When working in expansive soils such as clay and other soils that expand with moisture content, you must take special precautions to avoid structural damage to the foundation and basement walls. One of these precautions is floating walls. A floating wall is not joined at the top and bottom like most walls. A floating wall can move with the house and prevents cracks from opening up in the floor, foundation and walls as the moisture content in the soil changes.

Basement floating walls are usually attached to first floor floor joists and then nailed into the floor to leave a gap under the wall. This space is covered by skirting boards and cannot be seen.

A reverse floating wall is attached to the floor. You place the flooring on the base plate on the floor and nail it on top so the wall is stable but only attached at the bottom. This is done on wet walls to keep the pipe stable. The open space is at the top of the walls and is covered by molding. You can cover the entire wall with sheetrock, but be careful to leave the top open for movement. This means you can’t attach the drywall to the wall all the way to the top or it will crack as the wall moves with changes in moisture in the soil.

For reverse floating walls, follow the basic instructions for floating a wall, but instead of hanging the wall from the floor joist, you’ll attach the floor to the base plate and the spike to the top plate. Make sure your wall is plumb. If you don’t have an exactly square wall, it will cause you problems. A 4 ½ inch gap is needed at the top of the wall. The wall should also be nailed the same way as a regular floating wall, just at the top instead of the bottom. See the floating wall instructions for more information.

To cover the open area at the top of the wall, you can use molding. Many people do not like the look of the molding around the ceiling. If you want alternatives, you may want to consider having a drop ceiling that can move with the walls and floor. You would have to attach the roof frame to the wall frames. When the house breathes, your entire room will move and you won’t notice it.