metal roofing for tiny house

We are now putting a metal roof on our 14x14 a frame time house, less expensive than plywood and asphalt shingles. Any hints or thoughts before we start?
We are in Oregon.

We used hex head roofing screws instead of nails. We felt that they would hold better.

To cut the metal roofing, use a circular saw with the blade put on backwards.

Use leather gloves or accept the fact that you're gonna cut your hands.

Hi Daphne,

I strongly discourage my clients from using any system of metal roofing that is not a "hidden clipsdown" system like traditional standing seam or similar system. I just removed another metal roof last week off a barn we deconstructed for reuse. It had a beautiful hewn timber frame from the 1820's, but the current client thought it was a good idea to take of the old rusted "standing seam" roof off (that was not leaking - just unsightly from their perspective) and replace it with a "screw down" metal roof. The grommets only lasted ten years, and the roof started to leak, leading to water damage to the rafter plate and some rafters.

It never struck me as logical to cover a roof in solid sheets of metal (a good roofing material) then put hundreds of holes into each panel thinking it would not eventually leak. The grommets have a very limited service life. Yes you can find some that are better that other, with a guaranteed service life of 25 years (and you pay for them) but it is not a matter if they will where out, but when. When they do fail, you may not know it right a way and only discover it after there is damage to the roofing structure itself. Assuming that you discover the leaks quickly, you still have to go up and take the old screws/nails out and replace them with new ones. Just a waste of time, and a risk not worth taking.

As a special note, in 35 years of working in and around the architectural field, I have never seen a warranty for gourmeted fasteners that fail honored by a roofing company or manufacture, which renders such guarantees worthless.

Regards,

jay

If you use screws or nails with or without grommets, paint some roofing tar over each one as a final step to seal out rain, it also works well around any pipes or cables that might be going thru the roof. I would probably secure well with fasteners at the edge of the roof, under the ridge cover, and at the bottom edge, buy some specially short screws to secure the seams to one another, double check wherever you put a screw in the vast areas of the roof that there is something to screw to there, you don't want to miss any rafters, but if you do, leave the screw in there anyway, or sometimes you can back it out & change the angle of the screw & hopefully catch the wood. Those screws cost a lot, but they are worth it, get a good amount of the seam screws, & even more of the longer securement screws. You will need a driver bit, and I would buy a spare also. Plan on using flashing/rubber gasket & roofing tar in any valleys or around pipes. A good set of metal shears is usually necessary, they should be at least a foot long and best quality.

Buy your metal where it will be long enough to overhang as much as you think right, on my regular roof it overhangs past the walls about 2', make sure your rafters extend on the edges of the house too, as the metal needs be sturdy supported in those areas. Sturdy enough to hold a man standing on it. Short seam screws come in handy at the bottom edge in addition to whatever rafter support you have. Rain will still splash against the house walls or foundation. So make sure your house below the roof is moisture proof in that area also where the rain might splash, use metal there if you want, or gutters might be a huge improvement. Not sure about your A-frame set-up, but doorways and windows also need a large overhang to prevent rain/splash, especially if there an entryway stair or stoop (a concrete stoop splashes rain on a doorway or wall like crazy).

I would use the best (heavy) asphalt tar paper you can find, it must be water tight & any seams or holes or staples should be sealed with roofing tar, don't buy old or damaged rolls unless you want to make extra work for yourself. Overlap each strip of tar paper well & use roofing tar to glue it to the next strip, the overlap is such that the water will always shed on top of the paper. (lay the first strip of paper at the bottom of the roof, then overlap each strip as you go up the roof, hope that makes sense) I really recommend the tar paper, as metal roof is guaranteed to condensate moisture on the underside whether the house is heated or not, a simple light frost being melted by the sunshine will cause the metal roof to literally 'rain inside the house'. If you can imagine a foot of snow on the thing, and a nice warm house, or even very cold...it will condensate on the metal underside, this is why I recommend the heavy tar paper & seal well with roofing tar.

