A hairline crack (less than 1/8 inch) is usually fine. If you can fit a coin or a finger into the crack, it needs professional attention.

A vertical crack runs straight up and down (or nearly straight, within about 30 degrees of vertical). You’ll most often find them in drywall, plaster, or concrete foundation walls. Unlike horizontal cracks, which usually signal severe hydrostatic pressure from the outside soil, vertical cracks are typically the result of the house "settling" or materials shrinking. 2. Common Causes

If a crack appears perfectly straight and follows a seam, it’s likely just the drywall tape pulling away due to poor installation or humidity. 3. How to Tell if It’s Serious

While most vertical cracks are cosmetic, you should look for these "red flags" that suggest a structural issue:

That night, you dreamed of the house before you were born. An empty lot. A single tree. A woman in a long coat digging a trench with her bare hands. She wasn’t burying anything. She was opening something. When she turned to look at you, her face was your mother’s, then yours, then a face you would wear in twenty years—older, wearier, with vertical lines etched beside your mouth like parentheses holding a secret too heavy to speak.

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