Microwave ovens in purpose built cupboards

Hi, I have a microwave on the end of a cupboard. When i cook something with lots of water (stewing apples etc) it is dripping with steam at the end when I open the door -which is expected.
But some steam must come through the vent holes at the back, as due to limited space at the time I had a wall unit backed up against it for a while, and being chip board it ended up a bit damp and when like weetbixs. Thankfully only a small area so not to big a problem.

So I was thinking with microwaves put into specially built cupboards over ovens or where ever in kitchens now days, is there ever a problem with steam built up from the vents at the back of the microwave? since they are often very fitted into the cupboards with not much air space.

Also put this in recipes board.

I have had my microwave in a purpose built cupboard over the oven for almost 5 years and don't have a problem. However, the "hole" is quite a bit bigger than the microwave and I never push it right to the back so it seems there is plenty of ventilation round it. I do, obviously, life out the microwave from time to time to clean the shelf and no signs of damp so to repeat myself I think it just needs to be well ventilated.

I am pretty sure that the cupboard above my microwave is shorter (front to back) and therefore there is a vent to take the moisture. There is also a similar vent behind the built in fridge.
You could call into a kitchen place to "discuss your new kitchen design"

I recall that my microwave requires 50mm air space on sides, back and top.

Your message made me check ours, our microwave is in our pantry and we don't have any problem, it has limited space above and at sides but plenty at back and everything is as dry as.

This, google the clearance your microwave needs to operated safely. If its in the correct amount of space, the condensation/moisture will not be happening. I think your microwave is either too big for the space, or you have no ventilation at the back or top.