- Standing seam metal roofing is versatile enough to be used
in many applications, including open framing.
Today, we're going to discuss profile selection,
the differences between architectural and structural,
testing requirements and more.
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What's up guys?
Welcome to The Metal Roofing Channel, I'm Thad Barnette.
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Today, we're talking about open framing applications
for standing seam metal roofing.
All the questions that will be discussed
will be in the description down below.
You can jump ahead using those quick links.
I have Jeff Hock
from the Sheffield Metals Technical Department with me,
and we are going to jump right in.
All right, Jeff.
So the first question I have for you is
what does open framing mean,
and what what types of buildings
do you see that on typically?
- Open framing basically means
that you don't have a deck to attach your panels to.
You're going to be attaching them to supports.
They're going to be z purlins,
usually 16 gauge for structural applications.
Buildings that you will see them on are warehouses.
If you ever looked at like hangars,
airport hangars for small planes, things like that.
You'll see them a lot too on porches.
Lot of times, porches don't have decking in.
Those are usually made with wood purlins.
The idea behind open framing is that you don't,
you do not have a deck that you're attaching the panel to.
And you were spanning some kind of purlin structure,
whatever that may be made out of.
- Do you sometimes see open framing
on like agricultural applications, barns, things like that?
- Yeah, a lot of times.
And you know, a lot of times they do agricultural
or ag panels on those situations.
You know, ag panels are face fastened, screw down rooves,
compared to what, you know we'd mainly get into
with the standing seam rooves.
But yeah, absolutely.
Their purlin spaces are usually a little bit closer.
Common purlin spacing is around five foot.
But in those situations they'll put the,
the purlins a little bit closer.
So that way they can have
a tighter screw panel when they put it on.
- A couple of terms that we hear
when it comes to open framing
is architectural and structural.
Tell me about what the difference between those two terms
are and how they relate.
- Okay, so structural is going to be
in an open framing application.
I mean, that's where you are counting
on your roof to be the outer structure of your building.
It's going to take any loads that are on your building
whether they be live loads or dead loads,
you know, snow loads or mechanical equipment.
You know the structural portion of the roof
has to support all those.
They'll usually build up those areas where they have those,
like mechanical units and things like that,
with extra framing, to be able to support the heavier units.
But other than that, the panel that is going to be
spanning the purlins has to be able to support
the structural load that the building's going to require.
Now on the flip side, you have architectural panels
which is a waterproofing type aspect.
And it's, you know, for aesthetics as well.
But your roof decking, whatever that may be,
whether it's plywood, OSB, metal decking,
that's going to take the structural load
of what the roof is going to be handling.
- You're talking about panels.
What about panel profile selection?
What types of panels can you use
in open framing application?
- So the only panel Sheffield offers
for over open framing is the two inch mechanical.
It's a two inch high vertical leg.
It has 180 degree seam and that's our structural panel.
There are other panels in the industry that are offered.
Usually they're maybe a T panel that has the proper testing
trapezoidal panels, things like that.
Most of the time when you come
across open framing situations, it's usually
at lower slopes, below a 2:12.
So you not only need a panel that's going to handle
and be able to perform
to the structural requirements,
but you need one that's also going to be able to handle
the low slope and the hydrostatic conditions
that the roof is going to exceed as well.
- Sure, and we know that because the two inches
of mechanical seam, it can handle that lower pitch
but what are some other qualities that
that particular panel has
that you can use it for open framing?
Is it the high leg?
What is it?
- Yeah, it's a, it has a taller leg.
And you know, it seems to be what, you know, the taller
the legs are on the panel,
the stronger it is.
And what the 180 degrees seam, we also do a test
that's called foot traffic testing.
And basically they put a concentrated load
on the center of the panel.
That's, that's basically
for when you're up there installing on it,
you want to make sure if you have a five foot span
and your panel's spanning that, that that's the only thing
between you and the ground at this point, you know?
