Help me decide - Metal roof thickness

[newbury]

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Finally, if you haven't thought about it, I recommend at least a nominal layer of insulation installed under the metal with a vapor barrier between the insulation and the inside of the barn, preferably with a radiant foil layer too- to avoid the roof dripping when it has a snow load on a warmer than average day- otherwise you'll get awfully wet inside.

YOU are obviously from a northern climate

Forget about snow load, just need a Mississippi winter night and day. Moisture in the shed condenses on underside of roof, freezes, builds up a little, melts next morning, result rain showers inside if the water doesn't run down the inside of the roof.

I had an inch of "roll" foam applied under the new roof.

 

[SPYDERLK]

Good advice. I do trust the builder and he does recommend the heavier metal really for the warranty but said they are very close. I definitely see that in 40 years the odds of getting a warranty claim are slim and at that time I will just pay cash for a new roof. I just wanted to get opinions to make sure I was thinking correctly. I'm leaning towards the cheaper option and using the money either towards more insulation above ceiling or in walls or even upgrading lighting, etc. Plus the wife is not a fan of spending more for the slightly thicker metal lol.

The small difference can be deceiving because it is not necessarily intuitive. -- Stiffness goes up with the cube of thickness. That thicker metal is 1.33 times as stiff. That ratio of extra ruggedness can be valuable in many ways. The thinner metal is probably very easy to damage if someone ever needs to walk on it.

 

[dmccarty]

The small difference can be deceiving because it is not necessarily intuitive. -- Stiffness goes up with the cube of thickness. That thicker metal is 1.33 times as stiff. That ratio of extra ruggedness can be valuable in many ways. The thinner metal is probably very easy to damage if someone ever needs to walk on it.

What Spyder said. That extra thickness is a bigger deal than one thinks. Besides walking on the roof, I would be concerned with hail storm damage. A thicker material will have a better chance of not being dented. Having said that, I would want a thicker gauge than what they were offering. A hail storm went through Orlando a few decades ago and the shingle roofs of all of my family members there had to be replaced. Cars that were outside looked like they were attacked with ball peen hammers with not a square inch left without a dent.

One of the reasons we have a shingle roof and not metal was because of that hail storm. Insurance would not cover the dents in a metal roof but they would replace the damaged shingles.

Later,
Dan

 

[roadhunter]

I was thinking about this thread when I was on the menards website. I noticed that they had garage kits priced with 29 and 26 gauge steel. I pulled up a 36 x 40.

Here is the link. Pro Rib is 29 gauge and Premium Pro Rib is 26 gauge.
http://www.menards.com/main/buildin.../36w-x-40l-x-12-5h-garage/p-1444422251447.htm

 

[comancheflight]

I have use metal in my building's for almost 30 years. Not sure of the gauge. I bought #2 grade..their isn't any rust anywhere to date. I have expanded the building 4X and all is in great shape. The original building does have corrigated tin on the roof...it needs replaced from rust.

 

[PhysAssist]

Good advice. I do trust the builder and he does recommend the heavier metal really for the warranty but said they are very close. I definitely see that in 40 years the odds of getting a warranty claim are slim and at that time I will just pay cash for a new roof. I just wanted to get opinions to make sure I was thinking correctly. I'm leaning towards the cheaper option and using the money either towards more insulation above ceiling or in walls or even upgrading lighting, etc. Plus the wife is not a fan of spending more for the slightly thicker metal lol.

The builder is putting down a vapor barrier under the metal but I definitely need to ask about some type of insulation. Are you talking about just a thin sheet of foam of some sort?

Thanks again everyone for all the helpful input. As we get into this project I'm quickly realizing that there are so so many things to take into account haha.

Sorry it took me so long to respond, things have been kinda crazy.

I think our roof just has a 1" fiberglass bat with radiant and vapor barrier on its underside and it has been fine.

I learned about the condensation issue after building a woodshed with a tin [galvanized steel] roof, and having to put tarps over the wood [and splitter, etc] to keep them from getting soaked by condensation on warm days where the snow load cools the air under the roof causing condensation on its underside.