# Metal roof gauge



## brumer0 (Jan 21, 2015)

Hi,

FYI: I did search the forum for this, but came up empty which is shocking.

My question is: I am looking at barn building and have pretty much decided that it is most feasible for me to start out by just building the roof, and then framing off the sides and insides as I have time and money. When I have been looking around at prices, and kits, it seems that most metal roofs are 29ga steel. This just seems flimsy to me. I have very limited experience in such things. 

Is 29 gauge standard, or is 26? What about siding? 

I am thinking of some kind of kit like this to start out with (they are in my area too):

http://www.buildersdiscount.net/others/steel-trusses/


Thank you for any help or pointers you guys can provide!!
Brandon


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## TnAndy (Sep 15, 2005)

Most of the metal folks use in roofs IS 29ga. Most if it is "Century Drain" type stuff. I use it on all my sheds and barns, but I wouldn't put it on a house, personally.

1. It is fairly thin.

2. The screws are exposed. IF you run them into 1x (full 1" material), they don't tend to back out from the movement of the metal. But lot of people throw a 1/2" plywood or worse, OSB sheathing on their roof, and screw into that. They back out.....seen it a LOT....screws standing up 1/2" or more from the metal. That means a leak waiting to happen, or a sheet of metal waiting to blow off.

Commercial gauge metal is 26ga. Costs more, of course, which is why the 29ga is more popular. On commercial buildings, they tend to span more on the purlin distance, and the thicker metal allows them to do so.

Personally, if I were gonna put metal on my house, I'd use 26ga standing seam. Thicker, no exposed screws, lot better roof.

Little off grid place I helped build for a buddy of mine:











But to answer your question: I use it on my barn/shed roofs.....just something thick to run your screws into.

I haven't used it as siding (but you certainly can) because I side all my buildings with wood lap siding I cut myself....like this little chicken coop built for a neighbor, or my firewood sheds:


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## haypoint (Oct 4, 2006)

One of the problems with posting things on HT, you generally get answers to questions you didn't ask.
Most wooden truss pole barns have the wooden truss spaced either 2 feet apart or 4 feet apart. Then 2x4s are fastened to the truss as purlins, spaced 2 feet apart. So, as you fasten the steel roof, you have a 3 1/2 inch area to screw into.
On the steel truss design you are looking at, the truss is spaced 8 feet apart. Since a 2x4 aid flat, spanning 8 feet would sag and not last, the 2x4s are set on edge. Now you have a 1 1/2 inch area to target your screws. By going with trusses 8 feet apar, they line up with each post. So, there I no need for a thick board (2x12) at the top of each post to carry the truss. All you need is a 2x4 to screw the siding into. 
I witnessed a Morton brand barn with trusses 8 feet apart and the trusses set into each post. This really saves on lumber. But this barn was so wobbly, it leaned and swayed all over, until it ad the steel siding installed. They took dozens of chains and come-alongs to pull it into square. Then once the steel was screwed down, they removed the chains and the building was rigid. It is the steel siding that keeps that barn straight.
So, my concern for you is that without side support, the building will sway all over. In my area, a snow drift of a couple feet deep would shove the building out of square, without more support.
Steel trusses can withstand the downward pressure, but lacks the ability to control diagonal forces. 
Perhaps you could limit movement by sheeting the ends and running diagonal braces off each post. 
Check prices between steel trusses spaced 8 feet apart and wood trusses set 4 feet apart. Being able to lay the 2x4 purlins flat and endure less span, would give more diagonal strength I'd need.
But I have more wind and snow than you o, plus I prefer to over-build.


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## M5farm (Jan 14, 2014)

very few companies actually carry a 29 ga. Most have a 30 or 31 but its sold as 29. True 29 isa decent product imo it has its uses. It is very common on residential homes here and does its job. the biggest issue is oil canning on longer panels. most barn kits use 29ga as the metal used on a barn in most all cases has no warranty . 26 ga is considered entry level commercial ga and is a stiffer product and can span a larger distance.


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## brumer0 (Jan 21, 2015)

Thank you thank you thank you


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## Fishindude (May 19, 2015)

Most all post frame buildings use 29 ga siding and roofing. The panels are typically 36" width with 5/8" tall ribs at 9" centers. On a roof you will need a support purlin (typically a 2x4 laid flat) at 24" centers. If you try to go further apart than that you risk damaging the panels as you walk on them to install. Nothing at all wrong with this product installed properly.

Commercial and industrial metal buildings always use 26ga siding and roofing as standard. These panels are 36" width with 1-1/4" tall ribs at 12" centers. These panels will span 5' between framing members.

You can also get heavier gauges, deeper ribs, standing seam profiles, etc. as warranted, but costs go up accordingly.


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## jwal10 (Jun 5, 2010)

Here, roofs are 26 g and walls are 29 unless livestock pressure on the sides, then 26 also. We have lots of rain and condensation, sheet metal will eventually rust from both sides, good commercial roofing, 26 g has more galvanized stuck to more metal, better and more paint. You get what you pay for. Here, houses are all standing seam, 5/8" plywood and heavy felt....James


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## TnAndy (Sep 15, 2005)

haypoint said:


> One of the problems with posting things on HT, you generally get answers to questions you didn't ask.


Yeah.....that's the problem with free advice.


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## mreynolds (Jan 1, 2015)

Here's how you can remember how to tell the thickness of metal like that. 29 gauge takes 29 sheets to make an inch whereas 26 gauge only takes 26 pieces to make an inch. 

Therefore the lower the gauge the thicker the metal. Like Andy says, I would use 26. Its not that much more expensive and cheaper in the long run. The trim is where they get you on the money. The sheets are not that bad.


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## mreynolds (Jan 1, 2015)

Well, was going to post a picture of a pole barn I am working on but my attachment button doesn't seem to be working.


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## mreynolds (Jan 1, 2015)

Maybe this will work.


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## chuckhole (Mar 2, 2006)

My shop is all 26g. The roof purlins span 30' and are spaced 5' apart. It is a 40x60x16 shop and I would not have considered anything but 24g or 26g. We are in the process of getting a foundation prepared for our bardominium house and it will also be all 26g on the roof and walls. It will be a 40'x90'x14' structure with a 20x30 porch on the side at one end.

We do not have to worry much about snow loads here in Texas. If we did, I would have gone with the 24g on the roof.


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## M5farm (Jan 14, 2014)

TnAndy said:


> Yeah.....that's the problem with free advice.


BUT some free advice is professional advice. I pay the bills supplying roofing materials for residential and commercial.


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## Fishindude (May 19, 2015)

*"BUT some free advice is professional advice. I pay the bills supplying roofing materials for residential and commercial."*


Yep .... I build for a living.
Have built hundreds of post frame and pre-engineered steel buildings, as well as re-skinned and re-roofed a ton of structures.


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## PlowGirl (Nov 16, 2005)

Not to hijack this thread but a question for TnAndy. Are you recommending not to use any kind of sheathing under a metal roof. I've been wondering about this issue but really didn't know how to articulate it. I'm wanting to build a post frame with steel trusses and spray foam insulation. I think I won't need a vapor barrier but what about noise reduction.


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