Cantilevered Balcony

Balcony is about 8 x 5, cantilevered but no posts. Is this OK?


I’d recommend verifying that the engineered prints allowed that cantilever.

It also looks like they ran a little short on the ledger board flashing on the left under there.

Thanks Larry, :cool:

I’m not used to seeing a balcony without support posts, but thought this might be ok since the balcony size is relatively small. How can some get access to the engineered prints to see if this acceptable?

One could ask the homeowner if he has a set or check at the Bureau of Construction Codes (AHJ) locally as stamped prints are filed with the permit application and paperwork.

Where i live, the local authority that issues building permits would be who to ask.
Somebody is going to come on here soon and ask for more pics, and more info. :stuck_out_tongue:
Is that snow on there? That would be annoying when it starts to melt.

I built a deck like that once but kept it narrow at 4 X 8 feet on cantilevered 2X10’s. Waterproof deck with a slight outward slope. That has been good for 19 years now.

John Kogel

The backspan should be 2:1 or 3:1. Info here

Cantilevered balconies and decks are quite common out here.

Yes, so do we. I think the species, span, spacing and loading are in question here.

Whatever it is, it goes way beyond the prescriptive IRC, which means it comes under the IBC, and yes, definitely, it should have been engineered, The 2:1 and 3:1 backspan rules of thumb are just that…rules of thumb. If the backspan is less, again, it must be engimeered, and will likely require careful attention to uplift at the inboard end of the joists.

We don’t have many cantilevered joists out here, but when I do run into one… I wouldn’t even bother requesting my client to obtain prints for this install unless I observed obvious defects. I simply note that the interior length of the cantilevered floor joists can not be viewed.

If prints are available, a typical cantilever joist should not exceed 1/3 of the total joist length.

Note that you can’t confirm proper engineering visually, that engineering would be required for safe construction, CYA by “recommending examination by” or suggesting they “consider examination by” a structural engineer.
Then walk out there and bounce around a little. If it feels squirrely, tell them that the degree of movement when tested indicates that it may not have been engineered and “recommend” the SI. If it feel pretty solid (and any cantelever of that length is going to bounce some) you might use “consider”.
At any rate. pass on the liability by stating that you can’t confirm it’s safety and putting the onus on the client.

I agree with Kenton. Since there is usually no way you can determine the length of the joist inside the house, his wording is good. I personally dislike cantilevered decks for the above reason and for the fact that is virtually impossible for a real moisture seal to take place.

I completely agree with the last 2 posts. Personally, I think cantilevered decks suck. Deck joists are in the weather and have a limited lifespan in the soggy northwest. When they are eventually attacked by the always present and very patient rot fungus, the rot wicks back into the home, and the repair is much more extensive than it would have been with a typical ledger board installation.