Metal roofs have a reputation for being noisy, but with proper installation and adequate insulation, they are not significantly noisier than shingle roofs. The type of metal used can affect the sound level; for instance, steel roofs are typically noisier than slate or asphalt tiles but quieter than aluminum. While some people find the sound of rain on a metal roof pleasant, you can take steps to reduce the noise. Installing a thicker underlayment, adding insulation between the roof and the house, or using acoustic tiles can effectively muffle the sound. The gauge (thickness) of the metal roofing can also contribute to sound dampening.

The proper specifications for furring strips can vary, so you should always consult the roofing manufacturer's guidelines or your roofer. However, general recommendations are as follows:

• Thickness: Furring strips are typically 1 to 1-1/2 inches thick, meaning standard 1-by or 2-by lumber works well. In areas with extreme winds, a thinner strip may be preferred to limit how much air can get under the roof and cause uplift. A thicker strip can add slightly more insulation but will also increase installation costs.

• Spacing: The recommended spacing for furring strips is between 12 and 24 inches apart on center. Proper spacing is crucial for ensuring good airflow, adequate drainage, noise reduction, and better energy efficiency. The ideal spacing can depend on the roof's pitch and the specific type of metal roofing being installed.

Mansard roofs provide more attic space or living space on the interior than many other styles, and they offer a classic appearance and old-world charm to any home. They also often have multiple windows on the lower hip, providing ample natural light and ventilation. 

On the other hand, they’re more expensive to install and replace due to their complexity and rarity, and the low slope of the upper hip means that heavy snowfall can be an issue. Additionally, they’re more prone to leaking than many other roof styles.

Most shed roofs can last between 15 and 30 years, although some roofing materials like slate and clay tile can last for 50 to 100 years.  Choosing durable, waterproof roofing materials that can stand up to weather and the elements will help your shed roof last for years to come. Besides the noticeable signs that your shed roof needs to be replaced, it might also be worth replacing if it’s near the end of its life span.