Metal roofs - what questions should i ask?


#1

Hi Everyone,

I am needing to replace my shingle roof - we are considering metal this time around - we live in the west central florida area.
Can anyone tell me what questions I should be asking?
What should I be looking for a quality material and installation?
Should the existing shingles be removed?
Is there supposed to be a felt (or something else) liner before the metal is put on?
Metal roofing is totally new to me.
Any other comments or suggestions?

Thanks
Val :smiley:


#2

There are so many questions you would be wise to ask, and there are a few I want to ask you. First of all, is this for a residence or a business? What is your money situation, and how long do you want the roof to last? For example, I would recommend a zinc metal roof, but I don’t know anyone who can afford zinc. Next would be copper or lead-coated copper, but it too is going to be very expensive. So, for the sake of this post I am going to assume you are looking at installing metal on a residence that has 6:12 - 8:12 sloped roofs. Now, before you settle on metal you should realize that if you are in an area that gets much hail that your roof is going to get all dinged up; but lets continue. The first things you should consider are the types of metal and thickness/gauge. Your two basic metal roofing panels will likely be either galvanized/Galvalume or aluminum. If you go with either of those you need to make sure they have a 20-year baked on enamel finish (like Kynar). Of the two, the galvanized is generally more common and is easier to work with. Next, you need to decide on a thickness. The standard is 24 gauge, but you can also get panels in the thicker 22 gauge.

Now lets continue with your location. You are in West Central Florida, so I suspect that means you are susceptible to hurricanes and high straight-line winds. So, you need to make sure any metal roof system complies with the local codes, which probably requires the system to meet FM I-120 for wind-loss prevention. You may also want to review your roof deck to ensure it is able to withstand high winds, i.e., utilizes hurricane straps, etc. Next, since metal roofs DO tend to leak for various reasons, you will want to either have your roof deck covered entirely with an ice & water shield product (such as Tamko’s TW Metal and Tile) or two layers of 30# asphalt saturated felt underlayment. As an added precaution, I would also recommend installation of a felt underlayment beneath the metal and overtop of the ice & water shield, especially if you use one of the ice & water shields that have the exposed rubberized asphalt along the edge. Reason being, the gummy edge of the membrane will stick to the bottom of the metal panels, and when the panels expand and contract they will make a popping sound that will be loud and irritating to you inside. Unless you end up using copper, do not let the contractor install red rosin paper as a slip sheet since it retains moisture.

The next thing you need to decide upon is if you want to hire a contractor that will custom make your roof panels in their shop, or will buy pre-manufactured panels. How long is the longest panel run? It will make a difference with regard to expansion and contraction of the panels. Also, how many penetrations do you have in the roof? I’ve seen a lot of metal roof applications that were fine except for flashings around soil stacks and exhaust fans.

Anyway, since there are too many things to consider, here are the questions I would ask a contractor suggesting or bidding you a metal roof project:

  1. What type of metal are the panels?

  2. What is the gauge or thickness?

  3. Is it a pre-manufactured system, and if so what is the FM rating for wind-uplift (you want at least FM I-90, if not FM I-120)?

  4. What kind of underlayment will be used (ice & water shield is best, 2 layers of 30# felt would be the only other alternate I would accept)?

  5. How do they plan on flashing curbs, soil stacks, chimney’s, etc.? You will need to come back with their answer, but I can tell you Dektite makes a nice flashing for soil stacks.

  6. What kind of seems will be used?

  7. How will the panels be secured to the roof deck, i.e., hidden clips (good) or screws through the panels (not as good)?

And then if you want to find out if the contractor even has a clue, ask him if they are going to fix the ridge or float the ridge? In a metal installation either the ridge or eave has to be “fixed,” and then the other has to be “floated.”

Anyway, find out what you can, and then come back with your next round of questions if you like.

I’m also sure that I have missed a few things that others here will suggest, but that is why it is good to have several people’s opinions at once.


