Slanted Floor Joists

A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.

Slanted floor joists. You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings. Joists that are 2 x 10 at the same spacing are suitable for spans of up to about 16 feet. On the top side of the floor another fix it idea to lay down new hardwood over the existing floor. Thre ways to fix a sagging or sloping floor.

Common sense tells you that large floor joists can carry more load and spacing joists closer together also increases the load bearing capacity of a floor. The extra two inches of vertical distance when a floor is framed with 2 x 10 joists rather than 2 x 12s can be quite important for example. But larger is not always better when builders are constructing a home or adding a room addition. Assessing the design of a floor system usually requires a professional engineer but as a gross general guide joists that are 2 x 8 and are set 16 inches apart standard are suitable for spans of up to about 12 feet.

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. 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.