I was asked the following question:
I am looking at samples of several roofing products. Two of them claim to be 26 gauge, but they feel very different. One is clearly lighter than the other. Can I use a micrometer to test the thickness and figure out which one really is 26 gauge? Is there a chart that would tell me the appropriate thickness for the 29, 26 and 24 gauge of roofing materials? Please review and advise. This is very important to me.
My response:
As long as you gauge a flat area of metal, sure you can check it with micrometers.
I have long been a proponent of the industry looking at steel roofing in terms of decimal thickness rather than gauge.
Too many games can be played with gauge in regards to tolerances, with paint, without paint, etc.
You can find charts referencing gauge and decimal thickness but as you will see there is a wide range of tolerance on decimal thickness for each gauge.
What is “oil canning” ? I was asked to sign a waiver if I installed a 24 ga smooth flat standing seam roof. Thanks
Comment by Andre Leamy — February 5, 2010 @ 10:26 am
Great question Andre. Thank you.
Oilcanning refers to ripples which can appear in the surface of the panels. Most common causes are inherent and unavoidable stresses in the shape of the metal, and imperfections in the flatness of the surface being installed on. Other causes can be improper panel formation and improper installation.
Requiring this disclaimer is not uncommon.
You may wish to ask the contractor if they have any options for ribs or striations in the panel which can help to mask the appearance of oilcanning.
Comment by toddmiller — February 5, 2010 @ 10:42 am
I currently have a shingle roofed one story house in full sun in North FL. I am NOT on the coast, about 8 miles from the GA line.
I have two different metal roofing quotes.
First Quote-24 guage galvalume w/ a kynar 500 painted finish, metal standing seam roof system with 1.5″ risers, 1″ expanded polystyrene foam insulation underlayment, concealed fasteners, boots and vented ridge. This quote is double the cost of a shingle roof.
Second Quote-26 guage Versa-Lock metal roof system over titanium underlayment. There is no polystyrene insulation. This quote is only about 25% higher than the shingle roof.
My questions–
How much does the guage of metal matter? Is 26 guage (a lighter metal) inadequate?
Also, how important is the poly insulation? Should I definitely get it or just add additional attic insulation?
I appreciate any help you can give me!!
Thanks
Teresa
Comment by Teresa Faulkenberry — September 14, 2010 @ 1:35 pm
These are good questions. I would suggest a concealed fastener panel and these both may be that. I would also suggest a quality coating such as Kynar 500.
Generally I am not real fond of foam beneath systems and would prefer to see attic ventilation and insulation on the attic floor but some construction does not allow for that.
I would look for what wind uplift ratings they have. Heavier gauge doe snot automatically mean better performance. Product design and installation have great bearing as well.
Comment by toddmiller — September 16, 2010 @ 6:36 am
Have you heard of metal roofing over existing asphalt shingles with airway in between for venting. Is this do-able and what is your thoughts on it? Thank you for your comments.
Comment by Benjamin — November 9, 2011 @ 11:50 pm
There are various ways to do this depending upon the particular metal roof being installed and depending upon construction methods. Generally, I see this as a way to increase energy efficiency and decrease the possibility of ice damming. It can also be helpful with avoiding condensation issues in certain cases.
Every job must be looked at individually to determine whether this is worth the cost. Additionally, some products such as the metal shingles have integral airspaces to act as a thermal break and help with energy efficiency. Energy efficiency is also boosted by coatings with reflective pigments.
If anyone wants to call me at 1-800-543-8938 ext 201 I am happy to discuss your exact roofing situation and make a recommendation as to what would be best for you.
Comment by toddmiller — November 10, 2011 @ 7:58 pm
I was on the site and decided to contact you to ask a question. I needed to know if you could advise me about the exact thickness of galvalume metal roofing metal as to how thick 26 gauge is with the substrate and painted process combined. Is the metal .018 normally before any substrate or paint has been applied and if so then what is the thickness after the paint and applications on the metal combined? I ordered some 40 year galvalume but it only showed .018 thick totally. I felt it should have been thicker due to the layered paint on 26 gauge metal which is supposed to be .018 thick without any additions to the bare metal? Let me know if you will. Best regards, Floyd Rogers 7317074249
P.S. Your secretary did not know what galvalume was when i asked about this.
