Example - for a 3-bedroom, 2,000-sq.ft. home, with an exhaust-only ventilation strategy, and a target ventilation rate of 50 CFM you would need to install a 50 CFM fan with an adjustable-speed DC motor for continuous operation.
Quick Answer. Trenches were built during World War I to protect stalemated troops on both sides from artillery and rifle fire. Although the war began with rapid movement of the German army, when the Allied forces stopped the Germans, both sides dug trenches to help avoid losing territory they had gained.
âThe purpose of a French drain is to effectively drain water, while creating an aesthetically pleasing landscape, says Lunt. You donât want the pipes to show, so in a typical 12- by 12- by 4-inch system, youâd be digging a trench 12 inches wide by 12 inches deep and using a 4-inch pipe.unt emphasizes that your drain should be at least 12 inches below the ground at the groundâs lowest point; depending upon the topography, you may be digging a trench of varying depth.