Insulation or heat-pump installer did bad work — what do I do?

On defective insulation/heat-pump installation your rights sit under BW title 7:12 (works contract):

1. right to repair by the same contractor (BW 7:759), at no cost
2. on refusalright to substitute performance by a third party + cost recovery from contractor
3. on gross faultcontract termination + damages. Plan: (a) photos + measure performance loss (heat meter, thermography); (b) written demand within 2 weeks of discovery; (c) ISDE application: minimum requirements not met = ISDE entitlement at stake → leverage; (d) on refusal: VLOK building disputes committee or civil court. For heat pumps: STEK/Solis-certified installer = 2-5 year connection guarantee.