How To Stop Snow From Slipping Of Metal Roof?

 
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Old 07-03-2013, 08:45 PM   #1
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How To Stop Snow From Slipping Of Metal Roof?


I installed a 2/12 pitch steel roof. The owner is now having a problem I have to fix. Because of the low pitch, snow slides off the roof VERY slowly (like over the course of a few days). As it does, it hardens and turns into a giant mass of hard, heavy ice-snow. It then rips off the gutters and falls on the side walk-way. So, I have to figure out how to stop the snow from sliding off.
I've seen little brackets on metal roofs for this purpose. However, I'm thinking it might be better to avoid drilling hundreds more holes in the roof to attach them (and I'm thinking I'd have to put two grommets for every bracket--one between the bracket and the roof, one between the screw and the bracket). What do you think about attaching little metal "L" brackets to the roof with other methods? Like silicone?
Any ideas are greatly appreciated!!
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Old 07-03-2013, 08:52 PM   #2
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Re: How To Stop Snow From Slipping Of Metal Roof?


Can't say as I can recommend silicone and if it is heavy enough snow the individual screw on brackets pull out. Best way I have seen is a solid piece of angle that runs the whole roof. Might put one about a foot from the eave and one up high if you have long pans.

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Old 07-03-2013, 09:02 PM   #3
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Re: How To Stop Snow From Slipping Of Metal Roof?


...and why might you have to drill "hundreds" more holes?



Where are the "entrances" to the house.

Put "snow guards" above the entrances and exits to the house...



2-12, huh?
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Old 07-03-2013, 09:11 PM   #4
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Re: How To Stop Snow From Slipping Of Metal Roof?


My 2/12 copper roof did that without gutters. It would creep out and freeze solid hanging and then drop in a chunk. The gutters stopped it from doing that. I can't imagine how a 2/12 pitch is ripping gutters off. I would fasten your gutter screws to rafters or solid blocking and put a lot of them. How much run does the roof have? Maybe I don't have as much. My aluminum gutters have clips every 16" and are into a solid 2x
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Old 07-03-2013, 09:51 PM   #5
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Re: How To Stop Snow From Slipping Of Metal Roof?


Those ice flows can be a foot thick or more and weigh hundreds of pounds. I think at least with silicone, the silicone will get scraped off clean, so you don't have to scrape it off yourself before going a proven route.
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Old 07-03-2013, 09:53 PM   #6
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Re: How To Stop Snow From Slipping Of Metal Roof?


Quote:
Originally Posted by jdeck View Post
Can't say as I can recommend silicone and if it is heavy enough snow the individual screw on brackets pull out. Best way I have seen is a solid piece of angle that runs the whole roof. Might put one about a foot from the eave and one up high if you have long pans.
This.
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Old 07-03-2013, 11:02 PM   #7
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Re: How To Stop Snow From Slipping Of Metal Roof?


When you get done holding the snow back....

I have a guy who lives on the beach and would prefer high tide be about 20' farther out....
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Old 07-04-2013, 09:35 AM   #8
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Re: How To Stop Snow From Slipping Of Metal Roof?


You may get some real answers if we knew what system you installed on this house.
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Old 07-05-2013, 01:11 AM   #9
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Re: How To Stop Snow From Slipping Of Metal Roof?


besides what system WHERE? what works in the dry climates wont work in the wet. Snow is alot dryer in most high elavation areas ( CO NM WY ) then say vermont
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Old 07-05-2013, 01:20 AM   #10
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Re: How To Stop Snow From Slipping Of Metal Roof?


Why a 2:12 in snow country?

I know, irrelevant now. But still curious.
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Old 07-05-2013, 11:45 AM   #11
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Re: How To Stop Snow From Slipping Of Metal Roof?


One-post wonder. Best of luck.
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Old 07-06-2013, 07:36 AM   #12
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Re: How To Stop Snow From Slipping Of Metal Roof?


Thanks for all this thought. Below are the answers to the various questions. (Sorry it took me so long, I wasn't getting email notification that there were replies)

hdavis mentioned a "proven route," what is that? -the angle iron that runs the whole roof that Jdeck suggested? Thanks again!

-I'm in Minneapolis, MN.

-The roof was 2/12 already and the owner wanted metal on it so. Plus the city wouldn't let them raise the roof without a variance.

-The steel roof system is called "Premium Pro Rib" which is a pretty standard steel roof panel bought at Menards.

-The entrances are on the gable ends, so that's not a problem. But there's a walkway along the whole one side that ends up not being too safe to walk down and has to get shovel a ton several times over the course of 3 days.

-The run of the roof is 60'

-I referred to drilling hundreds more holes to install those little snow stopping brackets I've seen on other metal roofs (little 3"x3" brackets). I figured I'd need a ton of them up and down the roof.

Last edited by davidgustaft; 07-06-2013 at 10:06 AM.
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Old 07-06-2013, 10:41 AM   #13
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Re: How To Stop Snow From Slipping Of Metal Roof?


A flimsy 29ga, exposed fastener panel on a 2/12 in Minnesota.

If you put a snow break on it fastened through the ribs and into the decking it will more than likely rip off with a good snow load. This will leave you with big gaping tears and holes in the tops of the ribs.

If you adhere snow stops to the panels you need to calculate and install the correct amount or they will not withstand the load. Either they will pop off or they will lift and shred the panel they are attached to.

If you fasten snow stops to the deck, same as above or worse.

Just because it's metal does not mean it's a good system, especially for your area. Odds are if you are going to fight mother nature in that climate you need a howitzer but you brought a BB gun to the fight. I'd be wary of putting anything up there.
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Old 07-06-2013, 11:45 AM   #14
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Re: How To Stop Snow From Slipping Of Metal Roof?


