sagging floors


Old 07-26-01, 01:47 PM
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I recently moved into a 1922 colonial. The first and second floors have sagged in one quarter of the house approximately 1.5" from the walls. The problem appears to be the result of the house construction - the load bearing walls on half of the house are offset from the main structural beam (which is visible in the unfinished basement) by about 4'. Apparently, the builder recognized the problem and doubled up the 2x10 floor joists on this quarter of the house; however, the floors have still sagged considerably. The joists span about 18' from the 6x8 beam to the outside wall (there is no sag on the opposite side because the span is only 12'). My main concern is with the structural integrity of the house - does anyone have any suggestions on how to determine the extent of the problem and whether or not I need to go through the expense of hiring a structural engineer? Are doubled 2x10 floor joists at 16" oc generally strong enough to hold up 2.5 stories? New drywall was added over the lathe and plaster walls and ceilings within the past 10 years, and I am concerned that the additional loads may be too much. As a follow up, I may consider jacking the floor joists from the basement to level up the floors, but I'm thinking this may open up more problems than its worth. Alternatively, I could just install a few beams/columns in the basement to prevent the situation from getting worse, but I don't want to go through the trouble if I don't have a problem. Any thoughts? If a consultant is necessary, any recommendations on how to hire someone for the job?
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Old 07-30-01, 06:13 PM
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Hello wible1,
Your problem should have been picked up by a qualified home inspector. The sistered joists that you speak of seem to not have solved the problem. You could jack the floor joists from the basement to level the sag. If the house is all lat and plaster it will probably crack the walls above. This is a small problem if the primary concern is to have level floors without drastic sags. My suggestion would be to get a series of heavy duty jacks and jack the floor at the 4' area you talked about. Take the jacks up about a 1/4 turn a day until you gaet the floor level. After you have it level put in a structural beam at that location and repair the walls that have cracked.
Hope the info helps
The Carpenter's Son
Old 07-31-01, 07:05 AM
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The Carpenter's Son,
Thanks for the reply. Your solution sounds simple enough, but I still have concerns. I didn't mention that the flooring above the sagged joists is original hardwood planking. I'm concerned that this may crack/separate and be more difficult to repair than the walls, or that my windows and doors may get thrown out of whack. Have you actually done this type of repair before and are the side effects usually minor? Assuming I go forward with it, what are your recommendations for the jack spacing distance perpendicular to the joists? I will have to jack around 12'
or slightly more (9 doubled joists at 16" oc). Do I put a double or triple 2x12 across the joists with a jack at each end, or do I need more interim jacks? When I'm done, what do you recommend for the permanent beam? What will happen to my floor while this is occurring (concrete slab, not sure how thick)? Finally, the second floor joists are also sagged some, do you think the jacking will effect the upper floor also? Thanks for your time, sorry to bombard you with so many questions!

Old 08-04-01, 07:44 PM
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Hi Wible1,
Sorry so long to get back. AS for your first question about the hardwood planking, if the flooring has moved well with the settling I think it will move back as well. If you have just had them refinished lately you may have to go back and do some touch up refinishing. The windows and doors you are worried about is a good question/concern. If the sagging was on an outside wall or two walls at a corner you would most likely see problems already with your windows or doors, seeing how your floor is sagging 4' from the exterior wall windows should not be an issue. If doors are in the general area perpendicular to the sagging floor you should see the frames/jambs of them out of square. Look to see if prior owner may have cut the door to compisate for the settling. If doors look good you should be able to proceed with the jacking. I've had the pleasure of doing several jobs similar to what you discribe over the years. The slab you talk about I assume is in the basement, if this is the case and it covers the entire floor it is probably around 4" thick. You will need to put in footings where your beam supports are going to go this means busting the slab where they will be located and pouring some cement. I would use 3 posts to support the new beam, 1 each end 1 in center. Use the final beam for jacking(6"x8" like the other)and once you have it level set your posts and remove the jacks by backing down 1/4 turn till they are free. Locate you jacks near but out of the way where the permanent posts will go.
Hope this has givin you more food for thought, The Carpenter's Son
Old 08-07-01, 06:16 AM
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Thanks again for the reply, Carpenter's Son. I've decided to take your (and others) advice and try the jacking. The only difference is I'm going to try to purchase a steel beam instead of 6x8 wood beam due to minimal clearance between the joists and hot water boiler pipes beneath them.


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