Painting guide
Older Nashville Homes: What Changes When Repainting Plaster vs. Drywall?
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Plaster is different, and the reason usually given for it is the wrong one. The difficulty is not that plaster is harder to paint; it is that plaster and drywall fail differently, repair differently and take coating differently, so a plan built for one produces surprises on the other.
The first problem is that an older house can contain both, sometimes in the same room, and nobody has told the owner which is which.
How to tell which one you have
Four checks will tell you, and none of them requires a tool you do not already own.
Knock on it. Drywall over studs sounds hollow between the framing and solid on it, in a regular rhythm as you move across the wall. Plaster over lath produces a duller, denser sound with less variation, and often a slight rattle at the lath.
Push a pin in. In an inconspicuous spot, press a pin or a small nail against the wall with steady pressure. It enters drywall with modest force and it will not enter sound plaster at all. This is the fastest single test.
Watch what fasteners do. Look at whatever is already hanging on the wall and at the holes left by whatever used to hang there. A picture hook that went in with a tap, and a hole with clean paper edges, is drywall. Plaster resists the same hook, tends to crumble at the mouth of the hole rather than tearing cleanly, and often leaves a ring of fine gray dust below it. This costs nothing to read because the evidence is already there.
Look at an opening. Where a wall meets a window or a door casing, look at the exposed edge of the wall material. Drywall is a consistent thickness, typically around half an inch, with a paper face. Plaster is usually thicker, and where it has broken away you can sometimes see the lath behind it.
A house can contain both
Do the checks in each room, and in more than one wall per room if the house has been altered, because the answer is not a property of the house.
A single house can have original plaster in the front rooms, drywall in an addition, and patched sections of drywall inside a plaster wall where plumbing or wiring was run at some point. That third case is the least visible and the most likely to produce an unexpected result at painting, because from the surface it looks like the wall around it.
Two things follow if you find both. Preparation and materials planned for one substrate should carry room for finding the other. And in any room containing both, the repairs will not all behave the same way under the finish coat, which is a reason to know where the boundary runs before the finish goes on rather than after.
Why the difference matters for a repaint
Three properties differ, and each one changes the work.
Hardness and surface. Cured plaster is hard, dense, and often very smooth, particularly where the finish coat was well troweled. Drywall has a paper face with a taped and compounded joint system, and the surface is softer and slightly more absorbent. A wall that has never been coated behaves differently between the two, and even a previously painted plaster wall tends to have a harder, less forgiving surface underneath.
Absorbency, particularly at repairs. Patching compound is more absorbent than either painted plaster or painted drywall. A repair that is invisible before painting can reappear as a dull or shiny patch after, because the finish coat sank into the repair differently than into the wall around it. On plaster this is more pronounced, because the contrast between hard, sealed plaster and soft new compound is greater.
How they crack. Drywall cracks at its joints, at the corners of openings, and where fasteners move. Plaster cracks along lath lines, in networks of fine lines where the finish coat has aged, and in longer runs following structural movement. The crack pattern is often the fastest way to identify the material at a distance.
Read those patterns here as identification and nothing more. Which defects actually have to be repaired is a separate question about what is wrong with the wall rather than what it is made of, and it gets answered on its own terms: Nashville Interior Repaints: Which Nail Pops, Cracks, and Patches Need Repair?.
Repairs show differently on each
Of those three differences, absorbency is the one that shows up in the finished room, and it accounts for most of the disappointment in an otherwise good interior repaint.
A repair is a different surface. It absorbs differently, it has a different texture at close range, and unless something evens that out, the finish coat reveals it. The effect is called flashing, and it shows up as a patch of different sheen rather than different color, most visible in raking light across a wall.
Sealing the repair before the finish coat is what prevents it. On drywall this is routine. On plaster it matters more, because the surrounding surface is harder and less absorbent, so the contrast with a soft repair is greater.
Texture is the second half. A troweled plaster finish and a compound repair rarely have the same surface texture, and texture is visible under directional light even when color and sheen match perfectly. On a wall with any significant original texture, matching it in a repair is skilled work, and a repair that is flat against a textured wall shows regardless of how well it is painted.
An old plaster wall carries something else as well, and it sits on top rather than underneath.
Before you sand anything
If the house predates 1978, settle the lead-safe question before preparation starts. Sanding a plaster wall to knock back an old finish, sanding repairs and scraping loose coating all take material off a painted surface, which on a house of that age brings a federal lead-safe requirement into the picture, so establish it with Painting a Pre-1978 Nashville Home: When EPA Lead-Safe Rules May Apply first. Older plaster walls carry the oldest coatings in the house, and that is exactly where this is most likely to be live.
What this changes about your plan
Four things change, and all four are worth writing down before anything is bought.
Preparation time. A plaster wall in an older house has usually been painted many times, and older interior work was frequently oil-based. An aged oil film is hard, often slightly glossy, and less receptive to a new coating than a modern interior finish, so a waterborne coat put directly over one can lose adhesion well after the work is finished. Where such a film is sound, the usual approach is to dull the surface and use a primer suited to bonding over it; where it is failing, more removal is involved, and on a pre-1978 wall that is where the lead question stops being peripheral. All of that is time rather than product.
Repair method. A crack in plaster and a crack in drywall do not want the same treatment, and the difference comes from the material rather than from the crack. Knowing which wall you are standing in front of is what settles the method.
Sealing repairs. This is not optional on either substrate if you want a uniform finish, and it matters more on plaster, where the contrast between the hard wall and the soft repair is greater. Ceilings raise the same point more sharply, because they are lit more evenly than walls and show surface irregularity more readily.
Expectations about flatness. An old plaster wall is rarely flat, and paint does not make it so. Light across an undulating wall shows the undulation. That is a characteristic of the house rather than a defect in the work, and it is worth deciding in advance whether it bothers you, because the alternative is a skim coat across the whole surface, which is a substantially larger project.
Where the wall is currently covered in wallpaper, the substrate question and the removal question interact, and the removal comes first, because what is behind the paper decides both how the paper comes off and what condition you inherit when it does. Paper stripped from plaster and paper stripped from drywall are two different jobs with two different risks, and neither of them can be assessed while the paper is still on the wall.
Source. Sherwin-Williams’ problem-solver article on peeling from plaster, opened 10 September 2026: https://www.sherwin-williams.com/painting-contractors/products/resources/SW-ARTICLE-PRO-PEELINGPLASTER. It attributes loss of adhesion on plaster to insufficient wet troweling of the original white coat causing surface chalking, to very hard plaster being slick enough to reduce the adhesion of any coating, to new plaster with a high pH needing an alkali-resistant primer, to old plaster that has gone powdery, and to poor surface preparation. Any primer for bonding over an aged film is chosen from that product’s own data rather than from anything here.