<p>It would depend on how strong a preparation one had for structures in the BArch program including foundation things such as mechanics of materials, physics, and the like, and (sigh) math. Ask grad schools as to what prerequisites they would want to see for a successful applicant and go from there. </p>
<p>Methinks the other way may be more doable, i.e. BS Structural Engineering and MArch, since the 5 year BArch has few electives to begin with. The BS Arch / MArch route has more electives but is one year longer…</p>