I need to add 2′ to a second story room and I want to pop it out the side of the house. All of the joists over the first floor are going the wrong way to add a cantilever the easy way and I don’t have the option of tearing out the lower story ceiling to frame a cantilever the way it should be. I would like to avoid posts down to the ground. Is there any other options I might have? Maybe some sort of angle brackets, or maybe support above? Any ideas?
Thanks
Replies
Hang it
Create a framing that hangs from the walls of the second floor.
The best way to do it is by installing diagonal light steel straps on the side walls of the cantilever addition that start from the edge of the cantilevered floor at the bottom and run diagonally up toward the existing ceiling level and connected there to wall studs or a post.
The devil here is in the details to calculate the size and fasten the steel straps properly to the floor and stud/post.
This avoids anything added underneath the cantilever floor.
The other poster gave you a hint. Another way to do the same is to 'simply' run a diagonal brace in the 2 ft stud space from the base of the new wall at the existing house up to the upper, outer corner of that wall. Same result, really.
Another would be to create 'box beams' of the sidewalls of the room. Frame it out and plywood the entire wall to support the outer wall. The other question ... what is the roof situation?? Is this wall a bearing wall or on a gable end? If it is roof trusses on a bearing wall, you may have issues with supporting the existing trusses.
There are options, but your unique requirements to me says to take some initial ideas and go see an engineer. Money well spent. Building official may require it anyway.
Another approach ... make sure you 'need' the two feet (as opposed to want it). Reasses and double check your 'needs'. Try to minimize what you do. Also have you checked to see what this will do to the look of the house? I've seen a lot of practical expansions make houses turn into eye sores. I'm trying to encourage you to ensure you've looked at other aspects of your project so that you can maximize your overall success.
I like the idea that both of you had about the braces on the sidewalls. I think for the sake of strength maybe doing a 'box beam' and a diagonal brace might work.
There is no roof load on this side of the house, it is a gable end, and I might even be able to carry most of the new roof load on off of the existing roof load just by creating a 3' overhang from the existing trusses.
As for the look of the house... Most anything I do will improve it. It is also the back of the house.
Thanks for the advice!
I'm thinking it might be possible/reasonable to run the cantilever "joists" in the attic, tied to the ceiling joists, then **hang** the structure from that. You'd have to be careful to tie into enough of the (relatively weak) ceiling joists to appropriately spread the load, and you'd need to make sure you had a good strong header over the opening, but it should be doable.
(You'd also, of course, need to make sure the structure was well strapped together somehow -- simple hurricane straps would probably be insufficient to fully do the job.)
Some additional thoughts. You will be adding a roof (load), albeit small. That creates a bearing wall (unless you also gable it to the short side walls).
This is a bit of a unique structure and there are details that will make or break it. You have a floor to support and we've simply discussed structural sidewalls. It will be the details of how you use the sidewalls to support the structure of the floors. We're talking concepts here ... moving those to construction details will be the important part ... which is why I suggest you consult an engineer.
You're discounting the value of looks, I think ... 'anthything will be an improvement'. While that may generally be the case, I wouldn't assume that too literally. Sketch up what you are intending to see if it really is an improvement. What roof style you use can in and of itself make a big difference!
<<Another approach ... make sure you 'need' the two feet (as opposed to want it). Reasses and double check your 'needs'. Try to minimize what you do. Also have you checked to see what this will do to the look of the house? I've seen a lot of practical expansions make houses turn into eye sores. I'm trying to encourage you to ensure you've looked at other aspects of your project so that you can maximize your overall success.>>
As I have said before, sometimes instead of the question "Can I do it?" the question should be "SHOULD I do it?"
The answer to the first is invariable "yes" given enough time, effort and money. The answer to the second is often "no" due to time, effort and money versus doing something else.