You can apply Earthaus plaster over drywall — in fact, drywall is the most common substrate for Earthaus plasters and works well when properly prepared.
The Short Answer
Earthaus plasters apply directly over standard drywall (sheetrock/gypsum board) with proper priming. The wall must be finished to a Level 4 drywall standard (all joints taped, mudded, and sanded smooth) and primed with a water-based latex primer mixed with Earthaus Primer Grit.
This applies to all Earthaus interior plaster finishes: Tadelakt (non-shower), Marble, Stone, and Sand.
Surface Preparation: New/Unpainted Drywall
Requirements:
Drywall must be finished to Level 4 (joints taped, 2–3 coats of mud, sanded smooth)
Surface must be clean, dry, and dust-free
No exposed paper tears or scuffed areas (repair these first with joint compound)
Priming:
Apply one coat of water-based latex primer mixed with Earthaus Primer Grit (1 cup per gallon of primer).
Allow to dry completely (typically 2–4 hours depending on conditions).
Check the surface — it should feel uniformly gritty/sandy to the touch.
Why Primer Grit is required: Drywall is smooth and has variable suction (the paper face absorbs differently than mudded joints). Primer Grit creates a uniform mechanical key that:
Gives the plaster something to grip
Equalizes suction so plaster dries evenly
Prevents delamination or patchy color
Surface Preparation: Previously Painted Drywall
You can plaster over paint — with extra steps.
Requirements:
Paint must be well-adhered (no peeling, flaking, or bubbling)
Surface must be clean and free of grease, dust, or soap residue
Glossy or semi-gloss paint is OK — the new coat of Grit-loaded primer goes over it; just make sure the primer you apply is itself flat/matte, not glossy
Priming:
Apply one coat of water-based latex primer mixed with Earthaus Primer Grit.
If the existing paint is glossy, a light scuff-sand before priming improves results but isn't strictly required.
What about multiple layers of old paint? As long as the paint is firmly adhered to the wall and not delaminating, multiple layers are fine. The Primer Grit bond is to the outermost surface.
Surface Preparation: Textured Drywall (Orange Peel, Knockdown, etc.)
Plaster can go over textured walls, but texture may telegraph through thin finishes.
Light texture (orange peel, light knockdown):
Can often be covered with an extra coat of Stone Plaster or Sand Plaster as a leveling base
Prime with Primer Grit as normal
Heavy texture (deep knockdown, popcorn, swirl):
Skim flat with joint compound first.
Sand smooth, then prime with Primer Grit.
Alternatively, heavy textures can be scraped/sanded down before priming.
Why this matters: Earthaus finish plasters are applied very thin (1–2 mm). Underlying texture will show through as ridges or unevenness in the final surface.
Level 5 Drywall — Is It Needed?
Level 5 is not needed. Level 4 is sufficient for all Earthaus plasters. Level 5 (a skim coat over the entire surface) is unnecessary because the plaster itself acts as the final decorative layer.
Which Plasters Work on Drywall?
All interior Earthaus finishes work on properly prepared drywall:
Special note: Limewash on drywall. Limewash does not use Primer Grit. Instead, drywall for limewash should be primed with a flat/matte latex primer only (no grit). Limewash needs a slightly absorbent surface, not a textured one.
Common Mistakes
Skipping Primer Grit: Plaster may not bond properly and can delaminate
Not letting primer dry: Applying plaster over wet primer causes adhesion failure
Using oil-based primer: Only water-based/latex primers are compatible with Primer Grit
Ignoring texture: Heavy texture telegraphs through thin plaster layers
What About Moisture and Bathrooms?
For dry bathrooms (walls not in direct water contact): standard drywall with Primer Grit prep works fine.
For shower walls or wet areas: do NOT use standard drywall. Shower installations require cement board or equivalent with a waterproof membrane, and must follow the Earthaus Tadelakt Shower System.
Questions?
Email support@earthausplaster.com or text 1-800-917-2414 — our team is happy to help.