Better design with truss 2 feet deep or more depending on snow load.
How to support 20 foot roof.
Multiplied by 40 pounds per square foot equals 8 000 pounds.
For larger porches such as wrap around porches you will want to make sure that the support is more than you need.
By roof beam i assume you mean the beam will be carrying the load of the roof free span for 20.
Multiply the load per square foot by the total area of the roof.
Minimum roof loading is 20 lb sq.
Three 2x10 s or 12 s is not enough.
You need an engineered glu lam 5 1 4 wide and 24 tall.
Almost any wood will do the same geometry of beam or truss is the important thing.
If smaller beam will sag ugly.
If an example roof is 10 feet by 20 feet the total area is 200 square feet.
From photos i have it looks like single 4x6 not lvl that angles with the roof.
The other is just used to support the trusses.
Feet more in presence of snow.
Large 8 x 8 posts are necessary for the use of supporting a porch roof.
This is where a high pitched roof is necessary.
The larger the roof is the more support that you are going to need.
Once again a 2 by 4 inch piece of lumber is placed between the trusses and parallel to the ceiling joists.
A truss joist wood i beam is not enough.
The distance inside the house from peak to outside wall is 25 7 6m and the beam spans 19 5 6m wall to wall.
A higher pitched roof would be better for extra living space than a lower pitched roof.
This number represents the total load that your roof must carry.