What size beam you need to support 8 ft opening?

To determine the appropriate beam size for an 8-foot opening, you need to consider the load it will support, including live loads (like people and furniture) and dead loads (like the weight of the structure itself). Generally, a glulam or engineered wood beam, around 3x10 or 4x10 inches, may suffice for residential applications, but it's essential to consult local building codes and possibly a structural engineer for precise calculations based on specific conditions and materials. Always factor in safety margins to ensure proper support.