When trying to get your roof on straight, try the first piece at one end, and another piece of metal at the other end, scribe bright lines (with a chalk line) across the top & bottom for the roof span, IF all your metal is the same length then it should come out pretty good. It is worth the extra effort to make & set a 'runner board' along the bottom of the roof, that runs straight & square at the bottom edge line, get that set right and the metal install is simply set, sheets against the runner board to help hold the sheet as you neatly position the seams all the way to the ridge. There is a little 'wander or variance' that will happen while setting the seams together, so the runner board helps keep things square looking at least at the overhang edge. Your metal sheets need not butt at the ridge line to the other side sheets, nor be perfectly straight like at the bottom edge, because you will have a fine ridge cap to cover that gap, so if some sheets are shorter than others, it shouldn't matter much. Just try not to get 'off square'. Make sure your ridge line is completely sealed/capped with tar paper & roofing tar before the metal install. There is a thick gasket material that is made to fit your style of metal roofing, those strips fill the void between the ribs/flats of the sheet metal and the ridge cap, use those if possible, & use roofing tar too make them permanent in place. You can also find a gasket that fits on the underside of the metal sheet, it locates at the bottom edge of the roof & seals out dirt & wind, but I left those out so that all the condensate on the underside could drain out.

I've only put on two metal roofs, ~~~so take everything I suggest with a huge dose of salt!~~~ LOL

james beam;)

Thank you everyone for your valuable advice!
Daphne

Jay, I did a search for metal roofing hidden clipsdown and did not have any luck in finding what you were describing. I am not sure what I should be seeing so I may have seen it but with a different name or description. Can you maybe post a few links to some manufactures that make this kind of roofing? I'm in Arizona so one or two in the West would be helpful.

Thanks, Al

search for standing seam metal roof.

Hi Al,

This should get you going in your vetting contractors and/or suppliers. You can do the work yourself and there are companies that will, "cut and drop" pans for you as it is called in the industry. Check in with us here with your progression, and/or needs.

http://www.metalroofingarizona.com/standing_seam.htm

http://www.atas.com/

http://www.mastercraftmetals.com/

http://canyonstateroofs.com/services/standing-seam-metal-roofs


Regards,

jay

Thanks Jay, I'm still a ways off on my dream but like to plan ahead,

Al

I would like to suggest that instead of using metal for roofing you use natural products like bricks, wood or any other ecological items which will help to reduce the pollution of the environment. We too have recently purchased a house that is made according to green building and have also checked its sustainability.
LEED Commissioning

Hello Sheila,

I appreciate your concern, but your comparisons are a little inaccurate. For one thing, you can't use bricks for roofing, and it is no more or less natural than metal is so I will assume you meant clay tile which is a wonderful medium but in most markets much more expensive for folks than metal, and require extensive expensive shipping. As for a carbon footprint metal has one of the lowest because it can last so much longer than other roofing mediums, and is much easier per square foot of coverage to manufacture and ship than just about any other roofing material, making it one of the most ecologically sound roofing materials you could use. Wood is also good, yet comes with it's own issues, and limitations.

As for LEEDs, I am involved in several discussion groups that are confronting LEED for it "whitewashing" of green standards so "industrial products" and corporate sponsors take precedent over true and actual "natural and traditional building practices." LEED started with good intentions but has slowly devolved into a mechanism for the mainstream construction industry and corporations to try and influence and change what they think "green" standards are to be. I could, (and have been) challenged that this is a subjective opinion, yet I have not seen a, "natural or traditional" built home yet receive even the lowest LEED rating, and the gap is only getting larger. Now we are also faced with a potential monopoly as LEED is becoming mandatory in some area. This is actually much worse than general building Code, as LEED is but one standard, and true green architecture needs room to include other interpretations.

Al Turner wrote:Jay, I did a search for metal roofing hidden clipsdown and did not have any luck in finding what you were describing. I am not sure what I should be seeing so I may have seen it but with a different name or description. Can you maybe post a few links to some manufactures that make this kind of roofing? I'm in Arizona so one or two in the West would be helpful.

Thanks, Al

In the States, it's called "hidden fastener" vs. "exposed fastener."

I put one on my own house this summer.

