Trusted ADU Site Prep & Utilities for Van Nuys Homeowners
ADU Site Prep & Utilities cost guide: in Van Nuys it typically runs $35,000-$85,000 depending on foundation type, utility distance, and soil conditions, with most projects quoted at a single written price before any work begins. Ellery ADU Studio has designed, permitted, and built over 900 ADUs since 2015, and our site prep crews handle the full scope - foundation, grading, electrical service upgrades, plumbing laterals, gas extensions, and hardscape - under the same contract that covers your drawings and construction. Call (424) 523-8492 to schedule your free estimate; a live person answers 24/7.
Van Nuys sits on the San Fernando Valley floor with clay-heavy soils that expand in winter rains and contract through dry summers. That soil movement cracks slabs, shifts utility trenches, and turns a straightforward foundation pour into a retrofit if the geotechnical work gets skipped. We’ve seen it in Lake Balboa, where a 4-inch slab heaved three inches after one wet season because the original grading plan didn’t account for the area’s poor drainage. Our home page explains our full design-build model; this page covers the ground-up work that happens before your ADU walls go vertical.
Most Van Nuys homeowners come to us after learning their existing electrical panel won’t carry a second dwelling, or their sewer lateral runs through the exact spot where a detached unit needs to sit. The designer-versus-builder blame gap is real: one party draws the ADU, another bids the site work, and when the gas line needs rerouting, each points at the other. Ellery ADU Studio eliminates that gap. One contract. One written price. One phone number that reaches a live person, day or night.
What Our ADU Site Prep & Utilities Service Includes
Foundation & Grading
Foundation and grading is the literal bedrock of your ADU. In Van Nuys, we typically encounter two scenarios: a garage conversion sitting on an existing 4-inch slab that may or may not meet current load requirements, or a new detached ADU requiring full excavation, compaction, and a stem-wall or slab-on-grade foundation rated for the additional structure.
You’ll need new foundation work when the existing slab is under 3.5 inches, shows spider cracking wider than 1/8 inch, or sits below the FEMA base flood elevation for your Van Nuys parcel. For new detached units, the city requires geotechnical compaction reports to 95% relative density for the upper 12 inches of native soil, plus a 4-inch minimum crushed aggregate base before the pour.
Ellery ADU Studio Van Nuys brings a licensed geotechnical engineer to every site prep kickoff. We document existing slab thickness with core samples, specify any required over-excavation and replacement with engineered fill, and coordinate the foundation inspection with LADBS before the concrete truck arrives. Your permit set includes the structural calculations; your photo record shows the rebar tie and the compaction test results. Under Haven Standard Clause 1, the foundation line item is locked at signing - no surprise soil remediation charges after we break ground.
Electrical Panel Upgrade
An electrical panel upgrade replaces your existing service equipment to handle the additional load of a second dwelling unit. Most Van Nuys homes built between 1945 and 1985 carry 100-amp panels; California’s Title 24 energy code now requires minimum 200-amp service for a detached ADU with electric water heating, and many jurisdictions push toward 320-amp dual-lug meters for full independence.
You need this upgrade when your load calculation exceeds 80% of existing panel capacity, when the panel is a recalled brand (Federal Pacific, Zinsco, or certain Challenger models common in Valley tract homes), or when LADBS requires a separate meter for the ADU. We’ve found original 60-amp panels still in service in parts of North Van Nuys near Victory Boulevard, where postwar construction predated modern load expectations.
Our licensed C-10 electricians size the new panel from the permit set load calculations, not a guess. We coordinate the SCE service disconnect, pull the LADBS electrical permit, and schedule the meter spot inspection. For homeowners considering prefab systems, we’ve specified electrical rough-ins for Abodu and Cover units that arrive with pre-wired service panels - the site prep and the module delivery align to a single schedule. Your written scope names the panel brand, the amperage, and the conduit routing; your photo record shows the grounding electrode and the torque-specified connections.
