Some points on the engineered flooring that come to mind.
- At 3/8" thick that means it's the lower cost stuff and will have a really thin top veneer layer. More easily damaged and not repairable.
- At 3/8" thick you can or will likely run into thickness problems like under entry door sill, under cabinet doors, drawers, etc.
- At 3/8" thick as opposed to 5/8" or thicker, it will have fewer plies (layers) and will be more susceptible to damage from humidity changes.
- Engineered hardwood flooring is much more easily damaged from dropping things on it, dog's nails, walking around on dirt & grit tracked in from outside, etc.
- The edge abutting a tub or shower could be a problem in keeping moisture out while still allowing the floor to move.
- The greatest concern would be humidity. Engineered flooring will still shrink and expand somewhat and it's very important to maintain humidity within a certain range. Manufacturers state that it should be kept within 30-50%. Due to the wide humidity level extremes RVs experience from summer to winter, that's not possible (in a house that's easy once it's built and occupied and heating and/or A/C is running). If you travel around the country, you could experience low humidity in one region and high in another. It's also very important to maintain the same humidity level on both sides of the engineered flooring and that's not possible either. The top finish layer can shrink and expand at a different rate than the substrate and some wood species could exacerbate damage from moisture changes. Failure to control the humidity level can result in serious and permanent damage.
- You should make the flooring fully floating by using the interlocking type of engineered hardwood and not glue it down to the subfloor or glue the joints together.
Interlocking vinyl plank laminate avoids the pitfalls of engineered hardwood and is the way to go in a TT for a retrofit...