grove actually protects is the one out front, in the parkway strip between the sidewalk and the street. Your backyard oak is your tree. The Village’s own guidance is blunt about this: property owners are responsible for trees on their private property. There is no permit to pull before you put a footing near it, and no Village forester coming out to approve your layout.
That is the good news. The complication is that the oak is still going to dictate your deck, just for structural and biological reasons rather than legal ones. And the parkway tree you were not thinking about is the one that can genuinely slow your permit down.
Here is how both of those actually work in Downers Grove.
What the Village regulates, and what it does not
Village Forestry manages roughly 23,000 trees on land the Village owns. Those are parkway trees, trees in the right of way, and trees on other municipal property. The Village prunes them, removes them when they are hazardous, and replaces them. Downers Grove has been a Tree City USA since 1984 and holds Level 2 accreditation from the Morton Arboretum, so this is a village that takes its canopy seriously.
What that does not translate into is a private tree removal permit for a single family homeowner. If you want the silver maple in your back corner gone before the deck goes in, you can have it removed. What the code does regulate is who does the removing: tree companies working in Downers Grove have to carry a tree removal license, and the Village publishes the list of licensed companies. Hiring an unlicensed crew is the violation, not taking down your own tree.
Two things follow from this that are worth saying plainly.
First, nobody at Village Hall is going to reject your deck drawings because a footing sits close to a backyard oak. We have never seen it happen. If your permit gets kicked back, it will be for setbacks, footing depth, ledger detail, or guard height, which is the ordinary list. Ledger attachment in particular depends on what your house is clad in, and we break that down by siding type in a separate guide to ledger attachment.
Second, and less obviously: your permit paperwork may still involve a tree. Downers Grove issues a Parkway Tree Protection Sign along with certain permits, and that sign has to be posted on site before work starts. If your project triggers one, you pick it up at Village Hall with the rest of your permit packet. That is the tree requirement most people trip over, and it has nothing to do with the backyard at all.
If you want to read the Village’s own material, the Downers Grove tree maintenance page has the parkway tree protection requirements and the licensed tree company list, and lists the Village Forester’s direct line.
The parkway tree is a staging problem
Here is the part that catches crews off guard on the older streets north of the tracks, where the parkways are narrow and the trees are enormous.
A deck build means a dumpster, a materials drop, and usually a small skid steer or an auger truck. All of that has to get from the street to your backyard. On a 40 foot wide lot near the Main Street Metra with a mature honeylocust in the parkway, there may be exactly one path in, and it runs directly over that tree’s root zone.
Compacting soil over a parkway tree’s roots is how you kill it slowly, three or four years after your deck is finished, and the Village will not be pleased about a dead parkway tree in front of a house that just had construction. Root damage from equipment is also invisible on the day it happens, which is why it gets ignored.
On tight lots we plan the access route before we quote the job. Sometimes that means plywood or ground protection mats over the parkway and the path across the yard. Sometimes it means we hand carry material down a side yard instead of driving it, which costs labor hours and shows up in the price. Occasionally it means the auger truck cannot reach the backyard at all and we are digging by hand or bringing in a smaller machine.
If a Downers Grove bid comes in noticeably cheaper than the others and the lot is tight and treed, ask the contractor how they are getting equipment to the back. Sometimes the answer explains the whole price gap.
Your backyard oak is an engineering problem, not a permit problem
Now the tree you asked about.
A mature bur oak or white oak, the kind you find on the older wooded lots around Denburn Woods and the streets backing onto the forest preserve, has a root system that is wide and shallow. Not a deep taproot. Most of the absorbing roots sit in the top 12 to 18 inches of soil, and they spread well past the branches.
The rule of thumb arborists use for the critical root zone is a radius of about one foot for every inch of trunk diameter. A 30 inch oak has a critical root zone reaching roughly 30 feet out from the trunk. Cut through a meaningful share of that and the tree may look fine for two or three seasons and then start dropping limbs.
That number tends to land badly, because a 30 foot radius covers most of a typical Downers Grove backyard. So the practical question is never “can I avoid the root zone.” It is “how few holes can I put in it, and where.”
Fewer, smarter holes
A standard deck on poured concrete piers might use eight or ten footings on a six to eight foot grid. Each one is a 42 inch deep excavation, since that is the frost depth used across DuPage County, and each one severs whatever roots are in the way. Ten holes through an oak’s root plate is a lot of damage.
There are three ways we cut that down.
The first is simply moving footings. Roots radiate outward from the trunk like spokes, so a footing placed between two major structural roots does far less harm than one that goes straight through a three inch root. This is why we dig exploratory holes by hand near big trees rather than sending an auger down blind. When we hit a root over about two inches, we shift the footing a foot or two and adjust the beam layout. It is slower and it is worth it.
The second is reducing the count by upsizing the beams. Fewer, larger footings carrying longer spans means fewer excavations. A deck that would need ten piers on a conventional layout might need six with a heavier beam. You pay more in lumber or steel and less in root damage.
