Hi!
I am designing my house. There will be a 30′ x 24′ 3-garage at ground level and the main living floor above. I could put a bearing wall ~12′ from one garage wall and run the joists widthwise. This would make for shorter I-joist spans of 18′ and 12′. But I also want a cantilevered deck since it would be 30′ above the ground. The lot is on a 25% slope going away from the garage entry. One way would be to run the joists the opposite way spanning the 24′ depth. They would be 32′ long with the last 8′ being the cantilevered deck. This would have the advantage of not needing the bearing wall, making a completely open garage space.
If I can afford it, I would also like to wrap the deck 10′ or so around the corner. Here’s a YouTube video that addresses this: https://youtu.be/q5ktFVXZXcs
If a cantilever isn’t feasible, I would consider a deck supported by a reinforced house wall below that would support a series of diagonal knee brace that would extend horizontally about 6′ from the house. Or possibly suspended from above with diagonal cables.
Ideas?
Thanks,
Dan
Replies
An 8' cantilever 30' in the air that will handle a combined design load of 50psf minimum? I think you're asking questions that indicate you need to speak to an engineer.
My first reaction is that an architect would be a good first stop.
But if you want to just discuss, a few sketches would help clarify your thoughts and questions.
As a structural engineer I could suggest a variety of ways to frame the floor above the garage. With respect to the deck you describe, I would NEVER cantilever interior floor joists through an exterior wall to carry a outside deck. The exposed ends of the joists are going to be exposed to the elements and WILL eventually deteriorate to the point of requiring replacement, yet the interior portions will last almost forever. How does one repair them in the future? Multiple joists penetrating the wall also create a weatherproofing challenge around each individual joist.
Can it be done? Sure.
Should it be done? Not in MHO.
From someone who was hired a couple times to repair cantilevered joists out into the weather, I agree it’s not a good idea.
Thanks for the feedback. I certainly plan to talk to an architect and/or an engineer, but want to be more educated on what options are feasible. So if cantilevered joists through the house wall wouldn't work, what about the other options, like supporting it from above with cable stays or from below with gallows brackets? https://www.finehomebuilding.com/2013/05/16/second-story-balconies
Cables or brackets, it's your choice. The overall size of this deck will influence. BUT be mindful of how the deck attaches to wall and how you're going to weather seal around those connections. You should also consider how any future repair or replacement can accomplished.