A seal assembly for a gas turbine engine according to an example of the present disclosure includes, among other things, a seal arc segment that has a sealing portion and a first interface portion. The first interface portion defines circumferential mate faces. A support includes a mounting portion and a second interface portion. The mounting portion is configured to be fixedly attached to an engine static structure, and the second interface portion is radially inward of the first interface portion. At least one positioning member is dimensioned to abut the first and second interface portions such that the first and second interface portions are spaced apart by a predetermined distance in a radial direction.