Renovation guides

How to prep walls for painting

Quick review by a licensed contractor on Oct 7, 2026. This is not a certification. Follow product labels where they differ.

Without primer, paint dries blotchy.

Difficulty 1 of 5 · about half a day · you can do this

Photo of your room, the look you pick, then this guide with the materials counted for your room.

Step by step

1. Step 1 of 14

   Clear the room or pull furniture to the center

   

   Move everything out, or push it to the middle of the room and cover it.

2. Step 2 of 14

   Cover the floor

   

   Cover the floor with rosin paper or drop cloths, taped at the edges.

3. Step 3 of 14

   Remove outlet and switch covers

   

   Take off every cover plate and label each one with tape so it goes back in the same spot.

4. Step 4 of 14

   Tape the edges

   

   Tape the top edge of the baseboard and the door and window casing.

5. Step 5 of 14

   Inspect the walls with a flashlight held at an angle

   

   Hold the light sideways against the wall. Nail holes, dents, and cracks jump out in raking light. Glossy old paint? Rub it with a cotton ball and rubbing alcohol: if paint comes off, it is latex; if not, it is likely oil — scuff-sand and use a bonding primer before latex.

6. Step 6 of 14

   Spackle the holes, let dry, sand flush

   

   Built before 1978? Test the old paint first. If it has lead, do not dry-sand or scrape it — mist and wet-sand only the patch, or hire an RRP-certified painter. Fill every hole and dent. Let it dry per the tub (lightweight spackle: often 1–2 hours for shallow holes); fill deep holes twice. Then sand flush. Run your palm over it: you should not feel the patch.

   Before you sand

   • Building is from 1978 or later, OR a lead test (EPA-recognized kit) on this paint is negative, OR you only sand the spackle, not the old paint around it

7. Step 7 of 14

   Wipe the walls with a damp rag

   

   Get the sanding dust off. Dust under paint is a rough wall forever.

8. Step 8 of 14

   Kitchen or bath: degrease the walls

   

   Kitchen or bath walls: wash with a degreaser, rinse with clean water, and let dry. Paint does not stick to grease.

9. Step 9 of 14

   Caulk open joints at the trim

   

   Caulk open joints between trim and wall with paintable caulk, smooth it with a wet finger, and let it dry the paint-ready time on the tube.

10. Step 10 of 14

    Seal stains with a stain-blocking primer

    

    Water, smoke, or marker stains: once the source is fixed and the spot is dry, seal them with a stain-blocking primer (shellac or oil-based per the label) before any paint. A stain that is still damp or keeps growing is a leak — stop and find it.

    Before you paint

    • Walls feel smooth to the palm
    • Tape is on: baseboard and casing
    • Outlet and switch covers are off
    • Floor is covered
    • Stains sealed with stain-blocking primer, or there are none

11. Step 11 of 14

    No full prime? Spot-prime every patch

    

    No full prime? Spot-prime every patch with a brush, a little past its edge, and let it dry per the can. Priming the whole wall (next steps)? Skip this.

12. Step 12 of 14

    Cut in the corners and edges with a brush

    

    Only for new drywall, a big color change, or glossy paint. Brush a band about 2 inches wide along every corner and edge.

13. Step 13 of 14

    Roll the rest in a W pattern, then even it out vertically

    

    Load the roller, make a W about 3 feet wide, then fill it in and finish with light vertical strokes.

14. Step 14 of 14

    Let the primer dry

    

    Follow the can. Usually 1–2 hours before the first coat of paint.

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