Every now and then I come across text referring to construction on the Island early in it's settlement - here is one such bit of information:
In 1805 Jacob "Martin" Heartz, ( of Sleepy Hollow) married Ann M. Dawson, an Irish girl from County Caven - they had ten children. Martin was a very hard-working stone mason and did considerable work around the neighbouring countryside. Lord Selkirk's Diary of August 15, 1803, contains data about "M. Heartz, mason" and that he built chimneys for the Belfast settlers.
cf. "An Island Refuge: Loyalists & Disbanded Troops on the Island of St. John." Edited by Orlo Jones and Davie Haslams. Abeqweit Branch of UE Loyalists Assoc. 1983. Page 101.