251) The type of arch generally constructed over a wooden lintel or over a flat arch for the purpose of carrying the load of the wall above is

252) The type of joint commonly used at the junction of a principal rafter and tie beam in timber trussess is

253) The type of roof suitable in plains where rainfall is meagre and temperature is high is

254) Pitched and sloping roofs are suitable for

255) The type of roof which slopes in two directions with a break in the slope on each side is known as