Exposed fasteners versus hidden for metal roof

[reader2580]

I decided to resume posting here after taking some months off.

Anyhow, I think I will finally be building my garage in the next two years. If I can get the city to approve a metal roof I will have to decide between exposed fasteners or hidden fasteners. Are a lot of you having issues with exposed fasteners leaking after a time?

I do a lot of volunteer work at a Boy Scout camp and they have been having constant issues with exposed fasteners leaking on metal roofs that are 10 to 15 years old at most. They have replaced thousands of metal roof screws in recent years.

I really like hidden fasteners, but the cost is a lot more and it seems to be hard to find good quality hidden fastener panels that are 26 gauge so they hold up better. Menards sells 29 gauge hidden fastener panels. I can find all kinds of places that sell exposed fastener panels.

 

[jkeyser14]

There should be plenty of local roofing supply places that can either roll them order them for you. When I did my last garage there were 3 different shops in our area that rolled and coated standing seam roof panels to order.

 

[PugetDude]

Hidden fastener panels are certainly better, but they're a lot more expensive to produce and install.

The best roof currently available is a 3"deep x 24" coverage Quad-Lock Industrial Standing seam panel that is mechanically seamed after installation. It is fastened down with a combination of fixed and floating clips to allow for expansion/contraction in long spans. Typically 22-24 gauge instead of the 26-29 gauge you see on mechanically seamed panels. The panel also has a butyl mastic installed at the factory that gets folded into the seam.It has the highest wind load ratings in the industry, rated for hurricane/tornado force winds. Requires special clips/closures, flashings, etc. Panels don't nest like R-panel or Ag Panel so it's expensive to package and ship. You'll need a commercial roofing contractor for this, you can't buy it at your local home center and most residential roofers aren't qualified to install it.

More realistic option for a residential project would be a 2" deep x 16 or 18" wide Architectural hidden fastener standing seam panel. These are available as either clip-fastened or direct screw-down installation. Each subsequent panel covers the exposed fasteners on the previous panel, the final seam is covered by the gable trim. Some require seaming after installation, some utilize a snap-down design. I'm not a fan of the batten-cap designs that require a separate snap-on batten.

Some home centers offer a light-gauge 1-1/4" deep x 16" coverage hidden fastener snap-down standing seam panel. Some are OK, some aren't. I'll leave it at that...

I'd avoid the guy who pulls up with a tinkertoy rollformer mounted on a trailer and rolls the panel on site. Panel consistency is hit-or miss depending on the machine, the operator and the site conditions.

Look at the catalogs for the bigger architectural panel producers like Metal Sales, MBCI, Fabral, McElroy, or Whirlwind to get an idea of what is available and meets building code requirements for your area. (Miami-Dade is much different than Minneapolis-St. Paul for example.)

 

[PugetDude]

There should be plenty of local roofing supply places that can either roll them order them for you. When I did my last garage there were 3 different shops in our area that rolled and coated standing seam roof panels to order.

The shops are only rolling the metal, it arrives pre-coated from their coil supplier.
Large producers can specify their own color palette, smaller producers pick from a selection provided by the coater.

Often you can buy the exact same color under a different name from different suppliers if they bought it from the same mill coater.
An example would be:

Supplier 1 offers "Polar White"
Supplier 2 offers "Arctic White"
Supplier 3 offers "Snow White"

All of them buy their white coils as stock color code "XYZ" from the same company.

Supplier 4 is a large producer, buying hundreds of millions of dollars every year from the same company. They have a unique color they catalog as "Winter White" - it's slightly different than what you'll get from the smaller suppliers 1-3, deliberately so.

Another issue is that while nearly everyone offers "R-Panel", there are about a dozen variants, and many of them won't interchange. Angles and depths on the major trapezoids and minor beads can vary by up to 1/4"- and they won't end-lap or seal properly if mixed with a panel from a different supplier. Pre-Engineered metal building manufacturers are notorious for this- their panels are just different enough that panels from another g building manufacturer or the local lumberyard won't match properly. (And the color will be a shade or two off...)

Also panels produced on portable job-site rollformers are usually different than their factory-produced counterparts- the angles are weaker, corners aren't as crisp, and angles are inconsistent. You can't get the same panel quality out of a lightweight machine that gets towed down a bumpy dirt road and then set up in a gravel jobsite parking lot- which is why most of them limit their panels to 16 or 24" wide; they don't have a chance of producing an acceptable 36" coverage panel with a portable machine.

 

[Toolfool]

I've always used the hidden fastener roofing with the snap-lok feature, 12' -16' widths. Seems to be the best bang for the buck, and I've done most of them alone.

