Construction/Framing - Bringing adjoining floors level with each other.

[mound]

Another one for you construction and framing wizards.

The Kitchen Build saga (Rabbit Hole!) continues!
 
If you've been following along, removing three walls to make three rooms (which were all built as additions or extensions in different decades) into one large room has brought some challenges.

The Ceilings were all in different planes and not level.  So I sistered material to the joists to bring them all down level with the lowest point in the space, and installed strapping perpendicular to prep for drywall. This was an interesting challenge, but glad I took it on. My drywall guy approves!

I've discovered though that the floors suffer from the same problem. (in hindsight I should have seen this coming!) 

Bear with me as I explain!

Reference image (this pic was taken before the ceiling was finished, but that doesn't matter for this thread)

   

The thick purple line represents the location of the original outside foundation wall of the house as built in the 60's before anything was added on. There's a cinder block foundation wall below the purple line and the blue lines are the direction the joists run.

Then in 1991 the kitchen was bumped out into the area with the green lines.  The thick green line on the right has a cinder block foundation wall below it (and used to be an exterior wall) and these joists run left to right as drawn in green.  Below this space is a ~4' crawl-space with concrete floor.  This area has a a cathedral ceiling/roof whereas the main house has a shed roof in the opposite direction which is presumably why they put the joists in that direction)

Then in 2010 the space between the kitchen bump out (green) and what was a porch off to the right (outside the photo) was filled in with what I have outlined in orange (filled in while at the same time turning the porch into real living space.) The thick orange line on the right also has a cinder block foundation wall below it and is "unexcavated crawlspace" below (i.e. dirt about 4' down)

So....

Unfortunately it seems over the 31 years since this bump out ("green") was added, it's settled at the sliding door end, such that as you walk from point "A" to "B" you are walking down-hill. It's not dramatic, but enough to feel it, and it's a full (almost exactly) 3/4" offset/slope from where the addition joined the existing house to where the sliding doors are. The whole sliding door end settled evenly, it's all level at that end left to right, just not front to back. 

The whole upper area (original house where the blue joists are drawn) is nice and flat, solid and level. The corner I've now exposed (outlined in orange) by removing the two walls is also level, but sits ~3/8" below the subfloor in the original area outlined in blue.  This corner also sags in the middle and is very bouncy (the center 2x8 joist appears to be cracked at a large knot.

So, "blue" is all good. "Orange" is level (but could use some stiffening) and is a bit too low. "Green" aligns well at point "A" but then slopes away, so at the sliders, the sub-floor in the orange area is basically flush with the finished floor in the green. (that missing chunk of hardwoods in the blue area were never installed, there used to be a base cabinet there.)

So I think the solution is effectively the same thing I did on the ceiling.  Poke holes in my plan please, or offer new suggestions!

1. Use a circular saw and guide to cut through the hardwood floor straight across along the thick purple line.
2. Carefully pry up and remove all the hardwoods in the "Green" area, clipping the staples so I can reuse most of the boards. Leave hardwoods in place in the Blue area.
3. Cut out all sub-floor plywood in the Green and Orange areas exposing all joists.
4. Use a 360* laser level and sister new 2x6 joists to all existing joists using glue and construction screws, bringing them all into the same plane level with the "blue" field at the thick purple line (level, but offset the thickness of the hardwoods and sub-floor so once built up it'll be in the same plane)
5. Apply a new skin of 3/4 or 5/8 plywood sub floor using glue and screws.
6. Install hardwoods, feathering into the blue area which was otherwise left untouched.

I had considered replacing steps 3-5 with "use a self leveling compound" but I'm not sure I can go to a full 3/4" thickness with such a material and taper it to nothing. seems messy and possibly inconsistent.

I am also partly concerned that once the floor at the sliders is 3/4" higher than it is now, the sliders might want to be removed and re-installed an inch or so higher.  I'll deal with deciding that later I suppose. 

thoughts??

[joe1086]

You're likely to lose/damage some hardwood flooring in the process. Can you get suitable replacement flooring? Do you know if the wall that settled is now stable?

I had a similar issue a couple years ago when redoing the master bath. We had a 3/4" drop over 12' resulting in water dripping off the countertops. I did the same thing...removed the subfloor and sistered in new joists to level it all out. Worked out great although since I was a crew of one it was a PITA doing it on a second floor.

[mound]

You're likely to lose/damage some hardwood flooring in the process. Can you get suitable replacement flooring? Do you know if the wall that settled is now stable?

I had a similar issue a couple years ago when redoing the master bath. We had a 3/4" drop over 12' resulting in water dripping off the countertops. I did the same thing...removed the subfloor and sistered in new joists to level it all out. Worked out great although since I was a crew of one it was a PITA doing it on a second floor.

Yup, I'm sure I'll lose a few pieces. It's readily available 3.25"x3/4" square cut red oak. (This floor was actually just put in last year before we decided to tear down the walls and open it all up. Hindsight!) 

I don't know for certain the wall has finished settling, but it's been there 31 years now so I'm going to assume it's not got further to go.

[kencombs]

I'd be concerned with the area where the sliders are. As I understand it the current floor level would be raised 3/4" or so where it meets them. How do you plan to address that?

As an alternative idea, one could jack that outside wall up from its resting place and shim between the mud sill and foundation wall to level that area. Moving up

Of course the entire wall, including the roof would raise also, but that should put it all back to it's original as-built location. Hopefully with less labor and material.
Some heavy timbers at 90deg to the joists to spread the force and one really heavy one near to an parallel to the wall and a couple or 3 jacks should do it.