So you want to make sure that it's going to stay together
while you're up there working and installing the roof,
and you know, maintenance in the future
and things like that.
- Yeah, tell me more about the testing.
What kind of testing requirements are, is out there?
What kind of tests are available
for open framing, structural applications?
- So, so the main difference between structural
and architectural testing is the uplift testing
that it goes through.
The architectural testing that, you know
we've talked about plenty of times before in the videos
is a UL 580, UL 1897 tests.
It's a 10 by 10 specimen.
You know, it has whatever decking it is
you're testing over, and you build it
just like you would out in the field.
Well, that's the same thing we do with open framing testing.
But that test is now called ASTM E1592.
The difference is
instead of a 10 by 10 assembly that you build,
it's 12 foot by 24 foot long.
And the reason it has to be larger,
one of the main reasons it has to be larger
is that you have to be able to put these purlins spans
maybe five feet apart.
So, you know, if you only had a 10 by 10 specimen,
you'd have your, where the panel begins,
five foot in the center, and then where the panel ends.
That's not really showing you the,
how the panel is going to perform when it's going over,
you know, more spans.
So most of the testing requires you to be
over three or more spans.
So if you're assessing a five foot,
well now you have a 15 foot minimum assembly
that you're doing.
You know, and again, obviously, you know, with the testing,
there's no decking there to stop any of that pressure
from underneath the panels or to slow it down.
So most of the time, from my experience,
the open framing panels that are tested
don't get as high of numbers.
As you would say, over a solid deck.
You know, you don't have the underlayment,
you don't have the decking.
So all that, all that pressure
has nothing to stop it from,
you know exerting on those panels systems
that you're installing.
You know, that's, that's the main difference.
When it comes down to water tightness,
same test still apply as far
as your architectural panels do.
You have 1646 water penetration.
You have 2140 submersion testing.
You really want to make sure that your open framing project
is tested in accordance with the proper water standards,
because now you don't have a deck
or underlayment to stop any water from getting inside
of your building.
That is literally the only barrier you have
from as far as weather tightness or water tightness goes.
The other test that we talked about
is the FM 4471 foot traffic,
which is a specific in this portion to open framing.
Because again, you're counting on the panel
to support the load that's up there instead of a deck.
So I believe it's 250 pounds concentrated
in the center of a panel.
- And does open framing, structural panels,
do hey require a heavier gauge?
What's the what's that look like?
- It depends on the panel profile.
You will see 24 gauge panels used.
That's what we tested was a 24 gauge panel.
A lot of times you'll see 22 gauge panels.
When you're talking about mobile roll forming,
you won't really see anything higher than 22.
Cause most of our mobile roll formers
can't roll form panels thicker than 22 gauge.
You might see narrower panel widths.
Heavier gauges, narrower widths,
that will help provide strength,
and when you're spanning longer, purlin spans.
And just talking about uplift testing with open framing.
Usually what people do is they'll test five foot
as their maximum, and they'll also test at one foot.
So you have a one foot purlin spacing
and a five foot purlin spacing.
You know what those numbers are.
And then the engineers can do the calculations
to figure out what the pressures would be
for a foot and a half, two foot, two and a half,
three foot, and so on, and so forth
all the way up to a five foot.
And another thing that's changed is all the uplift
testing now has a 50% safety factor.
So you have a, like it's a 2.0 safety factor.
So if you have, you know,
UL 90 design pressures and negative 52 and a half.
So if you a 100 test pressure, you cut it in half.
You don't meet UL 90.
You only have a 50% safety, a 50 design pressure.
When I first started in the business,
it was a 1.65 or 1.67 safety factor for open framing.
So with that being changed to them
upping the higher safety factor
it makes it even harder to get those numbers
to the UL 90 requirements.
- What about other assemblies?
Does, do you see insulation used
in open framing applications, anything like that?
- You will.
Usually an open framing,
you're going to see blanket insulation,
where it's compressible.
