Tree Preservation Plans: What Bay Area Developers Need to Know

What Is a Tree Preservation Plan?

A tree preservation plan is a technical document. It tells the city how you will protect existing trees during construction and what you will do about trees that cannot be saved. It is not an arborist report (though it includes one). It is a construction-phase management document tied directly to your development permit.

The TPP typically includes 4 main components: a tree inventory with health assessments, tree protection zone maps overlaid on your grading and site plans, construction-phase specifications for fencing and root protection, and a mitigation plan for trees being removed.

In most of the stricter Peninsula and South Bay jurisdictions the TPP is a condition of approval; where it is required, an application without one is incomplete. With a poor one, you face revision cycles that add 4 to 8 weeks to your timeline.

What a TPP Includes

Tree Inventory and Assessment

The arborist surveys every tree meeting your city's size threshold, both on your property and within the influence zone (typically 15 to 25 feet beyond your property line, since root systems do not respect lot lines). Each tree is documented with:

• Species identification
• Trunk diameter measured at 4.5 feet above grade
• Canopy spread and height
• Health rating (good, fair, poor, dead/dying)
• Structural condition and defects
• Estimated remaining useful life
• Suitability for preservation (considering the proposed project)

Trees are physically tagged with numbered metal or plastic discs and plotted on the site survey. The inventory is delivered as both a spreadsheet and an annotated site plan.

Tree Protection Zones

For every tree designated for preservation, the arborist calculates the tree protection zone (TPZ). This is the area where no construction activity is permitted: no grading, trenching, material storage, equipment parking, or foot traffic from crews.

Two common professional rules of thumb, drawn from ISA best-management-practice guidance, are:

• Method 1: Drip line radius plus 5 feet
• Method 2: 6 times the trunk diameter (in feet) measured from trunk center
• Use whichever is greater

These are minimums for planning. Where the city codifies a zone it is often larger: Palo Alto and Menlo Park require a TPZ radius of 10 times the trunk diameter.

For example, a coast live oak with a 30-inch trunk diameter gets a TPZ of at least 15 feet radius under the 6x rule (30 inches = 2.5 feet x 6 = 15 feet). If its canopy extends 20 feet from the trunk, the drip line method gives 25 feet. In Palo Alto or Menlo Park the code requires 25 feet (10 x 2.5 feet) regardless. You would use the 25-foot radius.

These zones are drawn on the civil plans, grading plans, and landscape plans. Your civil engineer and landscape architect need this information before they finalize their drawings.

Construction-Phase Protection Specifications

The TPP specifies how trees will be protected during construction. Following ANSI A300 Part 5 (Management of Trees and Shrubs During Site Planning, Site Development, and Construction) and the city's own tree protection standards (for example Palo Alto's Tree Technical Manual), this typically includes:

• Protective fencing: at the TPZ boundary, installed before any grading begins; height and material per the city's tree protection standards (6-foot chain-link is what I specify)
• Signage: "Tree Protection Zone: Do Not Enter" on all fence panels
• Root pruning protocols: Where encroachment is unavoidable, clean cuts with sharp tools, no tearing or ripping
• Soil protection: 6-inch wood chip mulch layer within TPZ if any foot traffic is permitted
• Irrigation schedule: Deep watering every 2 to 4 weeks during construction (trees under stress need supplemental water)
• Monitoring frequency: Inspections by the project arborist at the interval the permit sets (I typically propose monthly), with written reports where the city requires them

Mitigation and Replacement Plan

For trees that must be removed, the TPP calculates the mitigation obligation per your city's ordinance. This includes:

• Number and size of replacement trees required
• Species selection (native species often preferred or required)
• Planting locations on the landscape plan
• Maintenance bond or survival guarantee period (commonly 1 to 5 years depending on the city)
• In-lieu fee calculation if on-site planting is not feasible

When Is a TPP Required in the Bay Area?

In cities that require a plan, the trigger is straightforward: if your project affects protected trees, you need a TPP. But the definition of "affects" and "protected" varies by city. Common triggers include:

• New construction on a lot with protected trees
• Additions or remodels that require grading near trees
• ADU construction (yes, even small projects)
• Subdivision or lot splits
• Demolition of existing structures near trees
• Utility trenching within the drip line of protected trees
• Driveway or parking lot construction within root zones

If you are unsure whether your project triggers a TPP requirement, use our Permit Checker or call your city's planning department before you submit anything. Starting the permit process without the TPP wastes everyone's time.

City-Specific Requirements

Every Bay Area city has its own ordinance defining protected trees and TPP requirements. Here is a comparison of the cities with the strictest rules, the ones where developers most often run into trouble. Figures are from each city's code as verified in October 2026:

Use our 56-city ordinance table to check the exact thresholds and requirements for every city we cover.

Typical Costs

TPP pricing depends on the number of trees, site complexity, and what your city requires. Here is what to expect, based on my typical fees:

These costs cover the initial assessment, TPP document preparation, and plan submission. They do not include monitoring during construction, which is billed separately per visit. Budget for 6 to 12 monitoring visits over the life of a typical residential project, or 12 to 24 for larger commercial work.

