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  1. #1
    Join Date
    Dec 2013
    Posts
    3

    Default sagging floors in a 1928 home help!! working on jacking it up.

    Hello everyone. I recently purchased a 1928 home in seattle and since i moved in almost 2 years ago we have noticed the floors seeming to sag more and more.

    Here pertinent house information: ~2 story house with a finished basement. (the top floor only has two small rooms slanted ceilings). The basement is carpeted cement floor, the exterior/walls of the house is brick. The basement floor is sloped to the center. The main floor also slopes to the center of the home. From what I can tell the joists are ~8-10" apart and appear to be 2x8's maybe larger. they run north/south in the house east/west runs a center main beam that is a 6x6. The east/west run is the longer run of the rectangular house.

    at some point a staircase was installed to access the basement at the east end of the house and the main beam was chopped. Everything is dry walled so we can't tell exactly how well it was re-enforced but it looks like the main beam is well supported.

    I've used a laser level at the worst part of the main floor and it registers a 1.6* slope. the areas of the floor around the walls seem level and firm, the closer you get to the center the more creaking and slopey it feels.

    On the main floor in the center of the house near the staircase(to upstairs), the bathroom, and main bedroom- I notice that the floor has pulled away from the edges of the walls(like at the bottom of the entrance frame) rough estimate of this gap is about 1/4". We identified the center of the house and where we thought the main support posts would be in the basement. removed the dry wall and purchased a couple 20 ton jacks.

    So far we have lifted this main beam in two different sessions and added metal shims to the top of the main support posts in the center of the basement. The two shims should now add up to a tad over 1/4".

    However, it might be that day-to-day living in the house makes it so we don't notice any change but it seems that our efforts havent made much or any impact. I did not measure slope or anything prior to installing the shims. I did take a measurement from the center of the house to the ceiling, and a measurement from a spot close to the exterior walls and it seemed as though there was a 3/4" difference in my measurements.

    Let me know if there is more information needed to aid in recommendations!


  2. #2
    Join Date
    Jan 2008
    Posts
    2,118

    Default Re: sagging floors in a 1928 home help!! working on jacking it up.

    Sags occur for various reasons- under-supported joists and over-spanned joists being the more common issues. In existing homes I do not aim to "level" floors; rather I "flatten" them since if the foundation isn't level, you'll never get the floor level and 1/8" out-of-level across the span of the average house is unnoticeable and common. Sags also have to be addressed from the bottom upwards- if a supporting member sags everything above it follows and if you fix the upper parts first, they will be high when you fix the lower ones.

    Go under the first floor and run some string lines a set distance from the subfloor which is enough to clear any beams or ductwork in the way. I use scrap wood with the nail for the string a set distance from the end which I push against the subfloor and tack onto position. Measure across the string in between to determine sag. Repeat this across the whole structure either marking the distance to be raised on the house or on a drawing (or both). As you go it should become obvious if sagging support beams are a problem- these can be checked similarly by stringing across the side of the beam(s) using spacers to keep the string free of obstructions. Once you determine where the low spots are, correct them. And this is where knowledge and engineering come into play as you may discover that you need more piers, better foundations under existing piers, added or stronger beams and/or joists, and sistered, replaced, or additional joists. Sometimes you'll find where walls were unsupported and have caused the floor to sag between joists. Until you know all this you're just guessing at where the problem really is based on limited information.

    It does little good to raise one point and leave the rest to sag, even if that helps with a problem specific to one area. Take care of the whole thing before moving upward. With luck, the usual result is that once the first floor is correct everything above it will have followed along and is now correct as well. If you have to do any significant lifting you will likely find some cracking of the plaster or drywall, but if you've truly fixed the problem that will be a one-and-done repair that never needs attention again. Pay careful attention to pier footings as these are often the culprit with sagging beams in multi-story homes. My feeling is that you cannot have too good of a foundation, only one that is not good enough, so I over-size mine beyond code minima- it's cheap insurance against future problems.

    Hope this information helps and if you have any specific questions after checking for flatness I'll try to answer them.

    Phil
    Last edited by Mastercarpentry; 12-28-2013 at 11:59 PM.

  3. #3
    Join Date
    Dec 2013
    Location
    New Hampshire
    Posts
    27

    Default Re: sagging floors in a 1928 home help!! working on jacking it up.

    If the sagging and settling has been recent it may be the result of posts being relocated in a basement remodel. The beam may have been left supporting too long of span for the load or a post could have been set directly on the slab without a footing under it.

    A post can easily punch a hole through an unreenforced slab. Efforts to jack up the house may just drive the post deeper into the ground without moving the house.

  4. #4
    Join Date
    May 2012
    Posts
    137

    Default Re: sagging floors in a 1928 home help!! working on jacking it up.

    Spend wisely and hire a structural engineer. There might be other issues you might be missing.

  5. #5
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,969

    Default Re: sagging floors in a 1928 home help!! working on jacking it up.

    I see some destructive investigation in your near future.

  6. #6
    Join Date
    Dec 2013
    Posts
    3

    Default Re: sagging floors in a 1928 home help!! working on jacking it up.

    Thanks for all your comments. Yes possibly expensive, destructive to drywall for sure!


    KShenefiel: Unfortunately I didn't buy the place from the orig owner. So I have nothing other then guestimation of how long it's been. I would guess that the basement has been finished for a while now. The sagging felt like it had gotten worse since I moved in.

    The cement/floor/"footings" are really strange and I assume not right. However, the main beam of this house appears to be supported by probably 4-5 other posts(possibly 4x4's +wall framing)) (i really cannot tell because of the drywall).

    Going back to the center posts, the one on the left appears to have a different footing then the other(possibly on some newer cement?). I'll take a picture if necessary. The post on the right in the pic at the bottom is supported by: Here's what I can see: there are two different pieces of cement with a 2" gap in the middle, spanning this gap is a 2-2.5" thick cement paver laid on top. I cannot yet see what the left side post is sitting on but I think it is "newer" cement.

    My dad and I are going to attempt to make some drawings of what is going on.

  7. #7
    Join Date
    Dec 2013
    Posts
    3

    Default Re: sagging floors in a 1928 home help!! working on jacking it up.

    Phil: Thanks for your help! We will work on that asap.

  8. #8
    Join Date
    Feb 2013
    Location
    Boston area
    Posts
    97

    Default Re: sagging floors in a 1928 home help!! working on jacking it up.

    I have the same issues in an 1865 home - sagging floors, a wall ballooning away from the house. This can be the sign of needing a lot of structural work done to prevent catastrophe, or totally normal. We hired an engineer for a few hundred and luckily we were fine.

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