Metal roof "oil canning" - any experts?

[Administrator_JSVN]

So, I need some help from the forum members, especially if any of you have experience or expertise with metal roofing. My parents are having metal roofing installed on their house and there is an unsightly issue which is being referred to by the installer as oil panning. I'm no expert on metal roofing or techniques for installation. I do know that it was cold formed presumably from a roll.

Does anyone know if this is normal? Does it fix itself over time or is there something that the installer can do to remedy it? Was the installation done correct or improperly? Any other useful comments insight be appreciated.

Thanks for the help.

Shane

[attachimg=#]

 

[jlyons]

you need some creases in the tin in the pans.  or maybe a smaller pan would help but that would bring the cost up.  thicker metal might help.  The standing seam that we normally install doesn't have that big of a pan and has creases in the pans to take a lot of that up.  Also could be an irregularity in the roof deck. 

 

[peter halle]

I don't install metal roofs, but even when installing aluminum trim you have to worry about the metal expansion between cold and hot situations.  The metal has to be able to expand and move.  If you install fasteners too tightly the metal is trapped at that point and then when it needs to expand it puffs out.  Look at the images and move to the right - into the shade.  The situation appears to get better.  The metal is cooler and has not expanded as much.  Tomorrow morning the roof when cooler will look better - I predict.  Tomorrow afternoon - like the images.

I thought that metal roofing was installed with clips nailed to the rood deck that allowed the material to slide when it expands and contracts.  My bet is that where the creases are are clips that are nailed tight thus trapping the metal.

This also happens when people nail vinyl siding too tight.  That is why the nailing slots on the vinyl are slots - not holes.

Just my thoughts.

Peter

 

[Old School Carpenter]

Hi Shane,

From the picture shown, the roofing looks like 28 or 29 gauge,  that is a fairly thin gauge to run without some kind of pressure rib on the panel, kind of like this one has.


Oil canning is a natural metal roof problem, however in my opinon the problem shown is threefold.
1. is the roof installed over existing shingles? Not good, we will not install a metal roof over shingles, Period.
2. the roof clips appear to be pulling the roofing down , could be caused by wrong clips, improper installation, installing over shingles, etc.
3. no pressure ribs rolled onto the panel

Do you know if the roof installed is a snap lock or a mechanical seam?
As I said oil canning is an occurance with metal roofs, but I've never seen a roof that bad that wasn't due to some error.

Mike

 

[Administrator_JSVN]

Thanks, guys. Mike, not over shingles. I'll have to check on the clips and get back to you. It's installed on OSB with some type of material (insulator or something) between the OSB and metal. Additional photo attached where you can see it.

 

[Old School Carpenter]

There are some different systems out there, but conventional metal roofing wisdom says that you have to install the lower roofing first, then the Z- mould, transition flashing, then the upper roofing , Z- mould, and finally the ridge cap.

I'm not sure what is going on there, but I don't see how it could be installed correctly using the sequence they are. It appears they may be cutting some corners and trusting on the underlayment to back their play. ( Incidently the underlayment is installed upside down, so its kind of hard for it to work as designed.)

Is it possible to get some close up shots of the panels, like the lock edge, the transition point and the ridgecap joint?

Mike

 

[farms100]

never installed metal roofing.

OSB on a roof, whats up with that?

 

[jmbfestool]

To me looks like they are bending the panels down to the roof.    

Looking at the area where the pitch changes the long sections look like they are bent up into the lower section.   Showing large crease marks.

I have never worked with metal roofing so cant help sorry

JMB

 

[Alan m]

To me looks like they are bending the panels down to the roof.   

Looking at the area where the pitch changes the long sections look like they are bent up into the lower section.  Showing large crease marks.

I have never worked with metal roofing so cant help sorry

JMB

that sounds about right.
it looks like the metal is forced in and not flat.
you get similar results when you put slat trim down a roof and along a bellcast. the metal has to give somewhere

 

[Old School Carpenter]

To me looks like they are bending the panels down to the roof.    

Looking at the area where the pitch changes the long sections look like they are bent up into the lower section.   Showing large crease marks.

JMB

Jmb,

They are making separate panels even though their transition flashing on the back isn't made the same as that on the front of the house.
( My company manufactures and installs mechanical lock standing seam.)

Farms,  Unbelieveable right?,  Next thing you know we'll be using nail guns to install it! [poke] [poke]

Mike

 

[jmbfestool]

To me looks like they are bending the panels down to the roof.    

Looking at the area where the pitch changes the long sections look like they are bent up into the lower section.   Showing large crease marks.

JMB

Jmb,

They are making separate panels even though their transition flashing on the back isn't made the same as that on the front of the house.
( My company manufactures and installs mechanical lock standing seam.)

Farms,  Unbelieveable right?,  Next thing you know we'll be using nail guns to install it! [poke] [poke]

Mike

I know they are separate panels between the two different pitches wasnt saying they where litterly bending them to transition point. 

Just looks like they are bending up where the joint is.

Just from the pictures.

I ain't got a clue about metal roofing.

