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Scotties rule!
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My house is 22 years old and the second set of shingles are wore out and leaking. Can't believe they only last 10 or 12 years. Anyway! I think it is time for a metal roof and be done with the mess. That will also give me better water in my cistern.

House is standard construction. Rood deck is OSB. Currently 2 layers of shingles on that I assume need to come off first. 5/12 roof with gutters. Has 3 valleys and 2 skylights. Attic is well insulated with 2 layers of 6" fiberglass batts and another 12' of blown in cellulose. There is also a moisture barrier under the insulation.

What is a good gauge metal? Screwed every 2 foot? How are roof valleys done. Should the metal trim on the edge of the roof be replaced? Is it laid directly on the existing decking or is there something put down first. Do they put anything into the bottom of the ribs to keep wasps and such from moving in? Or do I want the air flow? Anything special to keep snow from sliding off and taking gutters with? Currently have a ridge vent, can that be done with metal?

I want to get a couple bids and want to be able to ask the right questions and be able to compare apples to apples.

Thanks!
 

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Its likely that when you roam on down to the Home Depot they will tell you what they have.
You might want to run a little farther to a Menards and shop them too.
Both places will have a heavy and a light, choose the heavy and read the directions from the manufacturer.
If you are the kind that feels confident dealing with the Amish there is a great place just south of Arthur that is both a contractor and a reseller "Grabers" ,Ive bought a lot from them and found their advice to be solid.
The best way to keep the snow from sliding off is to run the ribs Horizontally!
 

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I have metal on the house, garage, and two barns, but it was installed originally, not as a replacement roof. Others will have better advice on installing over shingles/decking, but I have seen 1 inch lathing placed directly over asphalt shingles and then the metal installed on the lathing. I have a mix of gauges: 26 on the house and garage, 24 on the livestock barn (got a deal but that stuff was heavy and not the easiest to work with), and 29 on the hay barn. The heavier the gauge the more sturdy it is (and the finished structure will be sturdier too) and the harder it is to work with. Painted metal in our area is usually warranted for 40 years, and my painted metal is holding up, albeit a little faded after 16 years or so. I have one galvalume roof (non painted), and I much prefer it. Wish I had used it on all structures, as it doesn't fade and keeps a structure cooler (a bigger consideration in hot climates with lots of sun). They do sell (and I bought for the house/garage) foam insulation pieces to block entrances for bees/etc., but I didn't use mine. I wanted the airflow instead. My ridge cap acts like a vent cap, and if you don't install a foam or other barrier, yours should too. I replaced the metal screws on my dark green roofs after 15 years as the rubber seals had been cooked dry. It wasn't a big expense, but it did drive home that these are not maintenance free roofs, but rather low maintenance. A standing seem roof would not have this problem. All of my roofing metal was bought from places that actually cut/manufactured it, and I suspect there are some ads on your Craigslist for the same kinds of suppliers.

Good luck with your new roof.
 

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Our roof is metal. We did have to get it replaced because the people we bought the house from installed it themselves. It leaked. Our new metal roof is pretty good. We have to go up and caulk around the vents every now and then or it leaks but pretty good otherwise.
 

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You can put the metal on right over the shingles as long as the sheathing is solid.

The biggest challenge of a metal roof is sealing up all the things that come thru the roof, chimneys and vent pipes and such. It is harder to flash and seal up around the corrugations.

Metal roof is a lot stronger than shingles, should be a "once in a lifetime" roof for just normal storms and wind. Our town went thru a tornado this summer, some of the metal roofs did need to be replaced after that.
 

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We love our metal roof! Had one put on about 15 years ago, thought it would be our forever roof, but did not do well with a tree in it on April 27, 2011, but we replaced with the same roofing thanks to insurance. If you collect water off of it the water will be much cleaner than from a shingle roof. When we first got the roof I would think it's raining from hearing the water run through the gutters - but it's the dew condensing. This keeps some of our plants near the house well watered even when it hasn't rained.

Also, the metal roof is like a sliding board - not very safe to walk on. My husband uses two thick foam cushions to walk on when he has to go on the roof as they stick to the roof better.

