Very modern oasts bear little resemblance to traditional oasts. Another location that has oasts was Tyenna. Many redundant oasts have been converted into houses. Often kiln roofs have to be rebuilt, and cowls provided on converted oasts. Increasing demand for housing has led to many oasts being converted into houses. These oasts had louvred ventilators instead of a cowl. These oasts were much larger and constructed of modern materials. The Czech Republic also has oasts. A few oasts had square kilns with brick roofs, again covered in tar or pitch. In many cases, early oasts were adapted from barns or cottages. Some oasts were entirely brick except the front and floors, which were timber. Oasts can be found in the UK and abroad. With the increasing mechanisation of the hop-picking process, many oasts fell into disuse. Oasts were generally built of bricks, or local stone. Oasts were built of various materials, including bricks, timber, ragstone, sandstone.