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Old 08-18-2009, 05:37 PM   #1
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Correcting exterior wall build on slab


I have a shop behind my house that the previous owner added an additional bay to. They really goofed up on one thing, and now I would like to correct it so that I can hang an overhead door and enclose the space.

Here's the issue. They poured footing, and then foundation for the entire addition everywhere except for one spot right next to the original structure.

One the side of the addition furthest from the original building, it looks like this. (pardon the plants and ignore that wiring - it was never tied in to anything.)



On the other side of that 12X10 door opening, right next to the original structure, it looks like this. Here is the trouble spot.



They neglected to put any kind of foundation there. The wall is built directly on the slab that was poured not only in the addition, but outside of it as a walkway for the entire shop. It's all one piece, too.

The bottom of that wall is rotting.





That rot is making the wall slowly get shorter. The drop in height is now telegraphing through to the roof. Here are shots of the inside, so you can see just how far that corner of the addition is dropping.





Getting a jack post in there and slowly raising it back up shouldn't be a problem. (I've lifted a few floors and walls in the past.) What I'm unsure of I what to do with the wall itself. This is way beyond replacing rotten sill plates. As you can see, the base of this wall sees a little water each time it rains. I'd like to perform a proper, lasting repair, but I'm not sure what should be done in a case like this.
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Old 08-19-2009, 03:23 PM   #2
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It's never a good sign when no one has anything to say. Anyway, here's what I'm thinking. Feel free to jump in.

1) Raise the wall/roof back to correct height, support it with temporary Lally columns, and cut out the rotten wall to expose slab.

2) Cut access in to slab and excavate for footer if one does not exist.

3) pour footer.

4) bore holes in to adjacent existing foundation for rebar to tie old and new together.

5) build form and pour foundation.

6) reconstruct framed wall and achor to foundation.

7) show my wife what I did and collect points.

Does this sound reasonable? I know I could simply rebuild the wall on top of the slab using pressure treated lumber, but that doesn't solve the slab issues. In the future, I'd like to have the concrete in the addition ripped out and replaced with something smoother than the surface of the Moon. With the footer and foundation added below this little wall, I'll feel better about it being supported, and I won't have near the headache when it comes time to replace the floor.
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Old 08-19-2009, 07:27 PM   #3
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Sounds good! I would rebar/adhesive a few #4 into the footing as well as the wall concrete. Drill one size bigger- 5/8" for the glued holes. Support the trusses with a temporary wall, or a 2x6 upright under each, tacked in place. A couple of 2x6's forming a" V "under the one end of the header, resting under a scrape place(not to ruin the door header trim, tacked in place. Use J-bolts in the top of the 6" wide by frost depth wall. Add 2" square steel washers before installing pressure treated mud sill on bottom. Install H-1's on all the trusses for uplift, especially if in a high wind or seismic area. Use one of these to gain bearing, at least on this side: http://www.strongtie.com/products/connectors/hh.asp

http://www.strongtie.com/products/connectors/h.asp

http://www.simpsonanchors.com/catalo...set/index.html

Be safe, G
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Old 08-19-2009, 09:37 PM   #4
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After a bit of Googling, that all makes sense. (Hey, I don't do this every day.)

I'm unsure of how much rebar to use, or even which adhesive would be best for setting support in the existing foundation. For that matter, I still need to figure out frost depth in this area. I obviously have some research to do.

Thanks for the information!
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Old 08-19-2009, 11:10 PM   #5
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Here you go: http://www.soundfootings.com/pdf/US_...t_DepthAVG.pdf

And rebar placement: http://books.google.com/books?id=pD5...age&q=&f=false

And adhesive: http://www.lowes.com/lowes/lkn?actio...319+4294956772

Try to look at your City or County's website for info. It should tell you most of the important info. If not, just ask, we are here to help!

Be safe, G
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Old 08-20-2009, 04:29 PM   #6
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Awesome. Thanks GBAR!

I managed to hunt through the county website, which is about as well sorted as a pile of spaghetti noodles, and pulled from it a PDF file with the following information.

Seismic zone: D2

Wind Speed: 85 MPH (3 second wind gust)

Frost line: 18 inches

Yeah... I had to look up just what D2 seismic zone meant, and see it means we have pretty strict guidelines for construction. I will implement the various Strongtie connectors throughout the entire addition. There are two exterior "finished" walls that will need to have drywall removed to do this, but it's not a great loss, seeing as how the previous owner put up the 1/2" drywall with 1" roofing nails, and didn't bother to insulate either wall or run any wiring in them. With the drywall off, I will be able to spot and correct any unknown structural short comings.
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Old 08-20-2009, 05:11 PM   #7
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While you're at all this work, there seems to be a 1/2 to 1" gap between the top of the header and the top plate in your fifth picture and it looks like that section of the roof has sagged. If you've the energy, might want to jack that part up and shim between them so even out the roof line if noticeable.
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Old 08-20-2009, 06:29 PM   #8
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Quote:
Originally Posted by bob22 View Post
While you're at all this work, there seems to be a 1/2 to 1" gap between the top of the header and the top plate in your fifth picture and it looks like that section of the roof has sagged. If you've the energy, might want to jack that part up and shim between them so even out the roof line if noticeable.
That will be addressed as it is part of the problem. As the bottom of the narrow wall on that side of door opening rots, it drops. The header is dropping with it, and the trusses are sort of left hanging... and sagging. I'm thinking that once I lift the header and wall back up to where they need to be, that that bowed top plate will straighten up and the gap will vanish. It's a heck of a gap, so I'll lift it real slow.
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Old 08-22-2009, 07:21 PM   #9
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I got to thinking today, and of course, looking. It seems to me that the header above the garage door may not be adequate. Rather, I think the jack studs are inadequate. Bear with me while I describe some dimensions.

