A typical wall profile in the Brazos Valley starts with drywall on the inside; then a 2X4 wall with R-13 fiberglass insulation between the framing members. On the outside of the 2X4 wall is nonstructural sheathing and then the siding.
When replacing siding we usually remove everything down to the framing. This allows us to inspect and fix the insulation. This includes caulking the base of the wall thereby reducing air leaks. Occasionally there will be rot or other defects that need to be repaired.
We always use structural sheathing on the outside of a wall. Structural sheathing is made from wood and when put under stress the nails that hold it will fail before the sheathing does. This has the effect of turning the wall into a beam. This is a good idea anywhere, especially here, as we have expansive clay soils that often cause foundations to move. By using solid structural sheathing we create a much stronger house that will hold up even when the earth moves. It is also much more resistant to high winds.
On top of the structural sheathing goes a product called house wrap. this is a moisture and air resistive barrier that protects the home. Many house wraps allow too much air and moisture through for our hot, humid climate. On our projects we specify top of the line Tyvek brand house wrap. The house wrap must be taped at all of the seams and at the top and bottom of the wall. This is a crucial step in properly air sealing a home. It is important to use tape that has been specifically formulated to adhere to the the specific house wrap. Application of house wrap around windows and doors is somewhat intricate and each step is crucial to a properly functioning house.
In this profile, on top of the house wrap goes the siding. Proper application of siding requires a lot of attention to detail. Most often we see trim placed directly over the siding. While this is a much faster way to complete a job, it is a significant compromise to the overall aesthetics of a project and especially to the way the home is protected from wind, water and humidity.
It is not uncommon to see window and door trim run in ways that will cause leaking. Failure to properly install metal flashings is another cause of water penetration.
We call this our typical siding profile because it most closely mimics what is common in our area. But by adding just a few extra steps and using higher quality materials we are able to achieve a much better looking and longer lasting siding installation. It should be noted that this is not our most highly recommended siding profile and it is a profile that we strongly discourage for wood siding, which needs airflow behind it to be durable.