Comment by Floyd Rogers — January 10, 2012 @ 10:42 am
Floyd, that is a great question. One of my frustrations with the steel industry is the lack of clarity surrounding this. I call it the “gauge game”. I have lobbied for years to now avail that steel begin to be referenced in decimal thickness like other metals rather than in gauge which has wide variances and can be subject to individual interpretation. Frankly, if today you are getting 26 gauge that is micing out at .018″ with paint, you’re doing well. In most cases, yes, gauge refers to the thickness with coatings. Thanks much for your question. All Best.
Comment by toddmiller — January 10, 2012 @ 10:52 am
Well, I see that you agree that metal at 26 gauge is .018 with coatings. I assume the coating must be microscopic then?
Comment by Floyd Rogers — January 26, 2012 @ 4:55 pm
Yes, in a typical Kynar 500 or Hylar 5000 coating, there will be a primer that is approximately 0.00015 to 0.00025″ thick and a top coat that ranges from 0.0007 to 0.0009″ thick.
Comment by toddmiller — January 26, 2012 @ 5:07 pm
I found this site that was very informative. It explains the U.S. standard for gauge and decimal equivalents for sheet steel, galvanized steel, aluminum, galvanized alloy coated, and of course the cold rolled. Sheet steel is .0188, galvanized is .022, aluminum is .0159, galvanized alloy is .0217, cold rolled is .0179 this being sheet and coil. Now, with the added substrate one may assume that .0188 sheet steel coated with zinc and aluminum should read at least .0217 with no layered protection to the bare metal. The increase in decimal should be greater than .0217. I just bought 26 gauge galvalume which read out to be .0185 at the dealer’s yard and this had been painted with a 40 year paint. I sent a sample to the supplier and had it checked for paint and thickness. The only reply i got in return from the supplier where i bought 1200 dollars worthof 40 year galalume was that the metal checked out to be .021. I replied for an answer to why they had advertised that their metal was 6 percent thicker than other competitors and not to mention how thick my layers of protection amounted to and I got no reply from C.S. Now, i am stuck with having to have the metal lab tested in order to know if i really got what i paid for. I do know that the same company offers a 10 year paint warranty, so other than having a lab test it how am i to know what i really got? I feel cheated now since i could not get an accurate reply or even a reply to their advertisement. Now, i wonder whom i can trust in the metal roofing selling business.
Comment by Floyd Rogers — January 26, 2012 @ 6:00 pm
http://www.pkmetal.com/PDF_formats/steel/sheet_coil.pdf
Comment by Floyd Rogers — January 26, 2012 @ 6:05 pm
I would like to add another site to show an advertisement from a metal supplier which is considered to be a very faithful and trustworthy company adhering to their worth or word. They state their metal is thicker than any competitors. Here is the site: http://www.metalcentral.com/
Comment by Floyd Rogers — January 26, 2012 @ 6:53 pm
Thanks. I cannot vouch for them but I will include your link.
Comment by toddmiller — January 26, 2012 @ 7:41 pm
Thanks Floyd. I agree that folks need to be truthful. And, as I have stated before, I truly wish the steel industry would switch toward decimal thickness rather than gauge. That said, there are variances coming out of the mills unfortunately. With the speeds at which metal is made, there will be variances even within an individual coil. Industry tolerances allow this because with current technology it is impossible. I will also say that in terms of metal roofing system performance, the following items are what I feel are most important, from most to least important:
Installation quality
Panel design (and adherence to that design)
Coating quality
Metal type
Metal thickness
Comment by toddmiller — January 26, 2012 @ 7:46 pm
Is it worth the trouble to install vertical lathing before horizontal lathing over deck?
Thanks!
Comment by Burhman — May 21, 2012 @ 8:07 am
It can significantly help to keep heat out of the attic. If you live in a very warm climate, I’d say it is worth it, particularly if the home does not have really good ventilation inside of the attic.
