New Framing/Foundation Plan for Existing Addition

Discussion in 'Framing and Foundation' started by GeoffM, May 9, 2012.

  1. May 9, 2012 #1

    GeoffM

    GeoffM

    GeoffM

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    I have an existing sunroom off the back of my house, it's 13'8" deep by 17'6" wide. The current "foundation" runs 2/3 of the addition perimeter with one side open to access a partial dug out crawl space; which has an average of 4'6" headroom. The 2x8 joists are unevenly spaced but average 14" spacing. I'm using a trial of SmartDraw and I've attached a jpeg of the drawings.

    1" = 4'
    The brown is existing framing and the yellow is planned. I basically plan on cladding the rim joists with new 2x8. Creating a 20' beam with 3, 2x10's, glued and nailed. Sitting on 4 6x6 PT posts on metal saddle brackets set into my 18"x18", 6" deep square footings.

    I'll also be putting another 2x10 fastened to the house wall under the existing ledger board with 6" Lags offset every 12".

    Does this look good? Any comments would be appreciated.

    Thanks.

    Sunroom support.jpg
     
    Last edited: May 9, 2012
  2. May 9, 2012 #2

    GeoffM

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    Forgot to add, could I get away with 2 posts; one on each corner with a triple 2x10 beam or would I need a 2x12?
     
  3. May 9, 2012 #3

    nealtw

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    We never get away with post footing that small, most often 30 to 36 " sq. and 10 inches deep.
    Your best bet is to draw up your plans and go get your permit. You might be able to use three posts, draw your plans that way and if that isn't good enough they will let you know.
     
  4. May 10, 2012 #4

    GeoffM

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    I was originally thinking of doing a 12" depth for the footings but according to code it's min 4". The post height may change depending on what's down there, the house is sitting back from a rock face and I can see a bit of limestone sticking out of the ground a few feet from the sunroom.
     
  5. May 10, 2012 #5

    nealtw

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    The weight landing on it and the soil conditions do make a difference and then there is local codes. Up here the designer puts in what he thinks, if the city dosn't like it they will change it or ask for an engineer to look at, we call them geo-techs, they check the soil structure.
     
  6. May 10, 2012 #6

    AndyGump

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    What is your location?

    I don't mean to be harsh but that does not look like a safe addition at all.

    Andy.
     
  7. May 10, 2012 #7

    GeoffM

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    I'm in Ontario, Canada. It's not safe, we don't use it all; the current support is much worse. But it's grandfathered and I'd never get a permit to build a new one. I can get one to fix/reno the current footprint.

    It's mixed soil, sand/clay/rock mix and I might have to pin the footings to limestone.
     
  8. May 10, 2012 #8

    nealtw

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    Andy; The question was, "what do you think" I'm not sure a blanket statement like unsafe, adds to the discussion. Geoff is trying to develope a plan so he can understand what the problems might be.
    Geoff; A beam to support this for an 18 ft span on 2 posts would be huge and expensive.
     
  9. May 10, 2012 #9

    GeoffM

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    Is a beam made from 3 20' 2x10's strong enough for that span? with 3 support posts along the front and I could put one on each side.
     
  10. May 10, 2012 #10

    nealtw

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    It all depends on the room above. You will have to figure how much load you have, including snow load and how that load is tranfered to the beam, and how much weight is on each end of the structure, this the stuff engineers figure out.
     
  11. May 10, 2012 #11

    AlwaysOneMoreProject

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    I thought the building code dictates the load capacity to which the structure must be designed.
     
  12. May 11, 2012 #12

    AndyGump

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    The problems are many and varied as I see by his plan.
    Use THIS link, it is to the Prescriptive Wood Deck Construction Guide based on the 2006 IRC. I understand the 2006 IRC might not be the relevant code for his local but it is a better start than what I see here.

    A professional design for this is what he needs, but not necessarily what he is after.

    Andy.
     
