Installing Hardwood Floors Over Tile
For years the only solution to installing hardwood floors over tile was rip it out and install the wood floor.
What Types Of Installations Over Tile? Floating Floors
The simplest in terms of getting the job done without
messy demo work
would be a floating engineered floor. Floating floors were designed for these types of applications. Styles, colors, and appearances are numerous today specifically with the leader in floating floor technology; Kahrs.
Engineered Glue Down Floor
Only in recent years have some hardwood adhesive manufacturers given the green light to gluing over ceramic, but there are some important considerations before starting the job. For a successful glue down application over older tile the single largest issue associated with failures are older loosened tiled floors. Floors cannot be glued in this condition.
Preparation before installing any glue down floor will require some additional floor work in the form of skim coating the surface that also fills in any excessive grout joints. This would be especially prominent with Saltillo or Mexican/Spanish tile. In addition, the slick surface finishes of most tiles should be roughed up to accept an adhesive bond. This can be accomplished with the use of a flooring buffer and very coarse grit paper.
Solid 3/4" Hardwood Floors
Sorry folks, but this one may be out of the question in terms of functionality. Why? In order to install a solid floor one would need a proper subfloor. Solid floors are normally nailed to wood subfloors. In this case another subfloor would have to be installed over the tile with a minimum thickness of 5/8" Exceptions may include dealing with some of the more popular solid 5/16" products. However, we urge this procedure to be handled by very experienced professionals or those that have had success with the application.
Any new subfloor increases the finished vertical height 1 1/2 inches with a solid 3/4" hardwood. Appliance clearances with kitchen installations, baseboard profiles, and door clearances may be compromised. Furthermore, attaching a new subfloor (plywood) to the can be problematic. Fasteners may crumble or loosen tile beneath, causing potential noise problems underneath. IE; crunchy sounds.
Preparation. Steps Before The Installation
For any successful installation, floor preparation is paramount, specifically with the glue down method. 
All floors have to be checked for flatness. In my first photo example above the installer checks for flatness and higher tile edges with a straight edge. Next, grinding high areas (right) so the new wood floor will sit flat once installed.
Without fixing any of these conditions the new floor will flex with the undulations caused by a tile floor that is not flat. Creaking, and snapping sounds are likely. It's best to get it right first before any major complications happen after the fact.
Common Problems. Trim Moldings Don't Work Well
Unless you have plans to install the new floor in the entire home, transitions and moldings can create problems but there are solutions. For example, let's say the new floor connects to existing carpet. Prior to the new floor addition, problems did not exist when comparing the final finished vertical height of both floor coverings. However, when a new floor is added on top of the ceramic we now run into two different finished floor heights than can pose a troublesome trip hazard. Prefinished hardwood flooring companies do not manufacture a molding for this situation.
How to Overcome the New Floor Height?
Better installers will not leave you with a problem. Shims can be installed under the carpet on the adjacent side offering a gradual ramped up effect.
