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Very Uneven Subfloor for Solid Hardwood


fonneousse's Avatar
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08-04-12, 06:39 PM   #1  
Very Uneven Subfloor for Solid Hardwood

I'm trying to prep my subfloor where I'm going to install solid 3/4" 5" tigerwood using 2" cleats. My issue is that there is a HUGE drop in part of the floor, where it drops a full inch in three feet, and then levels out again, so I have a large part of the subfloor that is 1" lower than the rest.

How I can best fix this? I have a bunch of cedar planks that I thought I could possibly run across the floor where it is 1" lower, and then use roofing shingles to fix the dip, but I'm not sure if the cedar will take a cleat.

Any thoughts or suggestions would be much much appreciated!

 
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08-05-12, 04:42 AM   #2  
I would fix the dip in the subfloor instead of trying to just fill it in with shingles. I would cut out that section of subfloor. Once its up you can better see what's underneath and why the floor sagged and devise a repair plan.

Is the floor springy or bouncy? Does it flex as you walk over the area?

 
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08-05-12, 10:38 AM   #3  
Dane's right. Fix the floor, or the support below the floor (my choice). I feel either a sill has rotted out causing a dip in the outside wall and the main beam stayed firm, or you have joist problems that all need correction before you sink your money in the tigerwood flooring. The shims you suggest is a bandaid on hear surgery.

 
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08-05-12, 08:48 PM   #4  
poop

You guys were right. I had already gone into the crawl space, and the joists looked fine on the outside wall, but I went back down and looked at the other side, where it is connected to a steel i-beam, and lo and behold, there are five joists that have cracked along the sill plate on top of the i-beam. It looks like they only put the joists 1.5" over the sill, which is to code, but over the past 25 years, apparently it wasn't enough.

Now, any thoughts on how I can fix this? I'm guessing I have to sister joist each cracked joist...

 
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08-06-12, 03:52 AM   #5  
Can you post a couple of pix of this? I know......another road trip under the house. It sure would help us see what you see, though. http://www.doityourself.com/forum/el...your-post.html

 
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08-06-12, 02:15 PM   #6  
A Bit more info

So, here are a couple pictures. I'm wondering if possibly the cracks aren't from old settlement, and I can just get away with ripping off the subfloor, and shimming up a new subfloor at the right height.

Thoughts?

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08-06-12, 02:19 PM   #7  
One more picture.

Here's a picture of another joist where you can see that the wood has actually cracked.

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08-06-12, 04:21 PM   #8  
I think you need to do some joist sistering and try to jack everything back to it's original elevation. In cases like this, especially when the floor is going to be redone, I rip/cut out the sub flooring to create a pretty large hole from which to work. I usually find it much easier than working from down below where everything has to be brought in/out via a long crawl. It looks like your subflooring has been glued down which will make removing it difficult so you might be stuck working from below.

 
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08-06-12, 05:50 PM   #9  
In the first picture it appears the joist is crushed on the bottom. Is that the case? The splitting was caused by an ill placed nail and brittle wood. Probably not a deal breaker. I am concerned about the crushed wood, however. Are there more in this area that show this problem? Sistering after jacking the floor as Dane presents is the best solution.

 
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08-06-12, 11:03 PM   #10  
thanks again guys for all your help!

there are actually five that are "crushed" and three more with cracks in them that have resulted in the joists sinking over half an inch. I'm concerned that if I jack up the joists and sister-joist them that I'm going to cause cracking through all my walls. Is there a way to prevent this?

 
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08-07-12, 03:14 AM   #11  
If you do the lift gradually over time, you will give the house time to settle around the lift. That is not to say you may not have sheetrock problems. If you don't have them now, you won't have them after the lift, in all likelihood, since the sinking was after the sheetrock was finished. I had much rather patch and repaint sheetrock and have my house back like it should be than to leave this and chance it getting worse. Is there an inordinate amount of weight on that side of the house, like a fireplace? I don't understand why those joists are crushing like that. I have seldom seen it in newer construction as yours. 1922 homes, sure. This is interesting.

 
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08-07-12, 06:02 AM   #12  
I've jacked many, many houses and cracking is much less a problem than you would think. It all depends on how much it has sagged and over how large an area. As Chandler mentioned jacking slowly can do a lot to alleviate cracking.

First, always work safely. Be aware that you are jacking with many tons of pressure so if a spacer block or jack kicks out you don't want to get hit. Be ready for some creaking, and popping sounds. It's normal but can be unnerving especially in a very tight crawl space.

I like to use a series of hydraulic bottle jacks spread across the area to be jacked. Take up pressure on them all, maybe one pump at a time. Go up above and lay a long straight board across the floor to see how much you have to go. This going up to check is often enough time to let the house snap, crackle and pop as it adjusts to the jacking. Obviously you will have to do more jacking in the lowest spot and less near the edges of the damaged area.

 
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08-07-12, 11:10 AM   #13  
Weight and other things

Again, thanks for the info guys.

@Chandler: Where all of the floor joists have buckled, I have a washer, dryer, water heater and boiler, so I think that's probably what did it.

I just spoke to a rental co about renting some bottle jacks to raise the floor, and they told me that because of the height of my crawl space (3 ft), they recommend I actually buy a screw jack from home depot and raise it up with that and then I can sister joist it and leave the screw jack under the house. there are already two screw jacks along the i-beam, but I wasn't sure if I can use the screw jack to raise up the joists, or if I should go with your original idea about the bottle jacks.

 
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08-07-12, 11:52 AM   #14  
I create a "temporary footer" on the ground of the crawl space of solid cement blocks or heavy timbers (4x6 or 6x6) trying to get about a one foot square footer area but you may need to go bigger if the ground is soft. It's also a good idea to have a good block of wood under the jack if setting it on concrete blocks to help spread out the load.

Set the jack on top of your temporary footer. Then I measure from the top of the jack to where I need to jack. Then I cut a piece of 4x4 about an inch shorter. I put a piece of steel on top of the jack then cut 4x4 and finally another plate of steel on top to go between the cut 4x4 and the joist. The steel plates spread the load out so you don't try to shove the little round top of the jack through the 4x4.

You can usually get scrap steel pieces for free from welding and metal fabricating shops from their scrap pile. Just pieces about 4" square and the shape and exact size is not important. Thick stuff is better. 1/4" to 1/2" thick pieces are my favorite but stuff as thin as 1/8" (7ga) still helps.

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If you can't get enough jacks to put a jack in every location you can position your jack off center on your temporary footer. Jack a bit. Then stack blocks of wood to fill the height needed to support the joist temporarily. More pieces of scrap steel help to give that extra 1/8" or 1/4" of height you might need. Then back off the jack and move it to a different location. Then you can come back to your temporary post and jack some more, insert more shims/spacers, then move your jack somewhere else. It sounds like a lot of work but it goes surprisingly quick if you have an ample supply of wood blocks and steel shim pieces.

Another trick if you are short on jacks is to temporarily nail or screw a 4x6 or 6x6 to the bottom of the joists you need to jack. Then you can place your jack in between joists and raise two joists with one jack. This is also nice since the jacking force is spread along the length of the timber which helps smooth out the force.

 
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08-07-12, 02:24 PM   #15  
Where all of the floor joists have buckled, I have a washer, dryer, water heater and boiler, so I think that's probably what did it.
I doubt it, but anything is possible. That is a normal load for a house. That is why I was asking about heavy loads such as an unsupported fireplace. Now that would do it. I have never seen such squishing with normal load. You are on the right path, now. Keep at it and let us know if we can help.

 
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