  13. May 11, 2012 #13

    nealtw

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    Andy; I think you missed the fact that he can not tare it down and start over, as is the building is not up to code and dosn't have to be brought up to code. The thing is with these things when any work is done that work has to meet code. He hasn't said he isn't getting a permit, but he wants to devalope a plan and understand what might need to be done before he goes to the city. In a perfect world people like Geoff would hire a planner, contractor, engineer and who ever else has there hand out. What then would be the point of this web site.
    I'm in Ontario, Canada. It's not safe, we don't use it all; the current support is much worse. But it's grandfathered and I'd never get a permit to build a new one. I can get one to fix/reno the current footprint.
     
  14. May 11, 2012 #14

    GeoffM

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    Thanks Neal. That's it exactly, we knew upgrades were going to be needed when we bought the house but we were not expecting it so soon or to the extent that it is needed. If I had the $$ I'd be walking into a builders office that has all the "hats" under one roof and have them do it all for me. But I'm a retired Vet on a limited income and this money pit has already eaten away a lot of savings already.

    It is a single story above, not sure of the roof pitch and it's planned use is living space.

    I'll put some pics up tomorrow.
     
  15. May 11, 2012 #15

    nealtw

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    Don't get me wrong I agree with Andy that there are lots of things wrong with the structure. I like to solve one problem at a time, that's why I started at the ground. I'm sure Andy saw the span of the 2x8 floor joists, to make this a comfortable living space they will have to be stiffened up. They haven't broke and probably won't but I bet they sag a good inch in the middle.
    My fear is that as you see things that you know is wrong you ask about it, but if you don't notice and don't ask it may be missed.
    Some building inspectors don't look to close when they are inspecting a none conforming house. Really I think your best bet would be to spend $500 on an engineer if for nothing else but peice of mind.
     
  16. May 11, 2012 #16

    AndyGump

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    Thanks Neal, you are making things a bit clearer for me on this rather confusing thread.

    Thank you Geoff for your service, I am a vet too but not yet retired.

    Geoff, if I understand correctly now you are intending to convert this existing screened porch area into living space? And extend the area by about 150 sq. ft.?
    If so you need to consider carefully how the structure is going to be built for the safety of you and your family and friends.
    Getting a structural design passed by your local Building Department is a big step in the right direction on that score.

    Asking general questions of a DIY forum, even one like this with a butt load of good pros like Neal is not going to do much for the life/safety issues on a major project like this.
    Carefully consider your budget, maybe you can do the proper foundation this year and wait a year or two until you have the funds to continue with the living area.

    Andy.
     
  17. May 11, 2012 #17

    GeoffM

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    I appreciate all the replies. Here are some pics of the addition, if you want more of the structure let me know.

    I'm going to do a new drawing taking into account all the feedback and I'll post it up later this weekend.

    Thanks.

    image-2987792587.jpg

    image-2678138972.jpg

    image-1223471209.jpg

    image-94084725.jpg
     
  18. May 11, 2012 #18

    nealtw

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    A foundation would make the space below more usable but may not be allowed. With a foundation you would just build a wall to hold up the room.
    The floor is way over spanned, I would add a 2x10 to the side of each 2x8 joist, if the new joist can be close to full length the wall or beam can be configured to carry the floor and the wall above. You must have a ledger against the wall now it could be lagged to the wall then you could use hangers for the floor joists.
    I think your first plan would come close to passing the city for a permit.
     
  19. May 11, 2012 #19

    GeoffM

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    Thanks Neal.

    I forgot to add that the two PT 4x4's to the left of the last picture are just in there for added support right now.

    I was thinking of doubling up the joists already and adding a couple near the far end (spacing is pretty wide), already planned on joist hangars and lag bolting the ledger.

    Once I come up with a final plan, I don't think the building permit from the Township will be to hard to get. It's going to be getting permission to dig/move earth from the Conservation Authority.

    Here's a couple pictures of the view to show why I chose this crazy investment. :rolleyes:

    313 (640x480) (2).jpg

    297 (640x480).jpg
     
  20. May 11, 2012 #20

    nealtw

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    Nice spot!!
     

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