Jay C. White Cloud wrote:As for a carbon footprint metal has one of the lowest because it can last so much longer than other roofing mediums, and is much easier per square foot of coverage to manufacture and ship than just about any other roofing material, making it one of the most ecologically sound roofing materials you could use.

Yes! And what's more, it's maintainable. The off-the-shelf lifespan is excellent, but when you consider that it's perfectly possible to re-coat the metal when the initial coating deteriorates, then you're looking at a really magnificent service life. When your wood shakes deteriorate, what can you do? Same with clay tiles, and (much sooner) your asphalt shingles. When they wear out, you have to throw them away and install new ones. When your metal roof wears out, you repaint it. And if you like, you can repaint and repaint and repaint it for a very very long time. (As coating technologies are improving, the intervals are increasing, too.)

In Autralia metal roofing is common.
Its held down with hex headed screws and I have rooves here gone 38 years with no damage to the grommets.
I don't know why the other chap had problems

John C Daley wrote:In Autralia metal roofing is common.
Its held down with hex headed screws and I have rooves here gone 38 years with no damage to the grommets.
I don't know why the other chap had problems

I am not sure either.

I cannot do standing seam steel roofing as I do not have the tooling, nor do so enough to justify buying it, but can do the typical steel roofing. Here in Maine, look at old buildings that are still standing and they always have steel roofing, the asphalt roofed buildings have collapsed. Its because they shed the snow..

My only suggestion when working with steel roofing is to use a  5 inch grinder with cut off wheels. It makes cutting the steel fast and accurate. Just wear gloves and safety glasses.

I often tear the iron, by starting with a nick on the edge, putting a foot on it and just pull.
It works a treat.
Cutting with angle grinders can cause the little bits to damage the surface treatment.
I think a special roof cutter is made, I have one that spits out tiny bits of steel , but its noisy beyond belief and the bits are very hot.
Maybe its best to cut roof iron upside-down ,or in in the Northern hemishere it may be  'the downside up'

Perhaps I'm misunderstanding something or there's a lot of over thinking?

Firstly, in Australia we use a variety of roofing sheet profiles, but the main one used by far are corrugated galvanised steel which may or may not be pre-painted. Google: 'Colorbond'.

There's a ridge cap, and the roofing screws are placed on the 'hills' NOT the 'valleys'.

Sheets are overlapped by four or more valleys for waterproofing, etc.

The hexagonal headed screws have a rubber or neoprene washer and come in wood or steel self tapping.

To cut the sheets a nibbler is the preferred tool because it doesn't leave a burr or sharp edge.

The sheeting and screws are covered by the appropriate Australian/New Zealand Standard which covers UV, wind load and saline tolerances.

If you can use a cordless impact drill, then you're more than halfway there.

As far as longevity goes, we have this type of sheeting that's older than 40 years - the rubber/neoprene remains unaffected if left alone.

Above the snow line they use the same stuff but simply no guttering.

A lot of good info here I won't restate. I would only add that if you are installing a metal roof there are techniques for fastening through the "ridges" or the "valleys." Research it well before deciding. In either case, if you are unsure about the gasket seal, you can always get on the roof and coat each screw with a thin layer of clear, waterproof silicon as added protection. It won't be visible from the ground or a distance, so will not impact the appearance of the roof, and can be easily applied or re-applied.

I am wondering if you have trouble with metal roofs that do not have the stand up ridges, because of snow etc.
In Australia Corrugated iron roofing is by far the most popular roofing and it does need a reasonable slope to work effectively.
Perhaps the buildup of snow and ice, plus flatter roofs causes leaking at the seams.

So, I have some Standing-Seam roofing panels left over from when my house got reroofed....do they need to have the special tools to install them? Where would I get those tools? I need to reroof my chicken house, and would like a light-weight roof for the nesting boxes. Should I just buy corrugated roofing, or see if I can get the standing seam to work without the special tools...

Jay C. White Cloud wrote:Hi Daphne,
...a "hidden clipsdown" system like traditional standing seam or similar system. ...


jay

He's right, get a hidden fastener single seam metal roof and it will never leak. EVER in your life time. Unless an oak tree falls in it.

