Re: Lower/Exterior T1-11 rot/replacement - whole house
The siding has to be removed and replaced. Aesthetically, you will either have a strip of z-bar flashing around the bottom of the house or you can cover the flashing with the 2x as you suggest. The problem with adding a 2x is that it is only going to promote more rot because moisture will get between the 2x and siding. You could have some special z-bar made up that would extend out over the 2x as well, which will go a long way to preventing problems in the future.
Having said that, have you addressed the cause of the rot in the first place? For the skirt of most of the house to rot out suggests that the lawn sprinklers of some other regular water source is being sprayed onto the house. Another common cause is for dirt or mulch to be placed against the house. You need to determine what is causing the problem and rectify.
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