How to measure wave type curtains with trough

Intro

Gutter curtains with wave (or wave) system are an increasingly used solution in contemporary interiors, due to their fluid aesthetics, perfect fit and discreet operation. To ensure a harmonious and functional result, the measurement must be accurate and consider the type of rail, the space available in the groove, the fabric chosen and the desired visual effect.

Application system: technical trough

The technical trough is the ideal support for wave-type curtains. It can be:

Applied to the ceiling, on the face or embedded in a gromace;
Applied to the wall, when the structure does not allow upper attachment.

The specific slip system keeps the curl constant over time. The measurement must be done from the top of the trough to the end point of the curtain, depending on the desired style.

Applied to the ceiling, to the face or embedded in a gromming

Applied to the wall, when the structure does not allow upper attachment. The specific slip system keeps the curl constant over time. The measurement must be made from the top of the trough to the end point of the curtain, depending on the desired style.

Understanding the wave system

The wave system consists of a trough with regularly spaced sliders that create smooth and uniform folds - the so-called waves. The depth and width of these waves vary slightly depending on the spacing of the sliders, but on average, the width of the wave ranges from 6 to 8 cm (3 to 4 cm on each side of the fold).

🔹 Important note: For an installation embedded in an armhole, it is essential to provide at least 10 to 12 cm of free width between the ceiling and the front face of the molding, in order to accommodate the wave beam without the fabric touching the structure.

Measure the width of the curtain

The width of the gutter is normally equal to the total width of the opening (window, door or wall), but you should consider:

The curtain should exceed 15 to 25 cm on each side of the window to ensure good coverage and allow natural light to enter when collected.
For double curtains (central opening): divide the total width of the trough by 2 and apply the fabric calculation for each side.

Measure curtain height

The height depends on the form of installation and the desired bottom finish:

From ceiling to floor: It is measured from the ceiling (or the inside of the frame) to the floor.
For a finish Standard (without drag), 1 to 1.5 cm is subtracted from the total height.
For an effect with Light drag, add 2 to 4 cm to the height.

⚠️ Recommended measure at three different points: left side, center and right side of the gutter, to detect any unevenness in the ceiling or floor.

Tissue multiplication factor (yield)

To create the regular waves, more fabric is needed than the width of the trough. The amount depends on the light weight of the fabric:

Lightweight fabrics (e.g. voiles, fine linens): multiply the width of the gutter by 2.2 to 2.5
Medium to heavy fabrics (e.g. thick linen, velvets): multiply by 2 to 2.2

🔹 Practical example:

3-meter trough
Lightweight fabric → 3 x 2.4 = 7.2 meters of fabric needed

This calculation includes the volume needed to form the waves continuously and regularly, without tension or flattening.

Special situations

Curtains embedded in moldings: the measurement must be taken from the inside of the groove (where the trough is located) to the desired point (floor or other reference).
Uneven floors: should be considered the smallest measure to avoid contact with the floor.
Windows with sliding doors: Curtain at floor level, with minimum clearance, is recommended to allow daily use without friction.
Fabric with pattern or vertical stripes: provide visual alignment — more fabric may be needed.
Shrinkable fabric (ex: pure linen): consider natural shrinkage and indicate whether it is washed before cooking.
Gutter with side or central opening: confirm with the tailoring professional the type of attachment (tapes and sliders suitable for the wave system).

Conclusion

Measuring for gutter curtains with a wave system requires technical rigor and attention to detail. The final aesthetic depends on the combination of correct measurement, molding planning and the choice of the appropriate fabric. A good project must anticipate all these points to guarantee a functional, elegant curtain that is perfectly integrated into the space.