Plasterboard Finish Levels, and Where They Actually Matter

If you have been given a plastering quote that mentions a Level 4 or Level 5 finish and you are not sure what you are choosing between, this is the short version. It matters more than it sounds, because the level determines how flat the wall looks under light, and no amount of good painting fixes stopping that is not up to the job.

What the levels describe

The levels describe how thoroughly the plasterboard joints, fastener heads and corners are stopped and sanded, and how much of the board face is skimmed. They are a New Zealand and Australian standard, and while different plasterers work to slightly different habits, the ladder is consistent.

In plain terms:

• Level 3 is a basic stopped finish. Joints and fasteners are covered, but the surface is not refined. It suits areas that will be covered by a heavy texture, or spaces where appearance does not matter, such as a garage or a storage area.
• Level 4 is the standard finish for most homes. Joints and fasteners are stopped and sanded smooth, and the finish is suitable for flat and low sheen paints in normal lighting. This is what the great majority of residential work is, and it is genuinely fine for most rooms.
• Level 5 adds a skim coat over the entire surface, not just the joints. That makes the whole wall uniform in texture and porosity, which is what stops joints showing through under difficult light or at higher sheen.

The thing that decides it: critical lighting

Critical lighting is light that rakes across a wall at a shallow angle rather than hitting it straight on. It exaggerates any variation in the surface, so a joint that is invisible in normal light stands out as a broad shadow.

You get critical lighting from:

• Large windows or ranchsliders throwing light along an adjacent wall.
• Downlights or wall washers close to a wall.
• Long uninterrupted walls in open-plan areas.
• Stairwells with a high window.

If a wall has any of those and you are using anything above a flat paint, Level 5 is worth the money. If it is a bedroom with a window in the middle of one wall and a light in the ceiling, Level 4 will look perfect.

Sheen makes the same difference

Higher sheen reflects more light and therefore reveals more of the surface. A satin or semi-gloss on a Level 4 wall in a well-lit room will show joints that would never appear under a flat paint. If you want a washable higher-sheen wall in a hallway or kitchen, factor the finish level into that decision rather than treating them separately. Our guide to paint sheen room by room covers the other side of that choice.

Where the money is best spent

Specifying Level 5 through an entire house is usually more than you need. A more sensible approach is to identify the walls that genuinely have critical lighting, often the main living space and a stairwell, and specify the higher level there while using Level 4 elsewhere. Say which walls when you ask for a quote, so the pricing reflects it.

Sealing matters as much as stopping

Even a well-stopped wall will show joints if it is not sealed properly, because the stopping compound and the paper face of the board absorb paint at different rates. That difference shows as a variation in sheen, which reads as a visible joint even though the surface is flat.

A proper sealer coat over the whole wall evens out the porosity. Skipping it, or using a thinned topcoat instead, is a common cause of joints appearing on an otherwise good job.

Repairs and older homes

Much of the plastering we do in Wellington is repair rather than new work: patching after a leak, making good where wallpaper has come off, repairing cracked or sagging ceilings, and skimming over old lath and plaster or textured surfaces to get a flat modern finish. Matching an existing surface is its own skill, and a patch that is technically sound can still be obvious if the surrounding texture has not been considered.

Talking it through

If you are unsure which walls need what, we will walk through the rooms and tell you where the higher finish earns its cost and where it does not. Get in touch, or read more about our plastering services in Wellington.