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StructuralEng
StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 6682
Experience:  Structural Engineer
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Looking to add a 2nd floor to my house. What are the options?

Customer Question

Looking to add a 2nd floor to my house. What are the options?
I have a pretty basic house. Poured foundation 8" wide that goes at least 4 ft down. Its not a full basement, it has a deep crawl space, at least 3ft, I can move pretty good. There is also part of the foundation that runs along the middle of the house to support it there. Floors are 2x8, 14' long that meet in the middle, so the whole house is 28' wide. Walls are 2x4. Ceiling/roof is same as the floor, 2x8, 14' long meeting in the middle. There is just a single pitch on the roof, from inside the front ceiling is 8ft, and the rear ceiling is 7ft, so it drops a foot along a 28' run. It has a glued down rubber roof. The section I want to add on top of is 44' long. Of course I would like to not disturb the existing house as much as I can, I'm adverse to taking the whole roof right off at this time. What are my options?
I was thinking of adding columns in the walls front and back to support beams along the 44' and just build on that. Does sound like the the best way? Then we get into how many columns needed, and will I need to support the 28' width in the middle also and put columns there. That is if that's the best approach...
Submitted: 8 months ago.
Category: Structural Engineering
Expert:  StructuralEng replied 8 months ago.
I can help. Can I get back to you in a few hours?
Customer: replied 8 months ago.
Certainly
Customer: replied 8 months ago.
I added two files that are ms paints of the house and how I envision how to add a 2nd floor (not that it necessarily has to be done that way, I could be making a mountain out of an ant hill for sure, that is why I'm asking )
Customer: replied 8 months ago.
the first pic is wrong though, roof and floor are 2x8 for sure, not 2x10. I confirmed that with a measure
Expert:  StructuralEng replied 8 months ago.
Do you mean the foundation walls are 8" thick?
Customer: replied 8 months ago.
Yes, I meant to say the foundation walls are 8" thick.
Expert:  StructuralEng replied 8 months ago.
If you introduce columns with heavy point loads you will get differential settlement and possible serviceability problems. I would strongly recommend bearing joists on the walls as a typical house would
Expert:  StructuralEng replied 8 months ago.
The roof will have to come off no matter what
Customer: replied 8 months ago.
Does that still hold true if I'm not limiting the number of columns used? I don't need to do just end ones. Putting in more columns in the wall in between rafters is fine by me. My goal is not to disturb the existing house as much as I can. The existing ceiling is directly attached to the roof that is there, hence my desire not to remove the roof.
Think of this as building a house on a platform above my house. Can that platform be supported on steel lalley columns run in the wall to the existing foundation?
Customer: replied 8 months ago.
Added a simple jpg with the the roof-rafter-ceiling sandwich.
Customer: replied 8 months ago.
if you need it, email me directly and I'll send the link to the vision appraisal for my house with the sketch and photo
Expert:  StructuralEng replied 8 months ago.
But how do you plan to add a story to the house without removing the roof?
Customer: replied 7 months ago.
Maybe saying '2nd floor' is not the right term. What I want to accomplish is to add to living space, and not increase the footprint. Will this be accomplished? Seems like it would. Now the other goal- not disturb the existing house as much as possible. Seems that might work out as well. So would that be a viable plan given what I want to accomplish? From the outside it would be tied together to appear as a single 2 story house, even if that isn't the right term.
Now the remaining questions would that be the best way to accomplish those goals even if it isn't the typical path?
Expert:  StructuralEng replied 7 months ago.
How to add living space without adding a second floor, without adding to the footprint of the home and without disturbing the existing home? How would you possibly expect to do that?
Customer: replied 7 months ago.
So is the answer 'it won't work, you cannot add columns to support a 2nd story independently of your existing structure'? Even if I went every 4 feet with a column? That would only disturb the ends where the columns are run. I could even order trusses with room-in space and set them on the beams supported by columns then. I can't see why it would not work if foundation would support it.
Expert:  StructuralEng replied 7 months ago.
Are you saying you want to add a second floor above your roof? I am trying to be as open minded as possible here, but you are not at all clear in what you are describing.
Customer: replied 7 months ago.
In effect it would be another floor above my roof.
My roof is only a sheet of plywood and rubber on top of the rafters that my ceiling is also screwed into.
If I don't want to disturb the rooms in the house that are there, that seems the only way to do it.
It is a non standard request for sure, so I'm doing the best I can describing :)
Makes no sense to me to create a mess of the 1st floor that I'm fine with if there is another option.
Expert:  StructuralEng replied 7 months ago.
Please post a picture of what you want to do. It's not making practical sense to me.

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