I’ve got a house w/ a standing seam metal (tin?) roof, which was built in 1922. We have owned the house since ’71 and the roof has been painted every 5 years or so due to continual spot rusting and peeling. It flakes off in small areas all over the roof. Every painting contractor we’ve had over the years has attempted to scrape off the flaking paint with a hand held scraper blade and prime the bad areas but they never get it all, and after a couple of years, were right back where we started – with it flaking and rusting again.
The last time it was flaking off after just one year. The contractor came back and spot painted the bad areas again. It started flaking again 2 years later. I have had enough. I am considering these options: to require another contractor to remove 100% of the old paint, prime, and then repaint. My fear is that he won’t be able to get the rust off and it will come through. Are there primers that can go over rusty as well as sound metal? The next solution I have thought of is to require them to sandblast the roof to remove 100% of the rust. My fear here is that they could blow holes in the roof and start a leaking problem, which we have not had to date.
The other idea is to replace the roof with a new factory painted standing seam. The fear here is that due to having a square house w/ a hip roof there are 4 ridges, plus 4 dormers, and an addition off to one side, multiple lighting rods and cables would all be in the way, and may have to be removed/reset to do this the cost would be enormous.
How long are these type of roofs expected to last? Is it reasonable ( or cost effective ) to require a contractor to reomove 100% of the old paint? to sandblast? What kind of primer would be best in this application?
The house is in Virginia, it’s fully exposed to sun, it is green, and must remain so. Any suggestions or comments are appreciated. Thank You.
Replies
Is it reasonable ( or cost effective ) to require a contractor to reomove 100% of the old paint? to sandblast? What kind of primer would be best in this application?
I've been through a similar decision with a customer for an immense barn. Painters have tried all sorts of exotic primers and given lots of guarantees. Far as I can tell your choices amount to frequent repairs, every year or two, or a large bill up front for either total paint removal or replacement. I'd go with new copper. You're going to pay no matter what you choose.
Where are you? No, I'm not a roofer but I DIYed copper.
PAHS Designer/Builder- Bury it!
It'd be real expensive to replace this roof,especially since it doesn't leak.Standing seam is a high quality roof. The primer to use on bare metal is one that contains zinc chromate to ensure a good metal-to-metal bond. The topcoat should definitely be able to block UV rays,the most damaging,and the most likely culprit of your paint peeling.
Under the best conditions, a painted roof still needs to be re-coated every three to five years.My suggestion is to get real good references and find a qualified painter.What's on there now may be just a colored polyurethane and not a roof paint.
Jack-
I tried to locate a paint that had the zinc chromate and everyone went cross eyed. Said it was only available over seas although others have said they know it is avaialable off the shelf in their area.
Would you have a web site address for a internet sales. Thanks.
I used to get it from Duron(http://www.duron.com), but I couldn't locate it there or at http://www.benjaminmoore.com . I'd try an auto parts store like NAPA.It may be the EPA has banned chromates. However, German paints are renowned for their quality if you can find a supplier.
What about the Rust-Oleum primers? I have used them on a number of projects with rusty metal and haven't had any peeling problems. Most were auto/equipment related and haven't done anything like a roof, however.
30 mi. east of fredericksburg
Hi Scott,
You might want to check out the web sites with 'elastomeric' coating which is a rubberized coating commonly used of late for commercial steel roofs. It is a spray or roll on product available in 5 gal buckets as well as drums.
Different namebrands have thinner and thicker densities and some are recommended by roofers more than others.
I used several of the products last year but the preferred one slips my mind at the moment. If you decide to pursue these I could check on that name and post it here later.
I would appreciate it if you could post that name. Removal of the old 20 coats is going to be my biggest problem though, it appears.
removing 20 coats of paint will be relatively easy, containing the lead (which is almost certainly in the bottom 5 to 10 layers) will be the hard part.