 

[PugetDude]

I do a lot of volunteer work at a Boy Scout camp and they have been having constant issues with exposed fasteners leaking on metal roofs that are 10 to 15 years old at most. They have replaced thousands of metal roof screws in recent years.

If you have that many leaking screws, I suspect they were screwed through the peaks and not the valleys. Expansion/contraction and snow creep will wreak havoc on unsupported fasteners.
FYI- if they are indeed screwed in the valleys, oversized "rescue screws" are available- replacing a loose screw with an identical replacement won't solve the problem.

Screw head/sealing design have also come a long way in 15 years. Better sealing washers. better coating, UV shielding, etc.

If you don't have the budget to replace the roofs, I'd recommend screwing them down through the valleys with high-quality self-sealing washer-head roof screws and filling the old holes with short oversized washer-head stitch screws that will pull down tight without tying the roof to the substrate.

 

[reader2580]

If you have that many leaking screws, I suspect they were screwed through the peaks and not the valleys. Expansion/contraction and snow creep will wreak havoc on unsupported fasteners.
FYI- if they are indeed screwed in the valleys, oversized "rescue screws" are available- replacing a loose screw with an identical replacement won't solve the problem.

I believe they fastened through the ribs. At least one of the buildings the screws were not long enough so they came loose.

I just used the Boy Scout camp as an example of why I might not want to use exposed fastener roofing panels.

 

[reader2580]

I've always used the hidden fastener roofing with the snap-lok feature, 12' -16' widths. Seems to be the best bang for the buck, and I've done most of them alone.

Where did you find good quality panels? Menards locally sells snap lock panels, but only 28 gauge. I would like something thicker.

 

[Earp69]

There are new roofing screws that have a 40 year gaurentee, I used them on the roof of my barn. They have a crown that completely seals the rubber from the sun and elements once fastened. They were a little more pricey but not to much more. They were called ZXL WOODBINDERS

 

[Toolfool]

Where did you find good quality panels? Menards locally sells snap lock panels, but only 28 gauge. I would like something thicker.

All those jobs were while I was living in Washington. Purchased through local lumberyards. In the 35 years I was in construction I never purchased anything from a big-box store or Menards-type chain. Always from lumberyards geared to professional contractors. I'm finding those sources may not exist in Florida.

 

[bradpac]

The company I work for manufactures both of these types of roofing. It really comes down to budget and end use, then details from there. I would recommend contacting some metal roofing contractors in your area and asking opinions or drive around and spot a roof you like and knock on a door, that would probably get you the best opinions and names of who to contact. My own thoughts below...

If it's a finished space that you're making an investment in and want less maintenance and issues over the long run, a hidden fastener either snap lock or mechanically seamed is the way to go. Which depends on your slopes, lengths, substrate, etc. Some are better for different applications than others.

If that is not in your budget or you are looking for a little more DIY friendly application, then an exposed fastener system would also work well, once again a few different profiles depending on pitch, roof deck, etc. But definitely get a "long life" screw with a zinc head that fully covers the sealing washer when tightened. But even with these, the expansion and contraction on the metal panel and the wood structure will still cause them to come loose and possibly leak over time.

 

[SteveCh]

I have standing-seam metal on the house, corrugated "barn roofing" on the shop. The standing-seam with the hidden fasteners are fine, the "neoprene washer" deals on the barn roofing began leaking in earnest after about five years.

 

[reader2580]

My first preference would be a hidden fastener system, but cost could be an issue. It looks like hidden fastener is close to double the cost of 26 gauge exposed fastener. I am probably looking at $3,500 more.

One place to save money on my build would be to go with exposed fastener panels, but I will find the money for hidden fastener if exposed might end up leaking. I am also not sure if the city will allow exposed fastener metal yet. Technically, the siding and roof are supposed to match my house which is asphalt shingles, but I got preliminary approval for metal roofing.

Home Depot apparently can order Fabral hidden fastener products, but I have no idea if they compete on price with a lumberyard. They sure don't seem to compete on service.

 

[u2slow]

Exposed-screw roof will leak... just a matter of when. On a large roof, the expansion and contraction of the metal will back some screws out.

I have probably a dozen screws to change/re-seal on my 40x50 roof 6 years later. Noticed a few drips this winter along with dark water staining on the roof sheathing from below.

