Leveling Main Level

[John]

I am about to begin reflooring the main level in the house. One thing I know I'll have issues with is the fact that the floor is not level. I could see/feel dips and rises through the carpet, so I know I will have to adjust the underfloor to some extent.

I did a search online for some ideas of how to best level the floor, but none of the articles I found were very good. For example, what's the maximum thickness of leveling compound you should use? When should you shim instead of using leveling compound, etc? What do you do about rises right next to a wall (assuming the floor board actually goes under the wall? What unexpected special cases might I run into? Nails or screws? What about squeeks? etc

This is for the main level of the house, so I want to do this properly, but I also have a time constraint. I'd rather not run into situations at the last minute that I hadn't thought of. Does anyone know of any good articles on the subject, or can anyone offer any advice?

Thanks

John

[bob haller]

get a structural engineers opinion if the main level has standard floor construction.

if its woood you might have termites or carpenter ants weakening your floors

[aemeijers]

I'll second that bigtime. If the main floor is wavy, you start looking in the basement. If you don't have the skill set to know what to look for, pay somebody who does. If you don't want to pay for a 'real' engineer, a gray-haired semi-retired master carpenter would probably be good enough.

[EXT]

I had a problem where an addition met an older area of the house, there was a slight rise over a foundation wall and a drop on one side. I used leveling compound to level the floor after using a #36 grit belt sander to reduce the rise. Where I needed more than 3/4" of filler I glued and power nailed in plywood filler pieces to reduce the amount of filler needed and to add to the floor stiffness. Worked like a dream. Topped it all with 1/4" firply glued down the the old plywood floor and filler. This gave a flat, strong and level surface to nail the hardwood flooring onto.

[Evan]

ROFL... So you fixed the symptom but didn't correct the problem...

How many times are you going to keep adding leveling compound ?

~~ Evan

[Evan]

@John:

You need to determine why your floor is "wavy"...

You could have uneven settling, problems with the building being under-structured for the load or issues with the methods used to attach the structural members together when the home was built which are now weakening things...

Joists should be adequately supported by resting on the foundation or by means of being attached to a beam using a joist hanger...

If it is your joists which are sagging due to age you can try sistering new joists next to the older failing ones...

This is something that to do correctly is not a DIY task unless you are an experienced carpenter...

~~ Evan

[EXT]

No more adding. The problem was caused by a ridge forming when new wet joists were installed next to old dried joists. They started out perfectly level but as the new ones dried out they shrunk in height. They couldn't be jacked up to level them with the old joists because they were nailed and bolted in place with many utility items in the way. Originally carpeted, it didn't become apparent until the carpet was removed. The floor needed leveling in order to install hardwood flooring which would not be able to negotiate the ridge.

[John]

The bumps I have are not huge, its just that they would be visible if I have a nice shiny floor on top of them, and I don't want to go through all the work of putting a new floor on if I'm going to be disappointed at the end. Having taken the carpet off, it seems my problems are limited to one specific area, which is below the stairwell. There aren't any ants, molds, or other alarming things in the area -- I can see some of the joists from below. It just looks like there was some shifting over the years, but I'll know more once I take the actual floor board off. There is another section, right beside the main supporting wall there is a bit of a dip down. That's a little more concerning, but again, I'll know more once I take those floor boards off as well. It looks like I will have to reinforce the area underneath a bit before I continue though regardless.

John

[Evan]

Umm... When solving "dipping floors" it is actually much more effective to examine the problem from below so you can see which structural elements aren't doing their jobs properly or have settled/become detached/bowing/etc. as it is *impossible* to see those defects from above the floor even if you remove the finished layer of flooring to expose the sub-floor...

~~ Evan

[willshak]

John wrote the following:

Getting in late on the discussion. After my house was built, I noticed a distinct hump in the LR floor. Tested with a level and various smooth balls that rolled away from the hump in all directions. It seems that one floor joist was installed correctly with the hump side up, but the hump was much greater than normal. I went down in the basement and found the offending joist. I then took a reciprocating saw and made 3 cuts maybe 6" apart in the center of the offending joist from the bottom to about 1" from the top of the joist. Next, I went back to the LR and jumped on the floor above the offending joist. I heard a crack, and the floor was checked with the level and the ball, and was level. I then sistered a 2x6 to the cracked joist.