The kagome materials $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ ($A=\mathrm{K}$, Rb, Cs) host an intriguing interplay between unconventional superconductivity and charge-density waves. Here, we investigate ${\mathrm{CsV}}_3{\mathrm{Sb}}_5$ by combining high-resolution thermal-expansion, heat-capacity, and electrical resistance under strain measurements. We directly unveil that the superconducting and charge-ordered states strongly compete, and that this competition is dramatically influenced by tuning the crystallographic $c$ axis. In addition, we report the absence of additional bulk phase transitions within the charge-ordered state, notably associated with rotational symmetry breaking within the kagome planes. This suggests that any breaking of the $C_6$ invariance occurs via different stacking of $C_6$-symmetric kagome patterns. Finally, we find that the charge-density-wave phase exhibits an enhanced $A_{1\mathrm{g}}$-symmetric elastoresistance coefficient, whose large increase at low temperature is driven by electronic degrees of freedom.

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• Charge density waves
• Elasticity
• Electrical conductivity
• Phase transitions
• Kagome lattice
• Resistivity measurements
• Specific heat measurements
• Thermodilatometry