Subloor downward slope from exterior wall

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  #1  
Old 01-07-08, 07:54 AM
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Subloor downward slope from exterior wall

Hi Folks,

I recently removed all carpets, laminate, etc. in my 35 year old house to expose the subfloor and prepare the house to install hardwood flooring. Along one of my exterior walls, there is a noticeable downward slope away from the wall that extends 2-3 feet (i.e. the width of one sheet of the plywood subfloor). This slope extends across the entire wall of the house. I went to the basement to investigate, and it looks like the main support beam, which is completely level across the entire house, that sits on top of the foundation has settled over time. The reason I assume it has settled is that there is a small gap above the main beam in the concrete foundation where the beam rests. The supporting beam is perpendicular and to the wall in question, and directly in the middle. It seems like the floor joist that is sitting on the foundation has stayed in the same place over time while the rest of the house sunk. It looks, from looking below, like the last two floor joists from the wall have been pulled off the main support beam and are still connected to the subfloor. There is a small gap between the last two floor joists and the main support beam (not including the joist sitting on the foundation). The gap is approximately 1/4" under the first joist off the foundation wall, and 1/8" under the second joist, which explains the slope above. Can I fix this issue without having the raise the main support beam across the entire house? My first reaction was to pull the last sheet of subfloor from the wall and shave the joists to level them, but the gap between the joists and the main beam leaves me to wonder if this is the most important issue that needs to be addressed instead.

Thanks in advance!
 
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  #2  
Old 01-07-08, 05:24 PM
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I would probably try jacking the beam back into position before other remedies, such as shimming or planing joists. It might move easier than you think (or not). Clear any nails from between the joists and beam, get a healthy hydraulic jack and a post and give it a shot. Have some shims handy in case it moves, preferably steel or metal sheet of some kind. Check to make sure your not breaking anything upstairs as you go.
 
  #3  
Old 01-08-08, 06:19 AM
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Thanks. However, after doing some research, it would appear that I have the same issue as in the following link:

http://books.google.ca/books?id=iwSa...bnail#PPA52,M1

Go to page 52 for a picture.

Any thoughts on how to best address this? If I made a cut in the subfloor along the foundation wall, this cut would be approx 2-3 inches from the wall upstairs. So, I would also need some advice on how to remove/replace the 2-3" that will end up being higher than the rest of the floor upstairs IF the floor lowers as a result of the joist dropping back down on the main beam once the pressure is released.

Thanks again!
 
  #4  
Old 01-08-08, 06:34 PM
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I may not understand the situation correctly. Do your joists run parallel to, or at right angles to, the wall in question?
 
  #5  
Old 01-08-08, 07:15 PM
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Originally Posted by stpami View Post
I may not understand the situation correctly. Do your joists run parallel to, or at right angles to, the wall in question?
They run parallel. The slope gets worse as you start from the corners of the wall, and work your way towards the middle where the main beam is supporting each joist on each side. The joists look like they have been pulled off the main beam by the subfloor. I assume that the slope isn't as bad on the outer ends because the joists are embedded in the cement foundation.

Hope this clears it up a bit.
 
  #6  
Old 01-09-08, 02:00 PM
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See if this little diagram is what you've got:http://i256.photobucket.com/albums/h...ag/diydiag.jpg
If so, it sounds like the beam has dropped for some reason and bringing it back up as described in my earlier post would be the first fix. The shims would go under the beam's end to hold it up tight under the joists. The page you linked to shows a floor w/ jsts running at 90 deg to the wall with a different bearing situation. This would be more fuss to fix than what I think you actually have. Also, the subfloor ties the outside joist to the house and keeps it from flopping over so cutting the floor is probably not a good idea.
 
  #7  
Old 01-09-08, 03:24 PM
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Thanks Stpami. Your picture is correct. Are you saying that the same issue as described in my link on page 52 cannot be the same for my instance where the joists run parallel to the exterior wall instead of perpendicular? This issue I have is that the beam is perfectly level across the entire house, and this issue is not occuring at the opposite end of the house. Raising the main beam would only create the opposite effect at the other end of the house, wouldn't it? The main floor of the house extends over the foundation wall just as my link describes, and whether it's the main beam, or the joists we're talking about, couldn't both have shrunk as they dried and created the safe effect?

Another idea I had was to cut out the sloped 2-3 feet, and replace with a 3/4" subfloor. The current subfloor is 1" thick (two 1/2" pieces of plywood that are offset). With some minor shaving of the joist to level things off, it should take care of the 1/4"-1/2" that I need to lower it. Your thoughts?

Thanks again.
 

Last edited by andersp; 01-09-08 at 03:28 PM. Reason: Added text...
  #8  
Old 01-09-08, 05:26 PM
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The situation in your link, p. 52, shows subfloor running from joists to a flat sill plate on foundation. I think your house has a joist directly below the wall, supporting to the foundation, rather than just a 1-1/2" plate (correct me if I'm wrong). That sort of eliminates the shrinkage differential--shrinkage in joists would be @ the same. Also, how did you determine "level" on the beam? a 4' lvl on a 30' beam is only so accurate, and, a 1/4" difference over 30' is rather insignificant. I think I would bring the loose beam end up till everything was snug and looked good and leave it at that.
 
  #9  
Old 01-09-08, 07:39 PM
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Well, if this helps you out because I'm not sure about what you mean by sill plate, if I were to drill a hole flush with the interior foundation wall in the subfloor, the hole on the main level would be approximately 2-3 inches from the actual interior wall. So, I assume the foundation is wider than the exterior wall, and that there is a joist embeded in the foundation near the top of the exterior of the foundation wall, and one flush with the interior of the foundation (the joist I can actually see from the basement.

As for the level of the beam, I used a laser level as close the the top of and against the main support beam, and the bottom of all the joists across the entire house were the same distance to the laser.

Now, as for the looseness, I'm not sure what you mean. Every single joist is laying nicely on the main support beam across the entire house except these last two joists that are under the sloped floor. The last two joists have a space underneath them (the space is a 1/4" under the last joist before the foundation wall and 1/8" under the 2nd last) and are no longer sitting on the main beam. As I said, the subfloor looks like it "lifted" the joists off the main support beam. What is your solution for lowering these joists back onto the main support beam and leveling the subfloor above?

Thanks.
 
  #10  
Old 01-10-08, 03:39 PM
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Hmmm, things are becoming clearer, but murkier. Check your message box.
 
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