Reference
Drywall finish levels, 1 to 5
The five levels, what each one is for, and why the choice changes your mud order by a factor of three.
The finish level is a specification, not a quality grade: it states how much joint treatment the surface receives, and therefore what lighting conditions it can be painted under without the joints showing. Most residential work is Level 4.
The two distinctions that decide it
The table above gives what each level covers. Two details are worth separating out, because they are what the level numbers do not tell you.
- Level 3 leaves fasteners and accessories not fully covered. The joints get a second coat, so the wall reads as finished under a heavy texture or forgiving flat paint, but every screw head still shows through a sheen.
- Level 5 is the only level that is a full skim coat, and it is the one to specify wherever gloss, semi-gloss or enamel paint will show the joints, or wherever light rakes across the wall: a stairwell with a window at the end, or a wall washed by an uplighter. It roughly doubles the compound.
Why Level 4 fails under gloss paint
Joint compound and drywall paper absorb paint differently, so they finish with slightly different texture and sheen. Under flat paint that difference is invisible. Under gloss it catches the light, and every joint and fastener shows as a distinct band: a phenomenon called photographing, because it looks like a photograph of an unfinished wall. If you want gloss, you want Level 5, and it is much cheaper to decide that before the mud is ordered than to reskim a painted wall.
What "three coats" means in practice
A coat is not a thick layer. Each coat is applied, allowed to dry, and sanded back, and the sequence is bed coat, fill coat, finish coat, with the compound thinned slightly each time. Attempting to build the thickness in one pass produces shrinkage cracks as it dries, which is why the level is defined by the number of passes rather than by the depth of mud. Which compound goes in which pass is on the drywall mud guide.