Designing a Southlake Backyard Around Mature Trees

A Southlake backyard rarely begins as a blank site. On the wooded lots that define much of the city, the first constraint a design has to answer is not style, material or scope, but the trees already standing on it and the Southlake tree preservation rules that govern the ground around them. Knowing where those rules apply, and where they stop, changes what is possible in a rear yard long before a single line is drawn.

Schedule a design consultation to walk the property before the first concept is drawn.

Does Southlake's Tree Preservation Ordinance Apply to an Existing Home?

Southlake's Tree Preservation Ordinance, currently Ordinance 585-E, carries a broad residential exemption. Under the ordinance, a tree other than a street tree on a lot in a residentially zoned district that is the person's residence is generally exempted, with the exception of any lot designated as a tree preservation area. For most established Southlake homes, the ordinance is a design consideration rather than a permit gate.

That exemption is the single most misunderstood part of the rule, and it cuts both ways. Homeowners who assume every limb needs a permit delay projects that never required one. Homeowners who assume the exemption is absolute discover mid-project that their lot carries a designation the ordinance does not release.

Where the residential exemption stops

The exemption falls away in a few situations that are common in Southlake, and each one is worth confirming with the City's Planning and Development Services department before design begins rather than after.

• Lots or tracts designated as a tree preservation area remain subject to the ordinance regardless of who lives there, and that designation often traces back to the plat or the original development approval rather than to anything visible on the ground.

• New development applications trigger a Tree Conservation Analysis and, subsequently, a Tree Conservation Plan, which is the path a tear-down and rebuild follows rather than the exemption an existing residence enjoys.

• Street trees sit outside the residential exemption entirely, which matters on the entry side of a property where a motor court or drive realignment is under consideration.

• Properties whose plans or plats were approved before September 1, 2005 fall under an earlier version of the ordinance, 585-B, so the governing text is not always the current one.

What counts as a protected tree

The ordinance defines a protected tree as any tree with a diameter at breast height of six inches or greater, measured at four and a half feet above ground level. It separately describes a heavily wooded area as continuous wooded vegetation at a density of at least one protected tree per 325 square feet, where branches and leaves form a continuous canopy and the group consists of at least five trees.

On an existing one or two-family dwelling, trees under ten inches DBH are exempt. Those thresholds are worth measuring early, because they decide whether a specimen post oak in the middle of a proposed pool footprint is a design problem or a permitting one.

How Do Critical Root Zones Change a Backyard Plan?

The critical root zone is the area of undisturbed natural soil around a tree, drawn as a circle centered on the trunk with a radius reaching the outermost edge of the drip line. It is the reason a mature canopy consumes far more of a rear yard than its trunk suggests, and it is usually what forces a pool, a terrace or a court to move rather than the tree itself.

Because the radius is set by the drip line rather than the trunk, a mature post oak protects a circle as wide as its outermost branches. On a wooded Southlake lot carrying several of them, the buildable envelope left over is often a fraction of what the survey implies, and the design work becomes an exercise in fitting the program into the gaps between canopies.

What the ordinance restricts inside the root zone

Where the ordinance does apply, the list of prohibited activities inside a critical root zone reads like a construction sequence, which is precisely the point.

• Material storage and equipment cleaning or liquid disposal are both excluded, which means the staging plan has to be drawn at the same time as the design rather than improvised on site.

• Grade changes require written approval, and grade is the variable most often adjusted late in a build to make a terrace or a pool deck work.

• Impervious paving inside the zone is restricted, which affects how a patio, drive or pool coping meets an existing canopy.

• No trenching may cross the critical root zone of a protected tree without written approval from the Administrative Official, and trenching is how irrigation, gas, electrical and pool plumbing all travel.

Protective fencing is required before a building or earth disturbance permit is issued where the ordinance governs the site. The fence encircles the outer limit of the critical root zone, stands at least four feet high, and carries a tree protection sign every twenty feet. In active construction zones, the specification rises to six feet in chain link, similar metal, wooden material or semi-rigid vinyl tape.

