Ledger Board Point Load Code Maximums 1

[AlwaysLearning7]

A 2"x12" Ledger carries 15' long joists. Single span with other side bearing against a flush beam. Owner wants to install stairs at the end of the deck so parallel with the house wall, which means the stairs would be attached to the last deck joist/(Rim Boards). Considering the 100psf for stairs-LL what is the maximum load that I can place on this Ledger end? I've considered other solutions (2 to be exact) but I have not found any code describing the maximum load for a ledger especially at the end of the ledger.

 

[driftLimiter]

Depends on how many connectors, the spacing of the connectors, and the suitability of the anchoring structure.

Generally if I have a large point load on a ledger, I will place additional fasteners nearby the load location with sufficient strength to transfer the entire load.

 

[AlwaysLearning7]

Thank you driftLImiter. That's what I was thinking too, but I hesitated. Of course there is a limit to the amount of fasteners I can use before the ledger bd. becomes a swiss cheese. Followup up question... I was looking thru ICC Table R301.5 and the min LL for stairs is 40psf (distributed)/300 point load per stair threads. I always used 100 psf. Any advice on that? This happens to be a residential wooden deck and stairs for it.

 

[jerseyshore]

For residential decks I always use 60 psf LL min (1.5x LL served), thus using 60 psf min on the stairs as well.

If it's just 2x ledger to 2x ridge board, you can easily calculate the capacity of the connection. I do what DL does and add some additional fasteners where a bigger point load comes in if needed. AWC has a great online calculator.

 

[AlwaysLearning7]

Perhaps I should have mentioned where I am from. In NJ, (at least NOT from the Edison Refinery area) I believe the exterior deck load is DL:10, LL:40, SL: dep. on location. In California Code for example, Table 1607.1 Balconies and Decks - 1.5 x the area serves does not have to exceed 100psf. But for 2021 IRC (NJ Edit) it states 40 LL Deck and Stairs. (No mention of the 1.5x multiplier). I agree with using a bit more. Decks are often neglected and exposed to elements, the failure will simply come at a later time. I don’t think overdesigning to 60psf for this area is necessary…....or am I missing something critical?

 

[jerseyshore]

1.5x LL served is from IBC or ASCE7, I forget which. But that's what my office always used and what I continue to use as a minimum today. You can easily get over 40 PSF on a deck and stairs. It's just like roof snow, sure a lot of the state is 20 or 25 PSF by code, but everyone designs for 30 minimum to be safe. No chance I would design anything on a deck for less than 60 psf.

 

[kissymoose]

If I have a beam with a reaction more than 1500# or so I'll support it with a hanger directly attached to the sheathing/wall framing and install the ledger around it. It'll usually be at the end, so just hold back the ledger at the end. And no, I do not have a good flashing detail for this yet.

 

[gte447f]

AlwaysLearning, there is no point load limit on ledger boards in the code (IRC), but I believe it does prohibit girders from framing into ledger boards, so I guess you could interpret that as prohibiting point loads in excess of average joist reaction loads. Of course, that is a prescriptive limitation, and an engineered design can deviate from that prescriptive limitation.

 

[Aesur]

Why not run the calculations and provide an engineered solution instead of trying to rely on the IRC?

 

[jerseyshore]

Does anyone here even use the prescriptive stuff in the IRC for the final designs? Isn't that the point of hiring an engineer?

 

[gte447f]

Why not run the calculations and provide an engineered solution instead of trying to rely on the IRC?

Does anyone here even use the prescriptive stuff in the IRC for the final designs? Isn't that the point of hiring an engineer?

Well, the OP asked if the code places a limit on the magnitude of a point load on a ledger?

 

[phamENG]

When it comes to houses, whenever possible I find it best to stick to the prescriptive rules of the IRC. The IRC is what the plan reviewer expects, the contractor/subcontractors is/are (sort of) accustomed to building, and what the inspector is accustomed to seeing. Any deviation from the "norm" is asking for issues. Of course, we can't always follow it because, as jersey points out, we're the exception. When something doesn't fit, we get to come up with an alternative solution. The thing is, though, that the alternative solution needs to be as good or better (in terms of reliability) than what they would have gotten with a prescriptive build. So if the code says "you can't do this", we can't wave our engineering judgement around and say you can. Even if you feel that a ledger can support the point load with a standard bolt pattern, I think it usually best to not do that.

So....for ledgers, I think it best to treat it like a multi-ply beam. Check out guidance from your favorite LVL manufacturer for flush framed side loads. They give requirements for additional fasteners in the vicinity of the side load to ensure that load is transferred through and carried by all plies of the beam. A similar thing can work here, but be warned: those LVLs are generally assumed to be torsionally stable. In other words, they have sheathing fastened to them or they are held in place by joists sitting on them and fastened and whatever blocking arrangement. Your ledger isn't quite the same. Make sure you're not relying on a bunch of tension perpendicular to the grain to keep this thing in place.