A horizontal dividing rail is a section of wood 76mm wide, that fits between the side stiles of your shutter so it becomes part of the main construction, normally about halfway up.

Panel height limit

Its primary function is to provide strength to tall shutters, you’ll need a rail if the panel height is over 1981mm or 2133mm if you are upgrading to the Elite Plus shutter.

Adding a rail to your design, will not increase the cost.

Ideally, you should only use a horizontal rail in the shutter to match any existing rails or features on the window or door or if the height is over 1981mm and you have to have one.


Using a rail will divide the louvres into two halves allowing you to adjust the louvres independently either side of the rail. This will provide extra privacy by allowing you to keep the top louvres open and bottom louvres closed.

A dividing rail will offer a more traditional look to your shutter design, so if you have a period property or older sash window, a rail could be a nice addition.


One thing to note, when adding a rail in your design it might not end up exactly in line with the rail on your window. This is because of the number of louvres that can be fitted within the height of the shutter. If you’re lucky it will be fairly close, but just be aware the rails can be as much as half a louvre higher or lower than the specified height.

It is possible to match a rail to the exact height and request custom width rails, but this will also affect the heights of the top and bottom rails, so there will be a compromise in either the final rail position, thickness of the rails, louvre size or choosing smaller rails without a guarantee.

You don’t have to have a rail just to split the top and bottom louvres for privacy, the modern version of this is to have a split in the hidden tilt mechanism, we have a video covering this option with more advice.