For this type of attached pergola, proper mounting and support are critical. The two end assemblies feature stout timber screws that lock the components together and also secure them firmly to the wall by means of a vertical 2x2 cleat. It’s essential that the mounting screws attach to the wall framing itself and not to the surface trim of the siding. Because of its lightweight and strong weather resistance, Western red cedar makes a good choice for this attached pergola. A pair of 2x4 crossbeams can safely span 8 feet, but check your local building codes. Wider spans will require increasing the crossbeam size to 2x6 or 2x8 lumber.
