How to Measure for Outside Mount Blinds

How to Measure for Outside Mount Blinds

While inside mounting blinds is the more traditional approach, outside mounting blinds offer certain advantages many homeowners find appealing. In this ultimate guide, we discuss the pros and cons of outside mounting your blinds, then explain how to measure for outside mount blinds. Next, we’ll walk you through outside mounting both vertical and horizontal blinds, and, finally, we’ll discuss whether or not you need to use extension brackets or spacer blocks when outside mounting your blinds.

When Should You Outside Mount Your Blinds?

There are multiple reasons you might want to potentially outside mount your blinds over your windows. Some of the common reasons are:

When Should You Outside Mount Your Blinds

  • You live in an older home and the window frames aren’t perfectly square, so they won’t support inside mount blinds.
  • The windows aren’t recessed deeply enough to support inside mount blinds.
  • The window frame has blemishes, such as gouges or scrapes, that will not be covered if you inside mount the blinds.
  • You want to minimize light seepage as much as possible when the blinds are drawn.
  • You want the window to be completely uncovered when the blinds are raised up.
  • You want to install your blinds closer to the ceiling to create the illusion of taller windows.
  • You plan to install two window treatments—for instance, a roman shade on top of a solar roller shade—so you need to inside mount the bottom window treatment and outside mount the top window treatment.
Learn How to Measure Windows for Blinds

When Should You NOT Outside Mount Your Blinds?

Despite their many advantages, outside mounting blinds aren’t appropriate for all circumstances. Here are some situations when you might want to inside mount your blinds instead:

When Should You Not Outside Mount Your Blinds

  • You don’t have enough space above the window to install the blind hardware directly into the wall or window trim.
  • You plan to hang curtains above the window, which will be difficult, if not impossible, with outside mounted blinds.
  • You plan to put furniture or other objects relatively close to the window, which might bump into outside mounted blinds.
  • Your windows are surrounded by high-quality window trim you want to be visible even when the blinds are closed.
  • You have a deep window recess you want to take advantage of.
  • You want the blinds to sit flush with the wall and not stick out.
  • All the other blinds in your home are inside mounted and you want a consistent look.

How to Measure for Outside Mount Blinds

Whether you’re committed to outside mount blinds or just trying to confirm you have enough room to mount, it’s important to properly measure for outside mount blinds. To do this, you will need a tape measure and a pencil, as well as some way to make a note of your measurements—a note on your phone works, as do a paper and pen.

Get Custom Vertical Blinds to Fit Your Exact Needs
  1. First of all, measure from the top of the window to the bottom of the ceiling or crown molding, or whatever is above the window. You will need a minimum of 2 inches of vertical space in order to outside mount your blinds. If you don’t have that space, you will have to inside mount them.
  2. Measure the width you want covered at three points: the top, middle, and bottom of the window, and use the largest one as your measurement. For horizontal blinds, we recommend a minimum of ¾ inch overlap on each side, for a total of 1.5 inches of overlap. For vertical blinds, you will want even more overlap: 1.5 inches on either side, for a total of 3 inches. In either case, you may choose to have your blinds extend past the window even farther if you would like more light blockage.
  3. Determine how far above the window you will mount the headrail. You may choose to install it into the window trim, if it is wide and flat enough, or you may wish to drill it directly into the wall. Mark this location on the wall with a faint pencil line.
  4. Measure from the mark you just made to where you would like the blinds to fall below the window. If you have a protruding window sill, use that as your bottom placement. If your window sill doesn’t protrude, you can decide where you would like the blinds to rest below the window. Also mark this lightly with your pencil. Using the marks you just made, measure the total vertical length you would like the blinds to have.
  5. See if there are any obstructions that could stop the blind from being raised or lowered. If there are, determine whether you will need any spacer blocks or extension brackets in order to outside mount the blinds in your chosen location.
  6. Don’t take any deductions from your measurements, and double check all your measurements are correct and expressed as W x H. Be forewarned, the factory will not take deductions—the measurements you enter are the measurements you get—so make sure they are correct before submitting your order.

Measuring for Outside Mount blinds

To learn more about measuring for blinds of all types, check out our guide that explains how to measure windows for blinds.

How to Install Outside Mount Blinds

In order to outside mount your blinds, you will need a pencil, a measuring tape, and either a drill or a screwdriver, a hammer and a nail. You might also want a leveler to ensure the blinds are absolutely straight. Outside mounting horizontal blinds is a bit different from outside mounting vertical blinds, so we’ll walk you through horizontal blinds first, and then move on to vertical blinds.

