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How to level a joist-supported subfloor that's 3" difference over 21 feet?

How to level a joist-supported subfloor that's 3" difference over 21 feet?


  #1  
Old 01-22-05, 10:09 PM
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How to level a joist-supported subfloor that's 3" difference over 21 feet?

I live in a house built in 1950 with diagonally laid 7/8" thick 1x 6 boards for a subfloor. On top of that is 7/8" thick red oak hardwood floors that is, as far as I know, the original flooring when the house was built.

I have a room I'm remodeling which is approx 8' x 21' (used to be two rooms that I'm not combining into one large kitchen). The 21' side of the room drops 3" over it's span, and I'd like to level the floor. I plan on stripping the existing flooring down to the subfloor, and would consider replacing the existing subfloor with the newer tounge'n'groove plywood kind if it can help solve my problem. I plan on putting in a new hardwood floor after I can figure out how to solve the leveling problem.

So, how would I level a floor which drops an inch every 7 feet like this and still have a sturdy enough floor to install a new wood floor on top of? Is there some kind of skim coat material I can use which can handle elevation changes like this?

Thanks for any help you can offer!
 
  #2  
Old 01-23-05, 12:21 PM
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Hello Irestone,

Can you tell us some more about the house. Is there a basement or crawl space under the floor in question?
I'm remodeling which is approx 8' x 21' (used to be two rooms that I'm not combining into one large kitchen)
I'm guessing that there's a typo in that sentence and you actually are combining the two rooms into a new kitchen.

This sounds like settling has occurred, typically what one does is to get underneath the framing and raise the floor back to level,very slowly! You can't jack a floor that's settled 2"-3" all at once. You use adjustable jacks that can be put into place and brought up tight, then raised like 1/4 turn every couple of weeks. Eventually you will get the floor back to level. If you were to try to raise this in one large jump, back things can happen, cracked structural lumber, etc. Post back and give us as much info as possible about the situation. What's under the floor (crawlspace or basement); size, spacing, span and condition of floor joists; the more info we have the better we'll be able to help you resolve the problem.
 
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Old 01-23-05, 07:19 PM
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Under the new kitchen, which is a kitchen and bedroom that's being combined into one room, is a full basement. The new room will be approximately 8x21 where the original two rooms were about 9x10 (original kitchen) and 8x10 (original bedroom). There are 2x8 joists which are in good conditionin the basement, but the 3" drop over the span of that new room is typical of the house. I have put on a deck, a window, and a sliding glass door since I've lived here. All of them are square and level, but are clearly they are not square and level to the house. It really looks like the entire house slopes roughly an inch for every seven feet. No idea why, but I need to figure out how to level the new kitchen floor on top of the joists without any scenarios involving jacking up the joists under the floor or other long-term scenario like that. I would definitely prefer a fix that can be accomplished by putting something down either in conjunction with the new floor or prior to a new wood floor installation. Any suggestions?
 

Last edited by Irestone; 01-23-05 at 07:52 PM.
  #4  
Old 01-24-05, 06:53 AM
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In that sort of situation, I guess you could sister in some joists to bring the floor up to level, but you may run into problems at doorways doing this. What I mean is if you raise the floor up to where it's level, which by your description will mean bringing it up 3", that might create a problem if there is a doorway at what is currently the low end of the room. Is this house built on the side of a mountain or what? Never seen a house built on a slant like that on purpose.
 
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Old 01-24-05, 12:35 PM
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Yeah, it's definitely a weird situation. The house wasn't built like this on purpose, but it's definitely not square and level. The foundation looks good and has no cracks which would indicate any significant settling over the 50+ years the house has been there. It's built on the corner of the street in an area which is very high in clay content so the houses in my area haven't settled much, but have had to deal with water issues when it rains heavily. Just a little background for you....