 

[Flail]

In Oregon I have used Custom-Bilt metals for my hidden fastener roofs(snap-loc).They have been very good bending up specific flashing designs I’ve come up with. One flashing they made as a special for me was flashing to wrap the entire fasciae with metal with an included drip edge to make my fascia maintenance free. I love the snap-loc hidden fastener roof. My old barn with exposed fasteners has so many leaks that machinery needs to be tarped.

My shop roof is 44’ x 94’. One tip I have to keeping every thing straight and parallel is to mark the peak and eve tar paper every 16” (or whatever width of your panel is). This gives you a reference to stretch or compress the top or bottom of the panel to keep everything parallel. Without doing this you can easily gain inches on the top or bottom over the length of a roof. It’s a real ***** to fix your mistakes with snap-loc roofing!

 

[yeldogt]

If you read the exposed fastener specifications -- it's really not waterproof. You need to have a water shield under it and a proper drip for the water shield. It will leak ...

The thicker base sheets with the sealing membranes add to the cost ....

A true mechanical standing seam roof with double lock only has to be 1" high -- that's way they look so nice. The snap locked are higher and the height depends on the climate -- snow areas need higher for waterproofing.

I just did a true SS Zinc on my new builds addition .. but, I can't spend that kind of my on my outbuilding. The cost for the same roofer to do a black mechanical was actually cheaper than doing the less desirable and higher clip and cap type.

If you find a roofer that does lots of higher end roofs -- they have all the equipment to make and install the panels .. and they do it all the time .. so not huge up charge for speciality work.

 

[reader2580]

One thing I didn't realize is the majority of the hidden fastener panels require a substrate and can't be put over open framing. I was planning on open framing.

90 sheets of OSB or plywood is not a small cost plus the labor for installation.

 

[u2slow]

One thing I didn't realize is the majority of the hidden fastener panels require a substrate and can't be put over open framing. I was planning on open framing.

90 sheets of OSB or plywood is not a small cost plus the labor for installation.

Open framing was not an option for me due to shear. I sheeted in 1/2" plywood.

 

[bradpac]

For open framing, especially with snow loads up in Mn you will need to look at a structural panel, like 2" standing seam or a 1.75" snap lock, as opposed to an architectural panel If you're keeping the rafters/purlins 4ft o.c. or less, it shouldn't be an issue for those two panels. All of the manufacturers should have load tables with spans you can see if it meets your building codes. If your spans are greater than that you might have to look at a 3" trapezoidal panel which has a higher rib and more structural strength, but also more expensive components that go with it.

 

[reader2580]

Strange that exposed fastener panels have no problem with open framing and snow load, but hidden fastener panels can’t handle it.

I will most likely need engineering to verify the building can handle both the snow load and weight of the roof. 1/2” plywood adds 3,600 pounds of weight, but it likely adds strength too.

 

[850xpeps]

You can change and save money on many parts of a build..... a roof is not one. The look and quality of snap lok or standing seam is the reason I wouldn’t waiver on it.

No one out here has done it on any residential. I’m so glad I did. Just make sure you use the proper flashing as some metal suppliers don’t even know what’s proper in that respect. Hidden fastener means just that. Everything takes a flashing and looks fantastic when done.

If it’s a straight roof it’s easy peasy.

Mine was double the cost of regular tin and prob double the labour because of my roof and the inexperience with it. Take your time if you have compounding flashings.

 

[mcbane]

I have several roofs in snow country with high snow loads. Corrugated panels with exposed fasteners are a nightmare but standing seam with concealed fasteners work great. No leaks and the snow slides like it should.

I don’t know whether you have heavy or light snow but if you have heavy snow with a 100 psf or more design load, sloped roofs are designed assuming the snow actually slides. Otherwise you might accumulate enough snow to crush the structure. And to get snow to slide you need roof slope and a slippery surface. Exposed fasteners are as slippery as tire studs.


Sent from my iPhone using The Garage Journal mobile app

 

[PugetDude]

Strange that exposed fastener panels have no problem with open framing and snow load, but hidden fastener panels can’t handle it.

I will most likely need engineering to verify the building can handle both the snow load and weight of the roof. 1/2” plywood adds 3,600 pounds of weight, but it likely adds strength too.

Exposed fastener panels are fastened across the face of the panel, every 9-12";
most residential hidden fastener panels are only fastened on one edge and rely on the snap lock to secure the other edge. Snow loads will open up the snap seam if the panel isn't on a solid substrate. Architectural and commercial hidden fastener panels are usually heavier gauge and secured by hidden clips.

