Our kitchen floor is sagging in places from 1/4" to 1/2". Is there a way to determine about how long it took for this to happen? Could the joists sag this much since September, 2007?

Why is that important? It could have happened overnight, or over time. If everything was built right and the foundation was sound, it will not sag. What happened in Sept. of 2007?

Jaz

We had laminate installed over hardwood floor and old linoleum in Sept, 2007. Just before this Christmas, we noticed the edges were coming up slightly. Repair guy from carpet store where we bought laminate said that was happening because some joists were sagging making floor uneven. He said that we needed to either put down a leveling concoction before reinstalling the laminate or jack up the joists. My irritation lies in the fact that within just 15 months, we paid to have the laminate installed, then ripped up and reinstalled with the proper leveling agent. Shouldn't they have known the first time that the floor was uneven and would come up?
We've owned the house for 7 years; it is probably 20+ years old. There are very few hairline cracks anywhere in the walls or ceilings. No explosions, etc. to cause sudden settling of foundation.
I'd like to know if there is a case for making a plea that they should not have installed the flooring in the first case like they did, if the floor was already uneven.

Clarification: we haven't had the new laminate installed yet. We're deciding whether to go with the jacking or just spread the leveling stuff under the laminate.

Very confusing here how many floors were involved hear Id seems to be it was leveled and its not level and it is down now it not level and now its I didn't put not installed yet so which is it?
There are two possible things hear. If the joist were set in new with the backs up or down in different sequences then a deflection like that could occur. When a carpentry doesn't site down the new 1 1/2 side with his eye to keep the Hump up in the joist and just picked off the pile and 3 or so joist were set down for the floor with a 1/4 deflection down and the others were up 1/4 of an inch there's the 1/2 dip from new. Check to see if you can the joist should be 2x10s 16" on center
The floor over years can easily deflect what you have. The one situation here is how fussy was the installers of the floor. Was it string lined to look for deflections. Notice I didn't say level. In an older home especially the house moves and shifts. The floor overall levelness could easily be out 1/2 from new. Now if the dip is in the center and in a smaller area it should have been address. So to back to your questions look at joist under floor and check for size joist as I said above. You don't necessary want to jack up the floor because of the joist are old and dried and set that way. To jack a joist that is evenly low from end to end can be raised if its now straight and the whole joist is low. If it has deflection and its not a LONG joist to re curve then just sister/double up the joist(s) to lock in its position now and the sister joist will keep it from moving more. Then you can use the floor leveling mud to get it flatter. If you do have the 2x10 16 centers and know for sure the sub floor above that is 3/4 sub floor than just level the floor as long as joist are set on the foundation plates. This should give you all of your options other than tearing up the whole floor and sub floor and shimming it up that way, One other possible way is to get shims between the existing sub floor and joist but that's to difficult to get it tuned in well and then a squeak could develop.


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