Good straw makes a most excellent covering for buildings in the country; and as timber is becoming more valuable and slate can only be obtained from considerable distances, it is probable that straw will be used more and more in the future. Thatch makes a warm and durable roof; and owing to its porosity it tends to keep the air in stables and outhouses pure and clear, since the law governing the "Diffusion of the Gases" has full play.
The great objection to thatch is the danger from fire; but it may be rendered comparatively incombustible by soaking it in whitewash made of lime, or whiting and size, in the usual way, to every four gallons of which has been added one pound or rather more of alum. Alum would suffice by itself; but the rain would wash it off. The lime and size form a film over every straw, insoluble in water. If the interior of a thatched roof be kept dry, it will last as long as the timber which supports it.
As regards the durability of thatch under ordinary conditions, Loudon makes the following statement: -
" We have known many roofs of this kind in Scotland which have lasted the length of a farmer's lease (nineteen or twenty-one years) without any repairs; the surface of the thatch becoming covered with growing moss excludes air and moisture, and prevents decomposition."
Thatching is an art which requires a good deal of skill and experience; and the difference between a well-made roof and one that has been put together by an unskillful hand is very great, both as regards efficiency and durability. In many parts of Europe thatching is a regular trade, to which the beginner serves an apprenticeship, as to any of the ordinary trades. The following directions, however, if carefully followed, will enable the amateur to cover a small building in a manner that is at least respectable: -
Rye or wheat straw only should be used, and must be carefully threshed with a flail to leave the straws unbroken. Bind in bundles, distributing the buts of the straws equally to each end of the bundle. A good roof can not be made if the straws all lie one way. It was always customary to make the band three feet long, as this gave a bundle of convenient size for handling. In a dry time we sat the bundles on end and threw water upon them a day or two before we used them.
The rafters are placed in the usual way, and crossed by slats two by two, nailed 14 inches apart, though 12 inches will do equally well.
Begin at the eaves and lay a row of bundles across. Have an iron needle 18 inches long prepared and threaded with oakum 8 feet long. Fasten the thread to the slat and pass the needle through the bundle to a boy stationed under the rafters, making three to four stitches to the bundle. The boy draws the cord up tight, and passes the needle up through again, but on the other side of the slat. By this means the first course is sewed on. Succeeding courses are treated in the same way, being laid so as to overlap the stitching. Lay the heaviest row of straw at the eaves to make it look well. When you come to the ridge, fold the tops of the straw over until you bring up the other side, then get some thin sods, 10 by 14 inches, and 1 1/2- inches thick, and lay them neatly upon the top, using a small piece of board to clap them all slick and smooth. Boards put on like ordinary ridge-boards will do instead of sods, if preferred.
Get the point of an old scythe, about 18 inches long; attach a handle, so that it will be like a long knife, and with it "switch down" the roof all over, to carry off all the loose straws, and trim the others off smooth. If well done, the roof will be as smooth as a board. Stretch a cord along the eaves the whole length of the building, and trim off straight by it, leaving the outside a little lower than the inside, which will prevent its looking thick and heavy.
A roof made in this way will not be injured by wind and rain, and it ought to last from 25 to 30 years in the Middle States.