The decorative repertoire of the Romanesque was relatively limited: balls, small arches and cordwork. The Gothic used more abundant decoration with rudenture, sawtooth and zigzag patterns, trilobate arches, rosettes, sun discs and schematic heads like with ones in Idiazabal, which some scholars have identified with the apostles; the broadest ornamental field can be found in Deba where the sculptural carvings in polychrome stone are very rich in tracery, corbels and canopies over the sculptures. In the Renaissance period, typical Castilian decorations were used, such as balls, the coats of arms of patrons or founders and medallions with busts. Cockle or scallop shells and cords were also used; and the architecture itself included pediments and branching pinnacles.

In the first half of the seventeenth century the decoration was limited to the architectural features, concave surfaces or mortises or protuberances bordering the features, ornamentation of triglyphs and metopes, pyramids, pediments and niches. In the second half of the century the decorations became more abundant with thick and uneven mouldings at the entrances to the church, and sectioned plaques, modillions, naturalist consoles and demon-like heads or figureheads. This was all complemented in the Baroque century with lush vegetative forms such as ferns and palms, flowers, fruit, bunches of grapes or shells, and cherubs, such as those to be seen in Oñati. In the Sanctuary of Loyola we also have evidence of their taste for colour with the use of hard stone, marbles and jasper on walls and paving. Sculpture played an important role in the decorative programme of the entrances to the churches, stressing the patronage of the buildings, as we can see in Zegama. Rocaille was used in the French style to add a natural touch and fill many church doorways. The most splendid example can be seen in the church of Santa Maria in San Sebastian, where it were used as a frame for the stone carvings of the liturgical attributes of the Virgin. Such was the freedom afforded to artists in decorating these features in the eighteenth century that curved portions in stone were used as festoons in the belfry of the church of Santa Maria in Tolosa.

The wood carvings on beams, eaves and atriums are particularly interesting. Some constitute authentic works of art, such as the structure in the atrium of the church Soraluce-Placencia. In general any kind of support was used to decorate the doorways, with great variations down the centuries. This great ornamental outlay was cut back at the end of the eighteenth century, until it finally practically disappeared in the Neo Classical period, when incised decorations abounded, such as austere urns or other vessels with smooth surfaces, inscriptions and in some cases, as in the church in Elgeta, liturgical symbols to reflect the fact that the church was dedicated to the Virgin Mary.