Parts for this step · tap one to find it
The room from the windows and doors guide, with its roof framed, and the framing and the plumbing, electrical and mechanical rough-ins in and inspected. Now it gets air sealed, insulated, drywalled, finished and painted. The parts are below, in the order the steps use them.
≈2–3 weeks, with drying time between coats and inspection scheduling
This guide shows the sequence, not a design. Insulation values come from the project’s energy report, and fastening, board types and finishes from the plans and the makers’ instructions.
Insulation only works if air can’t move around it. Before any goes in, the gaps that let air through are sealed: along the bottom and top plates, around the electrical boxes, and wherever pipes or wires pass through the plates.
≈half a day · Caulk or foam rated for the job · fire-rated sealant where the plans call for fireblocking
Parts: ≈4 tubes + 1 can × Sealant or foam at the plates, boxes and gaps
Air sealing is part of California’s energy code, and on many projects a rater checks it with the insulation.
Every stud bay in the outside walls gets a batt cut to fit: full width, top to bottom, with no gaps, no squashed spots and no voids behind boxes or wires. The small bays under and beside the windows get filled too. In Southern California, R-21 batts are the usual starting point for a 2x6 wall. Some climate zones also call for continuous insulation outside the studs, so the project’s energy report sets the final number.
≈1 day · R-21 batts are typical for 2x6 walls · the energy report sets the required value
Parts: ≈8–11 bags × Wall insulation batt, R-21 for 2x6 walls
Batts that are squashed, gapped or folded lose much of their R-value. Faced batts are stapled to the sides of the studs where the maker calls for it.
Before any drywall covers it, the city inspector checks the insulation. On a new home or ADU, the energy report may also require an independent rater (an ECC-Rater) to verify the installation quality, called QII. Small additions are usually exempt.
Inspection visit ≈1 hour · City insulation inspection · QII by an ECC-Rater only where the energy report requires it
Keep the insulation bags or labels on site until the inspection; the inspector may ask for them. The attic insulation is checked later, once it’s blown in.
The ceiling goes up first, so the wall board can hold its edges up later. Sheets run across the joists, with the end joints staggered, and are screwed to every joist. Ceilings often get ⅝ in board, which sags less over time.
≈half a day · Screws about 12 in apart on ceilings, as the code’s fastener table and the plans require
Parts: ≈6–7 sheets × Ceiling drywall, ⅝ in, 4×12 sheet; 12 in apart × Drywall screws
Some crews use ½ in sag-resistant ceiling board instead; the plans say which.
Wall sheets go on sideways, top row first, pushed up tight under the ceiling. Every sheet is cut around the windows, the door and each electrical box, and the joints in the two rows are staggered so they never line up. Then the window openings are lined with board too.
≈1 day · Screws about 16 in apart on walls, within the code’s maximum fastener spacing · heads just below the surface, paper not torn
Parts: ≈11 sheets × Wall drywall, ½ in, 4×12 sheet; 16 in apart × Drywall screws
Joints are kept away from the corners of windows and doors where the plans allow, because joints there are the first to crack. Wet areas get moisture-resistant board.
Before any taping, the inspector checks the board: the right type in the right places, and the screws or nails at the spacing the plans and code call for. Many Los Angeles–area building departments require this inspection to pass before any tape or mud goes on; your permit’s inspection card says when.
Inspection visit ≈1 hour · Drywall nailing / fastening inspection · before any tape or mud
Up in the attic, baffles go in at the eaves first, so the roof vents stay open. Then loose-fill insulation is blown in over the ceiling to an even depth, checked on rulers stapled to the joists. For about R-38, the bag chart usually calls for roughly a foot or more, depending on the material.
≈half a day · About R-38 in most of SoCal (R-30 in some coastal zones) · depth and bag count from the bag chart
Parts: ≈20–30 × Attic vent baffle at the eaves; a few × Attic depth ruler; per the bag chart × Blown-in attic insulation
The installer posts a signed insulation certificate in the attic, with the R-value, depth and number of bags.
Every joint gets a thin coat of mud with paper tape pressed into it, including the inside corners and where the walls meet the ceiling. The outside corners at the window returns get metal or vinyl corner bead. The screw heads get their first coat too.
≈1 day, then dry · Tape coat, then about a day to dry, longer in cool or damp weather
Parts: 1 roll × Paper joint tape bedded in mud; ≈6 × 8 ft × Corner bead on outside corners
Each coat goes on wider and thinner than the one before, feathered out so the joints disappear. The screw heads get covered again with each coat.
≈2–3 days with drying · Three coats for a smooth (Level 4) finish under flat or eggshell paint
Parts: 2 more coats × Joint compound (mud) coats
A Level 5 finish adds a thin skim coat over the whole wall, for glossy paint or strong side light.
Dings, dents and any missed spots get patched. Once it’s dry, everything is sanded smooth with a pole sander, then checked with a work light held flat against the wall, which shows every ridge and dip.
≈1 day · Fine sanding sponge or 120–150 grit screen · dust contained and vacuumed
Parts: as needed × Patched dings and holes; 1 × Pole sander
Over-sanding scuffs the paper face; it then needs a skim coat. The room is cleaned before any primer goes on.
Drywall primer seals the mud and the paper so the paint dries evenly. Then two finish coats, ceiling first, then the walls. In Southern California, paints and primers sold must meet low-VOC limits (CALGreen and the South Coast air district’s Rule 1113), which means less odor than older paints. Keep the room ventilated while it dries.
≈2 days · Primer + 2 coats · low-VOC under CALGreen and the South Coast air district
Parts: ≈2 gal × Drywall primer; ≈4 gal × Finish paint, low-VOC
Flat paint hides small flaws on ceilings. Eggshell cleans more easily on walls. Satin and gloss need a Level 5 finish.
That’s a finished room: sealed against air leaks, insulated in the walls and attic, drywalled, taped, sanded and painted, and inspected where the code requires it.