You clearly know alot more.  Awaiting Shane to post close up shots  [popcorn]

It's poor fitting in my opinion.

 

[Old School Carpenter]

It's poor fitting in my opinion.

Agreed.

Mike

 

[PeterK]

It appears to me that the roof under the metal is not flat or coplanner might be the correct term. Very common for trusses to be all slightly different height and normally not a visible impact with shingles. My roof has several dips and rises that I can see if at the right angle to view it. This would cause major problems with a metal roof installation and lead to what you see in the photos. I have not seen the wide non-ribbed panels ever used for house roofing before and can easily understand how the oil canning would occur. Would think great care would need to be taken to attach nailing ribs that would be exactly in plane with each other prior to the panels being attached. Don't see any fix for this other than to start over.

 

[ldmillar1981]

Hi Shane,

I am involved in quite a few roof constructions before the metal is applied, our regulations state that osb is not an approved substructure, we use a gapped boarding to allow air flow. Although oil canning is still present it is not as extreme as your parents roof.

[attachimg=#]
You will see the oil canning on the near side by the roof light.

The metal is provided on a roll and pressed into shape on site, the metal is passed through roller to flatten then cut to length before being pressed in to the profile. Sliding clips are also used to allow for panel movement.

What is the temperature at the roof location, it will most likely be less evident during the winter.

Regards
Leigh

 

[Jaybolishes]

Hi Shane,

I'm a roofer and I only do standing seam.  The oil canning must be from two things, the metal is a very thin gauge (I only use 24 gauge) and or the roofing deck may be uneven.  Looking at how he did things, the valleys on the dormer look funky, and the transition where they used two separate panels with a transition flashing is not very common,  I always use one continuous panel, and so do my competitors whose work I respect.    In fact every roofer around here uses one panel on transitions.  You snip the ribs and the panel scissors on itself making a very sleek looking transition.  Many folks simply choose the cheapest estimate, and that is always a scary thing to do with standing seam.  I'm not saying that's what happened here, but seems to be the case.  

If they used 24 gauge you would not see such dramatic oil canning like you see.  But I really wonder how flat the roof deck is, if its very flat then the metal is just really thin, 26 gauge or thinner, hopefully not thinner.  If a roof is installed in the winter, oil canning in the summer will be much worse than in the winter.  However I roof in the winter every year, and the 24 gauge really stays very uniform and flat even in the summer after its installed. 

 

[Old School Carpenter]

I'm a roofer and I only do standing seam.  The oil canning must be from two things, the metal is a very thin gauge (I only use 24 gauge) and or the roofing deck may be uneven.  Looking at how he did things, the valleys on the dormer look funky, and the transition where they used two separate panels with a transition flashing is not very common,  I always use one continuous panel,

Jay, I agree with you that one continuous panel is best, the only situation that we have used a transition flashing was where the two roof slopes are really out of plane with each other from one end of the transition to the other ( an old farm house). We only run 1 1/2"  180 degree mechanical lock standing seam, and I am not familiar with the various snap lock profiles by choice.
I think it is an inferior product so that's why we chose to manufacture what we do, and the panels in the pics don't seem to be a mechanical lock profile.

  As to thickness 24 ga is great and that accounts for most of our work, however I would rather see a well done 26 or even a 28 gauge standing seam than a shingle roof. Even with less than perfect roof decks, a standing seam roof (including 26 or 28 ga) can be done well and have very little oil canning.

Mike

 

[Old School Carpenter]

So how did it all work out?

Mike

 

[Tinker]

I have no experience with metal roofing but have done a few flashing jobs on my chimneys.  My usual sheetmetal contractor showed me how to use clips when installing any runs over a foot or so.  That was to allow for expansion and contraction.  When i constructed fireplaces, i always covered the angle iron over the fireplace opening with paper.  I wadded paper at the ends of the angle.  That was all to allow expansion without damaging the masonry.  I also surrounded the cast iron dampers with paper for the same purpose.  That roof looks to me as if whoever installed it had no idea of how much metal can shift with heat and cold. I agree with Shane that there is some concern.
Tinker

 

[Administrator_JSVN]

So how did it all work out?

Mike, my folks are still working with the installer to come to a resolution. I appreciate all of the feedback from you and the other members. Very insightful on a topic I know very little about.

Shane

 

[Old School Carpenter]

Glad to help, Here is a shot of the panel ribs that we run into ours, there are multiple profiles available, pencil ribs, v shaped, etc.


Ribs like these really help to strengthen a panel, and reduce the effect of oilcaning.

Here is a roof the guys are working on this week, a older house with a ridge that has alot of waves/ dips in the roof.
This is 28 ga. which is the thinnest we will run. Especially with metal this thin you will see more oilcanning, but the ribs help. This particular roof has some areas that have a swale of as much as 8 inches across the plane of the roof. We would recommend a heavier gauge and or some roof structure rebuild typically, but this is for a family friend and the budget wouldn't allow for extras.



Hope it all works out well for your parents, these sort of times can be frustrating for all.

Mike