There are metal roof systems which require crimp tools....don't buy those systems as they are twice the cost and labor intensive.

Get the type where you screw one side down and the next panel zip locks over the screws of the previous panel.

These stood up to 80miles per hour winds too!

It will cost you more up front than the non-covered fastners roof panels but you will save double or quadruple you roofing costs over 30 years

***you can buy the hidden fastener metal roof panels at Home Depot at the Pro Desk***

I am about to do a new roof on my house.
In discussions with a major roofing company, i was told asphalt shingles have class action suits against them due to failing 50% sooner than warranty.
Fiberglass is suffering the same as the degradation is not linear and when they fail prematurely the warranty’s are not covered.
His comments on metal: ugly on a house, screws need tightening every 5 years, replacing every ten. Expansion/contraction causes loosening and leaking.
They are replacing metal with rubber shingles. 50 year warranty. Tests show them to last probably 80-100 years. They don’t curl AT ALL. They don’t lose their granules. They soften in the heat of the sun and reseal themselves and the granules restick has on.

I have seen large buildings with them and they look like regular shingles

Ithink I will be going that route.

Daphne Singingtree wrote:We are now putting a metal roof on our 14x14 a frame time house, less expensive than plywood and asphalt shingles. Any hints or thoughts before we start?
We are in Oregon.

If you can afford it, try to select one that is not a flat design: On a flat design, any hail will leave marks that stick out like a sore thumb. Also, the waviness adds strength to the structure. We selected one that looks like the roofs on the Mediterranean.[tile]
The color may influence the temperature inside the building, depending on the insulation: Dark, and you will be toasty. Light and it will reflect the sun's rays to a degree.
In winter cold Wisconsin, we chose a warm chocolate color.
Also, before you install, or have one installed for you, it the roof is still sound, you may choose to keep the old roof underneath: That will save you money: Demolition is not cheap and takes time.

Jay C. White Cloud wrote:Hi Daphne,

I strongly discourage my clients from using any system of metal roofing that is not a "hidden clipsdown" system like traditional standing seam or similar system.  I just removed another metal roof last week off a barn we deconstructed for reuse.  It had a beautiful hewn timber frame from the 1820's, but the current client thought it was a good idea to take of the old rusted "standing seam" roof off (that was not leaking - just unsightly from their perspective) and replace it with a "screw down" metal roof.  The grommets only lasted ten years, and the roof started to leak, leading to water damage to the rafter plate and some rafters.

Agree totally. I recently received a quote from a roofing contractor for screwed vs standing seam. The difference was only $4k on a $14k job. I in fact will have to replace the screws on the outbuilding that the previous owner had erected.

But have a trained contractor do the job. They will bring a forming machine onsite that can create the proper lengths of panels so that there are no seams but on the verticals.

Brad Hengen wrote:

His comments on metal: ugly on a house, screws need tightening every 5 years, replacing every ten. Expansion/contraction causes loosening and leaking.

Don't believe it. Ugly is in the eye of the beholder. There are commercial and residential installs of standing seam roofing all over Texas 50+ years old and not had a lick of maintenance. Standing seam is becoming the standard here for commercial roofing material. The rubber is probably nice too. I suspect your roofer just does not like or does not have the set ups for metal roofing.

You guys are all really knowledgable and intimidating so I wasn't going to chime in and show what I did with my chicken coop but I did it but myself so please be kind
I had to consider heat and hurricanes so I positioned the coop and roof to deflect the afternoon sun. I laid down a 1" thick sheet of that foam insulation with the foil on one side with t facing up, on the rafters, and put the corrugated sheets over that, using trex roofing screws with the little rubber washer. Screwing down too much and squishing the rubber is bad so don't do that...and I'm sure I used way too many.
When I was done off course we had a bad storm and I only had one pin leak! I used a clear caulk you can apply wet to seal it. That stuff is a lifesaver around here. So far so good!
Oh, and I had to attach the new roof with the old one there at the peak. I thought I had it but when I saw it from the house I saw that hump... it only makes me crazy once in awhile 🙄

Leslie Russell wrote: That stuff is a lifesaver around here. So far so good!
Oh, and I had to attach the new roof with the old one there at the peak. I thought I had it but when I saw it from the house I saw that hump... it only makes me crazy once in awhile 🙄

For a Coop that's pretty nice. What do you have under the tin? Metal roofs radiate heat too well and you don't want to cook your birds. Go the extra step and add a gutter at the lower end and catch all that run off and feed it to the birds.

