A starter strip ripped from the same siding material acts like the top of a siding course as it holds the bottom of the first course of siding out from the wall.
Working from left to right, additional courses install in a stair-step fashion. Note the two siding gauges.
The butt joints in each course are flashed using aluminum coil-stock, which we form ahead of time into 4-inch-wide pans or cards that are as long as the nominal width of the siding that we’re installing. We then form a 90-degree leg at the top that is as long as the thickness of the siding.
The bend lets us place each card at the end of a course without nailing it in place. Because the card moves with the board, we can adjust a row of siding if necessary to compensate for a slightly bowed piece.
Pieces such as those around a window need to be notched. The exposed edges of the siding are sealed immediately after cutting.
For the pieces above a projection such as window trim, we hold the siding up 3/8 inch above the flashing to keep the siding from wicking moisture and to allow water to drain away freely.
We install a piece of rigid material over the top of each projecting element, integrate the top of the flashing into the WRB, seal it tight to the weather, and then seal around it with caulk.
We usually make our own flashing on a portable sheet-metal brake, forming it out of painted aluminum coil stock in a color that matches the siding or trim.
We apply sealant to all areas that require it, such as where the siding abuts vertical surfaces, doors, and windows and at the soffit or frieze juncture.