The TPP cost is small relative to the penalties for damaging protected trees during construction. A single damaged heritage oak in Palo Alto can trigger $10,000+ in fines plus replacement costs exceeding $25,000 for a mature specimen.

Timeline: From Hiring to Approval

Here is a realistic timeline, based on my recent projects, for a typical residential project in a strict jurisdiction like Palo Alto or Los Gatos. No city codifies a TPP review period:

• Week 1: Hire consulting arborist, schedule site visit
• Week 2: Site visit, tree tagging, data collection
• Weeks 3 to 4: Arborist prepares TPP document
• Week 5: Draft review with your design team, revisions
• Week 6: Submit TPP with development application
• Weeks 7 to 12: City review (2 to 6 weeks depending on jurisdiction)
• Weeks 12 to 14: Respond to city comments, revisions if needed
• Weeks 14 to 16: Final approval

Total: 3 to 4 months from hiring the arborist to permit approval. In my experience, faster jurisdictions (San Jose, Mountain View, Sunnyvale) can come in at 6 to 8 weeks total. Palo Alto, Atherton and Los Gatos have run closer to 4 months.

The single biggest schedule risk is starting the TPP after your design is complete. If the arborist identifies conflicts between your plans and protected trees, you face redesign cycles that can add months.

Common Mistakes Developers Make

1. Hiring the Arborist Too Late

This is the most expensive mistake. If you bring in the arborist after your civil plans are done, you may discover that your proposed grading cuts through the root zone of a heritage oak. Now you are choosing between a $50,000 redesign and a $10,000 penalty. Neither would have been necessary if the arborist had been involved during schematic design.

Bring the arborist on during site due diligence or, at latest, during schematic design. The cost is the same either way; the value is far higher when they can influence the design.

2. Underestimating Protection Zone Size

A 36-inch oak has a TPZ radius of at least 18 feet under the 6x rule of thumb. In cities like Palo Alto and Menlo Park that require 10 times the trunk diameter, the radius is 30 feet. That is a 36- to 60-foot diameter circle where nothing can happen. Developers who plan equipment staging, material storage, or temporary access roads through these zones face stop-work orders and fines.

Map all TPZs on your logistics plan. Your general contractor needs these before mobilization, not after.

3. Choosing the Cheapest Arborist

A $1,200 TPP that gets rejected and requires $3,000 in revisions costs more than a $3,500 TPP done correctly the first time. Look for an arborist with experience in your city: someone who has submitted plans to your planning department before and knows what the reviewers expect.

4. Ignoring Neighboring Trees

Root systems extend well beyond property lines. A 60-foot oak on your neighbor's lot may have roots extending 30+ feet into your site. If your grading damages those roots, you are liable regardless of whether the tree is on your property.

5. Skipping Monitoring During Construction

The TPP means nothing if it is not enforced during construction. Crews move fencing, store materials in TPZs, and run equipment where they should not. Regular monitoring by the project arborist catches violations before they become tree failures. Cities commonly impose arborist monitoring as a permit condition; the frequency and reporting requirements are set per project.

How to Hire a Consulting Arborist for TPP Work

Not all arborists do development consulting. Tree removal and pruning is a different skill set from construction-phase tree management. Here is what to look for:

• ISA Certified Arborist: minimum requirement for most Bay Area cities
• Tree risk assessment qualification: required in some jurisdictions for hazard trees
• Experience with your specific city: ask for 2 to 3 references from projects in your jurisdiction
• Professional liability insurance: protects you if their recommendations cause damage
• Familiarity with ANSI A300 Part 5: the national standard for tree management during construction
• Civil plan reading ability: they need to interpret grading plans and utility layouts

Get bids from 2 to 3 arborists. Ask each one: How many TPPs have you submitted to [your city] in the past year? What was the approval rate? How many revision cycles did they require? The answers tell you more than the price.

See our consulting services page for more on working with certified arborists on development projects, or visit our page for landscape architects on coordinating with arborist consultants.

Frequently Asked Questions

What is a tree preservation plan?

A tree preservation plan is a technical document prepared by a certified arborist. It inventories all trees on a development site, identifies which will be preserved or removed, defines protection zones during construction, and outlines mitigation for trees that cannot be saved. Many Bay Area cities, including Palo Alto, Los Gatos, Menlo Park and Saratoga, require one as part of a development application affecting protected trees.

When is a TPP required in the Bay Area?

Many cities require a TPP when a development project affects protected trees; the size threshold varies by city and species (see the table above). Triggers include new construction, additions, grading within the drip line, demolition, subdivision, and ADU construction. Palo Alto applies its tree protection standards to any development on a lot with protected trees (11.5 inches DBH for six native species, 15 inches for other species, 18 inches for coast redwood).

How much does a tree preservation plan cost?

