Portico designs

[caswell239]

Looking to build a portico type roof over the entrance.

Something like this but not a big. How do you do you design it to have no collar ties accords the bottom but still have the ability to handle a snow load.


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[captaindiode]

With no rafter ties (ceiling joists) you have to have a structural ridge beam . The beam carries the roof weight and prevents the bottoms from spreading apart. The beam must be carried on posts on either end which is why there is the center post in the picture you show. I do not know of a way to eliminate the tie across the end which carries the load out to the outside posts since the center post cannot extend to the foundation. The top plate shown below is replaced by the side beams in your design.

 

[caswell239]

Awesome that’s kind of what I thought. I’m fine with the end ties like that.


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[captaindiode]

If you look near the bottom of these tables there are span tables for southern yellow pine ridge beams.
Southern yellow pine is a specific type of lumber, normal framing lumber like studs are often a much softer type of pine that is not nearly as strong. You could also use a laminated beam and the lumber yard should be able to put in contact with someone to properly size it. Just be aware it is a structural ridge BEAM, not a regular ridge board, which only serves to make it easier to install the rafters; a ridge board is not designed to carry the roof load.

http://www.southernpine.com/span-tables/headers-beams-size-selection-tables/

 

[readhead]

You can use a steel bent on the gable end to carry the ridge. It can be concealed in the roof framing. No rafter tie needed.