On medium size projects one may use a prefab steel structure commonly used for carports and garages. Ask for the Boxed Eave style. If using our Cap & Trim System install blocking as needed. Their typical frame layout is 4 ft., so sheets will need to be trimmed to 47-3/4". If using Base & Cap System simply position purlins as needed. Two mfgs. are Eagle Carports & Carolina Carports. If you like this approach see further details.
On large projects use Base & Cap System. Build frame or see Metal Building & Laminated Timber Mfgs. for pre-engineered frames suitable for greenhouses, pool enclosures, etc.