I suggest blasting, find a contractor who uses a soft blasting medium (plastic beads or wheat husk). I've seen it done and it works. It wont damage the roof any more than it is already. Check the cost though, a new roof may be cheaper.
More than likely, it's a terne metal roof which is sheet steel coated with a lead/tin alloy. That gets damaged or blasted off no matter what medium is used. If the roof has previously been patched, the patches also get blasted off.
scott
In twenty some replies you have nearly as many paint suggestions as there are coats of paint on your roof. No concensus other than revert to copper should tell you something.
If I were the roofer you were calling on this, I might, given what little I know of it now, say something like this -
"I'll be glad to strip and paint it for you, if youy want, using the zinc primer and striping it down as clean as it can be, but I'm afraid that I can't gaurantee the job for you as a lifetime product like you are looking for. It might follow its own history and keep blistering off. I think that we can replace the roof for a comparable price. Why don't we detail that kind of a job for you?"
Or if I looked closely at the structure, I might even end up sayingh something like this -
"The condensation from under this rtoofs interior is pitting the metal from the back with rust also. It is in a state of failure, with little but the paint keeping the rain out. I don't see much of a reason to keep putting more paint on this roof. Would you mind if I made a proposal for replacing it with a new metal roof, either a factory prepared or a copper standing seam?".
Excellence is its own reward!
A word of caution on the elastomeric or rubber type coatings. No matter how "new" they say they are, they have been around for many years in one form or another. Every one I have seen, has become the last attempt at a roof coating.
Not only do they not prevent rust continuing on underneath that pretty finish, I would have to say they actually accellerate it. Moisture gets trapped underneath, and the rusting process continues, IMO, at an even faster rate. And once they are on the roof, you can forget about ever going back to any other kind of finish.
If the cost of total replacement is too much for you to tackle at this time, consider doing one or two sections a year over several years. I have done this for customers before, and it can work out quite well. Naturally, it would be less expensive , in total, to do the job all at once.The key is finding a contractor willing to do this without charging a huge premium for breaking the job up.
John Svenson, Builder, Remodeler, NE Ohio (Formerly posted as JRS)
I think what you said is what is going to happen. I am planning on calling some painters in the next month or so.
Thanks to all for the many replies.
If you're thinking about a copper roof you may want to consider whether if will look appropriate on your house. In our case, we live in a historic district in a small city here in the mid-west. It was primarilly a working class neighborhood constructed between 1880 and 1910. All of the porch roofs were made of tin (terne) metal. Copper was always considered an expensive roof reserved for fancy homes and public buildings.
I'm not sure if our historic district commission would allow copper roofs but, in my opinion, they look a bit out of place on more modest homes.
You raise a good point. Things are different regionally, but I've replaced many terne metal roofs in historic districts with copper. My experience has been that the roof must be layed out and tooled the same way as the roof being replaced. A modern painted steel roof with the big cumbersome ridge caps and edges looks more out of place than a copper roof with the same turned hips and ridges and delicate edging that the original roof had. Economics do not dictate using terne anymore (which is only available in Terne II, which uses a zinc/tin alloy rather than the old lead/tin alloy). The labor is the same for both materials ( copper or terne II), the material cost is slightly less for terne, but it must be painted on both sides before installation, and terne II is a relatively new product (5 years or so with no real proven track record). I've seen a lot of recent ( pre-Terne II ) terne fail. My guess is the lead content was being reduced before the switch to zinc. Copper can also be painted if a certain color is desired.
Greencu,
It's good to hear from someone who actually installs terne/copper roofs. It's becomming a lost art.....only one crew still does it around here. And, it really is an art if you watch these guys make the complicated cuts and bends at corners.
I agree with your assesment of modern painted steel roofs but hope you're wrong about modern terne metal roofs. We had one installed 10 years ago. The manufacturer didn't suggest back priming and we didn't do so. I don't think that terne was ever back-primed, was it? Wouldn't that interfere with the soldering? It has a mill coating which doesn't last when exposed directly to the elements but, I think, should be ok for the underside.