So, your suggestion of sistering joists might be the fix. What I assume the process is would be removing all the subflooring and sistering in a joist at the low end, leveling that with the original joist at the high end and leveling the two then filling in sistered joists along that level line, right? There are no considerations about doors or other existing parts of the house which would be disturned by the rebuild of the subfloor. With this remodel I have created one large open space that has no structural impedements to raising the floor to level.

Just so I know I'm understanding correctly, by "sistering" joists together you mean putting them side-by-side and nailing/screwing/bolting them together, right?

Thanks for all of your help, awesomedell. I see that you are quite helpful across lots of forums on this site. It's much appreciated by all of us non-experts!
 
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Old 01-24-05, 02:10 PM
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Yes you have the right idea, I generally use torx screws for attaching the sisters to the original joists. As long as there are no doorways on the low end, I think this would be an acceptable solution to the problem. Best of luck with your project and post back if you run into more questions.
 
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Old 01-28-05, 07:54 AM
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3" difference over 21 ft

Yes you have the right idea, I generally use torx screws for attaching the sisters to the original joists. As long as there are no doorways on the low end, I think this would be an acceptable solution to the problem. Best of luck with your project and post back if you run into more questions.
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I have a similar problem - mine is 5" not 3 - But - there is a doorway between rooms on low end.

No cracks and cellar is 7' high right across (I expected the measurement to be 5"lower in basement on low side). No clay here - but we are in coal mining country. I believe the absence of cracks or voids rules out subsidence - and the situation hasn't changed over the past 10 years or so.

Tenants are unaffected by it - but they're relocating in AUgust and I'd like to correct this before its occupied again.

1. How do I address the doorway situation?

2. Can I rip 2x6 and install on top of floor rather then ripping it all out?
 
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Old 01-31-05, 05:08 PM
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Do I need to put down felt in between subfloor layers?

I have decided to keep the existing subfloor, live with the 3" drop across the length of the room, and put down a layer of 3/4" plywood subfloor then a new hardwood floor on top of that.

I have the floor stripped down to the original subfloor and am wondering two things. First, can I nail down subfloor or should I screw it into place? Second, do I have to put down a layer of felt or something in between the original plank subfloor, the new plywood subfloor, and finally in between the plywood subfloor and the new hardwood floor?
 
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Old 02-03-05, 07:25 AM
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Sorry I missed these last 2 replies, an oversight on my part, taxes and what not have me a tad distracted right now.

kathie - I need a few more facts about your situation. 5" is a big drop in any floor, and may indeed call for serious modifications/repairs to rectify. Post back with more details on your situation, pls. If the place is settling all across one side thru two or more rooms, the entire affected part has to be raised, unless you want to have a step down into a sunken room. I guess you could rip 2"x6"s to taper them like shims attach them to the existing subfloor and then put the new plywood subfloor over that to compensate for the drop. If the doorway at the low end of this area swings back into the adjoining room, you would just end up with a 5" step down into that room. If it's not set up that way, you will have to swap out the door jamb & all to remedy this problem.

Irestone- I'd go with screws over nails, they don't back out like nails will sometimes and use some liquid nails in between the plywood layers. You could also do the same thing in your situation as I described in the paragraph above addressing kathie's questions. In your case you'd just need 2"x4"s since you don't have as big of a drop. Put the felt paper under the finish flooring only and you'll be fine.
 
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Old 02-03-05, 08:36 AM
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5 inch "dip"

Let me know what facts you need - I won't be doing the work for a few - but I want to be ready so I can get it done asap.

the "dip" is through two rooms on the first floor - I don't think it extends into the third room on first floor - but I'll check it out. Its a rental and I don't spend any time there unless it needs repair. It hadn't occurred to me before your question, but it seems that the center room has always been lower - the front room seems to be a more recent development (within the last year or so?) I say this because I'm sure the door didn't swing then like it does now.

I know that this is a big drop - let me know what additional info you would need and I'll get in there and get exact measurements and see if it affects the 2nd floor (although I did a lot of trim work and painting up there and there was no noticable dip (but I will take a level up and check it out).

