15-Inch Deep Cabinets? Your Over-the-Range Microwave Won’t Fit—Here’s the Fix
You meticulously planned your kitchen remodel, selecting beautiful, spacious 15-inch deep upper cabinets for extra storage. But now, as you try to install your new over-the-range (OTR) microwave, you’ve hit a major snag. The microwave sticks out, the door won’t open properly, and the entire setup looks awkward and unprofessional.
This is a frustratingly common problem. Standard over-the-range microwaves are designed for 12-inch deep cabinets, leaving homeowners with deeper cabinets in a difficult position. But don’t worry, you don’t have to rip out your cabinets or return your microwave. There are clear, effective solutions to make it work.
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Why Your 15-Inch Cabinets Create a Microwave Mismatch
The core of the issue lies in industry standards that haven’t kept up with modern kitchen design trends. Most OTR microwaves have a depth of around 15 to 16 inches. They are engineered to be installed under 12-inch deep cabinets, allowing the front of the microwave to sit roughly flush with the cabinet doors and ensuring the microwave’s own door can swing open without hitting adjacent walls or cabinets.
When you install that same microwave under 15-inch deep cabinets, the front of the unit is recessed by an extra three inches. This creates several immediate problems. The microwave door may not have enough clearance to open fully, and accessing the controls can become awkward. Aesthetically, it looks sunken and unbalanced, disrupting the clean lines of your kitchen.
The Hidden Danger: Improper Venting
Beyond looks and convenience, a poorly fitted microwave poses a functional risk. The venting system, designed to capture smoke and odors from your cooktop, is now positioned too far back. This significantly reduces its effectiveness, allowing grease and steam to escape into your kitchen, coating your new cabinets and diminishing air quality.
Furthermore, this recess can interfere with the microwave’s own internal ventilation. Obstructing the airflow can lead to overheating, which may shorten the lifespan of the appliance and, in rare cases, create a fire hazard. A proper fit is not just about appearances; it’s about safety and functionality.
The Ultimate Solution: The Bump Out Kit
The most reliable and purpose-built solution is a microwave bump out kit, also known as a mounting bracket extension. This simple but ingenious device is a metal frame or sleeve that mounts to the wall behind the microwave. It effectively pushes the microwave forward, away from the wall, allowing it to align perfectly with the front of your 15-inch deep cabinets.
By bringing the microwave forward by three inches, the bump out kit restores the intended geometry. The microwave door can open freely, the controls are accessible, and the ventilation hood is correctly positioned over the cooktop. It’s a clean, stable, and secure solution that bridges the gap between your appliance and your cabinetry.
Choosing and Installing a Bump Out Kit
Bump out kits are typically made from sturdy stainless steel and come in various depths, with the 3-inch extension being the most common for 15-inch cabinets. When choosing a kit, ensure it is compatible with your microwave’s brand and model. While many are universal, it’s always best to check the specifications.
Installation is straightforward for a moderately skilled DIYer. The process generally involves locating the wall studs, securing the bump out bracket to the wall, and then mounting the microwave’s own bracket to the front of the kit. The top of the microwave is then secured through the cabinet above as usual. However, given the weight of the appliance and the need for a perfectly level installation, hiring a professional is always the safest bet.
Alternative Strategies for Deep Cabinets
While a bump out kit is the primary solution, there are other methods to consider, particularly if you are in the middle of a major renovation. These options are typically more involved and costly but can provide a truly integrated, custom look.
Custom Cabinetry and Wall Modifications
One advanced technique is to alter the wall structure itself. A contractor can build a recessed niche into the wall between the studs. This allows the back of the microwave to sit inside the wall cavity, achieving a flush fit with the deep cabinets without needing a bump out kit.
This approach requires careful planning to avoid interfering with plumbing, electrical wiring, or structural components within the wall. It is not a simple DIY project and should only be undertaken by a qualified professional. However, the result is a seamless, high-end appearance that makes the microwave look like a fully integrated part of the cabinetry.
Modifying the Upper Cabinet
Another custom option involves ordering a cabinet for above the microwave that is shallower than the rest. For instance, if your flanking cabinets are 15 inches deep, you could order a 12-inch deep cabinet for directly over the stove. This creates a dedicated nook for a standard OTR microwave installation, making it look intentional and breaking up the cabinet line for visual interest.
This strategy requires planning during the kitchen design phase. It can be a great way to avoid the bump out issue from the start. It ensures your appliance fits perfectly without any aftermarket modifications.