Regarding cost, maybe the cost for copper has gone down, but 10 years ago, our porch roof would have been 3 times the cost if done with copper. Ten years ago Folansbee Steel was marketing a special terne metal which didn't need to be painted. The cost was almost the same as copper and I don't know if they're still selling it.
Uncle Dunc, copper will age eventually to a green color but, around here, it takes 4-5 years before it takes on a matte bronze color and close to 20 before it starts to turn green.
Chip
>> ... and close to 20 before it starts to turn green.
I didn't realize it takes that long. If you've got regulatory or neighbor issues that would definitely be too long. If you haven't already seen it, you might want to take a look at a discussion we had here some months back about ways to accelerate the process.
I won't touch terne anymore after all the problems I've had with it. There's a big difference in the old terne and what Follansbee was selling right before the switch to zinc. It's been a while since I've read it, but the instructions on the rolls said to paint both sides before installation. It was rarely done, but a company I once worked for had a frame to lay flat seam pans in to protect the edges to be soldered from getting paint on them when you pre-painted in the shop. Copper never was much more expensive than terne ( in my 15-20 years of dealing with it), but a premium is often charged because of the perceived value of copper.
When I did use terne, it was usually as a replacement for part of a roof (storm damage, etc). On complete roofing projects, terne has never been cost effective when the paint and further maintenance is figured in from my stand point. The labor cost is the same (terne or cu). A coat of primer and a finish coat of paint cost more than the materials cost difference.
I'm pretty sure Follansbee still makes terne coated stainless steel, which I think is what you are refering to.
Good luck with your roof. If it's 10 years old, it may have been manufactured before the real crappy stuff came out. I had to replace a couple of flat seam terne roofs out of pocket with copper, since I could not get any response from Follansbee about why they were failing other than to blame installer error or paint failure (their paint was not used). All work was done the same way and the same paint was used as the projects I did in the previous 10 years and the older roofs had no problems. Just the projects done in the year or two before the switch to Terne II.
Greencu,
Thanks for the additional information. I may be more hesitant in the future to recommend terne metal roofs. So far, our's is in great shape. I repainted it last year only because the paint had faded badly. Otherwise, the roof and the original paint were in excellent condition.
I'm assuming that you used the standard gauge terne on the roofs which failed. Our installer mentioned that there was a thiner gauge available but that he would never use it. You mention in your post that the worst stuff came out right before the switch to zinc coatings. Do you mean that there were several years of bad quality materials or that the zinc now in the terne is the problem?
In any case, I would bet that our new terne roof lasts 70-80 years just like the old terne roofs. Unfortunately, I won't be around to collect on the bet and, if I'm wrong and it only lasts another 10 years, I'll just be a very unhappy 70 year-old camper.
Chip
I hope you're right about how long your roof will last. I've never used the new Terne II (zinc/tin). All my failure problems were fabricated and installed right before the switch to zinc. They rusted out from below. The terne was laid over rosin paper and the roofs were vented. In the instances where I had failure, the roofs were over heated (and moist) livng space. That was Follansbee's reasoning for the neccessity of back priming. I can't remember any failure over unheated spaces.
The old terne came in 20# and 40# grades as well as IC and IX thicknesses. The IC was 30 guage and the IX was 28 guage if memeory serves me. The 20# and 40# indicated how much lead was used in a certain quantity of terne. I always supposed it to be a square, but never really new for sure.
Good luck.
Greencu,
Yes, it sounds like you were doing everything right.....rosin paper, a well-vented roof, etc. Our 10 year-old porch roof has an unheated open porch on the south side of the house but the roof wraps around a portion of the west side which includes our kitchen (a heated and moist area). I'll pay special attention to that section of the roof. But, so far, everything looks good. Thanks again for all the information you've provided. I've learned a lot.
