316 FARM BUILDINGS IN SOUTH AFRICA 



Another objection to thatch is that it forms a harborage for vermin and 

 small birds, and, if used for a cow-byre or other building housing live stock, 

 cannot be effectively disinfected after an outbreak of infectious disease among 

 the animals. 



Thatch is also liable to be stripped off by high winds, and it is not easy to 

 attach effective eave gutterings. 



Practice in Great Britain. — The following notes on British practice cannot 

 but be of interest. In Great Britain the materials generally employed are 

 wheaten straw, rye straw, and reeds ; while in Scotland heather and broom are 

 also used. Well-grown, stiff, wheat straw answers for all general purposes, but 

 the lasting qualities of rye straw and reeds are superior. Heather is used mostly 

 for ornamental thatching, e.g. for model dairies, cricket pavilions, and summer 

 houses. 



Oat and barley straw are only suitable for thatching ricks, where the corn to 

 be covered has not to remain in the rick for any considerable length of time. 

 The " Encyclopaedia Britannica " states that wheat straw lasts from fifteen to 

 twenty years, oat straw about eight years. 



The straw used is not passed through a threshing machine, which breaks it, 

 but is hand-threshed by flail. It is damped before use, made up into bundles, 

 beaten to knock out flag, etc., and well raked with a haymaker's rake to remove 

 all loose, short or twisted straw. 



The bundles are sewn to the thatching laths by tarred string, the butt ends 

 of the straw pointing down the roof-slope. Each row of bundles, when laid, is 

 overlapped by the succeeding row further up the roof-slope, to such an extent 

 as to cover the binding string. The thatch is laid from 9 to 16 inches thick, 

 and in well-finished thatching only the butt ends of the straw are visible from 

 the outer side of the roof-slope. Thatching poles (purlins) of rough fir, ash, 

 larch, or hazel are used, spaced up to 12 inches apart. Rough, round poles are 

 better than square sawn thatching laths in one respect, viz., that the lacing 

 string can be pulled tighter around them, even though the corners of the latter 

 be rounded off. 



The work of laying the bundles of straw (" staples ") is commenced at the 

 eaves and carried upwards till the ridge is reached. At the ridge a layer of good, 

 firm, fibrous turfs is placed on top of the straw in order to form a bolster, or 

 well-defined ridge. An alternative ridge is sometimes used, formed of two 

 boards fixed to overlap the thatch for some distance on each roof -slope. 



When the roof is otherwise completed it is raked down and longitudinal 

 runners or bands of hazelwood or twined straw are pegged to the thatch covering, 

 with hazel spikes, near the eaves and ridge and sometimes also intermediately 

 (see Fig. 219). These " runners," or " lacings," tend to prevent stripping of the 

 roof-covering in high winds, and also add considerably to its beauty. 



Valleys are smoothly rounded in with an extra thickness of thatch, no 

 valley guttering being employed. 



