Yes you can install laminate flooring over even a incredibly old saggy wooden floor on a 3rd floor with a 1in drop in the middle relative to the edges of the.
How to level an old timber floor.
A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.
On the top side of the floor another fix it idea to lay down new hardwood over the existing floor.
Self leveling compound or underlayment can be poured over a wood subfloor but it.
To level the entire floor it is best to start with the two end joists.
This will expose the subfloor underneath which is where most leveling problems lie.
Clean it well with a wet dry vacuum.
The ratio of water to compound will be written on the bag.
You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings.
Use a pry bar to pull up hardwood floors one section at a time or unfasten carpet or laminate and roll it up from one end.
They have a strong lip which is then inserted into a brickwork joint or fixed on a timber or steel support.
Mix the floor leveling compound in a bucket with an electric drill and mixing attachment.
Pour the leveling compound onto the floor to.
Lay a long level downhill on the floor with one end of the level on the level part of the floor and the other end at the lowest point.
Raise the lower end of the level until the bubble is centered then measure the distance from the bottom of the level to the floor to find the depth of the dip.
Pound nails into the subfloor with a hammer and set screws slightly below the surface of the subfloor with a screwdriver.
Then a string line can be fixed to the top of these two new joists giving you the level for the joists in between.
If an engineer found no structural issues you may be able to level the floor by applying a cement based self leveling floor product such as henry level pro self leveling underlayment available.