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Considering adding a bay "bump out". What am I in for?

Considering adding a bay "bump out". What am I in for?

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  #1  
Old 01-01-16, 09:32 PM
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Considering adding a bay "bump out". What am I in for?

I'd like to add a bay to my ranch house. I'm thinking about building a floor to ceiling bay similar to this one:
Name:  Big-Bay.jpg
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My windows don't need to be as tall as the ones shown in the picture, but I do want the bay to be floor to ceiling. I prefer this look over the pre-fab bays I've seen.
In my case, the bay would be beneath a 24" soffit, so the exterior "cap" will not be very complicated.
The building inspector told me that I will need to get a proper header spec'd out.
Aside from that, what should I be worried about?

Thanks in advance.
 
  #2  
Old 01-02-16, 04:50 AM
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How will you be supporting the floor?
 
  #3  
Old 01-02-16, 06:48 AM
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Addition

You most likely will be adding this over fill dirt. You need to dig the footings deep enough to reach undisturbed soil; otherwise you will have settling of the entire addition.
 
  #4  
Old 01-02-16, 07:58 AM
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A picture of your house would be more helpful than the picture above. We are left guessing whether your house is on a slab... if its elevated... etc.

You will either need to cantilever floor joists (not possible if they are parallel with the exterior wall) and then insulate the floor, or build a foundation below frost line then extend your floor joists onto that, and insulate. If there is existing ductwork, extend it to the center of the new bay. The wall area will also still need electrical outlets.

If your front window extends too close to the fascia, you may not like rain running down the window. No one ever thinks of how spotted that will get... especially if you are used to them being under 24" of soffit.

The header is the simple part. You need to figure out what all that will be sitting on.
 
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Old 01-02-16, 08:01 AM
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Thanks @marksr and @Wirepuller38

Regarding the floor, that's a good question. The area of the house where I want to add the bay is on a concrete slab. Currently, there is a concrete walkway over which the bay would be built. We (my wife and I) are debating whether or not we will be "moving" the walkway (i.e., tear out the existing one and have a new one created a little further from the house). So, if the concrete for the walkway would be a suitable foundation, maybe we could leave that section in place. I'm not sure about that. Thoughts?
 
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Old 01-02-16, 08:10 AM
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Thanks @XSleeper. Just saw your reply. I'll need to get out today and take a picture, but, there is no duct work in that area. There is electrical--in fact, there's a baseboard electric heater which we never use.
 
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Old 01-02-16, 08:22 AM
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Sidewalks and patios are never suitable to build on, since they aren't on a footing below frost. The only exception might be a porch if its already on a footing... but they are almost always at a lower elevation. The concrete would have to come out and you will need to excavate the area and pour the new footing, insulated wall and pad.
 
  #8  
Old 01-02-16, 11:50 AM
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pic

My wife found a usable picture.
Name:  Front-Of-House.jpg
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The proposed bay would go where the current window on the far right is. Overall, the bay would be wider by, at least, a foot than the current window.
The brick is going to be removed.
 
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Old 01-02-16, 01:17 PM
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You "could" can't eleven the floor joists but the cold floor and odd space under the exterior would make digging a footing more appealing. Brick doesn't "have to" be removed but I don't know your grand plan.
 
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Old 01-02-16, 02:36 PM
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In my case, the bay would be beneath a 24" soffit, so the exterior "cap" will not be very complicated.
In addition to the footings, you are going to have to figure out the new roof line in that area. I doubt you can just "tuck" it under the existing overhang. You need to account for ceiling joists thickness, adequate insulation and snow loads. I'm not seeing much headroom above your front door to work with.
 
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Old 01-02-16, 07:56 PM
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Thanks @XSleeper and czizzi.
There are no floor joists. That section of the house is directly on a slab. It is a newer area of the house. FWIW, the original section of the house (from the front door and everything to the left of it) is over a basement.
Regarding the brick (and a little bit about the "grand" plan), I am in the process of removing the exterior siding, sheathing, and insulation (such as it is). The original sheathing is Homosote and is breaking down in areas. I've already done the back of the house and will be moving on to the front when time allows. My wife doesn't like the brick and I am certain that Homosote is behind, at least some of if (not 100% positive about what's behind the brick to the right of the door). So, I'm motivated by a desire to replace the sidewall insulation and sheathing, as well as my wife's preference, to remove the brick.

Here's a look from the inside:
Name:  South-West-Window-from-Indoors.jpg
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There is a drop ceiling (about 7" below the original ceiling). We would like to remove the drop ceiling and create a "tray" ceiling.
Above that room is the attic crawl space which is constructed with 2x4 trusses.

I hope this helps create a more complete picture of the situation.
 
  #12  
Old 01-02-16, 08:20 PM
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Ok, forgot you said it was a slab. Right.

Well your trusses are currently supported by a header. If you intend to remove that existing header, and maintain an 8' ceiling height, the trusses (that's a big factor) would need to be modified which is generally something a structural engineer or the truss mfg would need to approve. What I imagine is that the trusses would need to be cut off at the interior wall surface so a new header could be installed, which would sit on TOP of the top plate, and the trusses would need sit in joist hangers and would hang from the side of that header... and would need to be reinforced on the interior side of the header with new framing and plates. Those are some big loads, so yeah, a structural engineer should be involved. If the height of the header is determined to exceed the truss height at the exterior wall, you would then be looking at building a hip roof out over the bay.

If you give up on the 8' ceiling height idea, and frame it as in the first picture you posted... you would leave the existing header in place, which would be much more simple. Then you just would need to address the lack of insulation in the ceiling, which as mentioned, would be minimal. I'd pack it full, or have it spray foamed.
 
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Old 01-02-16, 09:34 PM
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Thanks again @XSleeper,

I'm willing to give up on the 8' height.
Here are a couple more pics that might help.
This is a gable-end view of the trusses in the attic crawl space:
Name:  Gable-end-View-Of-Trusses.jpg
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The supporting braces may look like 2x6's in the picture, but they are 1x's

There is a "box bay" at the back of the house (original with the house). This is what the framing above the "box bay" looks like:
Name:  Underside-of-Roof-Above-Box-Bay.jpg
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I was hoping to get away with something similar when adding a bay similar to my first picture.
 
  #14  
Old 01-02-16, 10:31 PM
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That would be very doable. The "trusses" look homemade... i was expecting a modern engineered truss, with metal plates. The drop in your rafter tails will limit the ceiling height out there. If you are only projecting out a foot or so, you could use a corbel type of foundation... something like this that uses your existing footing.



But you would want it to be more smooth, so frost heave wouldn't catch on the corners.
 
  #15  
Old 01-03-16, 04:26 AM
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Overall, the bay would be wider by, at least, a foot than the current window.
If the new opening is wider than the existing windows you'll need a new, longer [possibly bigger] header.
 
  #16  
Old 01-03-16, 10:51 AM
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Thanks again @XSleeper & @marksr.
Yep. Looks like I have a significant amount of work cut out for me if I take on this project.
 
 

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