Dawn
 

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You can put the metal on right over the shingles as long as the sheathing is solid.
You can do this, but as the metal settles in through the season changes, the shingle pattern will become visible.

I replaced my ashpalt roof with metal last winter (Jan/Feb 2013). I bought the metal, the tools, and then did ALL of the labor myself - including scraping off the shingles, laying down new underlayment, cutting the metal, screwing it down, and sealing it where necessary. I had my BIL and FIL help with some of the square sections. Saved me about 4 grand, but I'm young and spry. ;) Nevertheless, the project beat the living crap out ofme.

Our house is about 1800 square feet, and we have a T-shaped section with two valleys. To do the valleys, there is a special piece that lays in the valley. That goes on first (but over top of the gutter flashings). The panels need to be cut and folded at the correct angle, and then screwed in THROUGH the valley piece and sealed.

I did mine standing seam, 26 gauge. It was more expensive, but also conceals the screws so it's more water-tight. The first thing to go is the synthetic ring around the screws. It looks like old pool caulk when it degrades. The standing seam does away with those, for the most part, and includes wide-threaded, flat-head screws that are completely covered by the adjacent piece. For anything where you're concerned about moisture ever creeping in, ever, at any point in forever, you should go standing seam. i built my chicken coop from the wide-ribbed, "exposed fasteners," and there is a HUGE difference in quality and longevity of the fasteners. Plus, the standing seam upgrade gives you a thicker gauge of metal, which is extra peace of mind for me.

Y'all can see pictures of my work here: http://homesteadcatholic.blogspot.com/2013/06/remembering-metal-roof-project.html
 

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Also, the metal roof is like a sliding board - not very safe to walk on. My husband uses two thick foam cushions to walk on when he has to go on the roof as they stick to the roof better.
I wore a pair of shoes that had flat, rubber soles. I had to carefully time the dew settling in the evening - every minute after Dew O'clock got more and more dangerous. :/
 

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What is a good gauge metal? Screwed every 2 foot?
You have the options for 26 and 29. I used 26 on my house, and 29 on my chicken coop. 26 is noticeably thicker.

How are roof valleys done.
See my first post above.

Should the metal trim on the edge of the roof be replaced?
I installed my new ones over the existing, since they were unobtrusive and in otherwise fine condition. That's an individual judgement call, but can be done successfully both ways.

Is it laid directly on the existing decking or is there something put down first.
I ripped out my shingles, stapled a plastic sheet to the wooden decking, then screwed the metal right over the top.

Do they put anything into the bottom of the ribs to keep wasps and such from moving in? Or do I want the air flow?
You can fill it with a foam, or crimp the edges. when you're done. Both have their pros and cons. Foam may wear out, while crimping is permanent, but foam could be more aesthetically pleasing.

Anything special to keep snow from sliding off and taking gutters with? Currently have a ridge vent, can that be done with metal?
Yes, that can be done with metal too. Here in TN, we don't much snow, so I didn't install anything for that. But, you can add something like that, or even extend the panels to almost over the gutter. Rain will curl around the bend of a standing seam, and drop off the cleat into the gutter. Extending the panel forward to prevent snow in the gutter should be fine. But again, i didn't do that, so can't speak to it personally.
 

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You can do this, but as the metal settles in through the season changes, the shingle pattern will become visible.


Y'all can see pictures of my work here: http://homesteadcatholic.blogspot.com/2013/06/remembering-metal-roof-project.html
That didn't happen on ours. We put steel over shake shingles on one of the outbuildings. It was supposed to be temporary but after 20 years, we never got around to re-doing it. You still can't tell the lumpy, bumpy cedar shakes are under there. The profile of this particular metal probably helps, it is the coated steel version of "barn tin", square corrugations instead of rounded, but one right after the other without any flat spaces in between the ribs.

We put steel over regular shingles on our garage, it is the more common corrugation profile with less ribs and more flat sections. The shingles don't show thru yet and it's been on 10 years or so.

I wish I could remember what gauge it is. I do remember, I accidentally backed onto some of that shed metal laid out on the ground, two or three sheets together, and they didn't bend. It was the back end of the pickup, not the "heavy end", but still!
 