Glad I live in Florida and don't have to worry about snow..
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Old 07-06-2013, 11:55 AM   #15
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Re: How To Stop Snow From Slipping Of Metal Roof?


Quote:
A flimsy 29ga, exposed fastener panel on a 2/12 in Minnesota.
Yeah, I don't live in MN, but we get enough snow/ice here.... I'd sure worry about that flimsy panel on a 2/12. Especially with exposed fasteners.
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Old 07-06-2013, 04:06 PM   #16
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Re: How To Stop Snow From Slipping Of Metal Roof?


Take that **** back and go to a real metal shop and get some 26 gauge.
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Old 07-06-2013, 05:45 PM   #17
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Re: How To Stop Snow From Slipping Of Metal Roof?


It is not clear to me how the ice/snow breaker/stops angles are going to do anything for 'slow' moving snow but perhaps aid in packing it around them. I doubt they see alot of dynamic load and rip off. Sounds like the panels and decking is taking the loads for now, but one has to wonder about fatigue over time. The Premium Pro Rib is .020 steel which can take about 35-40KSI compression/tensile depending on grade and supports.

In order to get the lap strength you need from silicon you have to strip the corrosion protection finish off, bond, then reapply, but again I don't see this doing alot to help the situation.

Seems like the best solution is heat strips and gutters that are designed to pass snow not pack it. Price you pay for flatter roofs in major snow country.

Last edited by TLP; 07-06-2013 at 05:50 PM.
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Old 07-06-2013, 09:29 PM   #18
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Re: How To Stop Snow From Slipping Of Metal Roof?


I built a very large pole barn/warehouse 6 years ago and the roof slope is 55' (2 pitch) and when the ice/snow breaks free they say it sounds like a freight train going down the roof.
They didnt want us to put any Snojax on b/c they said "we can do that". They still havent put them on yet.
Here is the Snojax web site. There is a pattern that needs to be followed when installing these.
http://www.snojax.com/
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Old 07-06-2013, 09:44 PM   #19
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Re: How To Stop Snow From Slipping Of Metal Roof?


Quote:
Originally Posted by TLP View Post
The Premium Pro Rib is .020 steel which can take about 35-40KSI compression/tensile depending on grade and supports.
From their website:

Premium Pro-RibŪ is truly a premium wall and roof panel and can be applied to a tremendous variety of agricultural, residential, commercial, and industrial construction projects.

Actual .0157 minimum thickness before painting .018 nominal thickness after painting.


I guess people's definition of "premium" is all relative. 29ga, they have to count the paint in the thickness (lol, never seen that before) to almost reach 26ga

Last edited by Renegade; 07-06-2013 at 09:49 PM.
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Old 07-07-2013, 06:20 AM   #20
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Re: How To Stop Snow From Slipping Of Metal Roof?


Quote:
Originally Posted by Renegade View Post
From their website:

Premium Pro-RibŪ is truly a premium wall and roof panel and can be applied to a tremendous variety of agricultural, residential, commercial, and industrial construction projects.

Actual .0157 minimum thickness before painting .018 nominal thickness after painting.


I guess people's definition of "premium" is all relative. 29ga, they have to count the paint in the thickness (lol, never seen that before) to almost reach 26ga
Yeah I seen that, that’s nominal gage so I assumed we can round up. If you have any experience in ordering raw material you know the tolerance on it is .006-.007 on average, you can get tighter tolerance .003 - .004 but you pay about 1/3 more which I doubt. The other variables we don’t know is grade, I used the lowest (35-40KSI) assuming construction grade steel. It can go as high as 90K-110K for higher grades. My bad I missed the grade 80 on their website, so this stuff has a tensile strength of 80,000 psi nominal depending on decking supports. That is where they get the ‘premium’ definition since it has high strength-to-weight. So if this were construction grade steel @ 35-40KSI it have to be about twice as thick and weigh twice as much to equal premium grade strength. Other factors are temper and manufacturing, temper or roll forming steel improves steel to a point of becoming brittle. So my point is to not just look at gage, not considering all the other factors can be misleading.

Steel has a density of about .28 so depending on the size increasing it one gage can add a lot of weight to already high snow load, load to substructure causing the failure path to move. The 80 grade he used is 75lbs/100 SF. From what the OP says I assume it is taking it now, but fatigue may set in over time if it is not supported well.

Silicon is probably not a less labor intensive route since you have to strip the finish and reapply galvanized/zinc typically done in a factory. You could brush anodize/alodine it but it won’t last as long.

If you go with screwing the brackets into decking you can dimple the holes which will again cold work steel make it harder, prevent tensile cracks from propagating from the holes, also debur. Due to the slope I don’t see these brackets taking on a lot of dynamic load, more static coupled with the panel weight 75 lbs which makes no sense to me . At some point the panel will buckle from static load then the first place it will probably tear is at the holes, depending on how much span the decking supports have.

http://www.snojax.com/

I’m no snow flow expert here but seems like these products work better for steeper roofs and are designed for them. Steep roofs produce a different type of snow load than flat.

I goggled ice and snow gutters and found some interesting designs. I be looking at that and better supports for them, put them on a header with support coulombs or gussets if I had to, and/or a way to melt the snow and keep it moving to the gutters before it bulks up.

This is why our liability insurance does not allow flat roofs or we pay a premium if we want to do them. That substructure comes crashing in a homeowner the contractor is in for a big lawsuit.


Last edited by TLP; 07-07-2013 at 09:45 AM.
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