Building a Deck Around a Mature Tree in Tacoma: Roots, Framing Openings, and the City’s Tree Rules

By Daniel Rotaru, Owner and CEO at Decks Restore. WA Contractor License # CC DECKSRL797P2. Tacoma, WA. Updated October 2026.

A lot of Tacoma backyards have a big tree right where the deck should go. Sometimes it’s a Douglas fir behind a North End Craftsman, sometimes a bigleaf maple that shades half a yard in Proctor. Homeowners in that spot usually want to know two things: can we keep the tree, and is the city going to care?

Usually you can keep it. Whether the city cares depends on where the tree stands and whether anything has to come down. I start with the rules, because a tree you aren’t allowed to touch changes the design before anyone draws a joist.

The short answer

Yes, you can build a deck around a mature tree in Tacoma. The city doesn’t require a permit to prune or plant a tree on your own lot. Removing a private tree does need a permit if it stands in a regulated critical area, and any tree in the planting strip or other public right-of-way needs a city permit before it is pruned or removed. Never fasten the deck to the tree. Keep footings out of the area close to the trunk where the big structural roots are, and frame an opening that gives the trunk room to grow and sway. The deck itself goes through the normal Tacoma building permit.

Start by figuring out whose tree it is

The rules change depending on whether the tree is on your lot, in the planting strip out front, or on your neighbor’s side of the fence.

A tree on your own lot

The City of Tacoma’s tree FAQ says you don’t need a permit to plant or prune a tree on private property. Removal is where permits come in. You need one to remove a private tree that stands in a regulated critical area, and you need one to remove trees during development activity in an Urban Residential zone (the zones Tacoma used to call single-family). Whether a deck project counts as development activity on its own is a question for the permit counter, so ask before you cut anything.

Tacoma’s critical areas are wetlands, streams, fish and wildlife habitat conservation areas, biodiversity areas, frequently flooded areas, geologically hazardous areas such as steep slopes, and aquifer recharge areas. Two of those come up on deck jobs more than the rest. Steep slopes are common in the North End, and I wrote about how they change a project in deck building on Tacoma’s North End slopes. The other is Oregon white oak. The city lists Oregon white oak trees and woodlands among the most common fish and wildlife habitat areas in Tacoma, so a big oak in the yard can put part of your lot under critical area rules.

If you aren’t sure, call the city’s Planning and Development Services at (253) 591-5030 and follow the prompts for Land Use and Zoning. Their critical areas specialists can tell you what applies to your parcel. It’s a short phone call, and much cheaper than finding out after the tree is on the ground.

A tree in the planting strip

The strip between the sidewalk and the street is public right-of-way, but Tacoma makes the property owner next to it responsible for maintaining the trees there. Planting, pruning, or removing a right-of-way tree takes an RTRE permit from the city. Planting and pruning permits are free. A removal has to qualify under one of the city’s approved reasons, a notice has to stay posted on the tree for at least 14 days, fees may apply, and you have to plant a replacement. Topping a right-of-way tree is not allowed. If you can’t tell where your property ends, the city’s DART map shows the right-of-way boundary.

This matters most for front porches and side-yard decks. A large street tree can send roots a long way under a front yard, so find out what you’re dealing with before footings go in near the sidewalk.

A tree on your neighbor’s property

The city treats a neighbor’s private tree as something the two of you work out. If its roots or branches reach where your footings or deck will be, talk to your neighbor before anyone digs. Damaging someone else’s tree can turn into a legal fight in Washington, and paying an arborist to say how much root loss the tree can handle costs far less than that.

Heritage trees and the coming code update

Tacoma created a heritage tree program in December 2023. A private tree only gets the designation with the owner’s written permission, and the city’s application form says designation doesn’t limit the owner’s ability to prune or remove the tree as long as the work follows the municipal code.

The rules for private trees may tighten. The city is working on a Tree and Landscape Code Update that is studying tree retention standards for private property, including removals that have nothing to do with development. Its timeline puts City Council adoption in early to mid 2027. If your plan depends on taking out a large tree, read the City of Tacoma’s Tree and Landscape Code Update page first to see where things stand.

Is the tree worth building around?

A well-built deck should last decades. Before you design around a tree, make sure the tree has that long left, and that it isn’t going to come down on the deck in a winter windstorm.

