Cantilevered Wood Balcony @ Condo

[Jerehmy]

With all the talk about cantilevered wood balconies, I figured I'd post some photos of the balcony at the condo I'm staying at.

Looks to ne that they have 2x12's @ 12" OC inside and cantilevered half of them out for the balcony. Then used 2x12's in between. Cant imagine they carry much moment. Cantilever is about 6ft.

The part I dont like is where they have 7 cantilevered joists that stop at the face of the building. It seems very suspect to me. The connection is just a shear connection (see attached).

 

[Jerehmy]

https://www.dropbox.com/sh/r01lhmvxripwzhd/AABXgKpg7hRXtEWDO1W7gV4Fa?dl=0

rest of photos.

I dont like that bump out where they are cantilevered without continuous wood joists. Its not a moment connection and making a moment connection with wood is hard without steel straps.

 

[KootK]

Making a moment connection in wood with with steel straps is hard. You've basically got about six cantilevered joists either side of the bump out holding up the whole thing, right? At least, if it rots, you'll have a fighting chance of seeing what's going on on the outside. The every other joist business looks kind of neat visually.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Jerehmy]

Haha yeah luckily we won't be loading this to capacity. i never use wood cantilevered in that way, and the only way I could think of is with steel straps. Just doesn't seem you could get a good enough connection to do it with wood.

I'm just curious whose bright idea it was to csntilever those 7 joints in that way at the bump out.

 

[KootK]

You say that now but the lure of the drunken deck family/party photo is soooo strong... apparently. Is there a fireplace or something on the other side of the bump out?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Jerehmy]

vent stacks that go to the roof. 3 of them maybe 18" diameter? hard to tell. can post photo later

 

[CANPRO]

not sure why you think those 7 joists are cantilevered. Looks to me like they're simply supported. There is a header spanning between the joists that flank the bumpout. that header supports the joists along the edge of the house and the other ends are supported by the rim joist at the edge of the deck (the rim joist is supported by the adjacent joists). Whether or not all of these members/connections are properly sized to meet to code is another question.

Reading your questions and answers on previous threads it is clear you're knowledgeable, but thoughts like this "...just curious whose bright idea it was to cantilever those joists..." can overshadow your technical know how. Just because you don't immediately understand how something has come together you shouldn't jump to the conclusion that the other guy must be wrong. Just some friendly advice from one young engineer to another. I have caught myself in the same line of thinking and it is not productive.

 

[Jerehmy]

I agree with what you are saying about the header and jumping to conclusions.

Hmm I overlooked the loadpath in my haste to grab my pitchfork. I'm a little more wary about balconies since the Berkeley incident. Not sure if the single 2x's could handle the extra load from the header.

It was also a "hey heres a balcony at the ocean, hows she look". There are positives. All the joists are exposed so you can see any damage easier. The short pieces seem to be preservative treated. I can't tell if the lonner joists are. The hangars seem to be galvanized. Theres caulking on at the continuous just interface with the blocking.

 

[KootK]

I was hoping that the "header" closest to the building was really just rim board sitting on a bearing wall.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Triangled]

hard to tell from photos.... but, the orientation of the joist hangers at the tip of the balcony suggest the joists are being supported at the end rather than supporting

 

[lsmfse]

The bump-out aside, it looks like the decking was replaced with "IPE" or composite decking which doesn't span as far as 2x. The intermediate joists may have been added to reduce the deck span.

 

[Skeezix]

I think "lsmfse" is right. The intermediate joists look greener than the cantilevered joists and the deck boards look pretty new.

Good to see some white metal flashing along the wall. Better if it turned down and had spaces to allow drainage and drying between the flashing and the deck boards. Even better if it turns up and under the sliding glass door sills.

If the loads at the bump outs were designed to be picked up by adjacent cantilevered joists, you would think they would double or triple the joists. The joist hangers don't look like they have much capacity to resist wind uplift loads during the next hurricane.

As "Triangled" indicated, the exterior rim boards are not supporting the joists (except at the intermediate joists and the bump outs). The rim boards are actually hanging on the ends of the cantilevered joists. Joist hangers transfer gravity loads from the joist to a support - not so much the other way around. Let's hope that the rim boards are secured to the cantilevered joists with bolted angle brackets (that we can't see in the photos) especially if the hand rail posts are bolted through the deck into top of the rim boards.

Skeezix

 

[Triangled]

actually, my point was that the hanger orientation suggests to me the joists are simply supported at the edge of the balcony.

One of the photos suggests that balcony edge may consist of a 3x, which directly receives the joist hangers at the outward end of the deck joists, plus another 3x.

again, hard to tell from this collection of photos.....

 

[Jerehmy]

seem to be same hangars at balcony edge

 

[Skeezix]

Triangled: Sorry if I misunderstood your point. I agree that the joist hangers indicated that the joists appeared to be simply supported at the exterior edge of the balcony. If the joists are bearing on the 3x rim board, what supports the rim board?

Skeezix

 

[Triangled]

skeezix, no need , as sometimes my sentences are cryptic. one of the photos indicated there may be a double 3x. 2-3xs properly connected may be sufficient to carry the deck if it's carrying 40 psf live load (which I do not like), as well as provide something adequate for the attachment of a handrail, but I am in agreement that as a cantilevered system it doesn't seem to work... that's why I searched the photos for any evidence that it was, at least in its current state, designed to be simply supported from an edge beam. The joist hangers seemed to indicate that, and, as I looked, I think I was able to discern a double 3x or similar. But quite hard to tell from photos, so I could be completely wrong.
check out this photo from the OPs 2nd post.... maybe my eyes are deceiving me....

 

[Jerehmy]

its a double 2x that is supported by the cantilevered joists. the white is a 1x fascia that is longer than the 2Xs

 

[Triangled]

there you have it!, Thanks Jerehmy!