BUILDING CONSTRUCTION 135 



A common situation in which this disease is found to be in a 

 thriving condition is under ground floors, where the joisting and 

 flooring boards are attacked, particularly if the solum of the build- 

 ing has not been cleared of vegetable matter and properly coated 

 with tar, asphalt or concrete. It is obviously necessary thoroughly 

 to ventilate, in such a manner as will create a through draught, all 

 spaces under ground floors. 



Spaces in roofs, enclosed by timber, are particularly objection- 

 able, as in the event of a leakage and the presence of infected timber 

 the fungus will rapidly take root and grow, ultimately reducing 

 the timber to a powder. 



The appearance of the fungus varies with the situation, stage of 

 growth, and the facilities for promoting its growth. Sapwood, 

 particularly in white pine, is very liable to the attack of the fungus. 

 Those with experience of this disease can often detect the presence 

 of dry rot in a structure by the unmistakably musty odour emitted 

 by the fungus, and the atmosphere which it creates. 



The fungus grows and spreads rapidly, in the early stages having 

 an appearance somewhat like frost, and afterwards developing into 

 a mushroom-like skin, which spreads over the surface of the timber. 

 The fungus spreads over and into the joints of brickwork, plaster, 

 masonry, &c., in its search for moisture with which to sustain its 

 growth, but deriving nourishment only from the woodwork, which 

 it destroys. 



Resinous woods appear to be less liable to attack than white pine, 

 and in every case soft, unseasoned sapwood is attacked. 



It may be taken as an established fact that there is no cure for 

 dry rot in timber which has been attacked. The only safe method 

 is to cut out all affected parts and the parts adjoining. These should 

 be carefully placed in a saturated sack and carried out carefully, 

 without allowing any of the dust or spores to be blown about, and 

 burnt in a fire in a situation away from all dwellings. 



The replacement of woodwork should be carried out with per- 

 fectly sound, well-seasoned timber, and it is advisable to coat all 

 surfaces of such timber with creosote oil, after having scorched the 

 surfaces of all walls and remaining woodwork in the vicinity with 

 a blow-lamp. Immediately after the application of the blow-lamp 

 the surrounding woodwork should be thoroughly coated with a 

 solution of water and corrosive sublimate, 2 per cent., but in no 

 case weaker than 1 per cent. Great care must be taken in the use 

 of this solution. 



A safer but less effective method is to use a solution of copper 

 sulphate. 