Comment by toddmiller — May 21, 2012 @ 8:24 am
Todd, we are so confused on all the metals out there. We live in Kentucky and we’d like to get a metal roof, but, very reluctant to rely on ppl here. Quotes are so very different from each. In our working life both my wife and I were buyers, so, needless to say we’ve quoted the material at several places and they too differ so.
We were told by our insurance company that we would need 37 squares. Some of the contractors told us we’d need to remove the two layers of composition shingles and some said just one layer (yet another told us when you remove the top layer you’re going to mess up the bottom layer, is this true?), while others said we don’t need to remove any, just place metal over it all. Then some said, doesn’t need fir’g strips while others said we do, and, we’ll need the felt as well……HELP PLEASE.
Do you know anyone in western Kentucky that we can trust to not who-do us? Or do you travel, lol?
Only companies locally are Lowes (they suggest ExSel Porta/Grace, Menards is ProRib and Coles is Mack Metal…all to be 29 ga but like Floyd, don’t know the thickness or which mfgr is better than the other???? HELP AGAIN PLZ
Comment by Paul Oglesby — July 12, 2012 @ 4:57 pm
Thanks for the note, Paul. It indeed can be very confusing. Also, metal roofing has grown so fast that all kinds of contractors, qualified and caring or not, have jumped on the band wagon. That is why I run this website … to try to deliver accurate information and be of help whenever I can.
As far as tear-off, I am generally a believer in going over old shingles when you can. I see it as increasing the home’s thermal mass for energy efficiency. It also saves our landfills and allows homeowners to spend their money on a better roof instead of labor to remove and dispose of their old one.
That said, the International Building Code calls for no more than two layers of roofing. If you’re in an area subject to building codes, this will be something you need to consider. Sometimes building inspectors have waived the two roof maximum to allow a metal roof to be installed over the old roof. The low weight of metal roofing encourages this.
Now, all that said, if you’re considering a through-fastened style of metal roof or one of the shingle-type metal roofs, they are very forgiving for going over the old shingles. Standing seam, though, I feel less good about as its appearance can be affected by an uneven surface being beneath it.
I have rarely known anyone to remove just one layer of a two layer roof. Its just isn’t worth the bother. If you’re up there removing shingles, you may as well remove both layers.
Your insurance company likely will want the old roof layers removed. Have you asked them about that?
As far as furring strips … very few metal roofs MUST be installed over furring strips. Some can be installed over them or direct to deck. And others must be installed direct to deck. So, much depends upon what type of metal roof you’re installing.
I know this is all confusing. I’d love to discuss it with you on the phone … 1-800-543-8938 ext 201
Now, interestingly, my company does have an operation in Kentucky. Whereas normally we are a manufacturer only and do not install roofs, we do have one “retail” operation and it’s based in Louisville. This operation sells and installs our metal roofs which can be seen at http://www.classicroof.com
The Kentucky operation is called Classic Metal Roofing of Kentuckiana. They cover the entire state and it is managed by Joe Knife who has been a member of our team for nearly 20 years. Their website is http://www.classicky.com
If you’d like to talk to Joe, feel free to contact him or call me. At the very least, he may have some ideas as far as who the better contractors are in your area.
Oh, one more thing … regardless of whether you remove the old shingles or keep them and regardless of battens or not, be sure to install a layer of underlayment prior to the roof. It is inexpensive but very wise and, to my interpretation, required by code.
Thanks so much.
As long as you have a well vented attic, though, I do not feel that furring strips add real value and fact is they can create a less secure roof.
Comment by toddmiller — July 12, 2012 @ 6:54 pm
I was is there a difference between a 24 and 26 gauge? I’m planning to nuy a new gauge and didn’t know what is the best gauge to buy.
Comment by roofing quotes — February 12, 2013 @ 9:41 pm
24 gauge should be heavier than 26. However, so many other factors go into determining quality — things like paint finish, product design and engineering (including things like concealed vs exposed fasteners, and uplift resistance), and proper installation. While metal thickness may be one consideration, it is not the only one and perhaps not even a real major one.
Comment by toddmiller — February 13, 2013 @ 5:32 am
Todd, We are about to have a 24 gauge metal roof installed on our home. Somemone told my wife they had a friend with a metal roof that had encountered problems with using their cell phone after it was installed. Have you heard of metal roofs being a problem for reception with cell phones?
