Hi,
13 years ago, I moved in a cottage that was built around 1979.
On the 2nd floor, we have a guest bedroom that still had original wall to wall carpet. This room gets little use and no improvements were performed since then.

I recently emptied the room for what I thought was a weekend project; removing carpet and laying laminate floating floor. As soon as the furniture was out of the way, we felt going up when walking the last third of the room.

Subfloor is 3/4" plywood nailed to 2x10 floor joists. The room is about 12 x 13.
Using a circular saw, I removed about 2/3 of the subfloor, here's what I found:
The first 7 floor joist are level to each other, but the last 3 joist (including last one that's under the outside wall), while also level to themselves, are almost a full inch higher, hence the title of my post.

I don't know if such a big difference in plane could be caused by crown up/down mistake, but I now think it is not a concidence this room was carpeted, while most of the house was hardwood floored.

So, the last third of the room is higher than the rest. If I bring up the lower 2/3 of the room, it will create a one inch step entering the room, not to mention extra work for entry and closet door.

It seems more logical to bring down the high third of the room, but I am puzzled as how I'll manage, considering the last joist in the high part is under the outside wall.

One idea would be to reinstall the high portion of the subfloor flush to the joist, instead of above it like rest of room. Anyone ever done something like this?

 

I have abandoned my last (crazy) idea to insert subfloor within joist.

Instead I'll be shimming the middle joists just before the sharp step-up as to smooth out the height difference. This way, the floor feels much flatter, if not level.

 

What do you think caused the slope? I doubt it had anything to do with the crowns on the joists. Look at the ceiling on the first floor. Does that tell you anything?
Your post made me think of my grandparents' top floor apartment in Park Slope, Brooklyn. The master bedroom floor which was at the front, was on a huge slope. That was in the 60s & it's probably still like that.

 

Why not just rip the high joists to the level of the lower ones? Snap some chalk lines, and make sawdust. If the joists are close to being over-spanned, then forget about the idea. If not, just go for it. The last one under the wall can be left as is, with a new sistered joist added to it at the lower, correct grade.

Trying to make up a full 1" in just a few joist spaces will not feel "level". Trust me on that.

 

To Pulpo: I think it was just built like that, subfloor layed on a monday morning or late friday. I am sure at one point they found out, but by then that 2nd floor was all layed down and 2nd story walls already built above the faulty subfloor.
Nah, we'lll just carpet this room, they must have said...
btw, the ceiling of the room just under looks ok, they must have corrected with extra forens

 

To BridgeMan45:
It it still an option for me to shave those high joists, albeit the left-right walls will be in my way when I get cutting close to them.

My handyman neighbour is coming back from vacation this weekend; I will have him take a look and likely borrow some elbow grease.

Also, it would be a great opportunity to do some lighting improvement to the home office room below while the sub floor above it is gone. Running wire without punching access holes in finished ceiling at every other joists sounds good to me.

Thanks for your input!
ps: what do you mean by over-spanning joist

 

Till Bridgeman checks back in...over spanning means, if the lumber is sufficient for the span. For instance, a 2x6 can span about 11' unsupported. The thicker your lumber, the more clear span you can have. At 12' and 2x10, you should be OK. Cut off 1" of that 2x10, your span reduces accordingly. I'll let him address that, too.

 

Well thx for the explanation, my joists are spaced 16" center and they're 2x10 (nominal)

 

Just a quick update.

The first of the 3 high joist was slightly higher then the last two at the end of the room. We shaved off 1/4" or so off of just that one, and progressively shimmed up the 3 previous joist (in the middle of the room), to achieve an almost perfect plane.
Now ready to lay down new flooring bright and early tomorrow!

Thx for your help.

 

Glad we were of some help. C'mon back anytime!