Minimum Pitch for Metal Ribbed Roof

[lzicc]

I have a 12 x 10 deck that I want to build a slant style roof. The roof will start from the patio door and end at the front of the deck. I was going to frame a roof and use ribbed style metal roof for the cover. What is the minimum pitch a ribbed metal roof can be? Since this is just a porch cover, I don't think code comes into play.

Here is a picture of the partially finished deck. The roof frame would attach to the wall above the door and right below the overhang. The overhang sticks out about 18". I can't extend it from the facia board of the overhang since the 2 roof lines meet there and create a valley. I only have about 1 foot to drop from the wall to the front of the porch. Any lower and it will be too low in the front.

I could easily get away with a 1/2"/12 pitch, but is that too low of a pitch for a metal roof? The manufacture recommends a minimum of 3/12, but this is just a patio roof.

 

[JimRB]

If you never get snow then you could try such a low slope. If you ever get a foot of snow or more in a week, having a roof that can shed snow may be a good idea.

 

[dieselcrawler]

For what you're doing, you'll likely be ok. Considering something very similar on our patio, wife and I were talking about it yesterday.

The mfg recommendation of 3/12 pitch has to do with warrenty, you'll loose it at that shallow pitch. The concern I would have is snow load, make sure your rafters are up to the task.

 

[Jchonline]

Insurance might not cover damage or injury if you dont meet mfg specs.

 

[radios1]

it's NOT just a patio roof, it's a place where people can get killed if not done properly!..:shocked:

 

[M5farms]

2 1/2 on 12 is what most manufactures recommend . If it were me (i'm in the roofing business) I would use a versa rib panel this is just like the standard rib panel except the top of the rib is flat without striations . use a 2" long life zac screw and DO NOT OVER TIGHTEN. You will likely never have an issue with leaks .

 

[lzicc]

We don't get much snow. I'm in eastern pa. Once is a blue moon, we may get 6" at once. I would just need to pull it off. I was looking at buying a gazebo, but the roofs of those gazebos slant all 4 ways, so when it rains, it would come down by my door. My concern more is water leaks at such a low pitch, not that it would hurt anything, but I want to be able to sit on the porch while it is raining and not have the water drips down.

 

[RNeumann]

I am totally confused what you are asking- it sounds like you are looking for some to validate a contrarian decision. The manufacturer says 3/12.....

What is the roof for? Just a sun shade or is it waterproof cover like the house? If it’s just a sun shade and the structure can handle the snow in PA and leaking maybe the manufacturer has a different spec.

I’d be almost as concerned with your connection or detail with the existing roof lines. Between two sheds and the valley I’d spend some time making sure that was right. Tie into the building and do a proper flat roof with a membrane or don’t attach it to the building and run the metal for a sun shade.

 

[newbury]

Have you thought of going with a retractable awning?
A quick look at records https://www.weather.gov/media/pbz/records/snow.pdf shows Pittsburg gets a snowfall of 5" or more twice a year.

A retractable would let you escape the snow on the awning.

 

[lzicc]

It's a sun shade type structure. The one framed end of the sun shade will mount against the wall above the door and the front of the sun shade will mount at the front of the porch and rest on 4x4 post that I mount on the front of the deck. I will be framing the roof with 2x6 with 24" center, then put strapping horizontally so I can mount the metal roof panels.

Something like this but it will mount on the house side under the overhang instead of on the facia board.

 

[LS Tractor Owner]

I did a similar "deck cover" as pictured. 2x6 rafters 2' OC, secured to the house, 4x4 posts 4' OC, 2x6 beam across the top of the posts. Ran 2x4 stringers(?) perpendicular across the rafters. Used typical "R" panel roofing. In order to get the most pitch, I dropped the outer edge down to 7' clearance. Ended up with 1 1/2" / 12 pitch. We have had it for over 10 years, no problems. The most snow it has seen is 30" at a time, again, no problems.

 

[Oldoak]

In a situation such as yours (1/2"/12 pitch), I would put down 1/2 inch plywood sheathing down and put the metal roofing on top of that.

 

[lzicc]

I thought about putting a layer of plywood down instead of the strapping to give it more support.

 

[gsganzer]

I'm doing a 6"/12' for a horse stall awning. I'm in N. TX, so snow load isn't typically an issue. I'll also tape the seams where the sheets overlap.

 

[lilranch2001]

I am totally confused what you are asking- it sounds like you are looking for some to validate a contrarian decision. The manufacturer says 3/12.....

What is the roof for? Just a sun shade or is it waterproof cover like the house? If it痴 just a sun shade and the structure can handle the snow in PA and leaking maybe the manufacturer has a different spec.

I壇 be almost as concerned with your connection or detail with the existing roof lines. Between two sheds and the valley I壇 spend some time making sure that was right. Tie into the building and do a proper flat roof with a membrane or don稚 attach it to the building and run the metal for a sun shade.

From my reading of this thread, your bolded comment above seems to be exactly what he is doing

 

[ovrszd]

You'll have no load problems. Worse leak problem you might have is that water running off the eave may try to turn the edge of the tin and come back toward the house. If you give this roof an 1.5" of drop it'll be fine.

Don't worry about "The Sky Is Falling" crowd.

 

[Diggin It]

I have something very similar, but in translucent fiberglass panels. I ran 2x4s on 24" centers from the house to the posts and 1x4s across those to support the panels. They've held 10+ inches of snow more than once with no problem.

 

[Diggin It]

Plywood will just add unnecessary weight and be something to rot from leaks or humidity. If it makes you feel better add extra 1x4s or go to 2x4s for stringers.

 

[ovrszd]

Plywood will just add unnecessary weight and be something to rot from leaks or humidity. If it makes you feel better add extra 1x4s or go to 2x4s for stringers.

I agree. Wouldn't consider plywood at all.

 

[Industrial Toys]

I have almost no pitch on a 72 foot long driveshed. I did not want an imposing roofline at the particular location. The Engineer simply built the truss system accordingly and I even asked for it to be bumped up from that. We are in a high snow area. The building is windswept but I don't think that ever figured into the design.