Standing Seam Metal Roofing: The Ultimate Guide for Florida Contractors

Standing seam is the concealed-fastener metal roof. The panel legs stand up above the water plane and everything that holds the roof down lives inside or underneath that seam, so no fastener and no washer is exposed to Florida sun, rain or salt. That is the whole argument for the system, and it is why five of the six standing seam profiles we stock hold High Velocity Hurricane Zone approval.

If you already know the system and only need the profile, the working summary is this. SL150 covers most residential and light commercial work. NS150 is the clip-free install that still holds HVHZ. M100 and M150 are the coastal and high-load answers. SL100 is the widest coverage in the line. NS100 is a good panel that you cannot use in Miami-Dade or Broward, and we will say that plainly rather than let you find out at plan review.

What standing seam is, and what it is not

A standing seam roof is a series of flat pans joined by raised vertical seams that run from ridge to eave. Water is carried down the pan and the seam sits above it. The panel is attached either by a concealed clip screwed to the deck, or by an integral nailing flange along one leg that the next panel covers. Either way the fastener is out of the weather.

What it is not is a structural panel. Every standing seam profile in our line is approved over a solid deck, not over open purlins. All six require a minimum 15/32 in. plywood deck, with the 26 ga nailstrip also approved over 7/16 in. OSB. If your job is open steel framing with no deck, you are looking at PBR panel, not standing seam.

It is also not the cheapest way to a metal roof. Exposed-fastener systems like 5V crimp and rib panel cost less per square and install faster. They are the right call on plenty of Florida jobs. Standing seam earns its price on appearance, on the absence of exposed fasteners to maintain, and in the HVHZ where the alternatives largely are not approved.

The six standing seam profiles we stock

Every figure below was read out of the signed Florida Product Approval evaluation for that exact panel. Coverage widths are maximums, so a job may be ordered narrower. Verify the current revision of any approval at floridabuilding.org before you submit.

Two rows deserve a second look. NS100 is the only nailstrip in the line without HVHZ approval, and it is the only standing seam profile we carry in 26 ga. SL100 has the widest coverage of any profile here at 17 in., which is worth real money on large simple planes.

Attachment method: snaplock, nailstrip or mechanical lock

The three methods are the substantive difference between these panels, and we have written a full head-to-head on snaplock, nailstrip and mechanical lock. The short version:

• Snaplock (SL100, SL150). The panel snaps over a concealed 18 ga fixed clip fastened with two #12 x 1 in. pancake screws. No seaming machine, no second pass, no equipment to mobilize.
• Nailstrip (NS100, NS150). The panel fastens straight through an integral flange into the deck and the next panel covers the fasteners. Fewer parts on the roof and one less step in the sequence.
• Mechanical lock (M100, M150). The seam is closed with a powered seamer after the panel is set. M100 rolls to a 180 degree double lock. M150 closes to 90 degrees. This is the most labor and the most equipment, and it produces the most closed joint.

Seam height: 1 inch or 1.5 inch

Seam height changes three things at once: how the roof reads from the street, how much roof each panel covers, and what the assembly is rated for. A 1.5 in. seam throws a deeper shadow line and sits further above the water plane. A 1 in. seam covers more roof per panel on the snaplock, which reduces panel count, clip count and linear feet of seam.

The coverage differences are not trivial. Across our line the range runs from 17 in. on SL100 down to 15.5 in. on NS150. On a 40 ft wide plane that is 29 panels versus 31. We work through the tradeoff in detail in 1 inch vs 1.5 inch standing seam.

Gauge, substrate and material

The standing seam line is 24 ga steel at 50 ksi minimum yield, with a few exceptions. NS100 is also offered in 26 ga under a separate approval with its own coverage width and its own load rating, M100 and the aluminum M150 are 0.032 in. aluminum, and both nailstrip profiles (NS100 and NS150) are also available in 0.032 in. aluminum with a PVDF finish.

The aluminum decision is a corrosion decision, not a strength decision. Aluminum does not rust where a coating gets scratched or a cut edge is left exposed, which is the failure mode that matters within sight of salt water. On oceanfront work in Monroe, Miami-Dade, Broward, Martin and along the Gulf beaches we quote aluminum with a PVDF finish as the default. Inland, Galvalume steel is a fair and permittable specification, and it is stiffer for the money.

