yarns 10 and 12 should be backwoven a greater distance to maintain the integrity of the fabric non loop forming md yarns 10 are backwoven a shorter distance since no load is imparted to those yarns during usage where the warp fill of the md layers is 50 or less there is no necessity for providing non loop forming yarns since the spacing between the md yarns may provide sufficient space to intermesh loops formed from all of the upper layer md yarns fig7 and 8 illustrate the finished loop construction for one seam end of the papermakers fabric 2 the group of stacked loop forming md yarns shown in solid and the group of non loop forming md yarns shown in phantom the doubling of the middle md layer yarns 12 which form loops does not significantly add to the caliper of the seam since the cmd yarns tend to become offset as illustrated in fig2 where the fabric 2 is configured with different size cmd yarns 16a 18a and 16b 18b as shown in fig5 yarns having the same diameter as the smaller diameter yarns 16a 18a can be substituted for the larger relatively non crimped cmd yarns 16b 18b to maintain both vertical alignment and stacking of the cmd yarns without any significant increase in fabric caliper at the seam a nested double loop seam can also be provided where the fabric 2 has a.