Leveling 1904 pier and beam on clay soil

Discussion in 'Homesteading Questions' started by sarastro, Feb 12, 2005.

  1. sarastro

    sarastro New Member

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    I'm brand new and fascinated with what I see here. I look forward to participating.
    I have a new old house in north central Texas that still sits on the original Beaux dArc posts for the most part, although some concrete block supports have been added here and there - all just sitting on top of the ground. Most of those have sunk and fallen away from the beams that they were supporting. I have had a local expert come out and give me an estimate for leveling/repair of the piers and I can't bring myself to the idea of paying $8K for this when it looks so 'doable', I just need a jumpstart. Anyone out there taken on something like this? It is a 2-story Victorian farm house. Footprint is about 1500 sq. ft. The worst part of the floor dip (probably 3 inches over a 15' run in one room) all goes toward the fireplace (chimney has been removed long ago, I guess).
    I guess my main question is, do I need to lift the whole house off of the original foundation (piers) at the same time to begin the intensive process of digging 2'X2'X2' holes in the ground to get to some secure footing, or can I start on one corner and work around?
    Also, is there a different consideration for supports in the center of the house than around the perimeter?
    I know that at this point there are questions that I should be asking, but don't know enough to ask. Any help would be greatly appreciated.
    Thanks!
     
  2. Cosmic

    Cosmic Well-Known Member

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    We actually have to see what you have to be very exact. Some pictures help a lot.

    These are some of the major considerations for any work of that type.

    1. Understand how the present support system is supposed to work. You must judge is the support points adequate or should something be changed / upgraded / modified. In general the pier type system should support the major load bearing beams. Probably like a normal house with a foundation except the piers are spaced at some intervals. You must understand, as built does the house have a main center beam, exactly how are the internal load bearing walls supported.

    2. Diagram out a Master Plan of what the new pier system will look like. Paying particular attention to the footing design. Most good footings will be poured concrete with rebar in it. A two foot cube sounds like something in the area for a normal house, depends on how many there are / spacing / load / etc.

    3. You must be able to establish a reference level line for the house as a whole in some manner. This is your final point to bring the entire structure to make everything level. Understand what must be jacked up and in what sequence to not damage the house. Usually you cannot jack just one corner or one support pier point. Usually houses are lifted as entire sides as the minimun type lift. Plus this means monitoring inside as the lift is being done. Things like what is best served in areas like windows. Usually they are put into a position that gives the most free play movement. Maybe both sashes at mid point.

    3. Most house lifting is done by first installing some sort of a cribbing system which is temporary heavy beams that carry the joists and allow spreading the lifting forces over a larger section. The amount will vary depending on who is doing the job and what is at hand.

    Lifting the entire house is probably not required at once. You can block / crib in sections and lift enough of the house to free up a few piers at a time, get some working room, pour their footings, reinstall piers and move to another section. A section is probably best if it includes an entire wall run. Usually you lift slightly above what the final elevation will be. Some may start out and completely level the entire house with temporary blocking / cribbing before starting any footing work. Is a nice approach but can require a rather large amount of heavy materials. The other downside, all the extra bracing, means getting good working room can be a challenge. Most pros will use massive wood or steel beams long enough to go completely thru a section and be supported far outside the footprint of the house.

    A little lifting in many places is far superior to a massive jack in one place in a home brew method like yours. Many automotive jacks can do the job, tweating each a bit at a time. The key is having beefy enough temporary lifting beams. The noises a house makes are important. Listen for it telling you where things are getting strained. Cracking sounds are not good. Popping and creaking are normal.

    Depending on the job, the existing piers may / may not be removed in larger sections. Also want to think about how the top plate on the piers is designed. The more a particular pier bridges its carrying span with a top plate the better.

    In your case, if only a few people, allowing the footing to cure enough probably won't be a problem. You won't move thru the job fast enough to set piers. Probably do want to allow the footing(s) to cure a few day before applying heavy load to them.

    Lot is going to depend on exactly what your support system is and the number of supports involved. The big trick is to plan all lifts carefully, full monitoring as it is being done, sometimes taking either hours or a few days if your cribbing / blocking system is not super beefy. Also think about what interior doors, openings, etc that may have been modified, planed, shimmed to accommodate the settling over the years. Things might not work very well after the house is level again. :p

    The center supports are like anything else, depends on the number and exactly what type of load they are carrying.
     

  3. agmantoo

    agmantoo agmantoo Supporter

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    I have done exactly what you are wanting to accomplish. Using very simple tools you can get the house level again. You will need a couple of heavy duty jacks and preferrably mechanical instead of hydraulic. You also need to make or buy a water level. This is a low tech but extremely accurate device that is super cheap. Once you determine how to use the water level find the highest point at the bottom of the floor joist. Having determined the high point decide if that is a suitable height. Using the jacks slowly start working your way around the foundation and gradually start bringing the lowest point up a little at a time. Use cribbing to hold the house will you level. A google search should find you some info on cribbing techniques. With patience you can raise the entire house over several weeks time. The more gradually you raise the house the less damage you will have. http://www.geekazon.com/house/cribbing/
     
  4. sarastro

    sarastro New Member

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    Thanks for the reply. I think I get the general idea. Is there a general rule of thimb for the distance between piers for a good solid ride?
    Thanks!

     
  5. Cosmic

    Cosmic Well-Known Member

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    Not really, you basically want to understand the concepts of floor joist span tables and all of the in's / out's and incorporated in the practical World. Try absorbing these two sites. Basically there are span tables in many references, being on the conservative side will make it feel super solid.

    http://www.umass.edu/bmatwt/publications/articles/understanding_loads_using_span_tables.html

    http://www.bestdecksite.com/introJoistsPg2.htm

    There is a workmanship component. Most good carpenters will have their own tricks for really tacking together a solid floor and bearing system. Load bearing is really a complicated subject and I am not a qualified C-S-A type engineer. Even those types get it wrong. For home building a good rule when in doubt over build it, the money is nominal. Materials is typically only ~33% of all home type jobs. For DIY, go on the heavy side.

    One good trick is always invent a way to use all your scrap pieces to make super strong ties, connections or bridging in a framework. In a number of decks I did, major square foot layouts, I could carry the scrap away in a small garbage can, mostly sawdust.
     
  6. Darren

    Darren Still an :censored:

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    The original builders couldn't have chosen a better wood for the floor beams. If you want long term stability you'll need to put footings in below frost depth unless the winter temps can't reach the soil because of skirting, etc. It all depends on how much work you want to do. You could just shim those piers that have sunk. Lots of old houses have piers added over the years.

    The work can be done without resorting to the cribbing and H beams the housemovers use. You can replace each of the orginal piers if they've sunken by adding temporary supports on either side and then digging out the original pier, putting in a footing and laying up the new pier. Make sure the temporary supports are far enough from the pier to not fall into the hole. You can do that by extending an imaginary line of 45 degrees down from the edge of the temporay support closest to hole for the new footing. Don't dig anywhere near that line.

    The use of a water level made out of plastic tubing is a good way to level the structure.