Inside v. Outside Mounts
The first thing to do when measuring for your mini blinds is to determine if you need inside mount or outside mount. Inside mount will fit the blinds within the window frame, while outside mount will fit the overlap of the window opening. There are both advantages and disadvantages to each method. It is up to you to figure out which is best for your situation.
There are three advantages of inside mounts. First, the wall space is not taken up by the blinds and they do not project into the room making it simple to use other types of window treatments in addition to the blinds. Second, if your window frame is a decorative feature it will be exposed. Blinds often look better when set into the window frame. The window opening defines the blind, giving it a finished, clean appearance. Lastly, in deep-set windows, the treatment can be installed close to the glass, in the middle of the window depth or flush with the inside wall. A treatment next to the glass with a deep window sill can allow plants or other items to be placed on the sill.
The advantages of outside mounts are the following. The blind may be extended higher or wider that the window opening. By mounting the blind above the window, it will not obstruct light or view when drawn open. Next, the light strike will be substantially diminished by ordering and installing the blind larger than the window opening. Also, there are fewer measuring and installation limitations with an outside mount. The problem of fitting the blind into an uneven or odd shaped window is eliminated.
Disadvantages of inside mounts include a small reduction in the width and length is taken at the factory to allow for proper operating clearance of the blind. This can cause a small gap on each side of the blind, affecting the blinds ability to insulate and prevent light from entering the room. The majority of windows are not perfectly square; therefore, light strikes may emphasize the irregularity of the dimensions of the window. The stack of the blind when it is retracted will obstruct a portion of the view from the window.
Outside mounts can also be disadvantageous. It may be more difficult to layer soft window treatments over outside mount blinds because the of the blinds projection into the room. Rod extensions on the soft treatment can help but do not always solve the problem.