The practical consequence is that root zones have to be resolved on the plan, not on site. That sequencing is the same discipline behind our Southlake design and build work, where the tree survey and the concept are read together rather than in series.

Designing for Cross Timbers Soil, Not Blackland Clay

Southlake sits in the Eastern Cross Timbers, a narrow band of blackjack and post oak that separates the Black Prairies from the Grand Prairies and averages no more than fifteen miles wide, running through the eastern portions of Denton and Tarrant counties. It is a different substrate from the expansive Blackland clay that governs construction detailing across much of Dallas.

That distinction matters because the failure modes differ. The movement and shrink-swell behavior that drives the detailing in our Dallas clay soil guide is not the dominant variable on a Cross Timbers lot, where a sandier profile over clay and the root systems of established oaks shape the engineering questions instead.

Two consequences follow for a Southlake rear yard. Retaining and grading decisions have to respect the root zones described above, which often means stepping a wall or holding a grade rather than cutting to a single elevation. And planting selection has to sit under an established canopy rather than in open sun, which narrows the palette considerably. Both are resolved earlier on a wooded lot than they would be on an open one, through grading and retaining wall design and through hardscape design that is drawn to the trees rather than around them afterwards.

How Does Southlake's Watering Schedule Shape Planting?

Southlake restricts outdoor watering to twice per week year-round. Even-numbered addresses water Wednesdays and Saturdays, odd-numbered addresses water Thursdays and Sundays, and automatic irrigation is permitted only between 6:00 p.m. and 10:00 a.m. on those designated days. Hand-held hose watering falls outside that window.

A year-round two-day schedule is a design input, not an operational footnote. A planting plan that assumes three or four irrigation days establishes poorly in its first two summers, and the plants that suffer first are the ones placed under a mature canopy, where established oak roots are already competing for the same water.

The City's own landscape guidance points the same direction: group plants of similar water usage in planting beds, use low-trajectory spray heads for turf and drip irrigation in beds, and favor native or low water use species. On a wooded lot, hydrozoning is what makes the two-day schedule workable rather than merely legal, and it is built into the planting design from the first concept.

Our Willow Tree Gardens project in Southlake shows what that looks like resolved on a real site.

Frequently Asked Questions About Tree Preservation and Backyard Design in Southlake

Do I need a permit to remove a tree in my own Southlake backyard?

Often not. Southlake's Tree Preservation Ordinance generally exempts trees on a residentially zoned lot that is the owner's residence, other than street trees, and exempts trees under ten inches DBH on existing one or two-family dwellings. The exemption does not apply to lots designated as a tree preservation area. Confirm your lot's status with Planning and Development Services before removal.

What is a protected tree in Southlake?

A protected tree in Southlake is any tree with a diameter at breast height of six inches or greater, measured four and a half feet above ground level. The ordinance separately recognizes heavily wooded areas as continuous canopy at a density of at least one protected tree per 325 square feet, consisting of at least five trees. Both definitions shape what a site plan has to show.

Can we build a pool inside a tree's critical root zone?

The critical root zone is the undisturbed soil area reaching to the drip line, and where the ordinance applies it restricts trenching, grade changes and impervious paving inside it without written approval. In practice a pool is usually relocated rather than approved inside the zone. Resolving that on the plan, before excavation is scheduled, is far less costly than discovering it during construction.

What happens if a replacement tree dies?

Where replacement is required, the ordinance calls for enough trees to equal or exceed the DBH of the tree altered, with each replacement at least two inches in diameter. A replacement that dies within three years of planting is to be replaced again within ninety days. A contribution to the City's Reforestation Fund is an alternative path where replanting on the lot is not workable.

Start With the Trees

On a wooded Southlake lot, the tree survey is the drawing that decides the design. Every other decision, from where the pool sits to how the terrace meets grade to which species survive under the canopy, follows from it. Reading the survey and the ordinance status together at the outset is what keeps a project from being redrawn after excavation begins.

Request a design consultation for your Southlake property and we will start with what is already growing on it.

By Bryce Arrington, Studio Manager, Blount Designs

Published September 2026