When you say swap out door jamb and all - what do you meant? rainins the sub floor right through the doorway?

I assume I'll need the following:

size of rooms
# of inches low (measurement each corner of each room 1st & 2nd floor) )
basement height floor to ceiling (again each corner)
ease of operation of windows
inspect for any cracks or wood failure.

Again, while it seems lower to me then it was in past - tenants claim its the same, whether its because they live with it daily or if it hasn't really changed I'm not sure.

And when all measuring is said and done - should I call in a structural engineer to tell me why this is happening? I'm sure the local building inspector wouldn't be able to tell me the cause. One more thing - this is coal mining country and while the absense of cracks makes me think otherwise - it could be instability due to undermining????
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kathie - I need a few more facts about your situation. 5" is a big drop in any floor, and may indeed call for serious modifications/repairs to rectify. Post back with more details on your situation, pls. If the place is settling all across one side thru two or more rooms, the entire affected part has to be raised, unless you want to have a step down into a sunken room. I guess you could rip 2"x6"s to taper them like shims attach them to the existing subfloor and then put the new plywood subfloor over that to compensate for the drop. If the doorway at the low end of this area swings back into the adjoining room, you would just end up with a 5" step down into that room. If it's not set up that way, you will have to swap out the door jamb & all to remedy this problem.
 
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Old 02-08-05, 09:06 AM
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this is coal mining country and while the absense of cracks makes me think otherwise - it could be instability due to undermining????
I'd say the odds are better than 50/50 that this is the underlying cause.

should I call in a structural engineer to tell me why this is happening?
Probably not a bad idea to have one in to make recommendations, seeing it first hand he can better judge what the causes are and approriate remedies.
 
  #12  
Old 02-08-05, 10:34 AM
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how to level a joist....

Well if it is undermining the good news is that we've got subsidence insurance......I should probably start there, the inspection might even be free...I'll post back after inspection - don't hold your breathe - the wheels turn very slowly with state agencies in this neck of the woods.....
 
  #13  
Old 06-05-05, 04:58 AM
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I'll bet its around Wilkes Berre, or Nanntycoke!

I would call an Engineer, there has been good results with pumping (high pressure) quick setting concrete under the footings and it will raise a house or Brick three story Apt. Building like it was on air bags. As long as it don't hit a coal shaft or the like.

But 3" or 5" lower needs to be corrected the right way, not just a quick fix. And hope for the best. Look at it this way, its going to get worse with time, even if you just level the floor on the low side, but whats it doing to other structural members of the house while it sinks. It could bust sewer or water lines, adding to the cost of repairs.

By the way, Wilkes Berre was my Dads old stompin grounds! (nine generations worth!!)
 
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Old 06-05-05, 08:26 AM
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Level joist supported floor

Next town over from Wilkes Barre!
I'll TRY to find a good engineer - haven't had much luck in that departmetn over the years! One condemned a house I was interested in buy (during occupancy inspection) then turned around and told next buyer he could repair it easily!


Fortunately no utility lines on that side of house - hopefully if its leveled to existing correct side - I won't have much damage. hitting mine is possible - my co worker delights in telling me how her grandfather walked under my house to get to the main shaft!

\Never heard of high pressure pumping - I'll check into it Thanks from Beeutiful N.E PA (largest per capita consumption of alcohol in the country ya know) probably explains a lot of the errors I find when remodeling!

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I'll bet its around Wilkes Berre, or Nanntycoke!

I would call an Engineer, there has been good results with pumping (high pressure) quick setting concrete under the footings and it will raise a house or Brick three story Apt. Building like it was on air bags. As long as it don't hit a coal shaft or the like.

But 3" or 5" lower needs to be corrected the right way, not just a quick fix. And hope for the best. Look at it this way, its going to get worse with time, even if you just level the floor on the low side, but whats it doing to other structural members of the house while it sinks. It could bust sewer or water lines, adding to the cost of repairs.
 
 

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