This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
18. Thatching on a house is an admirable covering for securing warmth in winter and coolness in summer, but, being subject to injury from birds and a great risk from fire, is very seldom used. A good thatch roof has been known, when well put on and composed of sound straw, to last from 10 to 14 years; while in respect to its being the most picturesque form of covering for cottages, arbors, and like buildings, there can be no room for question.
19. The roof is prepared to receive the thatching by nailing to the rafters, lath, or light purlins, at 8-inch centers (see a, Fig. 16), on which the straw is laid. Like slating or shingling, the thatching is commenced at the eaves by laying on bundles, about 3 or 4 inches in thickness, and securing them to the laths, using a thatcher's needle and rope yarn. The yarn is tied around the purlins as at a, Fig. 17, or hung with thatching hooks, which are tied to the head of each bundle and hooked over the purlins. Starting at the end wall, or at the gables, full-width bundles are laid until a row reaches the ridge, the thickness of the completed row being from 12 to 15 inches.
After two or three rows have been put on, they are interlaced with withes, or reeds (see b, Fig. 17), the ends of the withes being bound together and nailed to the purlins; the withes may also be tied to the purlins with the yarn.
The rods c are run through the thatch when 8 or 10 feet have been laid; they are spaced about 2 feet apart, and are secured by looping a withe over the rods and nailing the ends to the rafter.
Where the thatch comes against the gable wall, the joint must be well filled with lime mortar. After allowing this to thoroughly settle, it is pointed with cement mortar, carried well up against the wall. Similar pointing should be used about chimneys or other openings, or a canvas flashing may be nailed to the walls with a wood strip at the top, the flap being turned out on the thatch and the whole thoroughly tarred.
The ridge may be formed of thin bundles of straw, laid with the middle on the ridge and afterwards withed down to the roof [see (a), Fig. 18]; or the straw ends of the upper layer may be turned up and withed together and surmounted by a terra-cotta ridge cresting set in cement, as shown at (b), Fig. 18.
The eaves may be raked out until the edge is very fine, thus forming a round, easy shed for the water [see (a), Fig. 19], or cut off on the under side, as shown at (b), Fig. 19. As each course is laid, the lap ends should be raked out, to maintain as even and continuous a surface in the finish as possible.
20. The thatcher requires the following tools: a common stable fork, to toss the straw together before it is made into bundles; a thatcher's fork, to carry straw up to the roof; a thatcher's rake, to comb down the straw straight and smooth; a knife, to point the withes; a half glove of leather, to protect the hand when drawing or pushing in the smaller withes; a long, flat needle; a pair of leather gaiters, to come above the knees, used when kneeling on the rafters.
The materials required are: good straw of any kind, or straw reeds, wheat straw being the best; also rope, nails, withes, and rods.
To complete a square of roof, the materials necessary are: two-thirds of a load of straw, laid on about 12 to 14 inches thick; a bundle of oak laths, 1 1/4 inches wide and from 1/2 to 3/4
inches thick, nailed to the rafters, as in Fig. 17; 75 withes;
1 1/2 pounds of rope yarn, or, in its place, Manila rope; 35 rods; and 250 nails.