I’ve got an unfortunate issue, my garage length is 1.5 inches past the free span length for joists.

First, is it acceptable to fasten Double Ledger boards to make the distance work?

Before designing and submitting to the city for permits, how do I attach a double ledger if it’s acceptable architecture? Just lag through to the top plate with standard lag screw and washer?

Note the image isn’t to scale, I’m looking to span 20’

TIAMy span is much longer, at 20’

  • This question is best answered by your city building department. There are experts here who can give you a good answer but still better to check with your local permit folks before you draw up your plans. It could save you time and money.
    – HoneyDo
    Commented Nov 25, 2021 at 18:42
  • Have you bought the joists yet? Different types of wood and/or joist designs might be a solution, if you are going by plain wood joists(usually smallest free span).
    – crip659
    Commented Nov 25, 2021 at 19:25
  • If you are working with 16" centers, you can go to 12" centers to increase the span. You could also use a higher grade of lumber, for example Doug Fir instead of Spruce-Pine-Fir or yellow pine which is really strong but prone to bad warping
    – Jack
    Commented Nov 25, 2021 at 20:15
  • If your illustration is showing the doubled ledger in a clear span, with nothing but the ends holding it up, it is not a ledger but a beam. That may need to be tripled to carry the floor load imposed upon it... But if the ledger you have against the wall is the one in question, there may be no need for that, if you can run the beam straight to the wall the ledger is on with the proper connector, or cut it into the wall for direct bearing
    – Jack
    Commented Nov 25, 2021 at 20:31
  • I suggest you add some further details to the drawing, highlighting existing structural elements (posts, footings ...) , labeling the beam/ledger (A,B etc...), and proposed method of support (hanger, seated, bolted etc..)
    – P2000
    Commented Nov 26, 2021 at 0:22

1 Answer 1


1.5in is a lucky unlucky. Some options:

a) Double-up the ledger. If you through-bolt both pieces of the ledger with the house rim it's considered one ledger, and that buys you the 1.5in.

b) Add another lamination to your beam, on the inside, which will buy you the 1.5in. The added lamination must be supported by a hanger or seated on a post by at least 1in, so you need to ensure that the post is wide enough and properly footed for the additional width.

c) Shorten the design by 1.5in and visually make it match with trim, siding and other finishing.

(The way that beam is drawn, end-fastened to a ledger parallel to the joists is not correct, it must be hung or seated, and if hung, that other ledger that it's hung from needs to seated.)

Your entire design requires careful validation of the existing structure (beams, footings, posts...), since this is not a minor load addition. You should have an engineer approve it.

  • Thanks everyone! The diagram added isn’t really indicative. I’m looking to free-span a double car garage. Joists are going to be KD Doug Fir that let me go to 20’. It’s either that or I’ll have to do engineered wood. This will be full span from wall to wall, and the loft entry on one side.
    – bnewbold
    Commented Nov 26, 2021 at 3:22
  • I don’t understand. Did you resolve this issue by using KD Doug Fir? (What grade?) So the issue was for the joists not the beam?
    – Lee Sam
    Commented Dec 26, 2021 at 6:54

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