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That didn't happen on ours. We put steel over shake shingles on one of the outbuildings. It was supposed to be temporary but after 20 years, we never got around to re-doing it. You still can't tell the lumpy, bumpy cedar shakes are under there. The profile of this particular metal probably helps, it is the coated steel version of "barn tin", square corrugations instead of rounded, but one right after the other without any flat spaces in between the ribs.
Makes sense then. Mine has 18" flat spaces between the seams, and there are a few places where some of the roughness of the wood shows through. Yeah, you wouldn't have that if there are no large swaths of flat metal laying on textured underlayment.....
 

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I just finished the Barn,8/12 peak roof with 4/12 lean to attached on either side. I used 29 ga white. We have a manufacturer here (Higgins Metal)about an hour away. Put lath on the peak roof over the existing old metal roof. I attached directly to the shingles on the lean to roof, because this not being an insulated roof,it will not create a moisture problem under the new metal roof. For the price,and doing it myself,with two sons,I was very pleased with the results.
 

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I calls em like I sees em
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I just finished the Barn,8/12 peak roof with 4/12 lean to attached on either side. I used 29 ga white. We have a manufacturer here (Higgins Metal)about an hour away. Put lath on the peak roof over the existing old metal roof. I attached directly to the shingles on the lean to roof, because this not being an insulated roof,it will not create a moisture problem under the new metal roof. For the price,and doing it myself,with two sons,I was very pleased with the results.
Our run-in shed is open on one side and not insulated - but it still condenses moisture on the underside of the roof and drips in there on occasion. There will always be condensation under some conditions. But because you went over the shingles, they will protect the wood.
 

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After 30 years in the construction industry the best advice I can give you is to read, study, and read some more. Home Depot and Lowe's are great for small projects but I would suggest buying from the manufacturer or distributor. It is in their best interest that you install correctly and will bend over backwards to help you. I'm not knocking Home Depot or Lowe's but their interests are different than the manufacturer. I would not install over an old roof of any type. If the old roof is not good then why keep it? Weight is a major concern. Also, pitch is important. Most manufacturers of steel roofing won't warranty less than 5/12. Steel is beautiful, long lasting, but also creates condensation that can cause some severe long term problems. Freeze dams should be used and also eave heaters, depending on how far north you are.
The biggest thing to remember, the two most important parts of the house, foundation and roof. Don't skimp on either one. You are getting ready to spend a few thousand not to mention your time and the time of those who help you. This is a 20 to 50 year investment so take your time, study, ask questions. You can learn a lot from non professionals who have done this themselves, but you also need to talk to the guys who do this everyday and rely on the quality and durability of their work and product to be able to put food on their tables. Good luck on your project. Would like to see pics as you go. And don't stress, enjoy it.
 

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A lot of places, two layers is the max allowed by code, so they will probably have to come off. Good idea anyway even if not required. Sounds like you're asking all the right questions that will lead you to a good decision.
 

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Scotties rule!
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Discussion Starter #18
Thanks for all the information. I had the guy that installed my roof out yesterday afternoon. He said they were Globe shingles and the company went out of business because of too many bad shingles. So no warranty or anything, even though my 25 year shingle is only about 12 years old.

Taking to the roofer, he expressed concern with getting the 3 valleys and 2 skylights sealed up well. He said he does do metal roofs but wouldn't do mine. Said he could do a tearoff and new shingles in 2 days. Said the metal roof would be 4 days and at least twice as much money.
 

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We put on a metal roof a few years back ,we are out in the country . Put it right over the shingles . Don't know about codes didn't ask .Out thoughts was if it lasted fifteen or twenty years we wouldn't know or care anyway due to our age . Resale of this house in not a factor ,payments aren't a factor and if our insurance Co. don't like it they can go pound sand too . :hobbyhors
 

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Taking to the roofer, he expressed concern with getting the 3 valleys and 2 skylights sealed up well. He said he does do metal roofs but wouldn't do mine. Said he could do a tearoff and new shingles in 2 days. Said the metal roof would be 4 days and at least twice as much money.
Sounds about right to me. I think the extra time and expense up front is SO worth it down the road. Roofing is a project you definitely do not want to skimp or cut corners on.
 
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