The short answer is: it depends, but generally, it's much safer than being fully exposed. While a roof protects from direct sun and rain, it doesn't create a fully weatherproof environment. Here’s what you need to consider for your upholstered pieces under a cover.
First, check the furniture's fabric rating. Look for solution-dyed acrylic or polyester fabrics labeled as "all-weather," "outdoor," or "mildew-resistant." These are essential. Even under a roof, humidity, morning dew, and wind-driven mist can reach your furniture, making moisture resistance critical.
A roof doesn't shield from all moisture. In humid climates, cushions can trap dampness, leading to mold and mildew. Dust, pollen, and bird droppings can also accumulate. For long-term protection, using waterproof furniture covers when the furniture is not in use is highly recommended, or store cushions indoors during extended wet seasons.
Regular maintenance is key. Frequently fluff and rotate cushions to promote air circulation and even wear. Clean spills promptly and follow the manufacturer's cleaning instructions. Periodically check the furniture frame for any signs of rust or corrosion, especially on metal parts.
In conclusion, yes, you can leave upholstered outdoor furniture under a roof, but it requires the right materials and proactive care. Choose high-performance outdoor fabrics, use protective covers during inclement weather, and maintain a consistent cleaning routine to ensure your investment lasts for many seasons.