The first suggestion that I should undertake a thorough re- vision and expansion of Mr. Blakes work on Damp Walls was made to me about 18 months ago by Mr. G. S. Wheeldon, CBE, FRICS, FAI, FVI, FRSH, my former Chief and my friend for many years. Although the original work has been unobtainable for a long time past, no other book dealing specifically with this important aspect of building construc- tion and maintenance could be traced. Yet the need for conserving the national stock of houses in Britain is today as great as it has ever been and the dangers to health which arise from the existence of damp in inhabited dwellings are no less great than they were when Mr. Blake first noted them in the Preface to his original book. In revising the work, I have assumed in the reader some knowledge of the elements of building technique and the book will, I hope, be of direct use to the owner-occupier who possesses such knowledge. Since it represents what I think I may call an experienced attempt to seek out causes and to suggest possible cures for them, his less skilled neighbour may also, at worst, find in it some ideas to discuss with his local builder. Somewhat higher up the scale of knowledge, the resident maintenance man, for instance, may find it useful in diagnosing defects and selecting appropriate remedies while I am even persuaded that there are men working in the building industry itself who could draw profit from its pages The experts themselves, of course--the Clerk of Works right through to the qualified Architect and Surveyor-they will know it all already yet even they may find in the book a handy compendium for their junior assistants and for their students. I have received much help in preparing this new edition. To Mr. Wheeldon himself I owe not only the original inspiration to tackle the job, but continued helpful advice during its execution. I am grateful also to Mr. M. B. Black- shaw, CBE, MA, ARIBA, Chartered Architect, for many con- structive suggestions, to Mr. W. J. N. Oswald, FRICS, FAI, MRSH, to Mr. J. S. Thompson, ARIBA, Chartered Architect, for the line illustrations and to Dr. H. Hurst, BSc, Ph.D, FRES, for the chapter on the Actane process of waterproof- ing, with its photographs. My thanks are also due to my wife, who not only read the proofs but accepted the burning of much midnight oil in their compilation and to many others who must remain nameless, for much help in many directions. I have retained the original authors references to a num- ber of proprietary systems only after some personal inquiry into the merits of the systems in question and I make no apologies for mentioning one or two others as well. For, in my opinion, no handbook of this sort could be as complete as it should be without them. I have tried, wherever possible, to quote my sources or to give references for statements made or for claims advanced which I have not been able personally to corroborate.