Felt paper, thin structural sheathing or rigid foam sheathing are all used for the same reason people wrap their houses or sheds in plastic: homeowners want to protect their homes from the elements by controlling the infiltration of air and water. While water will inevitably make it through your first layer of brick, stone or stucco, wrapping your home during the framing stages will create the barrier you need to block the draft and water. Since tiny holes make the plastic breathable, water will continue to drain away from your home.
Since wrapping your home will slow down or completely stop the flow of air, you will have an increase in the R-value. The higher the R-value, the greater the insulating effectiveness. You will save energy by keeping your heat in and unwanted cold air out; you will save money, because you will definitely use less heat.
Homes that are wrapped will be protected from property damage that water may cause. Once water has saturated your wood framing, terrible things will happen: the wood will rot and the house may begin to settle or shift. Wet places are also ideal for mold growth. In addition to the damage that you may not catch at first glance, unwanted water may cause bubbling and peeling of paint, a sure sign to potential buyers that something is wrong with your home.
House wrap is a thin plastic sold on large rolls, and though you can compare brands, essentially they are all formulated to stop air and create a barrier. No matter which brand you decide to buy, be sure to purchase the right tape and fasteners. Handle materials with care when you are using plastic. If you are not careful, you may not get the results you want. Overall, house wrap is easy to buy and use.