# Adding a metal roof over shingles



## jjlrrw (May 1, 2006)

Was hoping it would have gotten done last year but the majestic whitetail decided to try and take me out on my bike.

I have a 1200 SQ cabin river side roof is 36' wide, 20' to the peak 12 - 2 pitch the balance is short 8' runs steep pitch.

This will be a DIY and the first of two project for the summer.

Adding metal over the shingles roof boards are good. asking for different options I have a two.

1) nail 2x4 every 2' horizontal across roof shim as needed to make them flat. put 3/4" foam between 2x4's metal on 2x4s

2) add bubble wrap to roof then place 2x4's on top as in #1

We really don't need much more insulation but figured a little that wont brake the bank would be okay

3) others?

I like the looks of the exposed fastener barn type roof for the cabin but a bit concerned about the large 36x20 low pitch area not shedding water or snow fast enough, could always do hidden fastener on that side or really the whole thing.


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## micooner (Dec 20, 2003)

Is there only one layer of shingles on it now? What is the deck underneath? Sheathing or boards? Multiple layers I would tear off. Hell one layer I would tear off but that's just me. Option one for me.


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## Classic8Track (Jan 23, 2020)

I might go over with one layer, any more than 1, tear them off.


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## Waif (Oct 27, 2013)

I'd want foam closed off to avoid rodents....


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## ESOX (Nov 20, 2000)

I'd tear it all off. Use HI Therm ice and water on any roof elevation that is less than 6/12, in all valleys, and around all dormers and projections like soil pipes , chimneys etc from 1' above projection all the way to the eave. Use synthetic underlayment on the balance of roof. Do it once, do it to excess, never do it again.


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## Butch-eye (Mar 4, 2018)

did my home about 10 years ago went over 1 layer of shingles we put 80 pound felt under steel I have not any troubles with it. it should last me the rest of my life.


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## jjlrrw (May 1, 2006)

micooner said:


> Is there only one layer of shingles on it now? What is the deck underneath? Sheathing or boards? Multiple layers I would tear off. Hell one layer I would tear off but that's just me. Option one for me.


One layer, OSB Looks like the roof was R&R less than 10 years ago.



Waif said:


> I'd want foam closed off to avoid rodents....


Are you talking about the foam designed to fit under the steel at the edge and under the cap at the top?


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## Waif (Oct 27, 2013)

jjlrrw said:


> One layer, OSB Looks like the roof was R&R less than 10 years ago.
> 
> 
> 
> Are you talking about the foam designed to fit under the steel at the edge and under the cap at the top?


No. Looking at defending the 3/4 inch sheet type foam between 2x4's.
Edge and cap foam would be the entry point.


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## Trophy Specialist (Nov 30, 2001)

In my opinion, a steel roof is a great option for a low pitch roof. In fact, if I were going to design a roof for steel, it would have a low pitch so the snow would not slide off, which is the case on my cabin and sheds. Water runs off fine with no issues. My pole barn by my house has a 4-12 pitch and it is too steep with the snow sliding off.


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## ESOX (Nov 20, 2000)

Trophy Specialist said:


> In my opinion, a steel roof is a great option for a low pitch roof. In fact, if I were going to design a roof for steel, it would have a low pitch so the snow would not slide off, which is the case on my cabin and sheds. Water runs off fine with no issues. My pole barn by my house has a 4-12 pitch and it is too steep with the snow sliding off.


Bad plan. Most steel roofs want a minimum of either 3/12 or 4/12 pitch. they make snow guards to stop the avalanches.


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## FREEPOP (Apr 11, 2002)

Better design stronger trusses to handle the snow load with a low pitched roof. Especially in the U.P.


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## Trophy Specialist (Nov 30, 2001)

FREEPOP said:


> Better design stronger trusses to handle the snow load with a low pitched roof. Especially in the U.P.


Agreed. I have 2x6 rafters 16 inch centers on my camp.


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## Trophy Specialist (Nov 30, 2001)

ESOX said:


> Bad plan. Most steel roofs want a minimum of either 3/12 or 4/12 pitch. they make snow guards to stop the avalanches.


4/12 it slides off. 3/12 is doesn't. I wouldn't go any steeper than that with steel. I'm guessing my camp is 2/12. No issues with steel. I like being able to walk on it without breaking my neck lime on a steep roof. I cleaned the flue on my buddies steeper steel roof. Never again.


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## Luv2hunteup (Mar 22, 2003)

This may be an option.

https://www.americanmetalroofs.com/do-it-yourself/


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## Luv2hunteup (Mar 22, 2003)

FREEPOP said:


> Better design stronger trusses to handle the snow load with a low pitched roof. Especially in the U.P.


My metal roof pole building is designed for a 6’ snow load and I’m not in the high snowfall zone of the UP.


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## ESOX (Nov 20, 2000)

Mancelona area, snow capital of the LP has very stringent snow load requirements. had to have trusses on a prefab modified to pass inspection. 

Steeper roofs tend to last longer. They suffer considerably less hail and wind damage. They also dont allow debris to build up on them nearly as much in valleys etc.


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## Butch-eye (Mar 4, 2018)

jjlrrw said:


> One layer, OSB Looks like the roof was R&R less than 10 years ago.
> 
> 
> 
> Are you talking about the foam designed to fit under the steel at the edge and under the cap at the top?


80 pound flet is the heaviest tar paper you can buy. the person that help me said it was the best way to go with 1 layer of shingles and save us a tear off. worked well for me.


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## jjlrrw (May 1, 2006)

Butch-eye said:


> 80 pound flet is the heaviest tar paper you can buy. the person that help me said it was the best way to go with 1 layer of shingles and save us a tear off. worked well for me.


Did you place the metal directly on the paper? If so I assume the reason for the paper was to keep the shingles from rubbing and wearing through the metal?


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## ESOX (Nov 20, 2000)

Metal roof should not be laid over an asphalt coated paper.. The heat kills the paper, sometimes even causes asphalt to ooze out from under the roof. That's why all metal roof manufacturers I ever dealt with called for synthetic underlayment and HiTherm Ice and water. Back in the day before synthetics, we used red rosin paper for the same reason.


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## storman (Mar 12, 2008)

Tear it off and high temp ice and water the entire 2/12 slope. Go with double lock seam hidden fastener on a slope that low. Only way i would put metal on a low pitch roof.


jjlrrw said:


> Was hoping it would have gotten done last year but the majestic whitetail decided to try and take me out on my bike.
> 
> I have a 1200 SQ cabin river side roof is 36' wide, 20' to the peak 12 - 2 pitch the balance is short 8' runs steep pitch.
> 
> ...


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