All six profiles are approved over a minimum 15/32 in. plywood deck. On a re-roof that means the deck has to be inspected and, where necessary, re-sheathed before the approval applies. An approval covers an assembly, not a coil.

Finish: PVDF or SMP, and what the warranty actually says

SL100, SL150, the steel NS100 and NS150, and the steel M150 are available in Galvalume, SMP or PVDF. M100 is PVDF only, and so are the aluminum M150 and the 0.032 in. aluminum NS100 and NS150.

The published material warranty terms are specific and we will not round them up:

• 35 years on Galvalume steel and aluminum coated with Sherwin-Williams Kynar 500 (PVDF).
• 40 years on Galvalume steel coated with Sherwin-Williams WeatherXL SMP.
• 20 years on AZ55 acrylic-coated Galvalume steel in mill finish.

The 40 year figure on SMP surprises people who have been told PVDF always warrants longer. It does not. What PVDF buys is resin chemistry that holds color and gloss better under Florida ultraviolet, particularly in the deep and saturated colors, and it is the only finish offered on our aluminum. That is a real difference, but it is not the difference the headline warranty number implies.

One more thing worth saying before a customer says it to you: oil canning is not a defect and is not grounds for a warranty claim. It is a visual characteristic of light-gauge flat metal in a flat plane. Striations, a narrower panel and careful deck flatness reduce it. Nothing eliminates it.

The HVHZ constraint

The High Velocity Hurricane Zone is Miami-Dade and Broward counties, and nothing else. Not Palm Beach, not Monroe, not Lee. Inside those two counties a product must hold an approval that specifically covers HVHZ, and there is no workaround, no engineering letter and no price at which a non-HVHZ panel becomes acceptable.

Of our standing seam line, SL100, SL150, NS150, M100 and M150 hold HVHZ and Miami-Dade approval. NS100 does not, in either gauge. If you are quoting Miami-Dade or Broward, NS100 is off the table before the conversation starts. We do not quote it into those counties.

Outside the HVHZ all six are permittable, subject to the wind calculation for the site. That last clause matters more than the HVHZ label in some places. Monroe County and the Keys sit outside the HVHZ and carry the highest design wind speeds in the state, so products there get chosen on the calculation, not on a label.

How to read a design pressure on an FL approval

Every approval lists installation methods, each with a fastener or clip spacing and a load. Tighter spacing buys a higher number. A few real examples from our line:

• SL100: 67.3 psf with clips at 24 in. o.c., 131 psf with clips at 6 in. o.c.
• SL150: 86 psf at 24 in. o.c., 108.5 psf at 12 in. o.c., 116 psf at 6 in. o.c.
• NS150: 78.5 psf with one #12 x 1 in. fastener at 11 in. o.c., 116 psf at 6.5 in. o.c. plus pan fasteners at 12 in. o.c.
• M150 in 24 ga steel: 101 psf with clips at 16 in. o.c., 131 psf at 8 in. o.c. with a continuous sealant bead on the male leg.

The critical point, and the one that gets misread: the design pressures on our standing seam panels are allowable loads with a factor of safety of 2.0 already applied. They are not ultimate values and they are not maximum design pressures. Do not compare them directly against a 5V crimp number, which is a maximum design pressure. Confusing the two is how a submittal gets rejected.

Why we fabricate to exact length

Panels are fabricated to exact length by our Florida fabrication partners and delivered crated. That eliminates end laps, which is the single most common leak path on a long metal run, and it cuts the waste factor because you are not cutting stock lengths down and throwing away the remainder.

Hardwood crates are set on the driveway by forklift and panels are pulled as needed, so they do not get scratched, stepped on or left in the grass. On statewide work that protection is the difference between a clean install and a punch list. Read more on crated delivery, and on field measurement verification, which matters more when panels arrive cut to length than when they arrive as stock.

Specifying a job

Work in this order: county first, because the HVHZ decides what is even eligible. Then substrate, because distance to salt water decides steel or aluminum. Then attachment method and seam height, which are the design and labor decisions. Then finish and color, which is where the client gets a say.

When you have those four, put the job through Instant Metal Quote and you will have a material list and a number in minutes rather than days. If you would rather talk it through, book a consultation or send the plans to our sales desk and we will work the panel selection with you. The full approval documents and installation instructions for every profile are on the Florida Product Approval page.