Gap at the top ... may be better to boost it up at the bottom instead of placing a filler at the top. Settle on a unit first, then check the installation instructions for dimension requirements.

She is headed in the right direction. Great update badgergal. Good use of space and safer microwave location. Much better exhaust fan solution as well. the overall job looks very professional. Each application has to be handled within the measurements and constraints of the space and very detailed measurements of both the appliances and space are critical to success. Don't forget "trim kits" too if needed. Buy the ones that are made for the microwave. Nothing else works as well.

Thanks Flo. The double oven options available in 24” width were actually all taller than what she was replacing and she would have had to alter that cabinet and doors above the unit. Since she wanted to get rid of the over the cooktop microwave but not give up counter space for one she went with too separate units in place of her double oven.

andyscott, I didn’t read your post carefully enough at first, to see that you want to replace the current double ovens with a combo oven/microwave unit. . So my daughter’s situation was actually different from yours

Never buy a combo MW ans wall oven It is best to have those as sperate itmes since the MW will need to be replaced long before the oven It will take a bit of work but that is the best solution.

Separate appliances. Wall oven cabinet, another cabinet above for microwave. I have a 1100 watt Oster, off-the-shelf from Walmart, $100. Built-in micros are expensive because they must be vented at the front of the unit. Countertop models (mine) require airflow space of several inches on one side (the side with the vent).

Separate units will require the addition of a new 110 circuit from the panel.

Patricia makes a good point

Having seen two cases of combo units with broken MWs, I think this is not a good idea. Get separate units.

Thanks, everyone for your advice! I decided to drop the idea of the combo and am looking at having a separate oven and microwave. Built-in microwaves are super expensive for some reason, but it looks like Panasonic has reasonable prices including the trim kit.