Upgrading your 30-inch cooktop to 36 inches seems easy; just take out the old and plop in the new. Unfortunately, this assessment is wishful thinking. Most of a cooktop's guts hang below its cooking surface, meaning that space requirements limit your installation options. It's certainly possible to replace a 30-inch cooktop with a larger unit, and in some cases it's not very difficult. The real challenge is figuring out the most practical way to rearrange your cabinets and countertop.
The rectangular cutout, the hole in the countertop holding your cooktop, is just slightly smaller than the dimensions of the cooktop's surface. Many 36-inch units have the same depth as 30-inch cooktops but rarely share the same width. The exact dimensions of your cooktop and countertop cutout vary according to your appliance's make and model. In most cases, installing the larger cooktop requires widening the cooktop opening.
Cooktop Base Cabinets
Construction professionals typically describe a cabinet by its outside dimensions. For example, a 36-inch-wide cabinet measures 36 inches between its opposite, outside edges. The cabinet's interior width is smaller than its listed outside dimensions because of the cabinet frame's thickness. Your 30-inch cooktop probably isn't mounted over a 30-inch base cabinet; it's likely installed in a 32- or 36-inch cabinet. Before purchasing your new 36-inch cooktop, measure the inside dimensions of the existing cooktop's cabinet. Compare the existing cabinet's dimensions to the new cooktop's required cutout size. Although rare, some manufacturers make 36-inch cooktops that fit into 36-inch base cabinets.
If your existing cooktop is in a 32-inch cabinet or smaller, installing the new cooktop probably requires a new cabinet. Removing and replacing kitchen cabinets is relatively straightforward; they usually attach to walls, floors and adjacent cabinets with screws. But rearranging your existing cabinetry to accommodate a new, larger base cabinet is a challenge. If the existing cooktop's cabinet is too small, you need to remove at least two cabinets to accommodate the new cooktop. You can replace the old cabinets with one or two new cabinets as long as one of the new cabinets is large enough to hold the 36-inch cooktop.
The possibility of using your existing countertop for your new cooktop depends on the countertop's materials. You might need to demolish your tile countertop before installing new cabinets. Alternatively, you can usually salvage solid surface or laminate countertops by removing them before you install new cabinets. If the existing cooktop's cutout dimensions exceed the replacement cooktop's required cutout dimensions, however, you'll need to replace at least the portion of the countertop that will hold the new cooktop.