Chip
You may be right, and it's definitely a consideration to keep in mind, but if the current roof is painted green, it's hard to imagine that a green patinated copper roof would be jarringly different.
My 1890's house has a terne metal porch roof that looked terrible when we bought the house a couple of years ago-flaking paint, some minor rust holes here and there...I was going to replace it with new for like 5 grand.
Luckily, I found out about Preservation Products elastomeric system for metal roofs. I cant say enough good things about the coating-it is truly awesome. Basically their stuff is a rubberized thick paint that is elastic enough to keep up with a metal roof's expansion/contraction cycle. You roll it on with a roller, and if you got holes you use a fiberglass mesh to reinforce it. Expect to pay about $90 a square.
Their stuff has been put on alot of NPS historic sites, and alot of houses at the Jersey shore. There is an observatory dome that got coated not far from where I live that is all copper...there were holes in the dome so that you could actually see daylight.
The only caveat is that you have to recoat every 10yrs or so.. but youd have to do that with terne anyway, right?
its http://www.preservationproducts.com
Homer,
Glad to hear there's someone else out there recommending Preservation Poducts, Inc. You said it better than I did in my original post. You need a paint which is elastic enough to expand and contract with the seasonal temperature changes on ####metal roof. It's the same reason you use spar varnish for exterior applications on wood. It's relatively soft and flexible. Other metal paints which dry extremely hard just won't last on a metal roof.
Chip
Scott and Rez,
The recommended paint for terne metal roofs used to be a linseed oil paint. Folansbee Steel which makes terne metal used to sell this special paint. It took forever to dry but remained fairly elastic. However, the EPA banned the product a few years ago.
Last summer, when I needed to repaint my terne metal back-porch roof, I went with "Acrymax" from Preservation Products, Inc. It's a water-based paint which, as Rez says, remains somewhat rubbery. You need to build up coats (two coats minimum). If the roof is badly rusted they recommend using a fiberglass mesh as the first step which you can also purchase from this company. My roof turned out great but it was a fairly new roof (10 years old) without any peeling or rusting.
Next summer, I plan to use the product on a much older terne metal roof on the front porch of my house. Like your roof, I've got multiple coats of paint on there and a good deal of peeling but not much rust. I'll try to scrape and wash off as much of the old paint as I can but doubt I'll be able to remove it all. We'll see how well the product works on this tougher test.
Preservation Products, Inc. has an 800 number. They'll send you color samples as well as several instruction sheets on how to apply their product. They'll also send some promotional literture which shows their product used on a number of historic homes and buildings including Churchill Downs. Good luck.
Chip
You know it sound like you need to take a trip to person that does nothing but paint steel and some plastic and ask them, how to stop the metal from oxidizing. Oh by the way they are called auto body painters.
It sound like your painters are not getting all the oxidation off/out the steel before it is being painted. Or after 17 coats of paint it is just to thick and it keeps cracking under underneath and letting air and moistur get to the metal to oxidize. If that is the case the roof needs to removed have the paint striped to bare metal and start over.
I don't know but a roof that old will have had lead paint used, if they use lead in a metal paint. So that means a chemical removal not sand blasting.
I think your right - the old paint cracks and that propagates the rusting. If I remove the roof, then I'll put back a pre-painted product with a warranty - I just couldnt never put back metal that needs to be painted again .
I think VaTom has your best solution. Replace with copper ~ No paint and it will definately turn green. ( Very Nice Green Too )On a hill by the harbour
I agree that copper would be the best way to go, but also the most expensive.
If this is steel and not close to rusting through, you can get many more years out of it. The problem is that rust is a chemical process that doesn't stop when you cover it with paint. What you have to do is remove as much rust as you can to get down to a strong rust surface, and then stop the chemical process with something like Chesterton's Rust Passivator. Then you can prime and paint it, and the life of the paint job will be determined by the quality of the paint, not by rust flaking off underneath the paint.