The third is helical piles, and near mature trees they are often the right answer even when they are not the cheapest one. A helical pile is screwed into the ground rather than dug, so instead of removing a 12 inch diameter column of soil and everything in it, you are driving a shaft a few inches across. The disturbance footprint is a fraction of a poured pier, and there is no spoil pile to dispose of on a lot where you have nowhere to put it. We go into the tradeoffs in more detail in our piece on second story decks, helical piles, and post sizing, and our comparison of footing conditions along the DuPage River and Ogden Avenue covers how local soil changes the calculation.
Downers Grove soil is mostly heavy clay, which holds water and moves with the freeze thaw cycle. Clay plus a big tree is a specific combination: the tree draws enormous amounts of moisture out of the soil in summer, the clay shrinks, and shallow or undersized footings can move. Getting below frost depth is the code minimum, not the whole answer.
The hole in the deck question
Roughly one in four homeowners with a big backyard tree asks whether we can frame the deck around the trunk and let the tree grow up through it.
We can. We usually talk people out of it.
The problem is not the framing. Boxing out an opening is routine carpentry. The problem is that the tree keeps growing, in two directions. Trunk diameter increases every year, so the opening you cut today will be tight in a decade and choking the tree in two. You have to leave a gap that looks uncomfortably large to make it work long term, which most people dislike the moment they see it.
The trunk also moves. Trees sway. A big oak in a Downers Grove windstorm has real deflection at the base, and if the deck frame is close enough to contact the bark, it will abrade it every time the wind blows. That wound is an entry point for decay.
Then there is the maintenance reality. The opening becomes a funnel for leaves, acorns, and rainwater, all landing on your framing at exactly the spot that is hardest to reach and clean. On a composite deck it is a housekeeping nuisance. On a wood frame it is a rot problem, and we have written separately about how a neglected deck can carry water damage into the house itself.
When it does make sense is when the tree is genuinely the centerpiece of the yard and the client understands they are signing up for periodic opening enlargement. We build it with that in mind, framing the opening so the header can be moved outward later without rebuilding the deck. If the tree is more of an obstacle than a feature, we design around it instead and everyone is happier in year eight.
Plan for the tree eventually not being there
This is the part nobody wants to discuss at the design meeting.
Emerald ash borer has already taken most of the ash out of DuPage County. Oak wilt is present in the region. Storms take down mature trees every year. If your deck design assumes a specific tree is standing, ask what the space looks like if it is not.
That mostly affects two decisions. Shade is the first. A deck sited to sit in an oak’s shadow all afternoon becomes a very different place in full sun, which changes the decking material you should be picking. Dark composite in full afternoon sun gets hot enough to matter, and the shade you are counting on is not permanent. The second is access. If a large tree in your backyard ever needs to come down, the removal crew needs a way to get equipment in and drop wood. A deck built across the only access path turns a routine removal into an expensive one, sometimes involving a crane over the roof.
We are not suggesting you design your backyard around a hypothetical. Just leave a path.
Frequently asked questions
Do I need a permit to remove a tree on my own property in Downers Grove? Not for trees on your private property. Property owners are responsible for their own trees. The requirement is that the company doing the removal holds a tree removal license from the Village. Parkway trees, between the sidewalk and the street, are Village property and are handled by Village Forestry.
Will a nearby tree cause my deck permit to be rejected? We have not seen it happen. Downers Grove deck permits get rejected for setback, footing, ledger, and guard issues. A backyard tree near a footing is not among them. Your permit may require a Parkway Tree Protection Sign, which you pick up at Village Hall and post before construction starts.
How close can a deck footing be to a tree trunk? The Village does not set a distance, so this is a judgment call about the tree’s health rather than compliance. As a working rule, we avoid cutting structural roots over about two inches in diameter and we stay well outside the trunk flare. On big oaks we hand dig test holes and move footings to fit between roots.
Are helical piles worth the extra cost near a mature tree? Often, yes. They disturb far less soil than a 42 inch poured pier, there is no spoil to haul off a tight lot, and they can be installed with smaller equipment. On a lot with a valuable oak, the upcharge frequently costs less than losing the tree.
Can you build a deck around a tree trunk? Yes, though we usually recommend against it. The trunk grows and sways, the opening becomes a leaf and water funnel over your framing, and the gap has to be larger than most people expect for it to work long term.
What is the frost depth for deck footings in Downers Grove? 42 inches is the figure used across DuPage County. Confirm the current requirement with the Community Development Department at 630-434-5515 before you build.
Building on a wooded lot in Downers Grove
Trees make the best backyards in this village and the most complicated deck projects. The oaks on the older streets are the reason people buy those houses, and they are also the reason a deck there costs more than the same deck on a bare lot in a newer subdivision.
If you have a tree you want to keep, tell us at the first site visit rather than after the layout is drawn. It changes the footing plan, sometimes the framing system, and occasionally the shape of the deck.
Wolf Spirit Deck builds throughout Downers Grove and the western suburbs. You can see our full range of services on our Downers Grove deck builders page, read more about steel deck framing, or check our deck builders FAQ for general questions.
To talk through a wooded lot, request a free quote or call us at (312) 765-3998.
