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29 versus 26 / 24 gauge
I live in the mountains in Idaho and currently have 29 gauge metal on roof which is two intersecting gables of 12:12 and 7:12. This winter we had a decent amonut of snow, and the metal was torn pretty badly in the valleys and where the ice exits the valley. I am wondering if it would be better to reroof with a heavier gauge, say 26 or 24, or to use cleats or fences. Is there a recommendation for metal gauge to use by snowload / climate zone? Thanks!
The performance of any product is dependent upon not only the base materials but also the design of the product. Metal is good in the way that, as you form it, it gains strength.

Just the same, there is something to be said for metal thickness as well.

I am a little unsure as to exactly why this tearing occurred. Certainly, though, snowguards could be beneficial.

If you'd like, email me photos and let me take a look at what's happening. My email is tmiller@classicroof.com
Thanks! I will take some pictures this weekend (I dont get home befor edark usually during the week). It is tearing across the face of the sheet where the ice hits the rib. It compresses the rib and then tears the sheet. This is in an area where a valley created by a 12:12-7:12 exits onto a 12:12 slope
I'm getting a 5 V metal roof in a few weeks. I can have galvalume in 24 gauge without color, or 26 gauge with color. My old shingle roofs (2 layers) are being removed, per local code. Down the street, a brand new medal roof looks dented all over, it was applied over asphalt shingles. I'm wondering if 26g ( I think that is what they have) is the reason why or is it more likely b/c of the asphalt shingles underneath, and 24 g would have done the same. Is 24g less likely to "oil can?". Will the gauge be of no concern in my case b/c it will be going down on a much smoother surface?
Appreciate that the 5V profile while very common is a basic profile and does not carry much strength. Further metal roofing will telegraph the substrate through if it is laid directly on top short of putting boiler plate dowm. As it is a through fastened panel the location of the screws is fixed and if they hit at a uneven spot like the edge of an existing shingle, the roof will dimple. This is not oil canning, just poor application.

Removing the old shingles is great and make shre all the old nail heads in the sheathing are pounded down. Have a layer of fely underlayment installed as this heps the metal roof float better, stopping the telegraphing and is required by code. More important than the gage, check that the substrate is a minimum G90 Galvanized for painted and a AZ55 Galvalume for bare. If you have chose a pre peinted sytem, then check out the paint. The two systems certified by the MCA is PVDF for Premium and an SMP for Standard. Watch that you do not get a lower durable agricultural finish.

Then the gage does not matter as much.

Thanks Allan,
Just one more Q. You wrote back, "More important than the gage, check that the substrate is a minimum G90 Galvanized for painted and a AZ55 Galvalume for bare." What is meant by "substrate?"
I was under the impression, that after they put down the 15 lb felt paper, they were done. Next the metal panels. Am I wrong in thinking that? Is there something else that is supposed to go b/n the felt and the panels? A substrate?
Ft Pierce, FL
Currently it is truss, plywood, felt, shingles.
New will be truss, plywood, felt, 5V metal roof
thanks again,
very useful site.
A steel roof is made up of a steel core which is coated both sides with a metalic coating that is rust resistant. Galvanizing is pure zinc and a G90 specifies the coating weight of the zinc. Zinc is a sacificial protector in that when exposed to the weather it releases the zinc in minor amounts into the rain water, eventially wearing off and exposing the steel core. This is best used with paint.

Galvalume steel is coated with a 55% zinc/aluminum metalic coating which then acually forms it into an alloy. The zinc provides the sacraficial element and the aluminum the rust resistance. Exposed this material has over a 35yr field proven performance and will last 2-6 times longer than galvanized, especially in a salt water environment.

There are a number of products available on the market that are a comodity base roll formed panel designed for the out building market and it is very difficult to tell a red from a red, however the paint system is of lower quality and/or thickness and the steel substrate could be a G60 or even a G40 zinc coating weight. This is why you must ask about the paint and substrate to make an valued decision.
Hi, Just discovered this forum, it's great! My 1898 N. Minnesota farmhouse needs a roof, and I'm thinking metal. Its rafters are 2x4 (the old ones that actually measure 2" x 4"), and it looks like there are three layer of asphalt shingles. The roof is pitched quite steeply--so the snow should slide right off--but I'm worried about the weight if I leave on the old shingles. Any insights and/or warnings? Thanks!
I read this post but still am confused about gauges. we have finished building another garage with 3/4" decking. want to put standing seam metal. When we have the next hail storm (probably within year or two) we will replace our existing freestanding garage & house with the same metal we will install on the new garage. We are getting quotes for 26 gauge. However, after talking to a saleman (key word salesman) he says we should consider 24 or 22 gauge (they don't sell 26). We are in the dallas/ft worth metroplex & hail of varying sizes comes through usually once every spring. Our two garages are low pitches 4 & 5:12 while the house is very steep pitch probably 12 or greater. I'm told that a 22 gauage will never show any hail damage. Of course its the most expensive. We don't have any bids back yet but are expecting this week (3/30/09). Can you shed more light on the subject. Also, the 26 gauge contractor suggested an underlay sheet he calls bubble wrap; looks like thin insulation comes in a roll.
The thicker the metal the more dent resistant it is. 24 gauge is the normal on commercial and 26 gauge is usually used on residential. The 24 gauge is about 33% thicker than 26 gauge.
We are located in the Metroplex and if you will email me your phone number I can talk to you about gauges, profiles and underlayments.
your email address didn't work.
I copied & pasted.
There is no "s" on the word system. wade@proroofsystem.com


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