Inside Mount vs Outside Mount: Which Installation Is Right for Your Windows?
Right after "how much does this cost?" the second question I hear most from homeowners is "what's the difference between inside and outside mount?" It sounds like a minor detail. It's not.
I had a customer in Brandon who ordered custom blinds online, measured carefully (or so he thought), and chose inside mount because he liked the look. When the blinds arrived, they fit the width perfectly. Beautiful. But his window frame was only 1 inch deep, and the blinds needed 2 inches of depth to mount properly. The brackets stuck out past the frame. The blinds hung crooked. The headrail pressed against the glass when closed.
He'd measured the right thing (width) but never checked the wrong thing (depth). Returned the blinds, ate a $200 restocking fee, and started over with outside mount.
This is the kind of mistake that happens when mount type gets treated as an afterthought. It should be one of the first decisions you make, not the last.
Inside Mount: The Clean, Built-In Look
An inside-mounted treatment fits within the window frame, between the side jambs. The shade, blind, or shutter sits recessed into the frame, creating a streamlined look where the treatment appears built into the window itself.
This is the preferred look for most homeowners and designers. It's clean, modern, and lets the window trim (if you have it) remain visible as an architectural detail. An inside-mounted plantation shutter, for example, looks like it was designed as part of the house. An inside-mounted roller shade almost disappears when raised.
When inside mount works best: - Your window frame has enough depth to accommodate the product - Your frame is relatively square (not warped, bowed, or out of plumb) - You want a minimalist, built-in appearance - You have decorative trim or casing around the window that you want to show off - The window recess is at least as wide as the product
The depth requirement is the dealbreaker. Every product needs a minimum depth inside the frame to mount properly. If your frame isn't deep enough, inside mount is off the table regardless of how much you prefer the look.
Here are the depth requirements by product type:
Roller shades • Minimum Depth for Inside Mount: 1.5 inches • Recommended Depth: 2 - 3 inches Mini blinds (1") • Minimum Depth for Inside Mount: 1 inch • Recommended Depth: 1.5 inches Faux wood blinds (2") • Minimum Depth for Inside Mount: 1.5 inches • Recommended Depth: 2.5 inches Wood blinds (2") • Minimum Depth for Inside Mount: 2 inches • Recommended Depth: 2.75 inches Cellular/honeycomb shades • Minimum Depth for Inside Mount: 0.75 - 1.5 inches • Recommended Depth: 2 inches Roman shades • Minimum Depth for Inside Mount: 1.5 inches • Recommended Depth: 3 inches Sheer shades • Minimum Depth for Inside Mount: 2.5 inches • Recommended Depth: 3.5 inches Plantation shutters (2.5" louver) • Minimum Depth for Inside Mount: 2.5 inches • Recommended Depth: 3 inches Plantation shutters (3.5" louver) • Minimum Depth for Inside Mount: 3 inches • Recommended Depth: 3.5 inches
Notice the gap between "minimum" and "recommended." At minimum depth, the product fits but may protrude slightly from the frame, and the operation can feel tight. At recommended depth, everything sits flush and operates smoothly.
How to check your frame depth: Place a tape measure inside the window frame, resting on the sill, and measure straight back to the window glass (or to the closest obstruction like a lock or crank handle). That distance is your available depth. Measure in at least two spots because depth can vary across the frame.
Outside Mount: Full Coverage, Full Flexibility
An outside-mounted treatment mounts on the wall or trim above the window, overlapping the frame entirely. The shade or blind hangs in front of the window rather than inside it.
This is less visually minimal than inside mount, but it solves a lot of problems that inside mount can't.
When outside mount is the right call: - Your window frame lacks the depth for inside mount - Your frame is out of square or has imperfections you want to hide - You want to make a small window appear larger - You need maximum light blocking (outside mount eliminates frame gaps) - Your windows have obstructions inside the frame (handles, cranks, sensors) - You're covering multiple windows with one wide treatment - Your frame is too narrow for the product width
The visual trick nobody talks about: Outside mount can make windows look significantly larger than they actually are. Mount the treatment 3 to 6 inches above the top of the frame and extend it 2 to 3 inches beyond each side. When the shade is down, the window appears taller and wider than it really is. Interior designers use this technique constantly. A small window in a South Tampa bungalow can look like a much grander opening with a well-positioned outside mount.
Light gap elimination: Inside mount always has a small gap between the treatment and the frame on each side. Light leaks through those gaps. For most situations this is fine. But in bedrooms, nurseries, or media rooms where you want complete darkness, outside mount with an overlapping treatment blocks light far more effectively. Some homeowners add side channels or "light blockers" to inside-mounted shades, but outside mount with proper overlap does the same job without accessories.
The Decision Framework
Here's how I walk clients through the choice.
Step 1: Check your frame depth. If you don't have enough depth for the product you want, the decision is made. Outside mount.
Step 2: Assess your frame condition. If the frame is square, clean, and in good shape, inside mount will look great. If the frame is warped, has paint buildup, or is visibly out of plumb (hold a level to each side and check), outside mount hides those issues.
Step 3: Consider your light control needs. Bedroom where darkness matters? Outside mount gives you better blackout coverage. Living room where a clean look matters more than total darkness? Inside mount.
Step 4: Think about your trim. Beautiful craftsman-style window casings? Inside mount preserves them. No trim, just drywall meeting the frame? Either works, but outside mount can actually add visual interest that the window currently lacks.
