A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.
Sagging floor 2nd story.
Foundation issues deteriorating wood supports especially sills which rest on the foundation footer improperly installed joists or sub floors and other issues can all cause a floor to slope or sag.
Termites can rot or damage the joists typically made of wood rendering the pieces unable to hold up the floor.
There are several problems that can cause a sagging or sloping floor which is one of the reasons why fixing a sloping floor is difficult.
Sagging floors are often the symptoms of structural damage to the floor joists below the surface.
If a load bearing wall is removed on the first floor then the second story floor joist or trusses may drop down in the area where the load bearing wall was removed.
Isolated to first floor isolated to second floor both floors.
A dozen metal rafter ties.
On the top side of the floor another fix it idea to lay down new hardwood over the existing floor.
Although most floors slope it is important to know how much and why.
The average person can sense if a floor slopes 1 inch in 10 feet and sloping floors or sagging floors are often one of the warning signs that structural engineers look for when analyzing a house.
This could be a sign of serious structural damage due to foundation settlement.
You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings.
Two four by six wood beams of 8 to 10 feet each as straight as you can find them.
Thre ways to fix a sagging or sloping floor.
Temporary adjustable floor jack tall enough to reach the floor joists from the basement floor.
Sloping to one direction.
Load bearing wall removed or altered on first floor.
Depending upon the conditions it is possible to strengthen or repair existing framing members such as floor joists or roof rafters by adding reinforcing material sandwiching the member on either side with plywood is sometimes worthwhile but the plywood must be installed correctly for greatest strength.
How can we evaluate whether the floors need reinforcement and if so what is the best way to do this.
The first and second floors in our house seem overly bouncy and sag toward the middle.
Four or five beams of the same size as your floor joists typically two by eight and as long as the room.
Common reasons for sloping or sagging second story floors.
If the floor is sagging visibly in the middle or is very bouncy you may want to reinforce the floor to eliminate the sag and reduce the bounciness.