How Do You Flash Around Doors & Windows?
Modern doors and windows come as assembled units from the factory and are ready to be dropped into their pre-sized openings. The joint between the siding and the door of window jamb is a weak point that can allow water to seep behind the siding and cause damage to the building’s sheathing and to the jamb itself if it is a wooden jamb. The vapor barrier alone is not enough to shed and channel water away from the underlying wood structure to prevent this damage, and so flashing is used to cover this weak point. Flashing can be of the rubber sticky-back type or the old fashioned sheet metal type. Determine the length of the flashing necessary to cover the vulnerable areas. Measure wooden or plain jambs from the edge of the hole. Measure aluminum or vinyl jambs from the edge of the jamb itself and not the edge of the nailer lip that laps onto the sheathing. The lip will be covered by the flashing. Measure the width of the flashing material and double the number, then add the new number to
