Most guides answer this with two lists of pros and cons and a shrug. In practice your house decides it for you. Here is how your roofline, gutters, windows and door swing determine whether an attached or freestanding pergola is even possible.
An open-slat pergola defines a space beautifully, but on a west-facing patio in July it can still leave you squinting into the late-afternoon sun. The good news is you don’t need to rebuild anything. Adding real shade to a pergola you already have is usually a weekend project, sometimes an afternoon, and the options range from a fabric sail you hang yourself to a motorized canopy that retracts at the touch of a button. Here are the practical ways to take the sting out of the sun, ranked roughly from fastest and simplest to most involved, with notes on what actually works in Northern Virginia.