In my practice, costs range from $2,000 to $8,000+ depending on the number of trees and site complexity. A small residential lot with 3 to 5 trees runs $2,000 to $3,500. Mid-size commercial projects with 15 to 30 trees cost $4,000 to $6,000. Large subdivisions with 50+ trees can exceed $8,000. Monitoring during construction is billed separately at $150 to $300 per visit.

Who can prepare a tree preservation plan?

Most Bay Area cities require the TPP to be prepared by an ISA Certified Arborist or a Registered Consulting Arborist. Some accept plans from licensed landscape architects if paired with an arborist's tree assessment. Look for a preparer who carries professional liability insurance and has experience with your city's ordinance.

What is a tree protection zone?

The tree protection zone is the area around a preserved tree where no construction activity, material storage, grading, or vehicle traffic is allowed. A common rule of thumb is the drip line radius plus 5 feet, or 6 times the trunk diameter (in feet), whichever is greater; cities such as Palo Alto and Menlo Park mandate a radius of 10 times the trunk diameter. For a tree with a 24-inch trunk, the TPZ radius is at least 12 feet under the rule of thumb and 20 feet in Palo Alto or Menlo Park.

What happens if trees are damaged during construction?

Penalties vary by city but are severe. Palo Alto assesses $10,000 per tree or twice the tree's appraised reproduction cost, whichever is higher, plus replacement at double the normal ratio and a possible development moratorium of up to five years. Oakland treats violations as infractions and requires replacement trees or fees up to the tree's ISA-appraised value plus the City's enforcement costs. Los Gatos can issue stop-work orders and requires a $5,000-per-tree security (up to $25,000) that is held for one year after the improvements are accepted and forfeited if a preserved tree is lost. Developers are responsible for replacement planting; most Bay Area cities size the obligation by the removed tree's appraised value or a trunk-size table rather than a single 2:1 or 3:1 ratio.

How long does it take to get a TPP approved?

No city codifies a TPP review period, so these are figures from my recent projects. Plan on 2 to 6 weeks for the arborist to prepare the TPP, then 2 to 8 weeks for city review. Palo Alto and Los Gatos have been slowest (6 to 8 weeks). Most South Bay cities have processed in 3 to 4 weeks. Total timeline from hiring the arborist to final approval: 6 to 16 weeks depending on jurisdiction and revision cycles.

Does CEQA require a tree preservation plan?

CEQA does not explicitly require a TPP, but projects removing habitat trees or those in areas with significant canopy may trigger biological resource review. If a Mitigated Negative Declaration or EIR is needed, the TPP becomes a supporting document. Heritage trees and oak woodland removal are common CEQA triggers in Bay Area development.

What is ANSI A300 Part 5?

ANSI A300 Part 5 is the national industry standard for tree management during site planning, development, and construction. It defines best practices for protection zones, root pruning, soil management, and monitoring. Bay Area cities incorporate its practices through their own technical manuals and tree protection standards, so your TPP should follow it.

Can I encroach into the tree protection zone?

Limited encroachment may be allowed with arborist approval and mitigation. Common allowances include hand-digging within the outer 25% of the TPZ, directional boring for utilities, and permeable paving. The arborist must document that encroachment will not compromise long-term tree health. Encroachment allowances are decided case by case by the city arborist; Palo Alto, for example, treats removal of more than 25% of a tree's root area (15% for oaks) as excessive pruning.

What replacement ratios do Bay Area cities require?

Most Bay Area cities do not use a single fixed ratio. Palo Alto's urban forester sets replacement per the Tree Technical Manual. Oakland requires replacement plantings or an in-lieu fee per its master fee schedule. Atherton follows its heritage tree standards. Los Gatos sets replacement per Town standards. San Jose sets ratios by trunk size (1:1 to 5:1). Menlo Park and Saratoga size replacement by the removed tree's appraised value. Check the Ordinance Comparison tool for current requirements.

Do I need a TPP for an ADU or home addition?

Yes, if the project affects protected trees. Even a small addition or ADU can trigger TPP requirements if construction activities (grading, utility trenching, equipment access) encroach within the protection zone of a protected tree. Palo Alto applies its protection standards to any development on a lot with protected trees; Atherton requires heritage trees to be shown on plans for any building permit and a protection plan when the town arborist requires one.

How do I find a consulting arborist for TPP work?

Search the ISA directory at treesaregood.org/findanarborist for certified arborists in your area. Look for those with consulting experience and familiarity with your city's ordinance. Ask for references from recent development projects in your jurisdiction. The American Society of Consulting Arborists (ASCA) directory lists arborists specializing in development consulting. See our consulting page for more.

What is the difference between a TPP and an arborist report?

An arborist report assesses one or more trees: their health, structure, and recommendations. A tree preservation plan is a project-specific document tied to a development application. It includes a full inventory, site plan overlay, protection zone calculations, construction specifications, mitigation plan, and monitoring schedule. A TPP is always more detailed and costs more than a standard arborist report. See our article on when you need an arborist report.