-- J.S.
Hey John,
The copper is definately the most expensive way to go ....
That being said .............. If you don't want rust on your roof IE: Paint every 3-5 years, & want your roof to be green it is the "efficient" way to go.
I spent years at sea applying zinc chromate primer as a deckhand on steel ships only to find that when we were finished chipping & painting at the waterline that we just started again at the top of the ship where it was rusting again. Point is that copper doesn't rust but oxidizes to a lovely green colour.On a hill by the harbour
We used this stuff on a steel deck..called "put on rust" or POR...http://www.por15.com/ check it out here...don't know why it wont come up as a direct link..copy/paste...
The surest way to make a URL active, short of coding your own HTML, is to put it on a line by itself and then hit return. The color should change when it is recognized as a URL address.
http://www.por15.com/
Thanx ...I forgot that ...
That's a browser dependency, or maybe an OS dependency. I've never had to do that to make text into live links.
works different if I am using A O Hell, or Mozilla..I do not have the same options when I am using Mozilla..like bold, italics, and underline...or the bottom wysiwyg/source..only on AOL is all that there..go figgure.
Sphere: When you past in a link, http://www.por15.com/ be sure and put a space on either side of it. Otherwise the browser can't reconnize it as a link.
Re the roof, listen to greencu - this is what he does for a living as a speciality - metal roofs. He is the man.Matt
We used this stuff on a steel deck..called "put on rust" or POR...http://www.por15.com/ check it out here...don't know why it wont come up as a direct link..copy/paste...
We used this stuff on a steel deck..called "put on rust" or POR... http://www.por15.com/ check it out here...don't know why it wont come up as a direct link..copy/paste...
There was no space before the "http" and there were two spaces after the ".com/"
The double space is coded in the "Reply" and makes the link look like xxx.com/ <WHICH a P address.
To get the "here" to be a link, I selected it (highlighted it with the mouse), then clicked on the "Create Hyperlink" button. The button is the round blue circle with a chain link in the bottom right, directly under the "- Color -" box on the "Reply" page. Just paste the link address into the "Create Hyperlink" window that pops up.
SamT
Geez...to think I used to program a CNC router..I want my DOS back. No, not really. Thanks I got it all ironed out I think.
You guys are as good with puters as homes..way to go.
>> I selected it (highlighted it with the mouse), then clicked on the "Create Hyperlink" button.
In Netscape it's even easier, at least in the obsolete version of Netscape that I use. I just type the URL in as plain text (making sure there are spaces at the ends and none in the middle, as you pointed out), and Prospero turns it into a link.
Prospero has its faults, as does every work of the hand of man, but it has its virtues as well.
Zinc chromate primer doesn't stop the chemical reaction that forms red oxide rust. The passivator solution converts red oxide to the stronger, more stable blue/black oxide. And that does stop the formation of red oxide.
-- J.S.
John,
Back in my deckand days 78-85 we used to use Zinc chromate cut with boiled oil in winter because it was the only mix that would freeze the paint on.
Please explain the chemistry in luddite terms :)On a hill by the harbour
I take care of an 1835 28 square corrugated metal roof - painted 3 times last 37 years -- just brushed last week -- we are in Frederick, Maryland. What you need to do is first paint it with the aluminum paint that has fiberglass fibers and tar in the paint and then top coat it with your green paint. Only, only, hire a painter that will roll the paint on -- use plenty of drop cloths -- you have to have the alu paint establish a second skin on the roof and the top coat if you need to all has to be rolled on so it soaks in and the fibers form the bridges where they have to ---------- ABC Roofing -- Old Washington Roofing here in DC (several locations around DC) has the Aluminum paint you need in 5 gal buckets (gal covers 75 to 100 sf but count on 50 to 75 because you really need it down in all the cracks and crevices) -- about $60 for 5 gal -- use plenty of it and second coat if you want to and your roof will last
In my tugboat days we used to chip by hand or with a needle-gun; then wire brush, the brush on Ospho. This is a brand of phosphoric acid. It's unknown here in Canada; I buy a product called Mik here that is about the same thing, only in domestic rather than marine strength.
