L-shaped Agricultural Range at Pen-yr-Allt

The L-shaped agricultural range at Pen-yr-Allt is a historic structure featuring a long primary barn with an adjoining stable and cart-bay at a right angle to the northeast. It is built of rubble, with the inner sides and barn gable whitened. The roof is covered with large, graded 19th-century slates and has simply-kneelered rubble gable parapets on the primary section.

On the front, there is a window opening with a fragmentary 8-pane window to the left, and three entrances in the center. The middle entrance has been reduced to a plain window opening, while the flanking entrances have boarded doors. To the right, there is a vertically-slatted window and another boarded entrance beyond it. At the far right, there is a similar slatted window and an external stone stair that leads to a boarded entrance for access to the upper level of the later range.

The upper level of the barn includes an exposed ventilation slit to the left and two 19th-century windows; the left window has a 4-pane lower part and an open upper section, while the right window has 6 panes. The later wing features a large cart bay that has been reduced to a modern entrance with a window. To the right of this is a through passage that leads to a rear farmyard, along with two small 19th-century 4-pane windows on the upper floor. The section to the right is roofed with corrugated iron and contains two plain cart bays and a boarded loading bay above, under the eaves.

The southeast gable of the barn has ventilation slits in the upper section and a modern gabled wooden dovecote attached to the wall. At the rear, there is a 19th-century catslide extension at the upper end, along with a low modern brick addition in the center.

Inside, the barn section has an eight-bay layout with tie-beam and raking strut trusses, one of which is dated 1725 (between bays 6 and 7). There are also reinforcing king post trusses from the 19th century.