To install a dryer duct, drill a hole for the vent cap outside, secure it with screws, caulk the edges, and finally connect the dryer to the vent cap with duct hose. The most effective dryer ducts run straight and should be no longer than 25 feet.
From inside of the house, determine the shortest and easiest route from the dryer to an outside wall. Go outside, and check the approximate location of the vent cap for any obvious obstructions. From the inside, drill a pilot hole to confirm the suitability of the location for the vent cap. From the outside, cut out a 4 1/4-inch hole. Insert the vent cap into the hole, secure it with screws, and then caulk around the outside to protect it from the elements.
Once the vent cap is installed, attach a section of rigid duct hose or an elbow to the vent cap from inside the house, and secure it with a hose clamp. In order to connect the vent cap and dryer vent outlet, add 90-degree or 45-degree elbows and additional sections of hose until the route is complete. Using a hose clamp, secure the end of the duct pipe to the dryer vent outlet. Seal any joints with foil tape, and if needed, support the ductwork by securing it to the joists with straps.