Metal Roofing Guage and Thickness Explained
A common question I receive from homeowners concerns what metal roofing guage they should purchase. While those who ask this are hoping for a simple answer such as “only purchase 26 gauge,” the answer is never nearly that simple. Below I will share my thoughts on what sort of metal thickness (or gauge) is best for residential metal roofing.
First of all, I despise what I call the “gauge game.” Referring to metal thickness by gauge is an old process that I believe is antiquated and should be eliminated. It is done primarily only with steel today. Other common roofing metals such as aluminum and copper have gone on to refer to metal thickness in decimal form — representing exactly how thick the metal is in inches. This would be my preferred method for steel as well.
The Problem with Metal Roofing Guage as Measurement
The problem with metal roofing gauge is that there is a wide range of tolerances. For example, one company might sell a product as being “24 gauge” but, in reality, the thickness of the metal could vary from 0.018″ to 0.0335″ based upon exactly how that company looks at things and how big of a tolerance they allow for. There are even different ranges referenced for steel versus galvanized steel. Overall, this creates a huge range! Now, in reality, the range will usually be narrower than what I have given above, but the fact is, this is open to interpretation and manipulation and I don’t like it one bit. I have lobbied the steel industry to change this but to no avail. I think some folks enjoy playing the “gauge game” but to me, it just hurts consumers and also hurts manufacturers who are trying to keep things honest.
- My first piece of advice when considering metal thickness is, if you’re looking at steel, insist on knowing the decimal thickness of the steel! Trust me, the manufacturer knows what it is — it’s just a matter of whether they want to tell you. If they do not want to tell you, look for a different supplier.
- Next, even once you know the decimal thickness of steel or aluminum roofing, you need to know if that is with or without paint. You can also inquire as to what tolerance they have on their stated metal thickness. There will be some nominal tolerance both plus or minus and that’s just a reality of the metals industry. Paint, though, will make a difference to the thickness and, if you truly want to compare metal thickness “apples to apples” of various metal roofing products, you need to specify whether it is with or without the paint or another coating.
- Please know that I will take a well designed and properly installed metal roof produced from thinner metal over a thicker metal product that is poorly designed or improperly installed any day of the week. In other words, the metal thickness should not be the first consideration when choosing a metal roof.
You need to do and know:
- Make sure that the roof panel being considered is appropriate for and approved by the manufacturer for your roof’s configuration. As an example, many metal roofs have minimum pitch requirements. Never allow a product to be installed at a lower pitch than its manufacturer specifies. Other considerations are things like valleys, dead valleys, flared gables, mismatched roof pitches, and non90-degree hips that could exist on your roof and become real issues for some metal roof products. Many times, salespeople have not been properly trained to recognize these things so they only become issues when the installation crew shows up.
- Know what sort of finish or coating is on your roof and what its expected performance is.
- Know what warranties you will get with your roof and who they will come from.
- Know if your roof is Certified Premium Quality by the Metal Construction Association. Make sure that your roof is not being produced from “secondary” metal that was rejected by other producers.
- Know how your roof panel addresses things like wind resistance, roof valleys, and fasteners. Know whether the fasteners are exposed or concealed.
- Know your installer and their experience level with projects like yours.
So, while metal thickness is not the key consideration when buying a metal roof and some folks will try to fool you on metal thickness, I understand the concern. Please understand that recommended metal thicknesses will vary based on the design and engineering of the metal product being considered.That said, here are a few general recommendations. These recommendations are with paint.
Metal Roofing Thickness Recommendations that Include Paint
Exposed fastener corrugated steel roofing: .014″ – .018″
Exposed fastener corrugated aluminum roofing: minimum .024″
Steel standing seam: minimum .024″
Aluminum standing seam: minimum .032″
Steel shingles: minimum .0145″
Aluminum shingles: minimum .0185″
Steel tile: minimum .024″
Aluminum tile: minimum .032″
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