[schwim]

Hi there everyone,

My wife has finally cornered me into continuing my home renovation(the guilt of having my family sit in a room with stud walls has begun to keep me up at night), so I'll be visiting often again :)

My first task is firring the ceiling in our living room. Originally, it had no ceiling, being part of an open floor plan. I closed it in to get the space upstairs and also so the people watching TV in the livingroom don't wake up the person(me) sleeping in the master bedroom.

Original stairwell to livingroom:



Framing for floor. Shot taken in same location:



Living room ceiling meeting the old cantilevered portion. This is important later:



Now for my problem. Due to variances in joist material in the new section of ceiling, I had to shim some of the joists to level the floor above. If this was the only problem, I would simply fasten 2x4's to the side of the offending joists as I had done in the kitchen. Unfortunately, that isn't the only problem.

You can see in the last photo, the old cantilevered section meeting the new floor. Due to a single sill plate and poor planning, the cantilevered section is in the shape of a smile, meaning it has a substantial(1"+) dip in the center. I braced the floor below and used a hydraulic jack to get as much out of it as I could when mating it to the new floor joist, but a lot still remains.

So, I'm dealing with a few oddball joists in the new section and a curving & dipping ceiling in the old section.

My original plan was to purchase enough 2x4's to mount to the side of every joist, both new and old, pull lines across the joists, mark the side of the joists at the point in which the whole ceiling drops 1", then fasten the 2x4's at the proper marks. Two things bother me about this:

1) The new section of joists are at 12" OC. It's gonna be tough to fasten the 2x4's securely due to the tightness of the bays. I can do it, but it would require a lot of finagling.

2) It seems to me that this is a poor method of leveling the ceiling. I would think floating something(1x4 or thinned 2x4?) below the joists would allow me to shim at each joist intersection, making the leveling process easier and it would save a bit of money because I wouldn't be restricted to 12" spacing or the odd perpendicular joist layout.

So my questions:

1) What's the best way to level a ceiling, taking my problems into account?

2) I've pulled lines across the ceiling, but it's hardly a foolproof method of finding level. What's the best method of determining level?

I'm very sorry for the rambling post but appreciate any input you may have.

thanks,
json

[schwim]

Have I finally found an issue so obscure that nobody has an idea?

I should get some award for this, right? With fancy lettering and faux marble base?

I can provide the ship-to address once it's ready.

Thanks,
Json

[hkstroud]

No, you just have to give us time.

[schwim]

Hi there Harold and thanks very much for your reply.

The smile is actually at the end of the cantilevered portion that meets the perpendicular floor joists. The joists at the load bearing wall is actually a straight shot.

You are correct that the new joists also have some variance between them. The floor above is perfectly level, but at the expense of the ceiling below. I knew I'd have to shim, but wasn't sure what method I would use.

Please let me know if I need to provide some more pics or info and thanks again for taking the time to help.

[hkstroud]

So the smile is at the end of the old joist which are perpendicular to the new joist which you installed.

How much variance is there between the lower edges of the new joist?
What size are the new joist, and what's the span and why did you put them on 12 " centers.
What's the length of the old canter levered joist.

[schwim]

1) The variance between the new(at it's worst) is almost 1/2", due to 1/4" variance in lumber compounded by the sill that they sit on.
2) The dimension of the joists are 2x10 and they span 13 1/2 ft.
3) The reason I put them at such a tight spacing is because of the stud spacing on what would be the load bearing external wall. Here's a pic:



The existing windows in the wall placed the studs at 24". On each side of the full stud, there are jack studs that hold the short run of sill plate over each window. I didn't want 24" spacing on floor joists, so I placed one set on top of each jack stud, then placed another joist mid-span, setting my spacing at exactly 12". Here's another shot of the floor joist placement:



The cantilevered portion extends about 6' past the load bearing wall.

The worst part of the ceiling is where the new ceiling meets the old. Aside from the smile, the actual dimensions are slightly different as well as the fact that the original builder was a little less that adamant that everything be level and plumb.

[hkstroud]

"The worst part of the ceiling is where the new ceiling meets the old."

That should be the easy part.
Step 1.
Pull a string across the new joist at each end. I suspect you will find them pretty much even. Pull a string across the new joist in the center of the joist. If the joist to which the old joist is attached, is even with or below all other joist, you are in good shape. You are not necessarily trying to make them level, you are trying to make them flat. If the new joist, to which the old joist are attached is above the line, nail a 2x4 along side the bottom to make it even with your straight line across the new joist.

Step 2
All of the old joist where the bottom edge is more than 1/4" above the bottom edge of the new, perpendicular joist. I assume that no of the old joist are below the new joist. Cut a 2x4 and lay one end on the wall plate and nail the other end flush with the bottom edge of the new joist. No need to worry about anything less than 1/4". You will be nailing your drywall ceiling to the new joist and to the old joist about 16" away. At 16" away from the new joist the gap between the drywall and the joist will probably be 1/8" or less. You will also be using drywall adhesive on the joist which will fill that gap and harden. Drywall screws will close that gap slightly, probably no more than 1/16". The ceiling surface may not be perfectly flat but not enough to be noticeable.

Step 3

Get some 1/2" plywood, some 1/4 plywood and some 1/4" luan. Rip down to 1 1/2" wide strips. 1/4" luan is 3/16" thick.

Pull some strings across the new joist about every 2 to 3 feet.

Where a joist is 1/2" above the string, tack a strip of 1/2 plywood, extending out to the point where the gap is 3/8". From the end of the 1/2 ply to the point where the gap is 3/8" tack two strips of luan. From the 3/8" point to the 1/4" point tack a strip of 1/4 ply. From the 1/4" point to the 3/16 point, tack a strip of luan. This puts you within a 3/16" tolerance.

Put a small, very small, bead of construction adhesive on each strip and tack into place with a few finish nails. The construction adhesive and finish nails are only to hold the spacers in place until you install the ceiling. The drywall screws will pass through and be secured to the joist themselves.

A tedious task, probably take you a couple or three hours. A pneumatic staple gun would be handy. If there is a Harbor Freight near you, they sell a cheap one that works very well, in the $20 range.