GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Garage overhang

lizbone2000 | Posted in Green Building Techniques on

I am building a 30 ft overhang with a metal roof over garage door and side door. I am using a 2x6s to secure bottom ledger into the header of the garage door, but there are only 2×4 s for the top ledger. I plan to run some 2×6 inside the garage vertically so the top ledger can sink into more than 2x4s. There will be 24 rafters 18Lx24wx30 and metal roof on top, I’m guessing weight will only be around 300 pounds. I will also have 3 support corbels. Is there any more structural work I need to do? 
Working on this with my dad who is really nervous about the weight of this overhang and sagging. Any advice would be fantastic! Photo is what I hope it will look like!

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. Expert Member
    MALCOLM TAYLOR | | #1

    Lizbone2000,

    I understand where you want to get to, but I get lost when you describe the various ledgers, 2"x6"s etc. What are the corbels supporting, and where are they? What is 18Lx24Wx30? A section would help immensely.

  2. lizbone2000 | | #2

    Tried to draw a picture. Let me know if it helps.

    1. Expert Member
      MALCOLM TAYLOR | | #7

      Thanks for the section. As you say, there isn't much to this. I'd use GRK RSS structural screws to attach the top ledger. Anything works for the bottom one which has n0 loading to speak of. I wouldn't get too worried about the connection between the rafters and top ledger either. The plywood sheathing will act as a diaphragm and hold it together.

      There isn't much point in adding more studs to the wall for more attachment p0ints. The connection to the existing 2"x4"s is fine, however you may want to make sure the studs are well fastened at the top and bottom, as they weren't anticipating horizontal loading. If they are particularly high you may want to double up some of them.

  3. user-36575 | | #3

    Thanks for sketching a picture. "A picture is worth a thousand words" underestimates a picture's value. I don't know who said it originally, but my dad used to say that if you couldn't sketch it, you probably couldn't build it. Sketching is certainly a valuable tool to help clarify thinking and communicate ideas.

  4. maine_tyler | | #4

    Consider that the top half of the structure will generally be in tension—pulling away from the garage—and the bottom half will be in compression. And all of it will experience shear.

    So you need some way to 'tie' the top back into the main structure. That usually goes beyond simply screwing/nailing the rafters into a ledger. I imagine techniques not dissimilar to those used to positively attach decks to houses might be useful. A positive attachment of the ledger with plywood nailed over it will help, or maybe a direct connection to the rafters; something like these tension ties: https://www.fastenersplus.com/Simpson-DTT2Z-SDS2-5-Deck-Tension-Tie-W-2-5-SDS-Screws-ZMAX-Finish?gclid=CjwKCAjw_qb3BRAVEiwAvwq6VhMMCBAo9uwK4gPFvBV9DuddKD49kdKL1gNp-KtkCfxHB5dB1b15CxoCjy8QAvD_BwE

    1. lizbone2000 | | #5

      Thanks, I did plan to use rafter fasteners to tie the rafters to the ledger board. And then lag bolt the ledger board into the wall’s 2x4’s. And we were also going to screw boards to the inside garage wall for the ledger to bolt into as well.

      1. Expert Member
        BILL WICHERS | | #8

        You don’t need extra boards on the inside wall, the studs will be fine. If you’re going to be spanning 3 overhead garage doors like that pic you posted, and your awning will weigh around 300 pounds or so (it’ll probably be more than that), you get 300 pounds distributed over at least around 24 feet. That’s only 12.5 pounds per foot, or a little shy of 17 pounds of additional load per stud along that wall. That’s really not very much.

        Just make sure to use suitable STRUCTURAL screws (not regular construction screws, there is a difference) to attach everything to that wall and you should be ok. The comments about making sure the studs in that wall are securely fastened at the top and bottom is good too. If you have any doubts, Simpson makes angle brackets that can be added to beef up those connections without disassembling the wall framing.

        I’m assuming you’ll be using lag-type screw fasteners here too. That’s good. Some people are tempted to use carriage bolts and fasten all the way through with a nut and washer on the far side, which is not always actually a stronger connection. Such a connection makes localized compressive loads on the wood and is often more prone to failure than a lag screw. You would also need unusually strong washers in such a connection (look at pole hardware on a utility pole to get an idea of what is involved since that’s how they’re done). Best to stick with structural lag screws here.

        Bill

        1. lizbone2000 | | #9

          Thanks, how about how far should the lag screws go into the 2x4s, how long should they be? Thanks!

          1. Expert Member
            BILL WICHERS | | #10

            You need to go through everything that is “in the way” until you get to the supporting structure, in this case the studs in the existing wall. Once you’re into that stud, you need to reach the minimum embedment specified for the fastener you’re using. This will probably be AT LEAST 1-1/2”, but check the specs for whatever fastener you’re using. It’s better to go in farther than required than it is to be a little short, so when in doubt, go long.

            Bill

  5. Zdesign | | #6

    If your bottom ledger is tieing into the OHD header you're off to a good start. The upper ledger should be one size above your rafter material, i.e. if your rafter top chord is 2x4 your ledger should be 2x6 due to the angle cut. With a 2x6 top ledger you can get 2 structural screws into each wall stud. I personally recommend Fastenmaster Flat Headloks over Simpson or GRK structural screws. Don't send any framing through the sheathing/WRB its unnecessary. The weight of the structure is actually quite minimal when you break it down into trib loading areas and run calculations.

  6. walta100 | | #11

    Did I miss it but how much support you need is driven by how much weight the roof needs to hold up. Someone likely to have several feet of snow will need more support than someone that will never see snow.

    Walta

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |