Usually a valance is approximately a fourth or fifth part of the length of the curtains, but sometimes less. To hang it, you'll need a ledge or plank, on which he would continue to hold. The ledge you need to choose based on the size and weight of your pelmet.
I usually try to hang all the decorative elements of a window on one design. That is, the pole should consist of several straps to fit all curtains and pelmet. It is important that each canvas was attached to its bracket, otherwise you will not be able to open and close curtains, and it is very important.
The pelmet has a different method of mounting from the usual curtains that do not conceal the curtain where they hang. He is usually kept in the Velcro, thanks to which the layer of fabric completely covers the eye all strap. One part of the Velcro is attached to the supporting structure (the eaves) and the other is sewn to the valance. Choose a wide and strong Velcro, to sustain the tissue mass.
The cornice for pelmets should also be strong enough. If the fabric is dense and heavy, plastic or aluminium as a material is not suitable, they will bend or break on its severity. Most likely, you will need a durable metal cornice or a sturdy wooden design. You can pick up a special cornice for lambrequin in the store. They are usually massive enough to withstand all the layers of fabric.
Cornice for lambrequin mounted near the ceiling, the fabric flowed from the top of the wall above the window. As in most cases the other two curtains are sheer and some kind of heavy fabric, the cornice is required triple.