Use paintable caulk for cracks along trim, corners, and joints

Apply a bead of paintable acrylic latex caulk along cracks that form where walls meet trim, ceilings, door frames, or window frames. Cut the caulk tube tip at a 45-degree angle to a small opening (about 1/8 inch). Apply a thin, continuous bead along the crack. Immediately smooth the caulk with a wet finger or a damp rag, pressing it into the crack and wiping away the excess. Let it dry for 1-2 hours, then paint over it.

Why It Works

Cracks at joints and transitions (wall-to-ceiling, wall-to-trim, around door and window frames) are caused by seasonal expansion and contraction of building materials. Rigid fillers like spackle and joint compound crack again because they cannot flex. Acrylic latex caulk remains flexible after curing, absorbing movement without splitting open. It bonds well to painted surfaces, wood, and drywall, and accepts paint within a few hours.

Tips

• Use paintable acrylic latex caulk (such as DAP Alex Plus or Big Stretch by Sashco) -- silicone caulk cannot be painted
• Big Stretch caulk is worth the extra cost for wide or active cracks; it stretches up to 500% without tearing
• Cut the tip opening as small as possible; you can always cut more off but cannot make the opening smaller
• Smooth the bead within 2-3 minutes of application before a skin forms
• For inside corners (wall-to-ceiling, wall-to-wall), apply caulk along the full length and smooth in one continuous pass
• Keep a cup of water and paper towels nearby to clean your finger and wipe tools between passes
• A single tube of caulk ($3-7) handles an entire room's worth of trim and corner cracks
• Common mistake: using too much caulk -- a thin, smooth bead disappears under paint, but a thick bead looks like a visible line