Keder Banner

Calculating the stretch 

The finished size of a keder banner is the measurement from the outside edge of the keder to the outside edge of the keder when it is in its non-stretched state.

It is important that you calculate the correct finished size when ordering your keder banner.
The sail track will add 20mm to each edge of the banner. In addition, you will be able to get approximately 0.25% stretch out of the banner without mechanical assistance. That is 10mm for every 4 metres.

For example:
If you have a pre-existing perimeter frame  made of 40mm Rectangular Hollow Section and let's say the outside dimensions are 3000mm (w) x 2000mm (h)

The width of the banner:
= 3000mm {the outside width of your frame}
- (20mm * 2) {for two sections of sail track one left one right} 
- (0.0025 * 3000) {to subtract  0.25% for stretch} 

= 2952.5 mm outside of keder to outside of keder (you can round it up or down to the nearest mm so say 2953mm

The height of the banner:
= 2000mm {the height to the outside of the frame)
-(20mm *2){for two sections of sail track one top and one bottom}
- (0.0025 x 2000)   {to subtract  0.25% for stretch}
=1955mm

So the finished size of the Keder banner size is 2953mm (w) * 1955mm (h)

Disclaimer
These suggested calculations are a guideline only.
Some installers prefer to use tools to get additional stretch. With most materials you will get more stretch across the direction of the roll than along the length of the roll. Some materials you will get more stretch than others.  The temperature of the day will affect the amount of stretch you get. If the dimensions are critical, then you are advised to perform your own tests and satisfy yourself that the sizes meet your specific requirements.