As I posted earlier, I have a metal roof that is overlapping sheets attached with hex headed screws. Our roof now is 15 years old on the old section and 12 years old on the new additions. It has never leaked from the screws. Never. We have had leaks in two places.....
....where the previous owner did not use flashing where the bedroom roof met the porch roof. We were able to put a fix on this by loosing the bedroom roof and sliding overly wide flashing under it.
....on the eaves edges where the previous owner did not treat the cut edges. The metal rotted out before we noticed the problem.

The past 15 years we have have lived with vog....volcanic acidic air, and acid rain. And for 3 months lived in the volcanic output of an active eruption, basicallyl super vog. Everything metal on our farm suffered, including the roof. Now that the volcano has shutdown and appears to be in a pause we plan to take the opportunity to replace the roof. What will we replace it with? The exact same system.

Why? First, we catch rainwater, so we need a safe surface to collect it from. Rubber, asphalt, and fiberglass are out. Aluminum and copper is expensive here, far beyond our budget. Clay, slate, etc are too heavy. Plus metal is readily available.

Why not the hidden seam roofing mentioned here? For one thing, it costs a lot more. That's an important issue. And we haven't seen a problem with the screwed down method. No, it doesn't leak at the screw heads. No, we haven't had to tighten down the screws every five years. No, we haven't had to apply roof tar to the screw heads. And we can install it ourselves, a major plus. We will save thousands of dollars using this roof type and doing it ourselves. Frankly, we don't have thousands of dollars to just give away to others.

If we keep our new roof clean, it should last us the rest of our lives, assuming a tree doesn't crash down onto the house. Most metal roofs rot out because leaves and debris are allowed to sit on the metal.

As someone pointed out, you can paint a metal roof. Treat any rust and paint the roof and it will last a lot longer than you thought it should.

Su Ba good to hear of the good news story about metal roofs.
One point, if you paint the roof, you may not ba able to drink the water from it.

We also have a screw-down corrugated metal roof, installed in parts starting about 8 years ago. The screws are even in the valleys so they can be cinched all the way down. We have had leaks but not at the screws (and we've been able to see and deal with them quickly because there's no insulation yet -- we're considering this advantage as we mull insulation options). We're about to replace a section that was done with inferior (ETA: too thin) metal early on. Once that's done we're finally going to coat the whole thing, so John Daley's point is well-timed. There's a good list of NSF-approved coatings for drinking water-quality collected rainwater here: http://info.nsf.org/Certified/Protocols/Listings.asp?TradeName=&Standard=P151. We'd prefer to find a safe product in tan or even gray rather than white so our home sticks out less in the desert.

John, if the correct roof paint is used, then the paint is allowed to season (2-4 weeks and 4 good rains), then there should be no problem. All metal roofs will leach a tad in acid rain. The idea is to use coatings with minimal toxic leachates. Sadly today, it's almost impossible to 100% avoid toxins (they are in our air, rain, food, clothing, etc), so I attempt to minimize them as best as is reasonable.

Su Ba wrote:John, if the correct roof paint is used, then the paint is allowed to season (2-4 weeks and 4 good rains), then there should be no problem. All metal roofs will leach a tad in acid rain. The idea is to use coatings with minimal toxic leachates. Sadly today, it's almost impossible to 100% avoid toxins (they are in our air, rain, food, clothing, etc), so I attempt to minimize them as best as is reasonable.

I find PermiDri Pond Coat usable. Its used in Koi ponds and other potable water solutions. Used it to build a wood aquarium. The fish did not die. Which is good they weren't my fish!

