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.

Properly maintained roof decking can last between 20 and 30 years on average, though it varies based on a few factors. Mainly, the quality of roof decking materials and environmental conditions have the most impact on longevity. You can extend its lifespan by regularly inspecting your roof and making repairs as necessary.

Concrete tile roofs last for an average of 50 years, but you could see more than that if you’re diligent about repairs, roof inspections, and maintenance to avoid major damages. Concrete tile roofs are prone to cracking, so they may not last as long without needing repairs in areas with extreme weather, especially hail.

Roofing material costs vary depending on the type of material you choose and whether you install it yourself or hire a roofer. Shingles are the most affordable option and cost between $70 and $400 per square, metal roofing is between $100 and $1,500 per square, and concrete tile is between $300 and $1,000 per square.