Cantilevering Wood Balcony, Anchored to Masonry 1

[b2frison]

So I want to design a cantilevering deck, 25 feet off the ground for an apartment. The deck will extend 5.5 feet from a double-wythe masonry wall, and will be 7.5 feet in width.

I don't want to extend the interior floorjoists for this application due to deterioration/leakage concerns. I want to have a system relying on anchor bolts to ledgers.

http://www.sharecad.org/CADView.aspx?Id=85f3fe3a-1e4c-4414-874c-18e66554ae18

The above link is what I was thinking of doing, with anchorages/through bolts going through the two wythes of masonry. My question is:

The horizontal force applied to the masonry wall from the diagonal support pushing the bottom ledger...what code ruling should I follow for concentrated horizontal load (per foot of wall of course)? Any other thoughts on design welcome as well.

Thank you.

 

[rscassar]

I wasn't able to download your attachment on my phone but I don't see it feasible to cantilever the balcony without a backspan.

 

[b2frison]

In reality the deck proposed would be supported on two adjacent sides (90 degree angle) (Think of an L, or think of a diamond with the top two lines being anchored into masonry). However, the analysis becomes 3D at this point.

However, I wanted to see if this scheme (without vertical support from one adjacent side) would work if I just considered anchoring into one wall, with diagonal supports imparting both horizontal and vertical force further below on the wall.

 

[apsix]

If you can show that the brickwork can resist the horizontal forces and that the tension fixing to the brick is adequate, it can work.
Good luck, I doubt that it will work as shown.

 

[a2mfk]

I am sure you could get this to work on paper somehow, but you are dealing with wood and brick in a situation where I'd like to see steel or CIP concrete. Also, balconies and decks seem to have ways of being overloaded (parties)... I would revisit cantilevering and then sitting down with the architect and working out flashing and waterproofing details. I also did not see how you are going to do your handrails, they will have cantilever up and take a pretty good lateral force, which also may cause you issues with a wood balcony.

This one may make me toss and turn a little at night.

 

[BAretired]

It is not appropriate to rely on masonry for this purpose. I would not even think about it.

We had a local situation about one week ago where a second floor balcony collapsed under the weight of seven people during a small party. It turned out there was wood rot (the newsreel showed mushrooms growing out of the beams lying on the ground). Fortunately, no one was killed, but there were some serious injuries.

Your situation is a little different, it is true, but you cannot take a chance on such a flimsy structure.

BA

 

[larsacious]

I would avoid this detail if at all possible. If the architect can not provide columns at the exterior corners of the deck than the best alternative would be to cantilever the floor joists. If you are concerned about waterproofing then perhaps you only make two exterior wall penetrations by cantilevering one beam at each end of the deck and framing the deck joist to these beams.