Letters Battle of the Ridge Vents To the Editor: In the article "Insulation and Ventilation: One Architect's Approach" (NEB, 8/86), the author states that the roof-venting problem has been solved by a product called "Cor-AVent." Two tests, however, throw a different light on this product, and might dampen his enthusiasm. One test, conducted by American Filter Co. in Louisville, Ky., found that Cor-AVent offered up to 2½ times the resistance to airflow of standard metal ridge vents (when tested at 12 mph of airflow). Good airflow is very important in winter when coldclimate houses need ventilation to remove moisture and prevent ice dams. The other test, conducted by Construction Research Laboratory, in Miami, Fla., showed very high water penetration with Cor-A-Vent at 50 mph airflows. At