The terms outside mount blinds and inside mount blinds refer to where the blinds are positioned on an interior window frame. Outside mounts are blinds that cover the whole frame while inside mounts are mounted inside the frame leaving the frame moldings or edges visible.
Outside Mount Blinds
Outside mount blinds are much easier to install since they can be mounted over a window and do require exact measurements. This also creates the illusion that the window is bigger. The mounts are simply placed on both sides of the valence and placed above the top corners of the window. This type of mounting treatment works well with no-depth window frames. Mounting blinds outside the window frame also has the advantage of hiding irregularities on a window frame so this is a good technique to do to conceal windows that are not very presentable.
Inside Mount Blinds
Inside mount blinds on the other hand is a mounting treatment installed within the window frame and requires a perfectly measured set of blinds. It will expose the window trim and the frame itself. These blinds are a good solution when you want to combine drapes with blinds because having the blinds contained inside the window frame prevents the drape and blinds from interfering with each other.
With inside mount blinds the depth of the window frame needs to be deep enough to accommodate teh depth of the blinds that the mounting mechanisms. If your window is a standard size, it will be easy to find store-bought inside mount blinds that will fit inside your window frame. But if your window isn’t standard, you will have to take accurate measurements of the inside frame so that you can have the blinds custom made. Make sure that you get good measurements because the frame manufacturer has no liability for incorrect measurement that result in blinds that do not fit. Also give measurements and do not deduct any measurement such as giving an allowance so that the blinds do not hit the frame. The blind company will automatically calculate this measurement.
So when choosing the type of mounting technique, consider all these factors. With a little planning you can buy and install the perfect blinds for your window.