Drywall Finishing
What the Finishing domain tests
Finishing questions target the levels of finish, compound and tape selection, coat sequence, corner treatment, and sanding. You will be asked which level a space requires, why a tape coat failed, or how wide a coat must be.
Levels of finish (GA-214)
- Level 1: joints taped only - concealed plenums and fire-rated cavities.
- Level 2: tape plus one coat - garages, above ceilings, surfaces receiving heavy texture.
- Level 3: tape plus two coats - walls getting medium or heavy texture.
- Level 4: tape plus three coats - the standard for flat-painted walls and ceilings.
- Level 5: three coats plus a thin skim coat over the entire surface - gloss paint, strong colors, and critical side-lighting.
Coat sequence and materials
- Tape coat: setting-type or all-purpose compound; embed paper tape and wipe it tight. Paper tape outperforms mesh on flat joints; mesh is acceptable for small repairs.
- Fill coat: tighten the joint and fill screw dimples.
- Finish coat: widen and feather. Butt joints finish roughly 10–12 in. wide, each coat extending about 2 in. per side beyond the previous one.
- Sand the final coat with 120–150 grit and light pressure.
Worked example
A butt joint is taped with a 5 in. knife. The fill coat should reach about 8 in. and the finish coat 10–12 in., with each coat overlapping the last. Jumping straight from a 5 in. tape coat to a 12 in. finish coat leaves a ridge at the 5 in. line, because there is no intermediate taper to blend the thickness down. Under raking light that ridge casts a shadow and the wall fails inspection even though the joint is filled.
Traps that cost marks
- Sanding through face paper - the fuzz telegraphs through paint.
- Using lightweight topping compound as a tape coat; it lacks bonding strength.
- Recoating setting compound before it hardens, trapping shrinkage cracks.
- Installing corner bead out of plumb, leaving a visible wave along the corner.