(Contribution from the U, S. /.rmy Engineers and the Department of 

 Agriculture) • ' , .. ' _ 



SP!]CIAL PROBLEMS OF DI^TERIORATION 

 IN APa'iY iJATPTiFRONT STRUCTURES 



by J. A. Beal, R. J. Kowal, I'L D. Reed 



INTRODUCTION 



During recent years there has been an increased interest in the deteriora- 

 tion of wood and wood products and particularly in the d amage caused to 

 buildings. This has been due, to a considerable extent, to the increasing 

 values of properties and the high cost of their maintenance. Costs for 

 some grades of lumber and structural timber have increased approximately 

 200!-? since 19ii2. 



There have been other reasons for t'lis interest, however. The wide use 

 of second- growth timber as a structiu?al wood has resulted in losses greater 

 than heretofore known, due to insect damage, decay, and other forms of 

 deterioration. Such woods, particularly second-growth southern pines, con- 

 tain little heartwood and a considerable volume of sapwood v^hich lacks 

 resistance to deterioration. 



Changes in style of building construction have also created conditions 

 favorable to insects. The practice of erecting structures upon concrete 

 slabs, for ex?jnple, favors termite activity, and the use of heating systems 

 in cold climates has had a marked influence— large central heating ahd 

 humidifying units serving to create conditions, even in tie substructure of 

 buildings, that enable insects to continue their destructive activities 

 throughout the entire year rather than on a seasonal schedule as they would 

 normally do. 



Estimates of current losses due to such organisms as subterranean and non- 

 subterranean termites, wood borers, powder-post beetles, marine borers, and 

 decay, are astounding. In the Cjial Zone alone, the Corps of Engineers 

 was until recently spending almost ,3'00,000 annually for repairs to build- 

 ings damaged by subterranean termites; establishment of ai effective termite 

 control program has reduced these losses greatly. Losses caused by non- 

 subterranean termites, although not so great, are very high also, particu- 

 larly in the semi-tropics and tropics. In certain areas, such as the 

 Florida Keys and the iest Coast, they are far more severe than subterranean 

 forms. There are a large number of ;;ood-boring insects v;hich in the aggre- 

 gate annually destroy finished products valued at several million dollars. 

 Accurate estimates of these losses are unavailable due mainly to the fact 

 that because of the insidious nature of the insects' activities, they have 

 atti^cted less attention, and as a result have been less intensively investi- 

 gated. 



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