Plumbing Lateral
A plumbing lateral is the underground pipe carrying wastewater from your property to the city sewer main. In Van Nuys, many laterals are original cast iron or orangeburg pipe installed during the Valley’s postwar boom, now deteriorated by tree root intrusion and soil shifting. Adding an ADU without replacing or upsizing this line guarantees backups, code violations, and expensive trench work after your unit is occupied.
Replacement is required when video inspection shows root intrusion exceeding 25% of pipe diameter, when the lateral is 4-inch diameter serving a property that now needs 6-inch capacity, or when the cleanout location conflicts with your ADU footprint. We’ve traced laterals in Valley Glen that ran directly beneath planned foundation corners, requiring directional boring rather than open trenching to preserve mature oak roots.
Ellery ADU Studio Van Nuys subcontracts video inspection to a licensed plumber before the permit set is finalized, not after construction starts. We map the lateral path on your site plan, specify trenchless replacement where feasible (pipe bursting or cured-in-place lining), and coordinate the LADBS sewer connection inspection. The permit set shows the new cleanout location; your photo record includes the pre- and post-inspection video. Haven Standard Clause 5 locks the lateral line item - if we hit unexpected bedrock and need hydro-excavation, that’s our contingency, not your change order.
Gas Line Extension
Gas line extension runs a new service branch from your existing meter or main line to the ADU location, sized for the additional load of water heating, space heating, cooking, and any fireplace. Southern California Gas Company requires a separate meter for detached ADUs in most Van Nuys zones, which means a new service line from the street main or a meter split with pressure regulation.
Extension is necessary when the existing meter lacks capacity for the combined load, when the ADU sits more than 50 feet from the existing line (requiring intermediate pressure regulation), or when the original piping is threaded steel with corrosion visible at joints. We’ve replaced leaking steel risers in Panorama City where soil chemistry accelerated external pitting, and we’ve run new medium-density polyethylene (MDPE) lines under existing driveways in Lake Balboa using horizontal directional drilling.
Our C-36 licensed plumbers calculate gas load from your ADU’s appliance schedule, submit the SoCalGas service request with the permit application, and pressure-test all new piping at 1.5 times working pressure for a minimum 10-minute hold. The permit set includes the gas riser diagram; your photo record shows the pressure gauge reading and the pipe fusion welds. For homeowners pairing site prep with a prefab ADU installation, we coordinate the gas rough-in date with the module delivery window so you’re never paying for temporary heating.
Landscaping & Hardscape
Landscaping and hardscape restoration completes the site after construction, replacing disturbed areas with finished grade, drainage, paving, and planting per your approved landscape plan. Van Nuys falls under LADWS water conservation ordinances requiring drought-tolerant planting and permeable surfaces for new impervious coverage exceeding 500 square feet.
This phase is required when your ADU construction disturbs existing irrigation, removes lawn or hardscape, or adds roof runoff that must be managed to prevent flooding. We’ve regraded properties in Sherman Oaks where a detached ADU’s roof drainage overwhelmed existing French drains, and we’ve specified permeable pavers for driveways in Encino to meet stormwater retention requirements without sacrificing parking space.
Ellery ADU Studio Van Nuys includes landscape restoration in the single contract, not as a separate bid you chase after construction ends. Our crews restore irrigation with smart controllers compliant with LADWS rebate programs, install drainage swales where grading analysis shows pooling risk, and finish with decomposed granite or poured concrete per your approved plan. The permit set includes the landscape plan; your photo record shows the finished grade elevations and the drainage test. Haven Standard Clause 8 covers landscape survival - if plantings fail within 90 days of substantial completion, we replace at our cost.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Brands We Service for ADU Site Prep & Utilities
Our site prep work integrates with prefab and modular ADU systems from the leading manufacturers serving California. We’ve specified foundation pads and utility stub-outs for Tuff Shed studio units across the Valley, coordinating the 4-inch slab specification with their engineered drawings so the module sets without shimming or field modification. For James Hardie siding systems on stick-built ADUs, we rough the exterior sheathing to their exact fastening pattern and moisture-management detail, eliminating the callback for siding crew confusion about stud layout or drainage plane continuity.
