Plant Prefab Junior ADU & Interior Conversion Nationwide

Plant Prefab Junior ADU & Interior Conversion in West Hollywood: What to Know First

We provide independent Plant Prefab junior ADU and interior conversion service in West Hollywood, typically completing diagnostic-to-permit-ready drawings in 4 to 6 weeks for interior scopes and 8 to 12 weeks for attached additions that require structural coordination with the main residence. Every project starts with a written cost range before we produce a single drawing, per Haven Standard Clause 1. This page is for homeowners who already own a Plant Prefab product and need to convert existing interior space, a basement, or an above-garage area into a permitted junior ADU, or who need to attach a Plant Prefab module to their main structure. Call (213) 329-7167 to schedule your free estimate.

Call (213) 329-7167

How Plant Prefab Products Fail - and How We Fix Them

• LivingHome 10 Series: Vapor barrier compression in basement conversions. The LivingHome 10’s factory-applied smart membrane performs well above grade, but in West Hollywood’s clay-heavy soil zones near the Beverly Hills border, basement moisture wicks through foundation walls and compresses the membrane against stud bays. We strip the factory barrier, install a site-applied fluid-applied membrane rated for below-grade use, and re-drywall with cement board at the sill line. The module’s structural frame stays intact; we’re protecting what Plant Prefab built, not replacing it.
• LivingHome 6 Series: Electrical service mismatch in room-to-ADU conversions. The LivingHome 6 ships with a 100-amp subpanel that assumes standalone deployment. When we convert an interior room or attach it as a junior ADU to a 1960s West Hollywood duplex, the main service is often only 125 amps. We spec a load calculation per LADBS Article 220, upgrade the main to 200 amps where needed, and coordinate with LADWP’s 6-week trench schedule on the west side of West Hollywood. The module’s panel stays; the service entrance changes.
• LivingHome 8 Series: HVAC short-cycling in above-garage installations. The mini-split cassettes in the LivingHome 8 are sized for the module’s tight envelope. Above a garage in West Hollywood’s afternoon heat island, the unconditioned plenum exaggerates temperature swings and the unit short-cycles. We add a dedicated return path from the ADU to the garage ceiling, insulate the plenum with closed-cell spray foam, and sometimes upsize the condenser by a half-ton. Plant Prefab’s ductless design stays; we solve the site condition it wasn’t built for.
• LivingHome 10 Series: Floor level discrepancy in attached additions. The LivingHome 10’s 8-inch raised floor system sits proud of typical West Hollywood slab-on-grade construction by 3 to 4 inches. When we attach it as a junior ADU to a 1940s bungalow near Norma Triangle, the step creates a trip hazard and a water dam. We design a tapered transition with a recessed channel drain, poured in place, that meets the module’s threshold without modifying its structural floor. The fix is in the site work, not the module.
• LivingHome 6 Series: Window egress conflict with JADU requirements. The LivingHome 6’s fixed clerestory windows don’t meet CBC Section 310 for sleeping room egress in a junior ADU. In West Hollywood’s R-1 zones, we specify field-installed casement retrofits with 5.7 square feet of clear opening, using the same thermally broken aluminum extrusion profile as Plant Prefab’s OEM supplier. The aesthetic match is close enough that the module looks intentional, not patched.

Our Plant Prefab Junior ADU & Interior Conversion Process

1. 1
   Diagnostic site visit with photo record. We document the existing Plant Prefab module or the target interior space, the main residence connection points, and any site constraints. You receive the photo record within 24 hours.
2. 2
   Written cost range before drawings. Based on the diagnostic, we deliver a line-item written price range. Under Haven Standard Clause 1, this is your number before any design hours are billed. No “call for a quote” here. The document is the promise. Everything else is a conversation.
3. 3
   Permit set production. Our drafters produce the LADBS submittal set, including structural calculations for module attachment, MEP coordination, and Title 24 energy compliance. Nadia Ellery reviews every set before it leaves our office.
4. 4
   Prefabrication coordination (for module-based scopes). We issue a shop drawing package to Plant Prefab or manage the interface with their production schedule, specifying any field modifications needed for your specific site.
5. 5
   Construction and inspection sequence. Our crews execute the conversion or attachment, pulling permits and scheduling LADBS inspections at rough, insulation, and final. The 365-Day Done Right Promise applies from final sign-off.
6. 6
   Documentation handoff. You receive the as-built permit set, the final photo record, and the written warranty. If it’s not built to the permitted drawings, we make it right.

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What Plant Prefab Junior ADU & Interior Conversion Costs in West Hollywood

Interior room-to-JADU conversions using Plant Prefab components typically run $85,000-$140,000 all-in, drawings through final inspection. Above-garage ADU attachments with structural coordination run $120,000-$195,000. Basement conversions with moisture remediation and floor lowering run $110,000-$175,000.

These ranges include our design, permit set, construction, and documentation. What moves the price up: main electrical service upgrade, foundation work in West Hollywood’s expansive clay soils, and facade matching requirements in the Norma Triangle or West Hollywood West historic zones. What keeps it down: existing plumbing stack access, adequate main service, and clear Title 24 compliance path. Call (213) 329-7167 for your exact written range; estimates are free.

Why West Hollywood Homeowners Call Ellery ADU Studio West Hollywood for Plant Prefab Work

We are an independent Plant Prefab service provider, not affiliated with or authorized by Plant Prefab. That independence matters: we specify and coordinate across Abodu, Cover, and Dvele systems too, so if your site conditions favor a different module for part of the scope, we say so in the first meeting. Our crews have handled 900-plus ADUs since 2015, including a stretch of detached studio builds along the hillside parcels near Laurel Canyon where foundation and utility work gets complicated fast. Every project carries the 365-Day Done Right Promise in writing, every visit produces a documented photo record, and a live person answers calls 24/7. The license number appears on every page because it is verifiable, not just claimed.

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