Comparing Microwave Solutions for 15″ Cabinets
Making the right choice depends on your budget, timeline, and desired aesthetic. A bump out kit is often the most practical choice for existing kitchens, while custom solutions are best integrated into a new build or full remodel.
| Solution | Best For | Pros | Cons |
|---|---|---|---|
| Microwave Bump Out Kit | Existing kitchens; DIYers | Cost-effective, relatively easy to install, maintains cabinet integrity. | May create small visible seams on the sides. |
| Recess Microwave into Wall | New construction or major remodels | Seamless, fully integrated look; no extra hardware. | Expensive, requires professional contractor, depends on wall structure. |
| Use a Shorter Upper Cabinet | New kitchen design phase | Clean, intentional design; no fitment issues. | Requires advance planning; not an option for existing kitchens. |
| Countertop Microwave & Range Hood | If OTR functionality isn’t critical | Frees up upper cabinet space, often better ventilation with a dedicated hood. | Uses valuable counter space, two separate purchases. |
Critical Installation Mistakes You Must Avoid
Proper installation is paramount for both safety and performance. Rushing the job or overlooking key details can lead to significant problems down the line, turning your kitchen upgrade into a source of constant frustration.
Electrical Safety Is Non-Negotiable
An over-the-range microwave is a high-power appliance that requires a dedicated electrical circuit. Plugging it into a shared circuit can overload the system. If you notice your breaker box buzzing when the microwave is on, it’s a serious warning sign of an overloaded circuit that needs immediate attention from an electrician.
For a clean and safe setup, many homeowners choose to hardwire your microwave directly into the circuit. This eliminates visible cords and ensures a secure, stable connection, but it is a task that must be performed by a licensed electrician to ensure it meets all safety codes.
Ensuring Proper Height and Stability
The height of your microwave is just as important as its depth. If your over-the-range microwave cabinet is too low, it can create a fire hazard by placing the appliance too close to the cooktop’s heat and flames. It also makes it difficult to stir pots on the back burners.
Always follow the manufacturer’s clearance requirements, which typically specify a minimum distance between the bottom of the microwave and the cooking surface. During installation, use a level to ensure the unit is perfectly straight. An unlevel microwave can cause the internal turntable to function poorly and may put undue stress on the mounting brackets over time.
Frequently Asked Questions
Can I install a standard over-the-range microwave with 15-inch deep cabinets?
Standard over-the-range microwaves are typically designed for cabinets with a maximum depth of 12 to 13 inches. Installing a standard microwave under 15-inch deep cabinets will likely cause the appliance to be recessed, which can prevent the door from opening properly and may affect ventilation.
What is a “bump out kit” and do I need one?
A “bump out kit” is an accessory that extends your over-the-range microwave forward, away from the wall. If you have cabinets that are 14, 15, or 16 inches deep, you will likely need a bump out kit to ensure your microwave is installed correctly and functions as intended. These kits create the necessary clearance for the microwave door to open fully and for proper ventilation.
Are there alternatives to a bump out kit?
Yes, some homeowners and installers create a custom solution to bump out the microwave. This can involve building a wooden frame behind the microwave to bring it forward. However, it’s important to ensure any custom solution is secure, fire-resistant, and provides adequate support for the weight of the microwave.
Will a bump out kit affect the microwave’s ventilation?
When an over-the-range microwave is pushed forward, it can create a gap between the back of the microwave and the wall vent, if you are venting to the exterior. You may need to use an adapter to extend the venting from the back of the unit to the wall duct. It is crucial to ensure a proper connection to maintain effective ventilation.
Are there any over-the-range microwaves specifically designed for 15-inch deep cabinets?
While most over-the-range microwaves are designed for shallower cabinets, some models may have a shallower depth themselves. It is always best to carefully check the manufacturer’s specifications and installation instructions for the specific model you are considering. This will help you determine if it is compatible with your cabinet depth or if you will require a modification like a bump out kit.
Final words
Dealing with an OTR microwave that doesn’t play nicely with 15-inch deep cabinets can be incredibly frustrating, but it’s a challenge with proven, practical solutions. By understanding why the mismatch happens and exploring the available workarounds—from extension kits to alternative mounting methods or choosing a compatible model—you can create a setup that functions flawlessly and looks intentionally designed. With the right adjustments, your microwave can fit beautifully into your remodeled kitchen, giving you the sleek, efficient space you envisioned from the start.
