DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Framing and Foundation > Leveling a foundation at the sills?




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Old 06-08-2011, 06:13 PM  
oldhome
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Default Leveling a foundation at the sills?

I have a 140 year old house with a mortared stone foundation - some walls are stone right up to the sills and some are stone below grade and brick above grade. One side of the house has settled 4" over the last century - we suspect undermining from roof runoff. (We plan to improve drainage this year.)

Setting aside the concerns about DIY house jacking for now...

Is it possible to level a foundation by jacking the low sides to just above level, and using lumber and/or mortar to fill the tapered void that my jacking created below the sills. I'm guessing that with a house this old, there is nothing other than the old mortar holding the sills onto the foundation. If that's the case, it doesn't seem that my "shimming" would make things any worse.

I don't think I want to bring the house up more than 2" - that seems like enough trauma to do to the house, even if I go slow - I don't feel like refitting any windows.



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Old 06-09-2011, 06:30 AM  
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Well, settling of a home by 4 inches is usually a combination of some stone settlement, and the wood rotting. I would check att my sills with a good heavy probe from inside and outside first. Replacing the sills is a different job than jacking the house.
140 years old and the home is not post and beam?
And the wood also gets what we call "creep". (not to be confused with some of the characters here) It tends to stay the way it has settled sometimes, so jacking it up can make certain areas worse.
Pictures are always fun for us to see also.
Welcome.



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Old 06-09-2011, 08:25 AM  
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Default Sills are OK

Thanks, InspectorD.

The sills are sound and 6" tall all the way around the foundation - they are 2' above grade, and give a good "knock" when struck. I have verified the height of the foundation with a laser level and confirmed that it is stone settlement of one kind or another. The worst side of the house is in the corner of an "L" that gets runoff from both the original gabled roof and the hip roof addition...

Much of the original house is post & beam, though the addition shows hints of balloon framing: walls open to the basement.

I can see how old settled wood might resist adjustment. I'm thinking of only correcting the 4" drop 1/2 way to a 2" drop (why push my luck?), and doing so over 3 weeks or so. Do you think that will help?

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Old 06-09-2011, 02:59 PM  
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Yes, you need to go slow with it as you already know, but over days not weeks. Keeps the cracks in the walls to a minimum.
There is no way to get them perfect, and they do always need maintinence, but old walls are really neat. I would also put in a dehumidifier for the summer months if you do not already have one.
Good luck with getting the jacks in place...and be careful.

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Old 06-09-2011, 07:06 PM  
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We raised one last year from 3 1/2 to within 5/8. It's a scary job. It will only move about 1/4 at a time. Sometime we had to waite 2 or 3 days before it would move again. We didn't use big jacks as to not break anything.
We figured the weight to be 100 lbs per sq. ft for each floor and the roof. More for the kitchen and furniture and more if the roof has more than one layer. After breaking the basement floor we figured a way to put all the weight back on the foundation while lifting.

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Old 06-09-2011, 07:22 PM  
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Default Buiding up the sills?

Yes, slow will be the operative word.

Do you think my idea about building up the sills with mortar and (in the higher spots) lumber? There will be some spots where the gap below the sills will be as much as 2" and other places that may taper off to nothing. Considering that my goal is to raise the house as little as possible before repairing, it raises a few questions in my mind:

1. How to best integrate lumber? If there is enough height to slide in a 2x6, I feel that I should tie it in so the 2x and the sill act as a single unit and have a little lateral resistance - such as mounting right angle braces in the bottoms of the 2x's before setting them in mortar.

2. How much higher than level do think I'd have to raise the sills to be able to lay down new mortar? For example the gable end of my house will get raised 2" on one corner and not at all on the other. It's a little hard to visualize if I would need to lift the entire length of sill off the foundation or just lift from the low side until level, then chip & re-pack as much mortar as I can reach.

If I'm not making sense, I'm happy to sketch.

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Old 06-09-2011, 07:36 PM  
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Nealtw - how long did the raising take? Did you put low profile jacks on the foundation? I can't visualize how you transferred to entire load to the foundation.

I was thinking of building cribbing and using needle/carrying beams. The house has a bump out addition on one side so I have 4 different walls to deal with. Most of the house is post & beam, so the corners will all have point loads.

Every time I think it through, I come up with another location that will need a jack...

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Old 06-09-2011, 10:08 PM  
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Posts will be a different problem. We lifted the floor with beams added beside the bearing wall, we ended up cutting out parts of the sill and set the end of a 6x6 on the foundation the other end was 8 ft into basement and blocked to level. As the jack was within 6 inches of the foundation the foundation took 15/16 of the weight. How are you planning to lift posts.
We did this with a finnished basement but we had 2 feet between cieling and floor. The center wall could not be moved so we raised the joists off the wall instead.
To level the foundation we cut up every scrap of plywood around treated them green and spaced it up. We added bolt extentions to bolt it down and did some artfull cutting to a 2x10 combed fasia to add to the outside to hide it all.

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Old 06-09-2011, 10:11 PM  
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oops forgot the question; 3 weeks!

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Old 06-10-2011, 10:54 AM  
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No posts to worry about (but plenty of other things.) The house is a bit of a hybrid - it's balloon framed, but all the floor joists are 3x6's that are either notched into the sills, mortised into the beams, or simply resting on the ledgers w/no notch or nail. This house would have been built at a time where balloon framing was becoming common, but some builders were a bit reluctant to go along...

With stud walls, it would normally be easy to lift the gable end of my house - just run a beam across the bottom of the all the joists and let the joists lift the sill. But, with the joists notched in place, I imagine that lifting them might only lift the floor.



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