Flat roof addition question.

[Indietim79]

Would love some advice on this! I'm extending my porch out 5 feet and now have a span of 11 feet. My roof is essentially considered flat/little slope. The 2x4's that did hold my roof will no longer be sufficient. Will rough cut oak beams 2x10.5's evey 24" be enough to support the roof, I live in central Pennsylvania. I can sit the beams on header for 3.5 inches but then they hit the roof. I will have to us hangers for the rest of the weight, what kind would be sufficient to hold them? Thanks!

 

[chopnhack]

Would love some advice on this! I'm extending my porch out 5 feet and now have a span of 11 feet. My roof is essentially considered flat/little slope. The 2x4's that did hold my roof will no longer be sufficient. Will rough cut oak beams 2x10.5's evey 24" be enough to support the roof, I live in central Pennsylvania. I can sit the beams on header for 3.5 inches but then they hit the roof. I will have to us hangers for the rest of the weight, what kind would be sufficient to hold them? Thanks!

Hey Tim, couple of questions:

When you say 'now have 11'' are you saying that is after the 5' addition or that you currently have 11' and are adding five more to it?
When you say you can sit the beams on the header for '3.5 inches but then they hit the roof' - to clarify, there is 3.5" of existing space since that is where the 2x4's are currently sitting on the header?

Assuming that the roof is an extension from the main home, you won't be able to 'sneak' in those oak beams without cutting back into the existing roof, the reason for that is you need the height to place those new taller oak beams on top of the header. Hanging the beams from the header will not likely work since you will now introduce a rotation force on that load bearing wall that it probably was not designed for. Assuming again that this is a total span of 11', you could double up 2x4's with 1/2" plywood in between - a common header construction practice. Assemble with construction adhesive and construction screws. That should be ample stiff to carry your snow loads in PA. As for hangers and spacing, you should consult two resources for this: simpson strong tie for appropriate hanger sizes and a span table. If this is to be inspected, you will have to consult with an engineer to get approval. The aforementioned sandwich is off the cuff but should work and to be conservative, frame it 12"o.c.

 

[Indietim79]

Hey Tim, couple of questions:

When you say 'now have 11'' are you saying that is after the 5' addition or that you currently have 11' and are adding five more to it?
When you say you can sit the beams on the header for '3.5 inches but then they hit the roof' - to clarify, there is 3.5" of existing space since that is where the 2x4's are currently sitting on the header?

Assuming that the roof is an extension from the main home, you won't be able to 'sneak' in those oak beams without cutting back into the existing roof, the reason for that is you need the height to place those new taller oak beams on top of the header. Hanging the beams from the header will not likely work since you will now introduce a rotation force on that load bearing wall that it probably was not designed for. Assuming again that this is a total span of 11', you could double up 2x4's with 1/2" plywood in between - a common header construction practice. Assemble with construction adhesive and construction screws. That should be ample stiff to carry your snow loads in PA. As for hangers and spacing, you should consult two resources for this: simpson strong tie for appropriate hanger sizes and a span table. If this is to be inspected, you will have to consult with an engineer to get approval. The aforementioned sandwich is off the cuff but should work and to be conservative, frame it 12"o.c.

Thank you so much for replying! Yes, I'm now spanning 11 feet. Here is a pic to kinda give you an idea of what I'm working with. The interior wall is brick and now has a 2x4 wall with 2 2x6 header covering it, did not want exposed brick. The exterior wall is 2x4 with2x6 header. I've already got the 2x4's, they were just to get the roof on. If I use the 2x4 sandwich how do I nail it and what kind of nails to use. I like my oak beam idea but I am worried about the weight too. I want to attach a drywall for a ceiling as well, so there is more weight. Thoughts?

 

[chopnhack]

Thank you so much for replying! Yes, I'm now spanning 11 feet. Here is a pic to kinda give you an idea of what I'm working with. The interior wall is brick and now has a 2x4 wall with 2 2x6 header covering it, did not want exposed brick. The exterior wall is 2x4 with2x6 header. I've already got the 2x4's, they were just to get the roof on. If I use the 2x4 sandwich how do I nail it and what kind of nails to use. I like my oak beam idea but I am worried about the weight too. I want to attach a drywall for a ceiling as well, so there is more weight. Thoughts?

Sorry for the long delay, I don't get into this email often enough!

Ok, Tim I looked at the photo and don't understand what the 2x6 is doing nailed flat under the rafters? I did notice that the existing rafters have already been tripled up. I assume this was done during some type of renovation since they are not original, but there are spray marks on them from either when drywall or painting was done.

Can you draw up a sketch of the existing floor plan and then another sketch with what you propose? Any other pictures will be helpful too.

As for nails, 10d or 12d are fine for constructing the headers.

nailing pattern should be in a W fashion from both sides, but don't split the wood

Are you leaving the exterior wall and just extending the overhang outside to create a carport or are you adding space under roof?