What the levels actually describe
Drywall finish levels come from the ASTM C840 and Association of the Wall and Ceiling Industry standard that North American specs lean on. They describe how much compound goes over the joints, fasteners and beads, and how the surface is prepared before paint. They do not describe how flat the wall is, and they do not promise a particular look under a particular light. That gap is where most disputes start.
For a commercial interior you are realistically choosing between Level 4 and Level 5. Levels 0 through 3 exist for temporary construction, plenum spaces above ceilings, and surfaces that will be covered by heavy texture or a rated finish.
Level 4 in plain terms
Level 4 is three coats over tape and beads, sanded smooth, with the fastener heads spotted. It is the default for commercial work and it is what most drywall bids assume unless the spec says otherwise.
- Tape embedded in one coat of compound, then two separate coats over the joint
- Two coats over fasteners and corner beads
- Sanded so the surface is free of ridges and tool marks
- Ready for a flat or matte paint, or for wallcovering
Level 4 works well where lighting is diffuse and the paint has some tooth. Corridors, back of house areas, storage, most offices with standard fixtures. The joint compound covers roughly the width of the taping knife, so under strong side lighting a trained eye can pick out the joints as slightly different in sheen. That is expected behaviour at Level 4, not a defect.
Level 5 in plain terms
Level 5 adds a thin skim coat of compound over the entire surface on top of everything Level 4 requires. The point is to make the whole wall one uniform material so paint dries at one sheen from corner to corner.
- Everything in Level 4
- A skim coat over the full face of the board, not just the joints
- Sanded again after the skim
- Ready for gloss, semi gloss, enamel or a critically lit flat
The skim is what kills joint photographing. It costs more in material and a lot more in labour and drying time, so it belongs where it earns its keep rather than blanketed across a floor plate.
When to spec Level 5
The honest test is lighting and sheen. If either one is aggressive, pay for the skim.
| Condition | Finish level | Why |
|---|---|---|
| Wall grazed by a linear fixture or a window | Level 5 | Side light exaggerates every change in sheen |
| Gloss, semi gloss or enamel paint | Level 5 | Sheen shows the compound outline through flat paint |
| Dark or saturated paint colour | Level 5 | Dark coats hide nothing and read every seam |
| Lobby, boardroom, feature wall | Level 5 | People stand still and look at these surfaces |
| Standard office with lay in fixtures | Level 4 | Diffuse light, no grazing, matte paint |
| Corridors, storage, back of house | Level 4 | Sheen and lighting are both forgiving |
| Above a T-bar ceiling | Level 1 or 2 | Nobody sees it and the spec should say so |
What it does to your budget and your schedule
The skim coat is a whole extra pass over every square foot of wall, plus the sanding and the dust control that goes with it. As a rough planning number, upgrading an area from Level 4 to Level 5 tends to add somewhere in the range of 30 to 60 percent to the finishing portion of the drywall line, and the spread depends far more on ceiling height and access than on area.
Schedule matters just as much. Every coat needs to dry before the next one, and drying is slower in a cold or humid building that is not yet on permanent heat. If Level 5 lands in your critical path in February, the temporary heat cost is part of the finish decision whether or not anyone priced it.
One more thing worth flagging early. Level 5 is a substrate standard, not a paint standard. A skim coat under a single thin coat of paint will still look uneven. Two coats of a quality primer and finish over the skim is what actually delivers the surface the client pictured.
How to write it so it prices cleanly
Ambiguous finish notes get priced defensively, which means either your number is padded or the low bidder is planning to argue later. A tight note is short.
- Name the standard. ASTM C840 and the finish level, not a description in your own words.
- Assign levels by room or by drawing tag, not by a blanket note.
- Say what the light is doing. If a wall is grazed by a fixture, say so on the drawing.
- State the paint sheen in the same note. Finishers price to the sheen, not the paint code.
- Say who supplies temporary heat and light, and when it will be available.
If you send us drawings with that much detail we can price the drywall finishing line without hedging, and the number you get is the number you keep.