We’ve also run electrical and plumbing rough-ins for Abodu units in Van Nuys and Studio City, where the module arrives with pre-installed service panels and wet-wall assemblies. Our site prep includes the exact stub-out locations specified in Abodu’s site manual - if we’re off by even two inches, the module doesn’t connect. Whether you have Tuff Shed, James Hardie, Abodu, or any other make, we can help. Our permit set includes the manufacturer’s installation requirements as an addendum; your written scope names the brand-specific tolerances and the coordination schedule.
Before
AfterSigns You Need ADU Site Prep & Utilities Right Now
- Your garage slab has visible cracking or uneven settlement. Cracks wider than a quarter, especially with vertical displacement, indicate the subgrade wasn’t properly compacted or the slab thickness is below modern standards. In Van Nuys, we’ve cored slabs in the Vanowen Street corridor that measured 2.5 inches - too thin for conversion without a new floating foundation or stem-wall retrofit. Ignoring this means your ADU fails the LADBS foundation inspection, and the permit clock resets.
- Your electrical panel is full - no spare breaker slots, or only tandem breakers jammed in. A panel with no expansion capacity can’t legally serve an ADU, and tandem breakers on incompatible bus bars create fire hazards. We’ve opened panels in North Hollywood with Federal Pacific Stab-Lok breakers, a known failure mode, still in service because no one checked before the ADU design started. The panel upgrade becomes the critical path item that delays your entire project.
- Sewer backups occur more than once yearly, or you smell sewage in the yard. Recurring backups suggest a compromised lateral - cracked cast iron, root intrusion, or negative slope from soil settlement. In the Sepulveda Basin area, we’ve found laterals with 40% root occlusion that the homeowner had been treating with annual hydro-jetting rather than replacing. An ADU adds flow that overwhelms the already-failing line, and the backup happens in your new unit, not the main house.
- Your gas meter is single-stage and more than 30 years old. Older meters lack the capacity and pressure regulation for modern ADU loads, and SoCalGas won’t add a second meter without verifying the service line and regulator. We’ve had projects in Valley Glen where the original 250,000 BTU/hr meter needed replacement with a 400,000 BTU/hr unit, requiring a service line upgrade from the street main that added three weeks to the schedule. Starting this process after construction begins means your ADU sits finished but unoccupied.
- Your property floods or ponds after heavy rain. Standing water near your proposed ADU location indicates poor grading, failed drainage, or a high water table that compromises foundation integrity. After the 2023 storms, we assessed properties in Lake Balboa where the water table rose to within 18 inches of grade, requiring engineered fill and subdrain systems that weren’t in the original budget. Addressing drainage in the site prep phase prevents mold, foundation heave, and code violations; ignoring it guarantees a lawsuit from your future tenant.
Our ADU Site Prep & Utilities Process - Step by Step
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Site survey and utility locate. We walk your Van Nuys property with a licensed surveyor and call USA North 811 for underground utility marking. We document existing conditions with 360-degree photography, measure setback distances to the inch, and flag any easements or utility corridors that constrain the ADU footprint. You receive the photo record within 24 hours; the survey becomes Exhibit A of your permit set.
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Geotechnical evaluation and utility video inspection. Our geotechnical engineer takes soil borings to 5 feet or refusal, tests for expansion index and bearing capacity, and specifies any over-excavation or engineered fill. Simultaneously, our plumber runs a video camera through your sewer lateral and pressure-tests your gas line. The findings go straight into the structural and MEP drawings - no surprises after permit issuance.
