We are renovating our bathroom and splashing out on a mirrored cabinet with built in lights, shaver socket etc. Problem is the one we really like the look of does not have a demister pad and I really wanted this. It does have double mirrored doors - so mirrored on the inside.
So my question is - do the mirrors on the inside of the doors steam-up?
if it has built-in lights, there will be a little residual heat which will warm it slightly after it has been on for a few minutes. Modern LEDs are very efficient so there is little waste heat.
if it is spaced off the wall somewhat, any coldness from an external wall will chill it less.
In my own bathroom, the mirror is not far from the radiator, and is spaced off the wall, so does not get very cold, and an effective extractor sucks the steam out. Your bathroom will vary, but since adding CWI I only get condensation on the window (on cold nights), and not on the tiles or mirror.
I've found that when there is no effective extractor fan, you always get condensation in a bathroom.