Step 5: Factor in the product. Some products look significantly better inside mounted (shutters, cellular shades). Others look equally good either way (roller shades, Roman shades). And some almost always get outside mounted (drapery, valances, cornices).
Product-by-Product Recommendations
Plantation shutters • Preferred Mount: Inside mount • Notes: Designed to sit flush in the frame. Outside mount works but requires a decorative frame kit. Cellular shades • Preferred Mount: Inside mount • Notes: Clean look, minimal light gap with proper fit Roller shades • Preferred Mount: Either • Notes: Inside for minimal profile, outside for full coverage Roman shades • Preferred Mount: Either • Notes: Outside mount allows fuller fabric draping Faux wood blinds • Preferred Mount: Inside mount • Notes: Sits neatly in the frame, shows off trim Sheer shades • Preferred Mount: Inside mount • Notes: Needs depth; the layered fabric requires room Drapery/curtains • Preferred Mount: Outside mount • Notes: Always mounted on rod above and beyond the frame Vertical blinds • Preferred Mount: Inside mount • Notes: Headrail sits in the top of the frame Panel tracks • Preferred Mount: Outside or ceiling • Notes: Track mounts on wall above or on the ceiling
Common Mistakes (And How to Avoid Them)
Mistake 1: Not Measuring Depth
This is the Brandon homeowner's mistake, and it's the most common one I see. People measure width and height religiously but never check if their frame is deep enough for inside mount. By the time they realize the problem, they've already ordered and are stuck with a restocking fee or a product that doesn't fit right.
Fix: Always measure depth before you decide on mount type. It takes 30 seconds and saves hundreds of dollars.
Mistake 2: Forcing Inside Mount on a Shallow Frame
Some homeowners love the inside mount look so much that they try to make it work even when the frame isn't deep enough. The result: brackets sticking out past the frame, the product rubbing against the glass, or the headrail creating an unsightly bump.
I've seen creative attempts to solve this. Shimming the brackets, routing out the frame to create more depth, even gluing brackets to the glass (please don't do this). None of these end well.
Fix: If your frame doesn't have the depth, go outside mount. It will look a hundred times better than a forced inside mount.
Mistake 3: Not Accounting for Obstructions
Window cranks, locks, handles, tilt latches, alarm sensors. All of these sit inside the frame and can interfere with an inside-mounted treatment. I measured a home in Westchase where every single window had a crank handle that stuck out 1.5 inches into the frame. The frames had plenty of depth on paper, but the crank handles reduced the usable depth to almost nothing.
Fix: Measure your available depth from the front of the frame to the nearest obstruction, not to the glass. That's your real depth.
Mistake 4: Ignoring Frame Squareness
Frames that are out of square create visible gaps with inside-mounted treatments. If the top of the frame is wider than the bottom by even a quarter inch, your shade will have a gap on one side. With outside mount, the treatment extends past the frame on all sides, so squareness doesn't matter.
Fix: Hold a level to each side of the frame. If the sides aren't plumb (vertical), measure the width at top, middle, and bottom. If the measurements differ by more than 1/4 inch, consider outside mount or have a professional evaluate.
Mistake 5: Wrong Measurements for the Mount Type
Inside mount and outside mount require different measurement approaches. For inside mount, you measure the opening (jamb to jamb, sill to top). For outside mount, you measure the coverage area you want (where on the wall the treatment starts and ends).
I've seen customers measure for inside mount, order the product, and then try to install it outside mount. The shade was sized to fit within the frame, so mounted on the wall it's too narrow and doesn't cover the window properly. The reverse happens too.
Fix: Decide your mount type first, then measure accordingly.
Hybrid Approaches
Sometimes the answer isn't purely one or the other.
Inside mount shades + outside mount drapes: This is the most popular combination I install. The shade sits inside the frame for clean, functional light control. The drapes mount on a rod above and beyond the frame for aesthetics and a layered look. Each product is in its ideal mount position.
Inside mount on some windows, outside mount on others: In many homes, frame depth varies by window. Master bedroom windows might have 3-inch-deep frames perfect for inside mount, while the bathroom windows have 1-inch frames that require outside mount. Matching the mount type to each window's characteristics looks better than forcing all windows into the same mount type.
Outside mount made to look like inside mount: By mounting the treatment brackets on the face of the frame (rather than on the wall above it) and keeping the overlap minimal, you can get an outside mount that mimics the flush look of an inside mount. This works particularly well with roller shades that have a compact headrail.
What I Tell My Clients
Most of the time, I recommend inside mount. It's the cleaner look, it's the way most products are designed to be installed, and in most Tampa-area homes the frame depth is sufficient.
But I never assume. The first thing I do at every consultation is check frame depth on a few representative windows. If depth is a concern, I test every single window because they can vary, even in the same room.
Here's the truth: outside mount is not a compromise. It's not the "backup plan" when inside mount doesn't work. It's a legitimate installation method that looks great when done properly and solves real problems that inside mount can't. Some of the most beautiful window treatments I've installed have been outside mounted.
The key is matching the right mount type to the right situation. When you get that right, nobody notices the mount. They just notice how good the windows look.
Not sure which mount type works for your windows? Bumble Bee Blinds in Tampa handles this during every free in-home consultation. We check depth, squareness, obstructions, and frame condition on every window before recommending anything. Call (813) 599-8175 or schedule online at bumblebeeblinds.com/tampa-fl.