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Permit set integration and written scope. The site prep specifications merge with your ADU architectural drawings into a single LADBS permit application. Every line item - foundation cubic yards, panel amperage, lateral footage, gas pipe diameter, landscape square footage - appears in the written scope with a fixed price. Haven Standard Clause 1 applies: this is the price before any work starts, and it doesn’t change unless you change the design.
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Coordinated construction and inspection scheduling. Our crews work in sequence, not in conflict: grading and foundation first, then underground utilities before the slab pour, then rough electrical and plumbing before wall closure. We schedule LADBS inspections at rough and final for each trade, and we don’t cover work that hasn’t passed. Your photo record shows each inspection sign-off card.
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Final grading, landscape restoration, and substantial completion. After the ADU structure is weathered-in, we return to restore disturbed areas to finished grade, install drainage and planting per the approved landscape plan, and conduct a final walkthrough with you. The 365-Day Done Right Promise begins at substantial completion: if the foundation cracks, the lateral backs up, or the panel fails within one year, we make it right - in writing, with a response timeline, not a vague commitment.
How Much Does ADU Site Prep & Utilities Cost in Van Nuys?
ADU site prep and utilities in Van Nuys typically ranges from $35,000 for a simple garage conversion on stable soil with adequate electrical service, to $85,000+ for a new detached unit requiring full foundation, 320-amp service, sewer lateral replacement, and extensive grading. Here’s how common scenarios break down:
| Component | Typical Range in Van Nuys | What Drives the Price |
|---|---|---|
| Foundation & Grading | $12,000 - $28,000 | Slab vs. stem-wall; soil conditions; need for engineered fill |
| Electrical Panel Upgrade | $4,500 - $9,000 | 100A to 200A vs. 320A dual-lug; SCE service line length |
| Plumbing Lateral | $6,000 - $15,000 | Trench vs. trenchless; pipe diameter; street-to-house distance |
| Gas Line Extension | $3,500 - $8,500 | New meter vs. split; MDPE vs. steel; directional boring needs |
| Landscaping & Hardscape | $5,000 - $18,000 | Permeable surface requirements; irrigation complexity; plant maturity |
What moves the needle: soil expansion index above 30 requires deeper over-excavation and replacement with non-expansive fill, adding $4,000-$8,000. Properties in the Sepulveda Basin flood zone need engineered drainage systems that flat sites don’t. Older homes with original clay sewer laterals almost always need replacement, while 1980s ABS pipe often passes inspection. Distance from the street affects both electrical and gas - a 150-foot service run costs materially more than 40 feet.
How to avoid overpaying: get the video inspection and geotechnical report before you sign any contract, not after. We’ve reviewed competitor quotes that assumed “typical” conditions and then loaded $15,000 in change orders once the slab was opened. Ellery ADU Studio Van Nuys includes contingency in our written price for conditions we can’t see - tree roots, buried debris, unexpected bedrock - and absorbs that risk under Haven Standard Clause 5. If we find it, we fix it; you don’t pay more.
Every free estimate includes the full permit set preview, the written scope with line-item pricing, and the photo record protocol. Call (424) 523-8492 to schedule yours.
ADU Site Prep & Utilities Near Van Nuys - Our Service Area
Ellery ADU Studio Van Nuys handles site prep and utilities throughout the central San Fernando Valley and adjacent communities. We regularly work in Sherman Oaks, where hillside grading and retaining wall requirements add complexity to foundation work; Encino, with its larger lots and longer utility runs; and North Hollywood, Studio City, Northridge, Tarzana, Burbank, Beverly Hills, West Hollywood, West Los Angeles, and Chatsworth. Typical mobilization to these areas is same-week from our Van Nuys base, with no travel charges within 15 miles. Properties in the Santa Monica Mountains foothills or Chatsworth’s rocky terrain may require additional geotechnical scope, which we identify and price during the initial site survey.