Comment by Arthur Bleakley — February 18, 2013 @ 3:02 pm
On very rare occasion I have run into this. Think about it — we use our cell phones regularly in buildings with metal roofs. WalMart is a great example.
However, if the home is located in an area where reception is poor to begin with, yes, the metal roof could be the tipping point for a worse situation. I personally have never encountered it though.
I do understand there are boosters you can put in a building to help alleviate this if it does occur.
Comment by toddmiller — February 18, 2013 @ 3:07 pm
I have had my 10 x 26 corrugated roof blow of an outer building (it flew like a kite as it hit the house, lol). The adjuster figured 29 gauge corr. metal while all I see at the stores is 26 gauge. Is 26 gauge thicker than 29 gauge or what? Which is best or more costly? (10 ft panels)
Comment by Bob K — March 4, 2013 @ 10:32 pm
26 gauge is heavier than 29 and this will normally be more costly. However, other major factors include the quality / type of the base metal, the quality of coatings, and the level of skill of the installer.
Comment by toddmiller — March 5, 2013 @ 6:29 am
Hi Todd,
We are having a home built and want a metal roof. It’s a two story over a basement and garage. It is also sits up on a ridge. We are looking at 26 gauge, Kynar 500, standing seem with concealed clips/fasteners. The entire top floor is the master suite and has attic space over the back half, but a 9ft tray ceiling in the actual 24X18 bedroom area. We love the sound of rain and are wondering what the best method is, without sacrificing insulation or structual integrity.
Also, do you know any companies,suppiers and/or installers, in the Rockbridge County Virginia area (Lexington 24450), that you would trust to refer us to? We have received so much conflicting information, lack of specifics and pricing all over the place.
Thank you for your time and any information. Kathy
Comment by Kathy — March 5, 2013 @ 9:24 pm
Unfortunately today’s construction methods really do lessen the ability for sound to transmit. Eliminating insulation would be your best way to do that but that does put you at some risk of condensation in the attic and of course makes your home less energy efficiency. If you do go that route I would suggest making sure you have a good vapor barrier behind your drywall to prevent moisture migration from the living space into the attic. That will help avoid condensation.
Unfortunately i do not know any good installers in your area. There are some manufacturers near you who may have some good ideas. ATAS International, Fabral, and Englert all come to mind.
Thanks so much and good luck.
Comment by toddmiller — March 6, 2013 @ 5:12 am
Hi Todd, What is your opinion of Midwest Manufacturing steel roofing?
.018 nominal thickness after painting
G100 galvanized coating plus zinc phosphate
Lifetime paint film integrity warranty
My hubby thought we needed 24 guage but it sounds like the most important thing is installation and we do have a great installer. Is this good enough for our IL home? Thanks
Comment by Diane — April 6, 2013 @ 6:42 pm
Diane, proper installation is critical. I would need to know which Midwest panel you’re looking at in order to yield an opinion. I am a fan of concealed fastened products and also PVDF (Kynar) coatings. I believe Midwest uses a super polyester coating which is a good finish as well — not as good as Kynar but still better than other available coatings.
Comment by toddmiller — April 6, 2013 @ 9:46 pm
I came across your site while looking for information on ga. thickness. I was pleased to fine there is someone who feels strongly that metal roofing/siding should be advertised as a decimal thickness.We have been in the business of selling metal roofing for years and we [my son and I] are constantly frustrated by having to explain why the 3 brands we sell are “thicker” than several competitors in the area. On the other hand many people do not take time to research and check out crosscut samples from an actual panel and they will say that all metal roofing is the same.We have always stressed quality by only selling those companies with guality thickness, paint systems and excellent trim among other things. Is there anything we can do to influence the industry to change to a decimal measure?It would benefit the seller of top quality metal and the customers. Thanks, Kelvin @ KP Steel
Comment by Kelvin Phillips — April 19, 2013 @ 8:32 am
Kevin, great to hear from you. I wish I knew how to change this in the industry … I have tried but never gotten very far. Many people like to hide behind the gauge game.
Comment by toddmiller — April 19, 2013 @ 8:35 am