The construction of the churches at Portmahomack provide good evidence of construction techniques and other associated technologies such as shaping blocks and creating lime mortars and lime-wash. Window glass was possibly used implying glaziers. Engineering expertise in the modifications of Church 3 allowed a crypt to be built. In the 13th to 14th century, a major rebuilding included the extension of the crypt and the addition of a barrel vault. Skilled masons left their masons’ marks. Most of the stone does not appear to be from the immediate vicinity, though some is likely to be from the peninsula (Carver et al 2016, 289ff, D112–D113).
The use of lime mortar shows that limekilns must have been used, though no closely dated examples are known from Scotland. Possible examples have been suggested at Castle Tioram (MHG4028), Lochaber and Dun Scaich Castle, Skye (MHG5171), but further work is needed to confirm (Thacker 2020).