We have decided to install wood flooring in bathroom. Is it a right decision??
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I'd like to suggest an alternative: There are tile product designed to resemble wood planks. That would obviously yield a much more water-resistant floor.
TL:DR - It can be done, but requires extra attention and caution
I grew up in a house that had hardwood in pretty much every room except the basement. Hardwood is more tolerable in places like a "powder room" or half-bath, since you don't get the additional exposure to moisture associated with a shower or similar.
Even well sealed, manufactured, hardwood, T&G flooring can expand and swell with excess moisture.
I highly suggest rotating your bathmats regularly, if not daily, and if they catch water, make sure they don't sit on the floor. This will hold that moisture against the wood, prolonging the exposure, rather than allowing it to evaporate.
Also, as @mikes pointed out, any ... ammonia containing contaminants (aka pee) ... can be especially troublesome.
In the end, if you love hardwood floors like my family did, you can make it work. It's also likely that if you made this decision you're already family with the near urgent cleanup of spilled liquids, and other care that can be unique to hardwood floors.
Enjoy them, and take care of them, and hardwood floor will last a VERY long time.
If that is what you would like for your floor material than you should install wood flooring. Depending on what type of flooring will determine its longevity and maintenance schedule. Solid wood strips 3/4" thick will need to be sealed with a urethane type coating in several built up applications and then occasionally resealed. Wood laminate can be installed with if some extra precautions are taken. Most manufacturers will state each seam needs to be sealed with a glue so as to create a waterproof joint. I'd consider laminate as a last choice. If any water penetrates it will swell the fiber board bottom layer. If you want a solid long lasting floor that has a "Wood" look consider a ceramic tile! I've just recently installed a bathroom floor that used a 5/16 inch thick x 6inch W x 18 inch L ceramic tile. I was impressed as to how well it's surface texture mimicked a real pine floor wood grain. What is truly impressive is the selection as to the 'species' of wood-types available! Oak, cherry, mahogany....all made of ceramic. I am not a spokesperson or an employee for any tile manufacturer. I am totally impressed by the way they are able to reproduce in detail a floor tile that so closely resembles real wooden plank. BTW: these tile install exactly as any other ceramic tile.