Typically the roof beam is made by nailing together a few pieces of dimensional lumber.
Roof rafter and beams.
Collar ties rafter ties tension beams structural ridge beams.
A rafter is one of a series of sloped structural members such as wooden beams that extend from the ridge or hip to the wall plate downslope perimeter or eave and that are designed to support the roof deck and its associated loads.
Rafters form the foundation for attachment of the roof boards onto which the final roof covering is fixed.
An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry.
Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
In traditional timber they are nominally 2 inches thick and typically 8 to 10 inches wide.
Once again you will need to look at your local charts and use your local snow load factor to determine the maximum span for a given wood rafter size.
Is that beam is any large piece of timber or iron long in proportion to its thickness and prepared for use while rafter is one of a series of sloped beams that extend from the ridge or hip to the downslope perimeter or eave designed to support the roof deck and its associated loads or rafter can be a raftsman.
Sample maximum roof beam span table feet inches.
You will need a roof beam as a nailing surface to support the rafters.
The table below shows built up beams for 31 3 psf of snow loading.
This article describes and illustrates the different types of support that prevents roof sagging and wall bulging at buildings including definitions of collar ties rafter ties and structural ridge beams.
Some of these can support the roof and prevent ridge sagging and wall spreading.