Building an ADU in Los Angeles: Materials Checklist from Foundation to Finish

An ADU is a small house built to full house standards, and that is exactly why material orders go wrong: the project feels small, so it gets ordered like a remodel, a trip at a time, and the gaps show up as failed inspections and idle crews. This checklist walks the build in inspection order, from footings to finish, and lists what each stage needs and which of our detailed guides covers it. Use it as a takeoff skeleton for a detached backyard unit or a garage conversion, then check it against your approved plans, which always govern.

The build at a glance

Most LA ADUs go through the same sequence of inspections, and each one has a materials package that has to be on site before the crew starts that stage.

The "Order By" column is the one that saves the most time. Hardware and sheathing are routinely forgotten until the framers ask for them, and the rough plumbing and electrical materials need to be on site while the framing is still open.

Foundation: concrete, steel and anchor bolts

The foundation inspection looks at what is in the forms before the pour: rebar size and placement, anchor bolts and holdown embeds in the right locations, and footing depth. For a small slab or a few footings, bagged mix is practical; our bagged concrete mix comparison covers which bag to use, and the concrete mix collection has the range. Our slab reinforcement comparison covers rebar versus mesh, and the aggregates guide covers the base under the slab.

Anchor bolts and holdown embeds are set before the pour and cannot be added cleanly afterward, so they belong in the foundation order, not the framing order. The holdowns and anchor bolts guide covers the hardware, and post-installed concrete anchors cover the corrections when an embed is missed.

Framing: lumber, sheathing and hardware

Framing is the largest single order and the one with the most inspection items. Lumber has to carry the grade stamp your plans call for, which our lumber grade stamps guide explains, and sill plates on concrete need to be treated lumber, covered in our pressure-treated vs borate-treated guide. The Douglas fir lumber collection has the framing stock.

In Los Angeles the shear walls are where framing inspections are won or lost. Panel type, thickness and edge nailing all have to match the schedule on the plans; our shear wall sheathing guide covers what inspectors check, and the plywood and OSB collection has the panels. The nails are part of the design, not a substitution the crew can make; see our framing nails guide.

Hardware closes out the framing order: joist hangers, straps, holdowns and structural screws or bolts where the plans call for them. Order it with the lumber, not after the framers ask.

Dry-in: roof and wall barrier

Once the frame is sheathed, get it closed to weather. On the roof that means underlayment fastened with the right cap nails and roofing fasteners, then the finished roof covering from the roofing collection. On the walls it means building paper or housewrap lapped correctly, covered in our housewrap guide. If the build straddles the October rains, the rain-ready dry-in checklist lists the full storm package.

Rough electrical and plumbing

Rough-in happens while the walls are open, so the materials have to be on site before insulation is scheduled. On the electrical side, an ADU usually needs its own subpanel or a service upgrade; our conduit comparison covers the feeder run from the main house, the power distribution collection has panels and breakers, and our electrical box guide covers box fill.

On the plumbing side, supply lines are copper or PVC depending on the run, covered in our copper pipe guide and PVC schedule comparison. Drain, waste and vent is typically ABS, covered in our ABS pipe guide, and every fixture and the unit itself need shut-offs, which our shut-off valves comparison covers.

Insulation and Title 24

New ADUs have to meet Title 24 energy requirements, and the insulation inspection checks the R-values on the energy compliance documents, not whatever was left over from another job. Our Title 24 insulation hub covers batt, foam board, mineral wool and blown-in options, and the insulation collection has the stock. If the unit shares a wall with the main house or sits close to a neighbor, add sound control at this stage; stone wool batts and sound-damped board do most of the work, as our mineral wool guide explains.

Exterior finish: stucco or siding

Most LA ADUs are finished in stucco to match the main house. The lath inspection happens before the scratch coat, so lath, weep screed and accessory metal all need to be right first time; our stucco systems guide covers both three-coat and one-coat, and the stucco collection has the materials. Where siding is specified, our siding comparison covers fiber cement, wood and engineered wood. Units in a fire hazard severity zone also need ignition-resistant construction, which our WUI and Chapter 7A guide covers.

Interior finish: drywall, trim and sealant

Drywall goes up after the insulation inspection. Where the ADU is attached to or close to the main house, some walls or ceilings may need a fire-rated assembly; our Type X drywall guide covers those, and our corner bead comparison covers finishing. Trim is the last carpentry order, covered in our interior trim guide and finish nails guide, and sealant closes out wet areas and exterior penetrations, which our sealant comparison covers.

How to order an ADU without running short

1. Build the takeoff from the approved plans, stage by stage, using the table above.
2. Order the foundation package including anchor bolts and holdown embeds before excavation.
3. Order lumber, sheathing, nails and hardware together, before the pour.
4. Order dry-in and rough MEP materials while framing is under way.
5. Confirm insulation R-values against the Title 24 documents before ordering.
6. Order exterior and interior finish materials after the rough inspections pass.

We deliver across Los Angeles County and can stage deliveries to match your inspection schedule. Send the plan set and the build schedule and we will split the order into stage drops so the right material arrives before each inspection, not after it.

Frequently asked questions

What materials are needed to build an ADU?

The same materials as a small house: concrete, reinforcing and anchor bolts for the foundation; lumber, sheathing and structural hardware for framing; roofing and wall barrier for dry-in; electrical and plumbing rough-in materials; insulation to Title 24; stucco or siding; and drywall, trim and sealant to finish.

Does an ADU in Los Angeles have to meet Title 24?

Yes. New ADUs are new conditioned space and must meet California's Title 24 energy standards. The insulation R-values and other requirements are set out in the energy compliance documents for your project.

Which inspections will an ADU go through?

Typically foundation, framing, rough electrical and plumbing, insulation, lath or exterior, drywall where fire separation applies, and final. The exact sequence is set by your permit, so confirm it with the building department.

What is the most common reason ADU framing fails inspection?

Shear wall and hardware details: sheathing nailing that does not match the schedule, missing or wrong holdowns, and lumber without the specified grade stamp. All three are avoidable by ordering exactly what the plans specify.

Can I order all the materials for an ADU at once?

You can, but staged deliveries usually work better. Material ordered too early is exposed to weather and theft on site, and staging each drop to match the inspection sequence keeps the site clear and the crew working.