Note well;
Its not usual to screw corrugated roofing in the valleys, it may leak.

Its good news to hear about roof paint safe for drinking water.
In Australia we dont have acid rain issues, so that may be why the paint you speak of is not used here.
I will  research it

From; Australian roof paint for potable water

If you’re looking for a roof paint that looks better and lasts longer, then you want Dulux’s AcraTex Next Generation Roof Membrane.
AcraTex showcases three new advances in roof paint, and comes with the Deluxe guarantee.
Keep reading to find out more.

Our harsh Australian climate is not kind to roofs, but Dulux has created a paint to combat the extreme conditions our roofs need to withstand them.
AcraTex roof paint can help keep your home cool and comfortable as it provides maximum solar reflectance. The paint contains InfraCOOL technology and acts as a radiant heat barrier. It is also specially formulated with low-dirt pickup to maximise its solar reflecting properties.


For people who wish to use their roof for water run off to a concrete, steel or plastic tank for safe collection of potable drinking water, AcraTex paint has been specially formulated for this purpose.
AcraTex is suitable for various roofing surfaces including: concrete tiles, metal roofs, zincalume roofing and corrugated iron.
When painting you can apply a recoat on the same day which saves time and money. It’s also easy to clean up and has a low odour.

Nicole Alderman wrote:So, I have some Standing-Seam roofing panels left over from when my house got reroofed....do they need to have the special tools to install them? Where would I get those tools? I need to reroof my chicken house, and would like a light-weight roof for the nesting boxes. Should I just buy corrugated roofing, or see if I can get the standing seam to work without the special tools...

Hi Nicole,

Would you send me a picture of one of your panels? I'd be able to answer your question if I can see what style.  there are hidden fastener types out there that use clips and special tools -this is not the type I'd use....you can buy the type that screw down at Home Depo at the Pro Desk.  I'll send you a pic of one of my left over panels plus a pic of what my roof looks like

Su Ba wrote:The past 15 years we have have lived with vog....volcanic acidic air, and acid rain. And for 3 months lived in the volcanic output of an active eruption, basicallyl super vog. Everything metal on our farm suffered, including the roof. Now that the volcano has shutdown and appears to be in a pause we plan to take the opportunity to replace the roof. What will we replace it with? The exact same system.

Why not the hidden seam roofing mentioned here? For one thing, it costs a lot more. That's an important issue. And we haven't seen a problem with the screwed down method. No, it doesn't leak at the screw heads. No, we haven't had to tighten down the screws every five years. No, we haven't had to apply roof tar to the screw heads. And we can install it ourselves, a major plus. We will save thousands of dollars using this roof type and doing it ourselves. Frankly, we don't have thousands of dollars to just give away to others.

This is a great example of putting in the right system for the environment. Here in the Midwest, I would expect metal roofs to last much longer than 15 years, so I would expect exposed fasteners breaking down to the main point of failure for the roof. However, if the metal was going to be worn away in 15 years, then I probably wouldn't spend the extra money on hidden fasteners.

Also, I wonder if the consistent temperatures in Hawaii help to maintain the integrity of the plastic fasteners. Having a ~130 F  operating temperature range can't be good for plastics here in Indiana.

john mcginnis wrote:

Leslie Russell wrote: That stuff is a lifesaver around here. So far so good!
Oh, and I had to attach the new roof with the old one there at the peak. I thought I had it but when I saw it from the house I saw that hump... it only makes me crazy once in awhile 🙄

For a Coop that's pretty nice. What do you have under the tin? Metal roofs radiate heat too well and you don't want to cook your birds. Go the extra step and add a gutter at the lower end and catch all that run off and feed it to the birds.

I'm sorry, John, I wandered away from this forum and got engaged in sheet mulching...lol
Under the tin are foamcore insulation sheets with the foil on the outside facing up to radiate heat away. I really thought this through because heat is huge here. If it wasn't enough insulation I was prepared to insulate the walls too but I'd have to have a thin lumber sheet over the insulation because chickens LOVE Styrofoam. :\
It's always 10+ degrees cooler in there.

Looks you got it covered