The cause is usually settling or shifting of the foundation underneath the floors.
Uneven floors in new house.
You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings.
Sloping floors are most often caused by normal and acceptable deflection bend in the wood joists which comprise the floor structure.
On the top side of the floor another fix it idea to lay down new hardwood over the existing floor.
A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.
Many older homes have problems with sloping and sagging floors.
A floor that sags towards the center of the house.
Mold and or rot in your crawl space.
If you re a home buyer seeking that perfect historic or old house uneven floors are something you ll have to deal with sooner or later and even if a home was recently built as it gets older the floors will become less level while you own it.
However when looking at a brand new home i have a higher standard that i inspect to.
Though a sloped floor might indeed bring some character to a house some of the issues that can cause them can lead to other problems down the road.
Cracks uneven floors and doors that don t fit correctly are signs of poor workmanship and need correction.
Uneven floors are rarely caused by problems with the floor itself.
Sloped floors are common in older homes and even in homes as new as 15 to 30 years.