Greetings All,
We did this addittion last summer. Approximate dimensions 12’x24′. It rests on triple LVL’s and (four) 4×4 steel columns imbedded in a concrete pier over footing’s at 3′-6″ below grade.
Assignment now is to build footings and cbu walls one block above slab height then build 2×6 walls to support what is now being held up by those columns and LVL’s. LVL and posts are currently set back 18″ from end of structure.
I say the structure needs to be jacked 1/4″ up from where it sits now in order to:
1) Remove posts and LVL’s
2) Compensate for the shrinkage of three 2x plates (sole,and two top plates)
Boss was clueless this morning when I mentioned keying or doweling the new footings and foundations to existing house.
Current pier footings are not poured to any set elevation other than 3′-6″ below grade and extend well into the area where the new footing will need to be. Remember; posts are set back 18″ from where the outside of the new wall will be and the fottings are a good 24″ in diameter. that means that they are cutting way in to where the new footings will be going.
Mason told the boss no problem we’ll just go around them? I see a failed footing inspection.
I’m getting tired trying to educate everyone.
What say you?
Edited 3/12/2008 9:06 pm ET by EricPaulson
Edited 3/12/2008 9:06 pm ET by EricPaulson
Replies
Just thinking about the "Planning Ahead" poster that shows large letters to start and then progressively smaller letters as the artist realizes he doesn't have enough room on the board to complete his sign.
So, no thought was originally given to the need for a continuous footing around the perimeter of the addition when the pier footings were poured?
I would treat this as a footing addition to an existing structure. Form your new footings to partially or even fully encase the pier footings and drill and epoxy dowels into them. You will end up with a wider footing but will please the inspector.
So, no thought was originally given to the need for a continuous footing around the perimeter of the addition when the pier footings were poured?
It was built as such as it was all they wanted. Saved money for no foundation.
Now the Mrs. is going to move her parents in and the space under will be enclosed and included into the existing finished basement area as an accessory apartment. This wasn't even a thought at the time.
What do you think about my concern for the issue of shrinkage at the plates?
Eric[email protected]
<<What do you think about my concern for the issue of shrinkage at the plates?>>
Your asking about the new plates to be used at the exterior wall?
I would get some KD or old well-seasoned material and use that for the plates. Also cut your studs a hair long and set them one at a time. I don't think there will be noticeable settling when you pull the LVL's and the columns.
Thanks
KD is not easy to find around here, but you validated my concern to a degree.
Eric[email protected]
First, you're asking the wrong people. Ask the building inspector, since his interpretation is the only one that matters and, if you ask for his advice BEFORE you begin, he's going to be more forgiving later.
Since a full perimeter footing doesn't need anywhere near the soil bearing width of pier footings (spreading the same load much farther), simply wrapping the new footing around the existing piers should not be a problem.
Shrinkage of plates is generally a non-issue, unless the wood is green. I'm not sure what you mean by "KD is not available", but any lumberyard lumber - Kdry or Sdry - is all milled at 19% moisture content, and unless it's taken on considerably more moisture in the yard should not shrink noticeably. Shrinkage of beams - across their width - is the problem.
Solar & Super-Insulated Healthy Homes
By the time we get to this, the floor and rim joists will all have been well seasoned.
I'd say of the 2 or 3 largest outfits around here you will not find kiln dried lumber except maybe some 2x2 or 2x3. Even depot here only has 2x4 kd.
We ARE going to use green lumber to frame the 2x6 walls with two plates on top and probably two beneath (one PT and one DF).
Would you say yes or no that my concern about shrinkage is valid? I'm guessing that wall could easily shrink a quarter of an inch.
Eric[email protected]
Sounds like you're using Doug Fir framing and a PT SYP sill.
Pine and Fir will shrink 4-5% radially from saturation to oven dry. So you could get 1/4" shrinkage if the lumber is very green at time of construction.
Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
Sorry to be off topic- It's amazing that being that close to the city,
you couldn't get any product known to man. Let alone PT.
KD is just not used for anything around here. Typically the 2x3's and 4's are going home with the ho's to do their little w/e projects.[email protected]
I doubt that there are any requlations against joints in the footing. Theoretically, if those pads landed on the outside and totally blocked the new footing, you would still get all the support you need from a "piecework" footing.
For instance, I had to install a foundation under an existing house. We jackhammered the hardpacked clay and dug out 4' sections, leaving the rods to interlock with each adjacent section. We blocked up every four feet. The house is still standing.
You have a valid point about the green wood shrinkage. Just cut them tight as suggested but keep in mind that it is probably impossible to get things "perfect" as you are trying. Heres the problem: you are thinking that you are going to raise the outside of that addition 1/4". How are you going to uniformly raise the entire addition 1/4"? Are you going to detach the framing from the existing house, temporarily while the house shrinks down to your desired height.
Basically Eric, you have to understand that remodeling is part art and part science. Raise the thing 1/8" on the outside wall and eventually it will be 1/8" low. You'd need a transit to prove it.
Oh yeah....it's probably required to pin the new footing if the original house has a basement becuase of the overdig. If it is a trenched and poured foundation, your new foundation might be landing on virgin soil and it might not really matter to pin it.
Bob's next test date: 12/10/07
Compensate for the shrinkage of three 2x plates (sole,and two top plates)
I've never heard of compensating for shrinkage like that. Don't even give it another thought. Leave the girder in place and build the foundation and then frame your walls and remove the girder and columns later.
If you think that the addition is down 1/4", jack up the girder 1/4" before you frame it.
Edited 3/14/2008 4:35 pm ET by Framer
Thanks Joe,
I'm just really stuck on thinking that the best results will come from at least un-weighting the girder before building a bearing wall to replace it.
If I am going to comfortably dismiss the shrinkage of the plates, then I would do so only if I were able to un-weight that girder first.
There are several tons of weight on that girder now. Even if I jamb every stud into that wall with a sledge I don't think it will unweight it.[email protected]
Just unbolt the the girder and jack up where each column is 1/4" and slip a metal shim under the bottom of the lvl under each column and then frame your walls.Joe Carola
Exactly what I've been thinking.
Next problem to solve will be getting those peirs out of there. I'm pretty sure that they are higher than the floor slab.
Bust off the top six inches or so and burn the posts off.
Thanks for the input.[email protected]