The phosphoric acid chemically stabilized any rust remaining on the surface of the metal and turned it hard and black. We then painted on red-lead primer, and WITHIN 24 HOURS, the finish coat.
Shipyards did it the same way, except they sandblasted with Black Beauty, then sprayed the Ospho, primer, and paint on. You definitely didn't want to leave your truck on the dock near a shipyard without putting a h-d cloth car cover on it....
I worked on one boat where an enterprisingly lazy AB figured out that he could use a parts washing spray gun to spray paint the boat if he thinned the paint out 1:1 with Varsol. He removed the solvent can, stuck a piece of plastic tubing onto the suction pipe, dropped the tubing into a 5 gal bucket of paint and blasted away. Not very fine control, but then, it was a work boat, not some rich guy's yachty-yacht....
Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
Assuming 20 coats - chemical reomoval sounds like megabucks - even the best strippers only get a few coats at a time dont they? Wouldnt a new roof be cheaper?
Today, I drove by a roof similar to yours that I repaired after being sandblasted nearly 20 years ago. It apparently had been recently repainted and still looks good.
That having been said, this project ended up costing more than a new copper standing seam roof would have cost. The sandblasing was expensive and created many small holes in the terne metal as well as making a mess. I spent several weeks on a twenty five square roof riveting down metal patches. The previously non-leaking roof leaked like a seive after the sandblasting. Plaster was damaged. The patching as mentioned above was labor intensive and expensive. Priming and painting was expensive and has been repeated several times already. This whole project must have looked good on paper to someone.
As you have already mentioned, your paint jobs are lasting a very short time due to improper preperation. If you've got that much paint buildup, you're never going to get it prepped properly by mechanical means. Strippers seem dangerous ( I once saw a similar project go bad when a surprise storm washed the stripper down the siding of the house) and cost prohibitive.
As far as prohibiting and killing rust, I have used Penetrol successfully. It is a paint additive, but does a great job of arresting rust. Hope this helps.
http://www.toppsproducts.com/
This is what I ended up using as it was the recommended product from a number of roofers that had used various namebrands.
It is a solvent base which produces a pretty durable rubberized sheet upon drying. Well worth investigating but I think with this particular Topps product you're stuck with either a dark grey color used as a gutter liner or white used for a heat reflective property.
Believe it or not but Sherwin-Williams makes a kickin' good metal primer I believe called Chromex or Chromate.
Covers well and dries quickly.
I was experimenting with different application methods as the roof I was working on was 4 buildings hooked together with nooks and crannies and I wanted the most efficient process. I had some 3 inch foam rollers I was messing with and the paint melted them. Roar!
GAF makes a latex modified paint like product that is disigned for roof applications can be had in varouis colors.When applied by autorized contractor is even warretied for up to twelve years try http://www.GAF.com there is a pspot in the web site for homeowers
http://www.gemplers.com used to sell a one coat paint made for rusting tanks and farm equipment.
You may find it on their site and ask for references by some that have used it.
I have heard that it worked fine on some old fertilizer tanks, but don't know much about it.
May want to look into that, if nothing else comes along.
Perhaps you might be able to find a source for the same paint they use on airliners.
Seems that must be some durable stuff.
I had a chance to get some once, didn't, and have kicked myself since then.
It was a two part epoxy if I remember correctly.
I hope I am not too late.
The people discussing automotive techniques are on the right track
Ant time you remove paint down to bare metal, any moisture in the air will cause it to begin to rust again. You can not see it but its there.
Good body shops use preparations sold by Dupont or others that convert this microscopic rust to keep it from spreading. Industrial painters use a product named Ospho. It works the same way