 

[Flail]

Your roof will so much better with plywood or osb under the metal. You’ll be able to walk on it, you can put tarpaper between the metal and the plywood. Your building will be much stiffer and have less air infiltration through all those seams in the metal. If you step in the wrong place when putting on tin without plywood you might take a quick trip to the ground. If you miss a purlin (and you will) when fastening down the tin you will be caulking the hole and have another potential leak. A 40 x40 roof is about $500 dollars of osb. Well worth the investment. My roof is 3/4 plywood. I recycled all my forms from my stem walls.

 

[u2slow]

Snow load is a funny thing. At what pitch is its shedding ability taken into account? My 6/12 pitch metal clears itself fast. It wouldn't do that with asphalt shingles, and they're heavier.

A 40 x40 roof is about $500 dollars of osb. Well worth the investment.

Not quite - plywood is a good investment. OSB swells up 50% thicker and loses some 50% rigidity in damp climates, like mine.

 

[reader2580]

We only get maybe 60" inches of snow here in Minneapolis. Most of the snow is less than 8" at a time. Generally, people don't want the snow sliding off the roof. Asphalt shingle roofs tend to hold snow due to the granules. People with metal roofs even put snow guards on them to keep the snow from sliding off.

I will almost certainly use plywood instead of OSB for the roof. The thing I really don't like about sheeting the roof is all the time and effort it will take to haul all those heavy sheets up to the roof and get them into place. It could wind up taking me a couple of extra days just for this.

 

[jkeyser14]

Snow load is a funny thing. At what pitch is its shedding ability taken into account? My 6/12 pitch metal clears itself fast. It wouldn't do that with asphalt shingles, and they're heavier.



Not quite - plywood is a good investment. OSB swells up 50% thicker and loses some 50% rigidity in damp climates, like mine.

I had a 4/12 standing seam roof on my last garage and it cleared snow pretty fast.

 

[850xpeps]

We only get maybe 60" inches of snow here in Minneapolis. Most of the snow is less than 8" at a time. Generally, people don't want the snow sliding off the roof. Asphalt shingle roofs tend to hold snow due to the granules. People with metal roofs even put snow guards on them to keep the snow from sliding off.



I will almost certainly use plywood instead of OSB for the roof. The thing I really don't like about sheeting the roof is all the time and effort it will take to haul all those heavy sheets up to the roof and get them into place. It could wind up taking me a couple of extra days just for this.

Anything worth doing is worth doing right.

 

[Showkey]

I would never consider exposed fasteners ............they leak at the fastener. No exceptions.........

 

[PugetDude]

I would never consider exposed fasteners ............they leak at the fastener. No exceptions.........

No.

Quality screws, properly installed into a good substrate will last for decades.
Cheap screws, through the peaks, no sheathing will leak.

Unfortunately too many people insist on fastening through the peaks cause that's how grandpa nailed down his leaky barn roof, use cheap screws, rough-cut green purlins, and no underlayment, then wonder why their roof leaks... .. and then make a mass generalization about metal roofs.

Been in the metal construction business for 35 years.

 

[shaeff]

We went with a standing seam roof on our home. We've got a 7/12 pitch, and the panels were formed on site. Some are against that, some aren't. I don't know, but I'm happy with my roof. It was laid over the green 5/8 Advantec with the joints taped.

It looks very nice, doesn't leak (only 5yrs old) and sheds snow easily. Though, that'll change when we put in a patio and front porch, can't have the snow shedding in those areas.

 

[u2slow]

We only get maybe 60" inches of snow here in Minneapolis. Most of the snow is less than 8" at a time. Generally, people don't want the snow sliding off the roof. Asphalt shingle roofs tend to hold snow due to the granules. People with metal roofs even put snow guards on them to keep the snow from sliding off.

I will almost certainly use plywood instead of OSB for the roof. The thing I really don't like about sheeting the roof is all the time and effort it will take to haul all those heavy sheets up to the roof and get them into place. It could wind up taking me a couple of extra days just for this.

I'm glad my snow clears off the roof fast. Here, it can change to rain suddenly and easily double in weight. Weight I'd rather have in car-parts in the attic. Snow guards are installed mainly over doorways where there's an obvious hazard.

Quite sure my builder had a telehandler on-site for sheathing. My eaves start at 12' and the peak is around 25-26'. 40x50' footprint so it took a few sheets.

 

[welder57]

MBCI, Has 16" wide 2" High Ribs Flat profile(s), 24"wide 3" high rib profile, Galvalume Plus and color panels. Clips can be fixed or floating when putting these on a roof, you will need a substrate, so you can put the clips on. I would put down thermal spaces on top of the substrate to help the panels from flopping when the wind blows. These are standing seam so you will need to rent their seamer for the panels of your pick. You can get Snow Guards for each of these panels for over the doors on the sidewalls.

