This is definitely a difficult question to field, as the common perception is that real wood is always better than MDF. The truth is that MDF can be better in the bathroom environment if finished properly. MDF will not expand or contract nearly as much with changes in the relative humidity of the air as real wood, however if the moisture is allowed to penetrate the surface of the MDF then you have a swelling problem. As long as the surface of the cabinet is well protected, you should not have any issues with MDF changing shape, warping, or shrinking.
Real wood tends to expand and contract greatly with the change in humidity common in a bathroom. When it does, it can crack the finish and allow moisture to penetrate, causing further damage. On the other hand, real wood can shrink in dry conditions and cause uncontrolled warping.
Both are good options if finished correctly. MDF gets a bad reputation, but it can actually be a high-quality material – and it’s much more inexpensive.
What’s your opinion/experience on the matter?
Randy Ritzenthaler