The costs of roofing materials depend on material costs (which fluctuate) and regional availability. In our area my neighbor Matt received several estimates and considered 3 different options:
1) Asphalt Shingle roof
Price: $7500.
Life Expectancy: About 20 years.
See the Advantages and Disadvantages of Asphalt Roofs here
2) Standing Seam Metal roof.
Price: $22,500
Life expectancy: 35-40 years or more!
See the Advantages and Disadvantages of Standing Seam Metal Roofs here
3) Exposed Fastener Metal roof.
Price: $75000
Life expectancy: 10-35 years or more
See the Advantages and Disadvantages of Fasten-Down Metal Roofs here
Matt kept thinking about the Exposed Fastener Metal Roof (Option #3). This is also called a “fasten down” roof because the screws are fastened right through the metal panels into the roof sheathing. The critics of this roof say that during the freeze/thaw cycle the metal panels move and corrode around the screws where the water can enter and this is something that we often see in our inspections. Some of the roofing contractors my neighbor spoke with refused to install them because of callbacks.
What is the best way to install a Fasten-down Metal roof?
Matt was about to give up on the Exposed Fastener roof when he spoke with a local Asheville Roofing Contractor named Francisco who said that the Exposed Fastener Metal Roof was his favorite option for the money but it had to be installed correctly. Francisco’s crew pre-drills holes into the crimps of the panels. The crimps are at the high points of the panels so if there is corrosion around the screws over time, it is unlikely that water will get under the panels (see diagram below). Francisco said that if the panels are fastened at the crimps instead of the flat areas homeowners can expect an extra 10-20 years of life expectancy.
This was a bold claim but it made sense. This was also consistent with my experience living in Central America where metal roofs are the most common roofing type. The metal roofing panels were ALWAYS fastened through the high points, not the troughs. I looked through several installation guides for these products and discovered that the best practice is installing the screws at the high points just like Francisco claimed.
Why are so many Fasten-down Metal Roofs Installed Incorrectly?
So why are so many roofers fastening the panels in the flat/low areas? The answer is upsetting. It’s simply easier and faster to ‘screw down’ the panels in the low areas because no pre-drilling is needed. This practice is convenient and profitable for the installers but a huge inconvenience for the homeowner when their roof leaks after 10 years!
After a lot of research, my neighbor decided on the Exposed Fastener Metal roof pre-drilled and fastened through the crimps (Installed by Francisco’s crew. See photo below). It looks great and they are looking forward to 25-30 years or more of a solid roof over their heads.
Note: Metal Roofs get an even longer life expectancy when they are coated with high-quality paint and re-coated every 10 years or so.
Advantages and Disadvantages of Different Roof Types:
Asphalt Roofing
Advantages of Asphalt Roofing:
- Very commonly installed
- Most contractors in most areas are very familiar with installing this type
- Predictable life expectancy
- Availability is excellent
Disadvantages of Asphalt Roofing:
- Sheds ballast or granules, asphalt, and fiberglass
- Susceptible to wind damage (can resist up to 60 mph)
- More susceptible to tree damage
- More and smaller components can mean more chance of installation error
- under driven nails
- overdriven nails
- improperly staggered, overlapped, or flashed
Standing Seam Metal Roof
Advantages of Standing Seam Metal Roofs:
- Longest life expectancy (30-50 years or more with regular painting and maintenance)
- Excellent wind resistance (Up to 180mph with warranties up to 100-120 mph)
- More resistance to tree damage than asphalt roofs
- More resistance to sun damage than asphalt roofs
- Does not shed granules, asphalt, or fiberglass
- Can be used for rainwater catchment systems
Dis-Advantages of Standing Seam Metal Roof:
- The most expensive type of roofing discussed in this article
- Noisier with rain (some people like it)
- Damaged panels or installation issues can be more difficult and expensive to repair (see ‘oil-canning’)
Fasten-Down Metal Roofs
Advantages of Fasten-down Metal Roofs:
- Depending on material costs and region Fasten-Down Metal Roofs can be as affordable as an Asphalt roofs and sometimes cheaper
- Easier to repair than Standing Seam Metal Roofs
- When correctly installed and maintained will last as long or longer than Asphalt roofs
- Cheaper to install than Standing Seam Metal Roofs
- Better wind resistance than asphalt roofs
- More resistance to tree damage than asphalt roofs
- More resistance to sun damage than asphalt roofs
- Does not shed granules, asphalt, or fiberglass
- Can be used for rainwater catchment systems
Dis-Advantages of Fasten-down Metal Roofs:
- When incorrectly installed will have a shorter life expectancy than Asphalt or Standing Seam Metal Roofs
- Noisier with rain (some people like it)
- Fasteners tend to loosen and corrode over time (Stainless steel fasteners are usually worth the extra expense). Regular painting or re-fastening will be necessary
- Fasteners gaskets deteriorate over time and may need to be replaced every 10-15 years
- Holes around the fasteners will open up and corrode over time (which is why it is important to fasten at ridges or ‘V’s
Conclusion
The best roofing type for each household depends on market prices, local availability and expertise, and the unique qualities that each material has. For my neighbors in West Asheville (back in 2017) the fasten-down metal roof was the best choice for their budget, design and desires for a rain-catchment system- they were also able to find a contractor with good availability that would install it the correct way.
Roof Inspections in Asheville and WNC
Our Company, Builder Buddy Inspections & Testing, provides thorough roof inspections as part of our Home Inspections, Pre-sale Inspections, Commercial Inspections and Annual Maintenance Inspections. We always carefully inspect all roof penetrations (chimneys, skylights, plumbing vents, etc.), valleys and flashing at gutters and side walls as these the most problematic areas of every roof. We inspect asphalt roofs, fiberglass roofs, fasten-down metal roofs, standing-seam metal roofs, slate roofs, wood shingle roofs, membrane roofs (EPDM) and more. We inspect all accessible attic areas in search for leaks and proper insulation and ventilation. If you are located within 40 miles of Asheville call us today to set up an appointment or schedule here.