I build decks and I’m not an arborist, so for a big tree I tell homeowners to have an ISA Certified Arborist look at it before we design anything, which is also what the city recommends for tree work. Ask about the tree’s health, any decay at the base, how it leans, and how much root disturbance it can take on the side where the deck will go.

The big trees in most Tacoma yards each come with their own problems:

• Douglas fir. Tall, heavy, and often shallow rooted in our wet soils, which is why firs go over when the ground is saturated during winter storms. Expect needles, cones, and pitch on the deck.
• Western red cedar. Shallow, fibrous roots that don’t tolerate soil compaction well. A lot of western Washington cedars have struggled after recent hot, dry summers, so a cedar that is thinning at the top deserves a close look before you build under it.
• Bigleaf maple. Large surface roots, and leaves that turn into a slick mat on the boards every fall. These maples are also known for dropping heavy limbs.
• Oregon white oak. Slow growing, sensitive to root disturbance and to summer watering near the trunk, and possibly regulated habitat, as covered above.

Roots decide where the footings go

Most of a tree’s roots are in the top couple of feet of soil, and they spread well past the edge of the canopy. That is the same ground deck footings go into.

Arborists often use a rule of thumb called the critical root zone: one foot of radius out from the trunk for every inch of trunk diameter, measured 4.5 feet above the ground. A fir that is 24 inches across has a critical root zone with a 24-foot radius. The inner half of that circle holds the structural roots that keep the tree standing, and nobody should dig there.

On a typical Tacoma lot you can’t keep every footing out of a 24-foot circle, and usually you don’t need to. This is how we handle it:

• Every footing stays out of the inner zone. If a layout puts a post there, we change the layout.
• Cantilevers keep posts away from the trunk. Under the residential code tables, joists can cantilever past a beam by up to a quarter of the joist span behind it, and a beam can extend past its post by up to a quarter of the beam span. The deck reaches toward the tree while the footings stay back.
• Near the tree we dig by hand instead of using an auger. If we hit a root thicker than about two inches, we stop and move the hole. Smaller roots get a clean saw cut, because a torn root is more likely to rot back toward the tree.
• Helical piles are worth a look. A pile shaft disturbs far less soil than a footing hole, and there’s no spoil pile or concrete truck in the yard. The shaft can still hit a root, so we probe each spot first. I compared the two systems in helical piles vs. poured footings in Tacoma’s wet clay.
• The grade stays where it is. Piling fill over roots, scraping soil away, or compacting it can hurt a tree as much as cutting roots. During the build that means no lumber stacks or parked equipment in the root zone, and afterward it means keeping any gravel under the deck to a thin layer.

Framing the opening around the trunk

The trunk passes through the deck in a framed opening, built the same way as a stairwell opening in a floor. The joists that would hit the tree are cut short and carried by doubled header joists, which hang from doubled trimmer joists on each side, and every connection gets a hanger. On a wide opening the headers are sized for their span like any other beam.

Nothing in the frame touches the tree, which rules out bolting a ledger to the trunk or setting a post on the root flare. A tree sways in the wind and gets thicker every year, while a deck needs supports that stay where they were built. Every bolt also opens a wound in the tree.

We also plan the opening for the tree’s growth:

• We usually leave 3 to 6 inches between the trunk and the framing. A young or fast-growing tree gets more, and so does the side a tall tree leans or sways toward.
• We set the headers a little farther back than today’s trunk needs. When the tree grows, making the opening bigger is a trim job and the frame stays as it is.
• The boards around the opening are screwed down where they can be reached and removed, so the opening can be cut larger later. On composite decks we picture-frame the opening with a border board, which covers the cut ends and makes the gap look planned.
• We look up before we frame. Low limbs set the headroom over the deck, and a limb that will need pruning is easier to deal with before there’s a deck under it.

Living with a tree over your deck

Under a tree, boards stay wet longer after rain and needles pack into the gaps, so moss and algae start sooner than they would on an open deck. Some of that gets handled in the build and the rest is maintenance.