[mound]

I'd be concerned with the area where the sliders are.  As I understand it the current floor level would be raised 3/4" or so where it meets them.  How do you plan to address that? 

As an alternative idea, one could jack that outside wall up from its resting place and shim between the mud sill and foundation wall to level that area.  Moving up

Of course the entire wall, including the roof would raise also, but that should put it all back to it's original as-built location.  Hopefully with less labor and material.
Some heavy timbers at 90deg to the joists to spread the force and one really heavy one near to an parallel to the wall and a couple or 3 jacks should do it.

My plan for the sliders, if it became necessary, would be to remove them and essentially re-install them an inch or so higher.. would be a PITA but doable. 
Jacking up the outside wall is also a possibility but like you said, that'd bring everything up with it - including that attached corner ("orange" in my original picture) that's already at basically the correct height, unless those two areas of structure were somehow detached from each other then re-attached after jacking up that one corner.

[kencombs]

My plan for the sliders, if it became necessary, would be to remove them and essentially re-install them an inch or so higher.. would be a PITA but doable. 
Jacking up the outside wall is also a possibility but like you said, that'd bring everything up with it - including that attached corner ("orange" in my original picture) that's already at basically the correct height, unless those two areas of structure were somehow detached from each other then re-attached after jacking up that one corner.

Since that corner was created with an add-on/remodel, it is probably just connected with nails.  So you should be able to insert a bar to separate the 2xs enough to slip a sawzall blade in there and cut the nails.  Jack and reattach.

[MstrCarpenter]

I have dealt with situations like this many times. Lots of options varying from long wedges (tapered sleepers) or varying thicknesses of plywood with Level-Lastic, to chopping the whole floor system into manageable hunks and starting fresh. Sistering the joists is somewhere in the middle, and doesn't necessarily require removing the flooring, but I have a few questions.

I see a post supporting the cathedral ceiling beam to the right of the slider. What's to the left of the slider. Is the "Green area" basically flat (we know it's not level) or is there deflection of the joists too? Is the floor solid enough as is, or should the joists be stiffer by increasing the size or shortening the span?

The "orange area is an easy fix. The specifics will, in some way, be best determined with consideration of the "green area" resolution(s).

[mound]

Sistering the joists is somewhere in the middle, and doesn't necessarily require removing the flooring, but I have a few questions.

Interesting. I can't visualize how sistering the joists to bring them higher wouldn't require removing the hardwoods and subfloors floors first.

I see a post supporting the cathedral ceiling beam to the right of the slider. What's to the left of the slider.

Yup, that post, and the beam it supports, are newly added when the walls were removed. To the left of the slider is the end of the house, corner of exterior wall. Here's a picture from the outside

   

Is the "Green area" basically flat (we know it's not level) or is there deflection of the joists too? Is the floor solid enough as is, or should the joists be stiffer by increasing the size or shortening the span?

Yes, the green area is flat, just not level and feels solid (no joist deflection that I can discern).

The "orange area is an easy fix. The specifics will, in some way, be best determined with consideration of the "green area" resolution(s).

Agreed. The orange area feels bouncy in the middle, but as I mentioned I think that's because the 2x8 joist is cracked in the center where there's a large knot. In fact aside from stiffening it, if the orange spot were the only concern, a thin layer of self leveling compound would have done the trick. It's really the green area that's of concern.

[MstrCarpenter]

Mound, I've been super busy, and it's late. But just a few more. Is that vinyl siding? Is "slider" wall 2x6 or 2x4 construction?  I doubt it, but is there 3/4" or more clearance space between the bottom of the header and the top of the slider jamb? And, do you have any idea of the header construction. 

I'm asking a bunch of questions because I'm thinking your best outcome would to have (only) the floor and sliders raised 3/4" without raising the ceiling you just spent so much time leveling. This means the beams and header must now remain at their existing elevation. (basically, some of it stays in place; some gets raised.) That's doable, but let's consider exactly where the best place for that intersection to be before we start pulling up floors.

[mound]

Mound, I've been super busy, and it's late. But just a few more. Is that vinyl siding? Is "slider" wall 2x6 or 2x4 construction?  I doubt it, but is there 3/4" or more clearance space between the bottom of the header and the top of the slider jamb? And, do you have any idea of the header construction. 

I'm asking a bunch of questions because I'm thinking your best outcome would to have (only) the floor and sliders raised 3/4" without raising the ceiling you just spent so much time leveling. This means the beams and header must now remain at their existing elevation. (basically, some of it stays in place; some gets raised.) That's doable, but let's consider exactly where the best place for that intersection to be before we start pulling up floors.

Thanks, no worries, we're all busy! Your input is always welcome and appreciated. 

Yes, it's vinyl siding.  I'm not sure if the slider wall is 2x6 or 2x4 as I write this, I'll have to go look more closely.  I'm also concerned the vinyl siding was added after the house settled (if I put my laser level outside on the siding, the siding is level across the whole house, not just this section.)  so to jack up this corner of the house would probably push the siding out of level in that area, meaning it'd have to be stripped and re-installed.  It sounds like you're saying the best outcome does not involve jacking anything up, rather, raising the floor and sliders (which I think goes back to the plan I had originally outlined of cutting out some floor, sistering joists as needed and re-installing?)

I did pull back the trim on top of the sliders and can see there's about a 1/2" to 5/8" gap filled with insulation between the top of the slider and the header.. 

The architect who spec'd the beam structure has a builder buddy who recently jacked up a corner of his own house to fix a sloping floor. That guy is going to stop over next week to give me his thoughts.