| Vinyl floors are typically laid over particleboard underlayment, which absorbs water like a sponge and then swells up. |
| If, however, the floor is off level, you will need to fill in the low areas before the underlayment is applied, to create a level floor. |
| Hopefully they did not do anything silly like glue the underlayment to the hardwood flooring. |
| Never use the foam underlayment with moisture barrier on wood floors or wood subfloors. |
| If the floor is concrete lay out the foam underlayment with moisture barrier with the membrane flap extended out onto the sub floor. |
| Use a leveling compound in all the low and dished areas, and then allow it to dry before installing the underlayment. |
