Cantilevered Upper Hallway/Mezzanine - construction?

Art Mulder

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London, Ontario
Hey Folks,

My wife and I are in the planning stages for a new addition to our house. Our plan is to rip the roof off of our attached garage and build a bedroom up there. The garage projects off of the front of the house. Our entryway is vaulted, and we will need to pull the upper hallway forward to meet the front wall, in order to be able to open a doorway there into the new bedroom.

The challenge, is that the upper hallway is a sort of balcony, and it cantilevers out about 14" from the side wall. Here are some photos:

Here is the upper hallway/mezzanine.
As you can see, the hallway is cantilevered out over the closet. That corner is the trick. We need to attach the new floor there.
IMG_3919.jpg

And here is the more vaulted area, where we need to pull the hall over:
IMG_3920.jpg

Here is a very rough doodle of what we're looking to end up with:
upper-hall-new1.jpg

Anyone ever done anything like this?

The load bearing wall in those photos is the back of the closet - which more or less lines up with the wall above.

My brother suggests that I run a 2x8 (I have 2x8 floor joists) along the FRONT of the upper mezzanine, so it is securely attached all the way along.

Yes, I will be getting permits, and contracting out the bulk of the work. But I still like to be well informed and see what suggestions people have.
 
Geez, Art! Didya rob a bank or something? I look at those pictures and all I see are dollars. Lots of 'em! ;)

Wouldn't it be cheaper just to buy a new house? ;)

But seriously, the contractor will have better advice than I would. If it were me, I'd tie in a 2x8 along the wall, and then I'd bolt another right underneath that stairrail. Rather like putting an addition onto a deck. Not very elegant, perhaps, but it might work. :dunno:

Thanks,

Bill
 
Art, I know you know this, but a structural engineer is going to be the one that knows how to do this. Maybe we have one in the midst that can give you some better ideas.
But......Looking at the photos, strictly from a non structural type lay person, I'd guess the floor joists from the rooms beyond the photo of the upper hallway were long and that part creates the cantilevered hall section. They are resting on 2 load bearing walls, with upper walls on top of them. The part you want to put the new extension of the hall does not have that. So, you would have to pull subfloor from above or ceiling from below, and add by securing on to the existing joists by bolts. I'd guess 2 to 3 times the length of the section cantilevered for the hall if not all the way to the other load bearing wall. Another issue is the existing section has the closet walls that will help support to some extent, so while are not truly load bearing for the building, they do bear some of the load of the walk way, cutting down the amount of stress of the cantilevered section. You won't have that on the other side. How wide is this lower room? (the one open to the walk way) A glue lam to replace the rim joist (is that the right term here?) that the existing walk way has that spans from load bearing wall to load bearing wall would make things much easier, if it is possible to do that.
Oh, are you planning on living there while the work is being done? :huh::) Jim.
 
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I understand what you want to do, and could offer my 2 cents. However, you need to get an engineer/architect to design this. This is one of those things you should just not cut corners on.
Now for thought would be to install a beam from the mezzanine to the load bearing wall by the new door. This would replace the band on the cantilevered section. Assuming the floor joist all run in the same direction, you can extend the floor joist from the existing floor the beam. Sorry I can't get a drawing into the post.
 
Geez, Art! Didya rob a bank or something? I look at those pictures and all I see are dollars. Lots of 'em! ;)

Wouldn't it be cheaper just to buy a new house? ;)

Buckets and buckets of dollars, Bill. :(
(at least, that is what we're expecting, we haven't gotten a firm quote yet.)

The main problem with moving, is that moving itself is so darned expensive. Around here, realtor fees are about 6%, what are they by you?
You live in the Washington area, I can just bet how much more your house is worth compared to mine. So I bet it would be even more expensive for you to move.

The secondary problem with moving (to a new house) is that IMHO most of the local developers are idiots. They design new subdivisions with 40' wide lots and where the majority of the lots run east-to-west. With a 40' wide lot, you have basically NO windows on the sides of your house, which means that on an E/W lot you get practically no sunshine. And frankly I already think my lot is too small, no way am I going to one of those postage stamp-sized lots. (and yes we look at established neighbourhoods also, but 4 bedroom houses are quite rare actually)

But we'll see. The price of an addition might just scare us right back to considering moving.
 
Any chance of land on the outside edge of town that wouldn't be a driving nightmare? If so, you might consider building and getting exactly what you want if something doesn't show up that is just right. That is if the addition scares you in that direction. ;) Jim.
 
Art what you want is not a hard thing to do. I have done lots of decks with larger spans and loads than that. Talk to at least 3 local contractors to get their take on it before going ahead. Also if you are doing an addition you will have to be taking out a permit and the submitting plans to your local building inspectors dept. They will be telling you what you need to get in the way of engineering ( if it is nessesary at all).

I am guessing that the existing floor joists are cantaleivered out to create that existing landing. I would keep the joists running in the same direction as that would make the shortest span. I would suggest bolting a wall plate of 2x8 to both walls into the studs with lag bolts and connecting the existing landing to the far wall with two 2x8's laminated together to create a beam. Install one first so that you can nail the joist in place through the 2x8 and add the second on after to create the beam. use joints hangers to support all the joists at both ends along the wall and one double for the beam at both ends.

I am sure that there are other ways to do it but This is the fastest easiest way that I would suggest doing it.
 
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