What are the restrictions for installing a metal roof on a low slope roof. I have a roof that transitions from a 5/12 to about a 1.5/12 for the bottom 8 feet. Can I install metal on the lower half or do I need to consider something different on the lower slope?
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What kind of metal roof? What kind of climate?
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
Sorry for not answering sooner, I've been away. I really haven't investigated what type of metal roof to use as I wasn't sure if it could be done. I live in upstate NY. I had always thought that you needed a slope of at least 3/12 for a metal roof but my neighbor had one put on his house two years ago on a very shallow roof. He hasn't spent a winter here yet so it hasn't been subjected to any freeze thaw cycles. The transition from the 5/12 to the lower slope is my point of concern. I want to install metal because I just don't want to bust my ### hauling and installing asphalt shingles any more.
I'll probably be doing most of this roof by myself. It's been a while since I've done any metal roofs. I was under the assumption that you put wood cleats across the roof with the metal across them but have been told that they don't do them that way any more so I'm figuring to approach this like I have no clue (probably a safe bet) and just gather info and make a decision.
I've just read the posts on the thread 'metal roof valley'. the pictures are very familiar to my situation only I have a gable with a valley intersecting the main roof instead of the hip shown. Right now there is a 1/2 lap roof on the lower section and it has lasted 15 years. This house is more of a camp but my shop is in the basement so I use it all year long. Possibly we may move but I plan on keeping it as a vacation/retirement home and want to be able to be comfortable leaving it unwatched for long periods of time. Do you have any better ideas for the lower section? I want to use metal on the rest of the house and would like to keep things consistent. If I don't use metal on the bottom section how would I stop the snow/ice from creating a major problem area? With the shingle/1/2 lap roof I would always have to shovel the lower roof during years with large snow amounts. I thought with the metal roof it would shed the snow easier once the sun hit it being it has southern exposure.
If I don't use metal on the bottom section how would I stop the snow/ice from creating a major problem area? With the shingle/1/2 lap roof I would always have to shovel the lower roof during years with large snow amounts. I thought with the metal roof it would shed the snow easier once the sun hit it being it has southern exposure.
That may be one of the bigger understatements you'll ever make! Have you ever seen an 18"-thick solar ice dam on a steel roof? As spring arrives and things warm up, big ice dams like that slide ever so slowly, often extending 3 or 4 feet out past the eaves before they suddenly break off or let go and the whole roof-load slides off all at once and crashes to the ground. That will rip the electric mast or chimney right out of a roof, kill anyone standing under it when it falls, or turn a full-size pickup truck into skateboard.
In snow areas, almost all metal roofs must have ice-barriers installed on all eaves over any accessible area. Contrary to popular belief, metal roofs below about 20-24 in 12 do not shed snow as it falls.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
The Montreal Neurological Institute is a six story building with a steep metal roof that regularly drops huge chunks of ice onto people walking below. Fortunately, it's a good spot for a head injury.
There ain't no 'good' place to get a head injury. Especially not one of that magnitude. :-)
The chalet next to my house has a 4:12 screw-down steel roof. (It also has no ventilation and damn little insulation in the roof and develops the worst ice-dams I've seen in 20 years of noticing such things.) Every spring, it was suicidal to get within 20 feet of the eaves of that place. When the ice on that roof finally let go, it shook the ground hard enough to wake me out of a sound sleep. Until the owners finally had me install ice-guards on the eaves, they arrived every year for the summer only to find the basement windows shattered and the window-wells bent and crushed. And the electrical service mast bent at a 15º or 20º angle from the vertical....
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
Head injuries may be nasty for the recipient, but they were my families bread and butter. My Father studied a specific frontal lobe injury that was very uncommon here, but in Glasgow where the tenements had outswinging windows with low sills he found plenty. So I got to spend a year there! When you see ice dams, you see broken windows. I see my education paid for.
All things considered I backed off of the idea of a metal roof. But I needed a solution for the low slope area and was prepared to put 1/2 lap on the area only to find that it isn't that readily available anymore and looked to find something and was directed to and purchased and installed an IKO Roof Fast membrane on that lower slope and when I went to look for shingles I have been getting all this negative feedback on the IKO shingles. Does any body have any feedback on the 'Roof Fast' product itself? Also. are the things that I've been hearing about the IKO's (like the granular surface coming off and curling after a few years) true?
