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Upstate NY clients of mine need to replace a 4 1/2″ steel column in the basement area (formerly a garage, years of salt exposure have led to a flaking rusted column and doors binding on the floors above it). It is midspan along a 20′ I-beam which runs the depth of the house, supporting bearing walls. There’s another post on the other side of the basement which is in fine shape.
Here’s the problem: in areas of the country not as seismically mute as the NE (on the west coast, for example, where I worked previously), it would seem the best course of action would be to remove the old post all the way down to the pad and install a freshly fabricated post embedded in new concrete. Of course this entails great time and expense, but it still seems like the right thing to do. However it’s hard to hear anything above the din of the natives chanting “jackpost, jackpost, JACKPOST!!” I can’t even seem to interest local fabricators in such a small job.
Looking for opinions (the stronger the better) about using jackposts as opposed to spending lots of dough. Specifics are appreciated- How can I properly estimate the load the house puts on the I-beam? Can the bottoms of jackposts be attached by bolts epoxied directly into the slab? Aren’t there code issues with something so…temporary? Would you even bother removing the existing column? Does the whole jackpost phenomenon strike anyone else as half-baked? Apologies for my long-windedness…
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This is of course my opinion only.
I don't like the idea of jackposts resting on the slap, I think that a 2x2 or 16"x16" poured pad is probably better.
If the top and bottom plates are bolted in place, A jackpost will only be expected to support an axial load and That's what it's designed to do.
I think a post cast in a concrete footing and welded to the beam above would look more substantial but I don't necessarily believe it would be more effective.
*Dear Smiley,If the post is mid-span, there should be a 2'x2' footing under it already, so putting a jackpost on both sides of the existing post will be OK. Setting them on the slab won't be a problem because they will bear on the footing below. I say two jackposts because you say the extg post is 4-1/2". One adjustable jackpost would not carry the same load for an extended period of time as a 4-1/2" S.W. pipe (since we don't know the load, two would be safer). The above will work; but judging by your question, you already know the right way to do it.I'm also wondering why the floor has sagged. Is the post rusted through and compressing under the load or is something else going on?Not an Engineer, Take it FWIW, Jerry
*....first determine the sag... either string and block it , or shoot it with a laser..if the beam is actually sagging then either it was installed wrong to begin with, or something has moved.. it wouldn't seem that the column has telescoped.. flaky and rusty arn't the same thing as failing..jack the beam back to true, and correct it.. either steel shims, or bring in a portable welder sub and weld some plates onto the column..you can do a load diagram and calculate the load .. it (MAY) be that the 4.5" column was oversized.. and could be replaced with a new 4"cement filled column available anywhere...the jack posts are not a permanent solution..
*Are the jack posts you are refering to the telescoping adjustable with holes and pins to set the length? If so I would not use them. around here thinker wall one piece columns are available that are much stronger. They are stocked in 3" or 4" increments and have an adjustable screw on the BOTTOM. The proper way to install is to embed the screw in the slab. In a retrofit situation it would be best if you broke out a 12"X12" section of floor. this would let you see if there is an adequate pad underneath. The whloe idea of the scwholen the bottom is that once you get it adjusted to the proper lenght you leave thelengthe rod in the hole and bury the whole end in the slab thus preventing it from giong out of adjustmgoingSafety is the main concern here but if you bury the entire screw section it will also provide some extra bearing on the threaded cap.Also the screw is only for adjusting the pole length, not for jacking up the house. Use a house jack or two to do the lifting this will allow you to get the old column out and put the new one in the same spot.It would still be a good idea to have some that is qualified determine if one (or two or three) of these posts will be sufficient in your situation. the bearing walls above with binding doors and the fact that it was a garage sugest to me that thhugesty be some other things that need to be considered.I hope this has been of some help. Tony
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Appreciate your comments.
The jackposts I'm thinking of aren't the hole and pin type, they have a long threaded bolt that can be used to adjust the height in reasonably fine increments. I've heard people call the same thing a house-jack in other parts of the country. However I would only use them temporarily, while the column is being replaced.
It's a good point to consider that it may not need replacing -some of the door problems may in fact be the result of ice dams. I've yet to shoot it properly but just in sizing it up the floor seems to have sagged roughly 1/4" midspan (ie it's at it's lowest point almost directly above the column).
Biggest problem is that clients are of the ilk that think they can spend money just here and there and skip things that don't add to the resale value. But they've hired the wrong guy if they want a hack-job. I was called in primarily to do some finish work, but as I'm finding more and more things that require a greater degree of expertise some of this stuff is going to have to get farmed out.
Thanks again
Smiley
*Those new steel posts should be either: 1. boxed in in sheetrock or, 2. filled with concrete. Either makes the post be able to hold the overhead load in the event of fire. Without, the post turns into a wet noodle from the heat and the overhead load falls.
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Upstate NY clients of mine need to replace a 4 1/2" steel column in the basement area (formerly a garage, years of salt exposure have led to a flaking rusted column and doors binding on the floors above it). It is midspan along a 20' I-beam which runs the depth of the house, supporting bearing walls. There's another post on the other side of the basement which is in fine shape.
Here's the problem: in areas of the country not as seismically mute as the NE (on the west coast, for example, where I worked previously), it would seem the best course of action would be to remove the old post all the way down to the pad and install a freshly fabricated post embedded in new concrete. Of course this entails great time and expense, but it still seems like the right thing to do. However it's hard to hear anything above the din of the natives chanting "jackpost, jackpost, JACKPOST!!" I can't even seem to interest local fabricators in such a small job.
Looking for opinions (the stronger the better) about using jackposts as opposed to spending lots of dough. Specifics are appreciated- How can I properly estimate the load the house puts on the I-beam? Can the bottoms of jackposts be attached by bolts epoxied directly into the slab? Aren't there code issues with something so...temporary? Would you even bother removing the existing column? Does the whole jackpost phenomenon strike anyone else as half-baked? Apologies for my long-windedness...