Mighty Buildings Site Prep & Utilities: The North Hollywood Owner’s Guide
Mighty Buildings-compatible site prep and utility connections in North Hollywood typically run $4,200-$8,600 installed, depending on whether your lot needs a full utility trench or just a final connection to the modular unit. We stock Mighty Buildings-spec conduit, junction boxes, and water/sewer connection kits on our North Hollywood trucks, and most replacements or completions are done in a single day once the permit is clear. Most owners discover a problem when the Mighty Buildings unit arrives and the existing site prep doesn’t match the connection points - or when the city inspector flags a trench depth or conduit size that doesn’t match the approved permit set.
Which Mighty Buildings Models This Applies To
Mighty Buildings currently ships two primary product lines to the California market: the Mighty Duo series (studio and one-bedroom configurations) and the Mighty Quattro (two-bedroom and larger footprint units). The site prep and utility specs differ between them in ways that matter for ordering parts.
The Duo series requires a single 200A electrical service stub and a 3/4-inch water main connection with a pressure regulator rated for 40-80 PSI. The Quattro needs dual 100A feeds or a single 200A depending on your local utility’s preference, plus a 1-inch water line with backflow prevention. You can identify your unit’s requirements from the Mighty Buildings serial plate, located on the utility chase panel - look for the “Site Prep Spec” field, which will read either “Duo-Std” or “Q-200.”
We source OEM Mighty Buildings junction boxes and conduit runs where the spec demands it, particularly for the proprietary weather-sealed utility chase gaskets that come standard on 2023 and newer units. For electrical conduit and PVC drainage, we typically specify Southwire and Charlotte Pipe equivalents that meet or exceed Mighty Buildings’ engineering - at lower cost and with faster North Hollywood availability. The decision point is usually the chase gasket: if your unit is under warranty, OEM preserves coverage. If not, aftermarket saves 30-40 percent with no functional difference.
Signs Your Mighty Buildings Site Prep & Utilities Is Failing

- Water pressure drops when both fixtures run. The 3/4-inch supply line may be undersized for the Quattro’s dual-bath demand, or the pressure regulator installed at the meter is clogged with Valley sediment. In North Hollywood, we see this often on older mains near the Tujunga Wash where mineral buildup is heavy.
- Electrical panel trips repeatedly after unit connection. The Mighty Buildings spec calls for a dedicated 200A subpanel with AFCI breakers on all living circuits. If your electrician used standard breakers or shared a neutral, the unit’s combined load will trip under normal use. This is a permit-fail, not just an annoyance.
- Sewer backs up during heavy rain. The modular connection point sits lower than many traditional foundations, and North Hollywood’s flat grades near the Los Angeles River basin don’t help. If the sewer lateral lacks a proper backwater valve or the trench slope is under 1/4 inch per foot, you’ll get reverse flow.
- Utility chase leaks at the wall penetration. The Mighty Buildings gasket system compresses against a flat, level surface. If your foundation pour or stem wall wasn’t floated to within 1/8 inch over 4 feet, the seal distorts and water enters the chase. We’ve resealed three of these on Hartsook Street alone after winter rains.
- Gas line won’t hold pressure test. Mighty Buildings units with gas appliances require a 2 PSI test for 15 minutes per LADBS. Small leaks at the CSST fitting or at the sediment trap are common when the initial install rushed the thread sealant or used the wrong tape grade.
Replacement Cost & What’s Included
Here is what Mighty Buildings site prep and utility work costs in North Hollywood, with every line item written before work starts per Haven Standard Clause 1:
| Scope | Typical Range |
|---|---|
| Electrical trench, conduit, and 200A service stub | $2,800-$4,400 |
| Water line trench, backflow preventer, and regulator | $1,400-$2,600 |
| Sewer lateral connection with backwater valve | $1,600-$3,200 |
| Gas line extension and pressure test | $900-$1,800 |
| Utility chase seal and weatherization kit | $600-$1,100 |
| Permit, inspection, and LADBS coordination | $1,200-$2,400 |
The wide ranges reflect trench length, asphalt or concrete restoration, and whether your existing main panel has capacity or needs a service upgrade. We document every condition with photos before quoting, so the price you sign is the price you pay - no change orders for “surprise” rock or undocumented utility conflicts. Workmanship is covered under our 365-Day Done Right Promise, and all permits are pulled and inspections passed before we call the job complete.
DIY or Call Us?

There is a clear line here, and it is drawn at the permit.
An owner can safely check the Mighty Buildings serial plate, verify the pressure regulator model, and confirm whether the electrical panel has open breaker slots. These are visual checks, no tools beyond a flashlight. What an owner should not do: trench across a utility easement without a USA North 811 locate, pull an electrical permit as owner-builder without understanding LADBS’s AFCI requirements for modular units, or attempt a gas pressure test without a calibrated gauge and the ability to lock out the meter.
The real risk is not injury - it is rework. A DIY electrical stub that fails inspection adds two weeks to your Mighty Buildings delivery schedule, and the crane rental doesn’t wait. If you are unsure whether your existing prep matches the unit spec, call us at (424) 407-8266. We offer a Free Second Opinion on any written estimate, and we will tell you exactly what is right and what needs fixing before the truck arrives.
FAQs
Properly installed utility connections last 25-40 years, but the chase gasket and pressure regulator typically need attention at 10-15 years due to Valley heat cycling and hard water mineralization. Call (424) 407-8266 for an exact quote - estimates are free.
Individual components - a failed regulator, a cracked junction box, a leaking gasket - can be repaired or swapped without redoing the entire trench. We only recommend full replacement when the original install predates current LADBS modular standards or when multiple systems fail together. Call (424) 407-8266 for an exact quote - estimates are free.
Final hookup of a pre-stubbed site takes 4-6 hours for electrical and water, assuming the trench and conduit are already inspected. If we are doing the full prep, plan on 3-5 working days for trenching, rough-in, inspection, and backfill. Call (424) 407-8266 for an exact quote - estimates are free.
We stock the chase gasket kits, pressure regulators, and common conduit sizes on our North Hollywood trucks. OEM Mighty Buildings-specific junction boxes ship in 2-3 business days if your warranty requires them. Call (424) 407-8266 for an exact quote - estimates are free.
Ellery ADU Studio North Hollywood is an independent service provider, not affiliated with Mighty Buildings. We also specify and coordinate site prep for Abodu, Cover, and Dvele units under the same single-contract model.
Tell me the lot dimensions and I will tell you what fits - everything else is paperwork we handle.
Ready to get your Mighty Buildings site prep right the first time? Call (424) 407-8266 to schedule your free estimate. Nadia Ellery and our team will review your lot conditions, your unit spec, and your existing utilities, then deliver a written price before any work begins - guaranteed under Haven Standard Clause 1.
Written by Nadia Ellery, Owner & Principal Designer, Ellery ADU Studio North Hollywood at Ellery ADU Studio North Hollywood, serving North Hollywood and nearby areas.