Dry Rot. 



5i7 



the mycelium, which possesses the power of remaining in a 

 latent condition for some time, commences active growth when 

 the wood is used in any part of a building where it is exposed 

 to dampness ; and this in some cases is unavoidable, as when 

 the ends of joists are built into a wall. Under such circum- 

 stances dry rot eventually appears. 



On the other hand, the fungus is by no means rare on old 

 beams and boards stored in wood-yards, &c, and it is mainly 

 from such sources that spores or portions of the spreading 

 mycelium are introduced along with new wood into buildings. 



Again, when repairs are being made to a house that has 

 suffered from dry rot, sufficient care is not exercised in the 

 nstant destruction by burning of diseased wood ; and portions 

 that are not too much decayed are often stored for repairing 

 purposes. By such means the air in towns always contains 

 spores of the dry rot fungus. 



During the building of a house the danger arising from the 

 presence of dry rot may be reduced to a minimum if proper 

 precautions are taken. 



A thorough system of ventilation and the avoidance of damp, 

 stuffy places is of primary importance. The endeavour to 

 exclude dry rot by hermetically closing all communication 

 with the outer air in the spaces between flooring-boards and 

 joists, and similar places, has been practically demonstrated to 

 be an utter failure, and one entailing a cost of many thousands 

 of pounds to rectify in the case of a mansion constructed 

 during recent years. 



Perhaps the greatest source of danger arises where the ends 

 of joists are built into a wall near the basement of a house, and 

 this is more especially true where there is evidence of red stripe 

 in the wood. As a precaution, the ends of joists should be 

 treated with creosote. Coal tar is not recommended, as its 

 power of penetration into the wood is very limited and by 

 forming a waterproof coating it prevents the wood from drying. 



Another frequent source of danger arises from the use of 

 damp deadening material, or " pugging," and covering it over 

 with boards before all the moisture has evaporated. Such 

 material should be used as dry as possible, coarse sand being 

 the best for the purpose. The surface of boards coming in 