So if you ever looked up in a warehouse
you seen those big white pillows coming down
in between the purlins, that's usually blanket insulation.
Another thing with, specific to open framing,
is you'll usually use an offset clip.
So it actually holds the panel maybe a half inch
to an inch above where it's being attached to the purlin.
A couple of reasons for that
is one, to accommodate that blanket insulation.
So it compresses down and,
you know you can hook clip to the purlin,
and still have the blanket insulation
between the panel and the purlin itself.
And two, is a what they call purlin chatter.
And that's, if you have a metal panel
sitting flat onto a metal purlin,
any type of wind or movement
the panel is going to go through,
it's going to smack against that metal purlin,
and that's, they call it purlin chatter,
because it's going to be noisy.
So floating it up in half an inch
or an inch off the deck or off the purlin, I should say,
is going to alleviate and let that panel be able to flex
without smacking into that purlin the whole time.
- So we've been talking about metal purlins so far
but what about wood framing?
Does that make a difference when it comes
to testing and open framing applications?
- Yeah, well, it absolutely does.
The testing is only as good
as the substrate you tested over.
So if I, if I have a testing for 16 gauge z purlins
that doesn't mean my testing is going to be applicable
to a pressure treated two by four, four by four.
Does that mean that you can't, there aren't ways around it?
There are.
You can do pull-out value calculations
and have engineers sign off on basically
what the pull-out value is with that fastener
into a 16 gauge purlin compared to a two by four,
or four by four.
But honestly a lot of times, you know,
especially when we're talking about people in the country,
and doing barns and things like that,
they aren't too concerned with engineering.
But when you get into more commercial projects
you know, warehouses, things like that, you know,
those are going to be where you're going to see a lot more
of the engineering requirements specified and whatnot.
And most of the time that those are gonna actually be,
you know, the 16 gauge or heavy, you know, heavier purlins.
But I mean, there's all types of different open framing
out there, whether it be wood,
whether it be light gauge framing, whether it be, you know,
the heavy red iron, z purlins, things like that.
It's, it's the same as you know,
when we talk about any other types of testing.
Just make sure that when you,
if you're using testing or if you require it,
that the test that you're giving provided
is going to be applicable to the assembly
that you're going over.
- So we've been talking about open framing.
We've mentioned architectural panels over solid decking.
But what about when it comes to installing slats,
or two by fours or something over solid decking,
when it comes to a re-roof situation,
and then putting panels on top of that?
Because that's kind of a, in the middle situation.
Tell me about that.
- Yeah, no, it, it, it absolutely is.
It's, you know, you have the decking,
so you have the,
the building has its structural performance,
but then you know, technically the metal panels
are still spanning the purlins that they're being put on.
I personally don't know anybody that has testing like that.
But things that I would keep in mind
if you do decide to go that route are,
you know, number one,
depending on how far apart your purlins are spaced
or your, your open, your wood framing is spaced,
or your furring strips, as they're called,
again you want to make sure
that you're going to be able to walk on those
and not have the panel disengage, or, you know
hurt the panel in any way.
So again, you know, mechanical locks
would probably be better in that situation,
more so than maybe snap locks, because, you know
especially some snap locks, the way they're designed,
you might be able to disengage the male and female leg
by the way you step on them and things like that.
You know another thing
I would definitely be concerned about
and and pay attention to is, you know,
walking on those panels.
You step the wrong way on say a two by four.
Well, now you have a nice crease in the flat of your panel.
There, there are things that come into play now
that you are spanning furring strips,
that you're going to want to take into consideration
as far as panel attributes.
- Well, I think we covered a lot
when it comes to open framing
and general overview on testing requirements,
and the differences between architectural and structural.
Make sure you comment down below.
If you have any questions for us, love to answer them.
Subscribe here to the Metal Roofing Channel for more videos
just like this one.
As always, I'm Thad Barnette.
We'll catch you next time.
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