Over-the-range (OTR) microwave ovens are especially popular in smaller kitchens because they preserve counter space that would otherwise be taken up by an appliance. OTRs usually incorporate task lighting for the cooktop and an exhaust fan that either vents smoke and odors to the outside or runs them through filters and releases the air back into the kitchen. Determining how much space you need between the top of the range and the bottom of the microwave is one of the biggest challenges of OTR installation.

Minimum Height

Every OTR microwave comes with installation instructions that include a recommended minimum height for mounting that specific appliance. Beyond that, your local building code may prescribe a certain height. As a general rule, though, there should be at least 30 inches of clearance from the top of the cooking surface to the bottom of any cabinetry before the microwave is installed. OTR microwaves mount to the bottom of a cabinet, and manufacturers design OTRs with those 30 inches of clearance in mind. Mount the microwave too low, and heat and steam from the cooktop could damage the components--possibly even melting plastic parts--and you might not even be able to see the back of the cooktop. Mount it too high, and the exhaust fan will be unable to capture and vent away the smoke and odors.

Considerations

Over-the-range microwaves are usually 30 inches wide--the same width as a standard range--and are about 15 to 16 inches tall in the front. Following the 30-inch clearance guideline described above would leave you with 14 to 15 inches of vertical space over your cooktop. That should work fine for most people. Taller individuals, however, will probably want a little more clearance. When you stand at the range, you should be able to see the entire cooktop without having to stoop.

Source:

Refurber: How to Install an OTR

Woodweb

Resource:

LG Electronics: OTR Installation Instructions

Frigidaire: OTR Installation Instructions

GE: OTR Installation Instructions