  1. First, remove the blinds and all hardware from the package and lay everything out to ensure you have all the parts. Review the instructions that came with the blinds for any specific guidance.
  2. Find the center of the window and make a light mark with the pencil. Grab the headrail and decide how high you want to install it, then center it on the pencil mark you just made and use the leveler to ensure it’s straight. Mark the edges of the brackets or the screw holes if you can angle your pencil to do so.
  3. Create a pilot hole for the screws, either by using a drill bit or by tapping a nail partway into the wall with the hammer, and then removing the nail. Screw the brackets into the wall and double check they are securely fastened.
  4. Place the headrail into the brackets. Either snap the headrail into place or close the clips that secure it, depending on the style of blinds you purchased.
  5. Next, secure the clips on the headrail and attach the valance to it. The valance is the trim that covers up the hardware at the top in order to make it more aesthetically appealing.
  6. Test the window blinds by raising and lowering them as well as opening the slats if applicable. Enjoy your new outside mount horizontal blinds!

mounting vertical blinds

Outside mounting custom vertical blinds require slightly different steps because you will have to attach the vanes (the wide vertical slats) after mounting the headrail. Here are the steps to outside mount vertical blinds:

  1. First, remove the blinds and all hardware from the package and lay everything out to ensure you have all the parts. Review the instructions that came with the blinds for any specific guidance.
  2. Decide how high you will install the vertical blinds. They need to be high enough that the vanes will not touch the ground or drag along it. Most people install their vertical blinds so the vanes hang 2-3 inches above the ground. Lightly mark this height with your pencil.
  3. Find the center of the window and make another light mark with the pencil. Center the headrail on the pencil mark you just made and raise it to the height you determined in the previous step. Use the leveler to ensure the headrail is straight, and mark the edges of the brackets or the screw holes if you can angle your pencil to do so.
  4. Create a pilot hole for the screws, either by using a drill bit or by tapping a nail partway into the wall with the hammer, and then removing the nail. Screw the brackets into the wall and double check they are securely fastened. Place the headrail into the brackets and secure it.
  5. Small plastic clips should hang from the headrail; these clips are designed to hold the vanes. Carefully pry each clip apart and insert a vane into it, making sure the clip closes securely. Repeat this until all the vanes are filled.
  6. If your vertical blinds came with a valance, attach the clips for that to the valance and attach the valance to the clips.
  7. Test the vertical blinds by opening and closing them, as well as moving them back and forth. Enjoy your new outside mount vertical blinds!

Comfortable workplace near window with horizontal blinds

Do My Outside Mount Blinds Need Extension Brackets?

As the name suggests, extension brackets extend farther than a standard bracket, holding outside mount blinds even farther away from the window. You might want to use an extension bracket for several reasons; for instance, to keep the shades from hitting protruding window trim or a secondary inside mount window treatment.

Extension brackets are best used when you need the blinds to stick out several inches, whereas spacer blocks are a better choice when you only need to push the blinds out a little bit—more on spacer blocks in the next section. Extension brackets come in two main designs. In the more common design, the longer arm is integrated into the bracket itself, forming a capital L shape with one short arm and one long arm. In the less common design, the extension bracket is a free-floating flat metal piece that is attached to one arm of the standard bracket using a screw.

Extension brackets can be installed using the same steps outlined above. You’ll measure and mark the placement, and then screw the extension bracket into the wall. Next you will attach the bracket that holds the headrail of the blinds to the extension bracket and secure the headrail to the regular brackets.

Do My Outside Mount Blinds Need Spacer Blocks?

If you only need your blinds to stick out between ½ and 1 inch, you will probably want to use spacer blocks instead of extension brackets. Spacer blocks look like a small grid made of plastic or rubber, and they go between the bracket and the wall. Spacer blocks are helpful to use if you are screwing the bracket into a wall or window trim that is uneven or slanted.

To use spacer blocks, go ahead and mark the placement of the screw holes and drill the pilot holes. Then place the spacer block over the pilot holes, making sure the holes in the spacer block align with the pilot holes. Next, put the bracket on top of the spacer block and line up the holes once again. Drill through the bracket and spacer block and into the wall using long drywall screws.

Refer to Our Guide

Outside mounting your blinds offers many advantages and can be an excellent choice in many instances. If you’re planning to outside mount blinds in your home, refer back to this guide as needed to make sure you are measuring and installing them correctly. If you’re looking to buy blinds in bulk, check out our commercial window shades.


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