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Old 06-16-2012, 12:23 AM   #1
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Location: Eastern Shore, MD
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Jacking Exterior Wall / Replacing Sill Plate


The Vitals:

- Located on Maryland's eastern shore
- 130 year old house
- Two full 10' stories and full 10' attic, belly crawlspace
- Footprint is 66', 28', 45', 40' (About 6000 sqft including attic)
- Either balloon framed, or timber framed or both (depends on who you ask)
- Rotten wood clapboard siding, nailed right to studs
- Rotten/termite damaged sills and studs

The Plan and Problem:

We're looking to replace a 12' section of rotten sill plate and then re-stud an exterior load bearing wall. We want to install sill gasket and a new 6x6 PT sill plate. We attempted to jack this section today and had some success, but were ultimately unable to remove the old sill plate.

The section in question is located close to a corner of the house. I've not been able to take photos yet, so I included a drawing that shows what we're dealing with. There are four original wall studs, two 2x4 and two 4x6. One of the 2x4 rests on a cross brace, which is just floating. The remaining 2x4 and one of the 4x6 are in solid condition. The other 4x6 is completely rotten at the bottom and is certainly not carrying any load. There is a horizontal beam that runs across the top of these studs and rests on the corner beam. We nailed (and later bolted) a 6' length of three sandwiched 2x12s to the inside face of the wall studs. We then cut a section of flooring out under each end of the 2x12 sandwich. Down in the crawlspace, we removed a couple inches of dirt and stacked two 2' lengths of 2x12 on each side. We placed a 20 ton bottle jack on each side and used lengths of 4x4 PT (with metal plate on end) as jack posts. These 4x4s were placed between our jacks and the bottom of the 2x12s on the studs. We used additional lengths of 4x4 between the stacked 2x12s in the crawlspace and the 2x12s on the studs as cribbing. Lastly, we ran a 2x12 horizontally across the exterior of the four studs. We nailed it into the corner beam (which sits on a different sill plate) and a beam to the right of our damaged section (which also sits on a different sill plate). Our intention here was to help prevent the studs from kicking out towards the exterior during jacking.

We jacked each side slightly to take some pressure off of the sill plate. We were able to run our reciprocating saw completely under each stud. We continued jacking each side a little at a time and the studs were lifting. After a couple of pumps on each side, the bottom of the studs started kicking out towards the exterior. At this point, the sill plate could be rocked back and forth, but we didn't remove it. We opted to return everything back to normal and re-think our strategy. We hammered the studs and sill plate back into position and lowered our jacks.

We think that the studs kicking out was a result of our jacks and/or 4x4 jack posts not being completely plumb. Our thought is that a diagonal force was being applied up and out (towards exterior) to the 2x12s attached to the studs. Gravity should be pulling the wall straight down, not down and outward, so surely we were doing something wrong. The 2x12 sandwich idea came from our building inspector and seems like it should work, I just don't think we're executing it properly.

We've spoken with engineers about our house in the past, but we've not consulted one on this project. (That's not to say we aren't going to.) We believe that we're approaching this task with a good plan, but our execution is off. The 2x12s on the studs were about 30" from the top of the sill plate during this first attempt. We're considering moving the 2x12s to just above floor level, or about 6" from the top of the sill plate. The idea being that by shortening the jacking distance, we may be able to keep everything plumb and jack straight up, reducing the possibility of the studs kicking out. We're also considering moving the 2x12 that's nailed to the exterior of the wall closer to the sill plate and/or adding additional 2x12s to help protect against the studs kicking out. We're also considering the idea of installing diagonal 2x4 or 2x6 braces between the wall and the ground and then staking them. Lots of considering...

So the questions are this...

1. Given the information provided and the included drawing, does our approach make sense? Do you see anything glaring that we're missing in our planning?

2. For those of you who have done this type of work with a house this size, do you have any advice that might help us during this process? Does the size of our jacks and jack posts compare with what you might have used on a similar project?

3. Any other advice or constructive criticism? Anything you'd change about the process?

Note: I'm not asking for beams to be spec'd, calculations to be done or any other type of engineering work. We're intelligent individuals and we will seek out an engineer, so please none of those canned responses. An engineer can design a plan, but ultimately we're still the one's who get to implement it. We'd simply like to compare notes with those of you who have done this type of work and see where, how or even if we've gone wrong. Many thanks for any early responses and I'll get some photos posted ASAP!

(On the drawing, the 12' area in question is located in the red box. Note that the corner beam and the vertical beam to the right of the affected area do NOT rest on the damaged sill plate. Also note that the horizontal beam above the studs sits on top of the corner beam, but does NOT sit on top of the vertical beam to the right.)
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Old 06-16-2012, 01:40 AM   #2
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Jacking Exterior Wall / Replacing Sill Plate


Rule of thumb when jacking a two story you need to carry bracing with temp studs between upper and lower floor joist floors and jack from under the ;pwest floor joist. Using one floor to raise another floor through wall studs can causes stress.

Other rule of thumb is not to be more then 1 foot away from outside wall when jacking

Try to determine what type of framing and that relation to floor joist and how they are carried and is it and end wall or a wall the roof sits on?

Pictures be worth a thousands words here. Also those 4x6 are another factor.

Last edited by 21boat; 06-16-2012 at 01:47 AM.
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Old 06-16-2012, 09:11 AM   #3
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Jacking Exterior Wall / Replacing Sill Plate


Quote:
Originally Posted by 21boat View Post
Rule of thumb when jacking a two story you need to carry bracing with temp studs between upper and lower floor joist floors and jack from under the ;pwest floor joist. Using one floor to raise another floor through wall studs can causes stress.
I understand what you're saying, but this seems like it would apply more to platform framing. The floor joists in this place are notched and "hang" off of the walls via horizontal members. The walls do not sit on the floors. The notches of the first floor joists are resting on the sill plate and the second floor is resting on the horizontal beam above the first floor wall studs. In the section we're working on, the first floor can be jacked independently of the wall. We've raised it the 1/4" needed to remove stress from the sill plate with relative ease. With regard to the second floor, I think it's possible to do more damage by having temp studs wedged in there. That's a question that we'll be asking an engineer, but given the short 1/4" distance that we need to move, I don't know that it will make a huge difference. Anyone that I've spoken to who has a jacked a home was jacking a couple of inches, usually to remove sag in a floor. They would jack a small amount each day over a longer period of time. In comparison, on our project a 1/4" seems like it should be no big deal. Given the penalty of failure though, we are making no assumptions.

Also, in response to your comment, we are jacking from the absolute lowest point. The bottle jacks are sitting in the crawlspace and our jacking points will be as low on the studs as possible.

Quote:
Other rule of thumb is not to be more then 1 foot away from outside wall when jacking
In the crawlspace, our bottle jacks are pushed right up next to the inside of the foundation wall. Given the diameter of the jacks, this places the 4x4 jacking posts about 6" off of the inside of the studs. All of the jacking force is applied to the three 2x12s sandwiched and bolted to the studs.

Quote:
Try to determine what type of framing and that relation to floor joist and how they are carried and is it and end wall or a wall the roof sits on?
As noted above, the floors "hang" off of horizontal beams on the walls. Looking at the place, it's like the walls are timber framed, but the floors are balloon framed. Really interesting stuff. This is a bearing wall, the roof rafters are resting on it.

Quote:
Pictures be worth a thousands words here. Also those 4x6 are another factor.
Will have these provided around lunch time today.
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