Membrane structures are material efficient structures made with a lightweight flexible membrane. Usually the membrane is made out of a woven textile. Because of the size restrictions of the woven patches of fabric, the membrane will contain multiple seams. This will not be the case when the membrane is a knitted fabric. Membrane structures are suitable for making lightweight formworks for concrete structures with complex geometries. Knitted fabrics can be made using a CNC knitting machine which uses weft-knitting. This machine uses two needle beds with needles which can catch the yarn and perform different knitting operations like a plain stitch, a float stitch, a tuck stitch, a transfer stitch and an interlock stitch. Different configurations of these knitting operations create different knitting patterns. The mechanical properties of the knitted textiles that are considered during this research are the Poisson’s ratio and Young’s modulus. Since knitted fabrics show orthotropic behaviour, the fabrics have to be tested in both directions (wale and course direction). The properties can be determined when fabrics are tested in a uniaxial tensile test, a wide jaw test or a biaxial tensile test. Digital image correlation can be used to measure the strain of the fabric in lateral direction. This research addresses the effect of different knitting patterns on the Poisson’s ratio and Young’s modulus of weft-knitted fabrics. To achieve this objective, homogeneous fabrics of multiple knitting patterns have been tested. The knitting patterns that are considered in this thesis are interlock, eightlock, hexagon, tuck, interlock_1float and interlock_2float. Afterwards, non-homogeneous textiles have been fabricated in which two knitting patterns have been combined. This is done with interlock as a primary pattern and tuck or eightlock as a secondary knitting pattern. The secondary knitting pattern is applied as a circle in the centre of the fabric. The results of the tensile tests show large differences in mechanical properties for the fabrics with different knitting patterns. In wale direction the Poisson’s ratios for the interlock, tuck, interlock_1float and interlock_2float pattern are between 0.5 and 0.65, while the ratios for the eightlock and hexagon patterns are larger; between 0.8 and 0.9. In course direction, the ratios are smaller than in wale direction. For the interlock, tuck and interlock_1float show a Poisson ratio between 0.45 and 0.5 while the ratio for the eightlock pattern is around 0.6. In wale direction, the Young’s modulus for the interlock, tuck and interlock_1float are between 0 and 2.5 MPa, while the Young’s modulus for the eightlock and interlock_2float pattern are between 8 and 12 MPa. The hexagon pattern is even more stiff, with a Young’s modulus around 30 MPa. In course direction, the Young’s moduli are way lower (between 0 and 0.5 MPa for all fabrics). In this direction, the stress-strain curves of the fabrics do not reach the elastic region because of rotation of the clamps in the test setup. For the non-homogeneous interlock_tuck fabrics, the Poisson’s ratio in wale direction is larger than the homogeneous interlock and tuck fabrics. This is caused by the interaction between the different knitting patterns. This effect is not visible in course direction. For the non-homogeneous interlock_eightlock fabrics, this is the other way around. The interaction between the knitting patterns plays a role in course direction, but is not visible to the same extent in wale direction. The Young’s modulus of the secondary knitting pattern is larger for both the interlock_tuck and interlock_eightlock fabrics. Therefore the Young’s modulus increases when the diameter of the circle containing the secondary knitting pattern increases.