The front wall of the addition is roughly 18' in length and has a 11' 6" ceiling height. The door opening is 12' wide and 10' tall. from above, it would look something like this.

|_______| ........Overhead door opening........ |_______________|
<- 2'1" -><--------------12' ---------------><-----3'9"-------->

(Wow. those are harder to make than I would have thought.)

The header spanning 12' seems to be a doubled 2X12, (at least I hope it is doubled!) and is supported only by a single 2X6 jack stud on either side. About half of the roof is being held up by this header. I thought it was just dropping on one side, but once I shot a laser at it, I could see that it is bowing, too. To make matters worse, I also found that the jack stud on the non-sagging side of the doorway is not even touching the ground. About six nails are keeping that jack stud fastened to the king stud, and if they were to fail, the header and a whole bunch of roof would drop almost 3" straight down.

I'm thinking now that I will probably need to put up a temporary wall along the entire front of the building so that I can put it back together the right way.

Personal note: I hope all that money I paid to the home inspector was enough to get him an eye exam and some glasses, because he obviously needs them.
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Old 08-22-2009, 09:37 PM   #10
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This is why in my earlier post, #3, I suggested a header hanger be installed when doing the work. " Use one of these to gain bearing, at least on this side: http://www.strongtie.com/products/connectors/hh.asp"

What is the rafter span? Or how wide is the building, in line with the rafters? If a 20' deep garage, 2-2x12's will support a 9'9" span and carry the load safely. A 28' deep garage with same will span only 8'5". I suggest to get a Building Permit so if you ever sell, it will all be legal and safe for you and your family. Be safe, G
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Old 08-22-2009, 10:40 PM   #11
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Quote:
Originally Posted by GBAR in WA View Post
This is why in my earlier post, #3, I suggested a header hanger be installed when doing the work. " Use one of these to gain bearing, at least on this side: http://www.strongtie.com/products/connectors/hh.asp"

What is the rafter span? Or how wide is the building, in line with the rafters? If a 20' deep garage, 2-2x12's will support a 9'9" span and carry the load safely. A 28' deep garage with same will span only 8'5". I suggest to get a Building Permit so if you ever sell, it will all be legal and safe for you and your family. Be safe, G

Well, there's my answer. The building is 28' deep. I had a nagging feeling I forgot a detail in my last post, and I did. Oops. I'll have to go with steel, or Glulam, I guess.

Yes, this has entered a level of complexity that I feel warrants a permit, though I shudder to think what sort of additional ways to spend money the inspector will force on me.

The original building was constructed with permits back in 1978, but there are no permits on file for the addition. You can probably imagine just how hairy this could get. I have this fear - probably an unreasonable one - that they will make me tear the entire thing down and start over.
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Old 08-22-2009, 11:27 PM   #12
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Those were the days..... I started building houses solo in '75. Figure a couple hundred for engineering and a permit and it will be safe with a record at your County. Call a lumberyard for glu-lam prices, you may be surprised. Be safe, G in Tacoma.
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Old 08-23-2009, 01:30 AM   #13
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Quote:
Originally Posted by GBAR in WA View Post
Those were the days..... I started building houses solo in '75. Figure a couple hundred for engineering and a permit and it will be safe with a record at your County. Call a lumberyard for glu-lam prices, you may be surprised. Be safe, G in Tacoma.
Ha! I wasn't born until '76. On the other hand, I had either the luck, or the misfortune, depending on how you look at it, of growing up in a circa-1850 fixer-upper that my parents were continually repairing and remodeling. I watched and learned as they did things the wrong way once, twice, and occasionally three times before doing it the right way, so I at least know the value of doing things right the first time.

I'll chuck a couple of telescoping adjustable columns up under the header for now to hopefully keep it from going anywhere, and talk to whoever it is I have to talk to to get whatever permit I need to fix this thing. I think the worse part of this project will be cleaning all of the junk out of there so that I have room to work. (Well, that and I bet it will be December before I can get started, since we've already been trying to save enough cash to replace the roof and rebuild a water damaged kitchen. Having to fix a collapsing structure is just icing on the cake. When it rains, it pours, eh?)

Thanks for the help, neighbour. I'd still be scratching my head right now if not for your assistance. I'm guessing I'll at least owe you a cup of coffee or two by the time I'm done with this mess.
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