Lean-to Porch Roof

[Brian_Weekley]

I have a general question regarding a lean-to roof for a porch:  If you have rafters attached between a ledger on the wall of a house and the other end sitting on a beam along the front of the porch, is there any outward thrust to be concerned about?  In other words, are there any ties needed between the beam and the house or any ties needed along the bottom of the rafters?  Does it depend on span and pitch?  Most examples I see do not have any ties.  Just trying to understand any forces involved.  Thanks.

Just a simple example sketch below:

[doc henderson]

if the ledger is well secured and does not move, and the house does not lean, i think you are good.  if a rafter sagged it would pull the wall in, in an open truss it would try to push it out so you need to tie the walls together.  if the ends are closed in, that stiffens the ends up.  however, a triangle is always a good thing.  if there is a long span, and you want to support the rafter mid span, then a tie could support more framework to truss up the span.  others will chime in.

[Don P]

Well said.
When the ridge and eave are supported, the toggle that creates the thrust goes away.
You could look at this more like a deck, with the same kinds of ledger connections.

[Brian_Weekley]

Thanks Doc and Don.

The reason for my inquiry is that I was looking at a friend's porch and we were discussing if the lower 2x4 ties could be removed (see below).  They're hoping to finish the porch interior with a more open look.  The rafters are nailed to the ledger--not sitting on top as I presented in my original sketch.  Considering the 2x6 rafters are 24" OC with only an 8' span between the house and the front of the porch, is there any practical reason why those lower 2x4 ties would need to stay?  I was thinking it might be a good idea to add hangers/straps at both ends if there are none there.  Thanks for any perspective you're willing to provide.

[Don P]

Yes, they can go away. Make certain there is a good ledger connection to the wall. Watch for electric in the wall if you add ledgerlocks. It would be a good idea to put hangers on the rafters.  Same for the upper end of the hip. Hurricane ties at the lower ends of the rafters and hip to prevent uplift, then trace down tie from post to beam and post to floor, etc to foundation to complete that uplift load path.

[Brian_Weekley]

Thanks, Don.  I just wanted to make sure I wasn't totally off base when I suggested he might be able to remove them.

[Mike W]

x2 on what Don mentioned, use hangers at the ledger as well as the H1's at the rafter tails for uplift and as mentioned followed down through the foundation.  if i am looking at the last photo correctly looks as if this is a hip style and not a simple lean too as i first thought with gable ends.  the header running back to the house for the hip rafter tails are more then enough to lock everything together, that is if i am seeing the photo correctly, either way i wouldn't fret over removing those lower cords, they are not really doing much at this point anyway unless they were initially planning on closing in the soffet at that level, but you mentioned wanting to open the area up.  cheers

[Brian_Weekley]

My friend removed the lower cords from the porch roof and it looks so much better!  He'll be adding the hangers/ties as recommended.  I suspect the contractor added the lower cords to attach a ceiling.  However, since they were located so low--right at the top of the door/window, it would have looked awful and claustrophobic.  Thanks again for the feedback.