Serving Van Nuys, CA - Our Local Coverage Area
We’re based in the Van Nuys area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
Frequently Asked Questions - ADU Site Prep & Utilities in Van Nuys
ADU site prep and utilities is the ground-up infrastructure work that prepares your property for an accessory dwelling unit: foundation and grading, electrical service upgrade, sewer and water lateral work, gas line extension, and finished landscape restoration. It’s everything that happens before and after the ADU structure itself is built, and it’s typically the largest single cost category after the building construction. At Ellery ADU Studio Van Nuys, site prep is bundled under the same contract as your design and build - no separate bids, no coordination gaps.
A typical site prep and utilities timeline in Van Nuys runs 6 to 12 weeks from permit issuance to final inspection, depending on foundation complexity and utility coordination with SCE and SoCalGas. Foundation work alone takes 2-3 weeks for a slab-on-grade, 4-5 weeks for a stem-wall with engineered fill. Utility upgrades add 2-4 weeks for scheduling and inspection. We sequence all trades to avoid downtime; your written schedule shows the critical path and float for each phase. Call (424) 523-8492 for a timeline specific to your property.
Most Van Nuys ADU site prep and utilities projects fall between $35,000 and $85,000, with garage conversions at the lower end and new detached units on challenging lots at the upper end. The foundation is typically the largest single line item, followed by the sewer lateral if replacement is needed. Every Ellery ADU Studio estimate names a written price before work starts, per Haven Standard Clause 1 - no “call for a quote,” no range that widens once you’re committed. Call (424) 523-8492 for your exact number; estimates are free.
Yes. We’ve specified site prep for Abodu, Cover, Tuff Shed, and James Hardie systems, coordinating foundation pads and utility stub-outs to each manufacturer’s exact tolerances. Prefab units require precision: the module arrives on a truck, and the crane fee is hourly. If our concrete pad is off by two inches, the module doesn’t set, and you’re paying for a second crane day. Our permit set includes the manufacturer’s site manual as an addendum; your written scope names the coordination schedule and the tolerance verification protocol.
Call 911 or SoCalGas/SCE emergency lines immediately for any active gas leak, exposed energized conductor, or sewer backup presenting health risk. After the immediate hazard is controlled, Ellery ADU Studio Van Nuys responds to construction-phase emergencies within our active projects with a live person available 24/7. For non-clients, we offer a Free Second Opinion on any written estimate already in hand, including emergency repair scopes from other contractors. We do not provide emergency dispatch for properties where we have no existing contract; your safety is best served by the utility emergency services first.
The 365-Day Done Right Promise covers all site prep and utilities work: if the foundation cracks, the lateral fails, the panel malfunctions, or the gas line leaks within one year of substantial completion, we repair at our cost. This is backed in writing before your project starts, not a verbal assurance. Beyond year one, manufacturer warranties apply to specific components (panel breakers, water heater elements, irrigation controllers), and our workmanship extends to 5 years on structural elements. The permit set, photo record, and inspection sign-offs are your documentation trail; we maintain copies as well.
Gather your property survey or plot plan if you have one, locate your electrical panel and gas meter for our technician, and note any recent utility issues - backups, flickering lights, gas odor. We’ll handle the USA North 811 utility locate, the geotechnical assessment, and the video inspection scheduling. There’s no charge for the estimate, no obligation to proceed, and no pressure to decide on site. We’ll leave you with the written scope, the permit set preview, and our direct line. Call (424) 523-8492 when you’re ready to schedule.
Schedule Your ADU Site Prep & Utilities Service in Van Nuys Today
Call (424) 523-8492 to schedule your free estimate. A live person answers 24/7. You’ll receive a written price before any work starts, a documented photo record on every visit, and the 365-Day Done Right Promise backed in writing. Ellery ADU Studio Van Nuys has handled site prep and utilities for over 900 ADUs since 2015 - one contract, one price, no designer-versus-builder blame gap.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Van Nuys since 2015.