 

[reader2580]

It sounds like installing plywood is the right thing to do. I'm thinking about maybe just going with good GAF shingles instead of the hidden fastener metal since I will have plywood already. It would save as much as $3,000 on the project.

Any accessory structures I build have to have same siding and roof as house. The city said they might approve metal roof if same color as house shingles. If I use shingles no problem with the city as it will match the house.

The city building department actually stated the policy of the city is to say yes for building plans unless the request is outrageous. A refreshing change from a lot of cities where the standard answer is no.

 

[u2slow]

Any accessory structures I build have to have same siding and roof as house. The city said they might approve metal roof if same color as house shingles. If I use shingles no problem with the city as it will match the house.

Wow, that's HOA and gated-community type requirements.

I liked metal, but renewed my house in asphalt shingles (year-and-a-half ago) for a few reasons:
- cost
- transport (used own truck, live on an island)
- confidence and experience with DIY install (standing-seam metal is costly stuff to eff up)
- a number of roofline changes & sheathing repairs to accommodate on-the-fly

 

[reader2580]

Wow, that's HOA and gated-community type requirements.

Just about every city in the entire Minneapolis area has similar requirements as far as siding and roofing requirements for new accessory structures. I called dozens of cities before buying my current house. The city will allow a pole barn if the lot is 5 acres or more. (I have 3 acres.)

Most cities only allow relatively small amounts of garage space. 720 square feet is not uncommon with upwards of 1000 or 1100 square feet in some cities. The 720 square feet often has to be divided among all garages and accessory structures on the lot. The killer is height of the garage. Most cities only allow 10 or 12 foot sidewalls.

The city I live in allows a garage up to 3,000 square feet and up to 45 feet to the roof peak, (Only one story unfortunately.) I can have an accessory structure up to 2,400 square feet and 23 feet to the peak.

Most houses built after 1995 or so in my city have deed restrictions and/or covenants. Almost all of them don't allow any RVs stored on the property and no other structures besides the house and a small shed.

 

[PNWguy]

I would not consider exposed fasteners for anything I cared about. Every one of them I've ever worked with leaked. Every. Single. One.

I plan to install a standing seam on my new house and shop, and use tabs to hold the fixed end, rather than screw it down directly. I expect to be dead before it leaks.

It's about the same price ($1/sq ft) as good roofing with exposed fasteners. Installation may be a bit more, but I really don't care.

My chicken coop will have cheap roofing with exposed fasteners, but not my house, shop, garage, carport, garden shed or wood shed.

 

[kbs2244]

One big thing a DIY metal roof install will overlook is the expansion/contraction cycles the panels go through.
It is never ending movement.

I remember sanding at a friend’s front door one morning.
He had steel siding on the house that he had installed himself.
I was startled by the snapping a crackling of the panels moving around the nails when sun came out from behind a cloud.

 

[u2slow]

Just about every city in the entire Minneapolis area has similar requirements....
...as far as siding and roofing requirements for new accessory structures. I called dozens of cities before buying my current house. The city will allow a pole barn if the lot is 5 acres or more. (I have 3 acres.)

Most cities only allow relatively small amounts of garage space. 720 square feet is not uncommon with upwards of 1000 or 1100 square feet in some cities. The 720 square feet often has to be divided among all garages and accessory structures on the lot. The killer is height of the garage. Most cities only allow 10 or 12 foot sidewalls.

Interesting. I'm in a rural area on a half acre, capped at 70 square meters (~753sqft) for one extra building allowed. Thankfully no roofing or siding restrictions (actually making the house look more like the shop now) and its height isn't linked to the house. The 'mean' roof height limit is 6m (almost 20').

 

[yeldogt]

I can't build a pole barn ...many areas don't allow what they call utility buildings unless you have a very large lot and the building is away from the house. Pole = Utility in many parts.

As I said above .. read the specification of the exposed fastener roofs. They leak and need a base -- you still cant use them if a building requires a "roof".

There are many fastening systems -- some are part of the panel. Some panels have bends to make them stronger. Lots of different possibilities today based on application ..look required and cost.

Anyway -- a true standing seam roof has tabs made from the roof material. The tabs are fastened to the roof deck -- typically with a nail of compatible material. The tab is then bent over the panel and is incorporated into the seam when the panels are bent together.

Here is a picture of the guy working on my new roof. It's Zinc -- and you can see the tabs cut from sheet zinc to hold the panels in place. That's the vent for the stove ...