• Use ground-contact rated lumber for the framing. Framing in the shade stays damp longer, and ground-contact treatment holds up better to that.
• Keep the board gaps at spec and keep them clear. Packed gaps hold water against the boards and slow drainage.
• Choose a surface with some grip. Wet maple leaves and fir needles on smooth boards are slippery, and our post on slip-resistant decking for rainy Tacoma covers the options.
• Sweep often in the fall, and don’t leave piles of leaves sitting on the boards.
• In dry summers, water the root zone outside the deck. The deck sheds rain away from the roots underneath it, and Tacoma can go weeks in July and August with very little rain. Skip this for Oregon white oaks, which shouldn’t get summer water.
• Check the opening every year or two and widen it before the trunk reaches the frame.
• If limbs near the deck are tangled in overhead power lines, don’t prune them yourself. Call the Tacoma Public Utilities tree line at (253) 502-8729.

If your deck is already built around a tree

Older decks built around trees tend to have the same problems. The trunk grows into the framing and starts pushing on it, the boards near the opening stay wet and go soft, or a post set too close to the trunk gets lifted by roots. If you see any of that, our 7-point deck inspection checklist shows what else to look at. When the frame is still sound, deck resurfacing is a good time to reframe the opening and give the tree more room.

Permits for the deck itself

Building around a tree doesn’t change what the deck needs. Tacoma requires a building permit for most decks, including any deck attached to the house or more than 30 inches above grade, and our post on permits and regulations for deck construction in Tacoma covers the details. The tree comes into it when your lot has a critical area, because critical area review adds documents and time. We pull the City of Tacoma or Pierce County permit for our customers as part of the job.

Common questions

Can I attach a deck to a tree?

No. A tree moves in the wind and grows every year, and fasteners wound it. The deck needs its own posts and footings, with an opening around the trunk.

How much space should I leave around the trunk?

We usually leave 3 to 6 inches between the trunk and the framing, and more for young or fast-growing trees. Framing the opening so it can be enlarged later matters as much as the starting gap.

Will building a deck kill my tree?

It can, if the work cuts major roots or buries and compacts the soil over them. Many healthy trees handle a deck that stays out of the inner root zone and sits on hand-dug footings or piles. An ISA Certified Arborist can tell you how much your particular tree can take.

Do I need a permit to remove a tree for a deck in Tacoma?

Not always. The city requires a permit to remove a private tree in a regulated critical area, to remove trees during development activity in an Urban Residential zone, and to remove any tree in the public right-of-way. Tacoma is also studying new rules for private trees, with adoption expected in 2027, so check with Planning and Development Services at (253) 591-5030 first.

Does building around a tree cost more?

Yes, somewhat. The extra cost comes from the headers and hangers around the opening, hand digging near the roots, and any added beams or engineering needed to keep posts away from the trunk. Ask for those items to be listed separately on your quote. Current per-square-foot ranges are on our Tacoma deck builder page.

What decking holds up best under a tree?

Capped composite and PVC boards don’t absorb water, so they handle shade and debris better than softwood. They still need regular cleaning to keep moss off. If you want wood, plan on cleaning it more often than you would on an open deck.

About the author

Daniel Rotaru is the owner of Decks Restore in Tacoma, Washington, and holds Washington State Contractor License CC DECKSRL797P2. He has built and repaired decks across Tacoma, Pierce County, and the South Sound for more than a decade, quotes every project himself, and walks active job sites daily. Finished projects are in our project gallery.

This post covers general building practice and the City of Tacoma’s published tree rules as of October 2026. It isn’t an arborist’s assessment of your tree or legal advice, and the city’s tree rules may change after the code update.

Planning a deck around a tree in Tacoma?

We build decks across Tacoma, from the North End and Proctor to Northeast Tacoma, and we also serve Gig Harbor, Federal Way, Puyallup, Auburn, Kent, and Renton. Request a free quote and I’ll come out, look at the tree and the lot, and tell you where footings can and can’t go before we talk about design. If the tree needs an arborist first, I’ll tell you that too.

Decks Restore
748 Market St #173, Tacoma, WA 98402
(253) 677-0290
Monday to Friday 9:00 AM to 5:00 PM, Saturday 9:00 AM to 2:00 PM
WA LIC # CC DECKSRL797P2

If you’re starting from scratch, we design new decks around the tree from the first drawing, and our page for deck builders in Tacoma covers materials, cost, and the permit process.