Waterproofing is a crucial aspect of construction and everyday products, ensuring that water and moisture do not penetrate and cause damage. In the United States, several parts are commonly designed to be waterproof, including:

1. Roofing Materials: Asphalt shingles, metal roofs, and rubber membranes are commonly used in roofing due to their waterproof properties. According to the National Roofing Contractors Association (NRCA), over 80% of residential roofs in the U.S. are covered with asphalt shingles, which are designed to be waterproof.

2. Gutters and Downspouts: These components are essential for channeling rainwater away from the foundation of a building. They are typically made of materials like aluminum, copper, or vinyl, which are inherently waterproof.

3. Windows and Doors: Modern windows and doors are designed with weather stripping and seals to prevent water from entering the home. According to the National Association of Home Builders (NAHB), energy-efficient windows and doors are a priority for new construction, with many featuring advanced waterproofing technologies.

4. Flooring: Waterproof flooring options, such as porcelain tiles and luxury vinyl plank (LVP), are increasingly popular in the U.S. These materials are designed to withstand moisture and are suitable for areas like bathrooms and kitchens.

5. Electronics: Many electronic devices, including smartphones, tablets, and cameras, are designed with waterproof features. According to a report by Statista, the global waterproof smartphone market is expected to grow significantly over the next few years.

The reason these parts are waterproof is due to the materials used and the design of the products. Waterproof materials like rubber, plastic, and certain metals are impermeable to water, while others, like asphalt and vinyl, are coated or treated to repel moisture. Additionally, the design of products often includes seals, gaskets, and other barriers to prevent water from entering. For example, the weather stripping on doors and windows creates a tight seal that keeps out water, while the rubber membrane on roofs prevents water from seeping through the shingles. These features are essential for protecting buildings and personal belongings from water damage, which can lead to costly repairs and health hazards.