This paper presents a multi-domain boundary integral equation approach of thermally excited crack surface interference observed under thermal transient conditions. According to this model, crack surface displacements and tractions are not free but subject to constraints simulating contact and prevailing overlapping of crack surfaces. The multi-domain approach allows the two faces of a crack to be modeled in independent sub-regions of the body, avoiding singularity difficulties and making it possible to analyze crack closure problems with contact stresses over part of the cracked faces. Crack-tip singularities are modeled through quarter-point elements. In order to approach the interference configuration, the interfacial traction distribution and solve the resulting equations, an iterative numerical procedure is applied. The numerical solution of this non-linear problem yields crack surface displacements and consequently the crack surface interference. Fracture parameters are evaluated from nodal displacements of singular elements utilizing proper formulas. Various results are illustrated and discussed for edge-cracks subjected to steadystate or thermal shock conditions.