I don't know the Roof Fast product, but I've worked with IKO shingles a few times and haven't had any problems aside from a tendency of the alignment slits to wander a bit from one pallet lot to another. I've got a feeling not all of IKOs machines are dialed in to match all the others....
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
So you've had no problem with the shingles other than what you mentioned? I had a salesman from a larger lumber yard in my area tell me that one of his main customers, who at one time requested IKO, started to have problems and the reps weren't standing by the product so he stopped using them and went to Certainteed. The lumber yard also had other customers who had problems and because of it they no longer carry that brand. I also did another search for consumer reports and found on another site a lot of other roofers warning people away from them. So it's an interesting dilemma, but I'm not sure I want to roll the dice with my roof. Consumer Reports rated the Certainteed Landscape Premier and TL very high. What do you prefer?
I have never used Certainteed; that brand is not sold here AFAIK. My preferred brand is BP; I will use IKO if BP doens't make the colour the HO demands.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
This thread gives me THE FEAR.I'm about to contract my own house with a large expanse of
standing seam galvalume with a very low pitch, almost flat.
Actually, I think it's a two inch rise in fifteen feet.I've had several rounds of discussions and head banging amongst
myself, the architect, and the roofer. Architect insists this
is fine, and roofer is ready to warranty it for ten years, but
honestly I want to see in writing from factory tech rep that
this will work. (this is a Japanese firm, so perhaps they have
some sort of wonder technology, but I think it goes against
common sense and everything I've read on this board on this
subject over the years).
I did see a hospital roof with Galvalum and similar low pitch. The pans were about 5" deep though with unique clips/seam locks, and there was an elevator access to the roof for the main guys to shovel it off when necessary. I didn't do the job, just stopped by for a day visiting a guy. I wasn't sold on it, but do get specifics from the makers for yourself. That low of a slope flies in the face of every roofing standard I know, with the exception of some old old BUR pitch roofs that were designed to puddle 4" of water for evaporative cooling and climate modification.
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I have successfully used several different kinds of metal on low slope roofs by first applying a good quality membrane to the deck and then installing the metal.
What are the restrictions for installing a metal roof on a low slope roof.
There should be manufacturer's instructions specifying what slope each product is usable on. This varies from product to product. All metal roofs are not equal.
If I were installing a brake formed roof, 1.5/12 would be no problem, but I would use I&WS under it as mentioned above.
View Image
Check w/manuf. if a manufactured system.
If not - no standing seam on bottom portion, and ice/water shield on 1.5 slope.
Jeff
There is tons of old standing seam low slope roofing on DC rowhouses. Did they construct the seams differently back then? I know that my neighbors roof still is water tight, though it looks like ####.Z
Not recommended under about 3:12 because there's no actual seal at the seam IIRC (Walter?)
Many older roofs are terne not copper. Those older terne roofs were generally painted. Today there is Terne II which can be coated with an elastomeric paint (Follansbee Rapidri) that does pretty well. There's even a residential grade, but keep in mind that although coated it is still steel.
http://www.follansbeeroofing.com/products/TerneII.aspx
Jeff
Edited 9/18/2008 6:10 pm ET by Jeff_Clarke
Not recommended under about 3:12 because there's no actual seal at the seam IIRC
Under 3/12, a cleat strip is soldered 6" or so below the top of the pan and the next pan is locked to the strip rather than the top of the pan. You can go down to 1/12 with this detail.
We've been doing a lot of Follansbee Klassic Kolors standing seam.
http://www.follansbeeroofing.com/products/KlassicKolors.aspx
It's terne II with kynar on both sides and then the top is factory painted with the Rapidri. The paint holds up well when tooled. After being less than impressed with Terne II, I'm pretty impressed with KK. We can do true standing seam with it for a little more than half the price of copper. View Image
Thanks for the info - I've had one client do a Terne II roof with Rapidri - 'terned' out well.
Jeff
There is tons of old standing seam low slope roofing on DC rowhouses. Did they construct the seams differently back then?
What you're seeing is true double rolled standing seam roofing vs snap lock standing seam. I go down to 1/12 on true standing seam. I have to treat the lateral seams differently below 3/12. With double rolled SS, the hips and ridges are the same as the other seams.
The old terne metal (which is likely what you're seeing) was a lead/tin alloy coating on sheet steel. Now they have substituted zinc for the lead (terne II). It starts to rust quicker.View Image
My mom's house was just re-roofed with a metal roof and it is a 2:12. However, they covered the entire roof under the metal with Ice and Water Shield (or similar). Hasn't leaked in the six months it has been there.