#3

hi val,
im in st pete and will be happy to help.
ill get rite to what ive come to learn.
the only thing that stays on in when the hurricane comes is the 5 v crimp
panel with a ton of screws in it.
when i worked in the hurricane zones ( punta gorda , vero beach, homestead) were there were houses, theese were the only roofs that
stayed on.
if your close enough i can take a look.
eme at roofsbygweedo@ij.net

gweedo.l


#4

Metal roofs that are properly installed WILL NOT LEAK!!! We install metal roofs w/ 20+year leak free warranties. All of the underlayment previously mentioned is not necessarily needed to prevent leakage. There is no need for the expense of ice and water shield under a properly installed metal roof. I can see using a good felt paper for several reasons but not ice and water shield. If you spend the money on metal don’t settle for less than an fm 120 wind rating and a 20 leak free warranty that covers both material and labor.


#5

I beg to differ, but I’ve seen too many metal roofs that do leak. I love how everyone here says “if the system is properly installed it won’t leak,” which can be said about any roof for the most part. Problem is, there is the human factor when dealing with roof installations, and sometimes there are other elements that can not be foreseen. For example, if you have a building that has negative pressure, water can actually be sucked into the building around vents, wall joints, etc. You also have to deal with wind-driven rain, which I’ve seen cause roof penetrations, standing seams, and ridges leak in metal roofs. There are also some poorly designed systems. I recently dealt with a school system near Houston that was suing a metal manufacturer because several of the manufacturer’s metal roof systems leaked. The case was settled out of court, and the manufacturer agreed to remove a large portion of the metal panels, install additional layers of 30# felt, and then replace the metal valleys that were rusting from the underside, before re-installing the metal panels.

I have another client that has several buildings with the BulterRib roof on them, and he is constantly having people go out to repair the roofs. So, don’t believe anyone that trys to tell you that metal roofs don’t leak, because it is just not true. That would be like me telling you that EPDM roofs don’t lead “if installed properly.” That would be a true statement, but in all likelihood someone will poke a hole in the membrane or something else will cause it to leak in the next 15 years. Same with metal, there are many things that can cause a metal roof to leak, and your best protection is either a layer of ice & water shield or two layers of 30# felt. The reason most designers prefer ice & water shield to felt is because it will generally seal around any penetrations. Remember, when you install screws or nails to fasten the panels in place the underlayment is being punctured.

The only other advice I will leave you with is this: If you decide to have RoofingProFrank or someone similar install your metal roof without the proper underlayment, demand not only a 20-year leak-free warranty, but make sure it is an NDL (no dollar limit) warranty. Also, make sure the warranty covers damage to the building contents and losses, or make sure you are well insured if you have valuables in the building like computers, etc. Like I said before, you also want to make sure the roof has an FM rating of at least I-90, and depending on your location you may need an FM I-120 rated system. Also, you want the contractor to not only comply with the roofing panel manufacturer’s recommendations and requirements, you will also want them to comply with SMACNA.

Now, I will agree with RoofingProFrank that ice & water shield will increase the price of the job. I highly recommend the ice & water shield as a consultant, but if you can’t afford it over the entire roof then I would suggest the following. Install ice & water shield centered over any valleys in the roof, and target patches around roof penetrations such as soil stacks. Install 2, yes two, layers of 30# felt underlayment with side laps that are staggered. Then install the metal roof system in accordance with the manufacturer’s specifications. I would recommend that the contractor install a cleat along the eave edge of roof, and fasten the panels along the ridge. Roofing contractors will know what you mean if you tell them to float the eave and fix the ridge. Assuming you are using a variation of a standing-seam system, you will then want the contractor to install Z-flashings along both sides of ridge, and seal the flashings with a high-quality sealant. Install a metal ridge cap along the ridge, with the cap attached to the Z-flashings on both sides of ridgeline.

With regard to type of system, I would recommend that you use a system that utilizes a mechanically hemmed standing seam, especially a double-locked seam. There are several other options, but when choosing it would be prudent to select a high standing seam to help prevent moisture intrusion. Once again, a mechanically hemmed seam or soldered seam is best, but the attached sites gives you some other options:

mbci.com/mbci/docs/catalog/2 … Panels.pdf

berridge.com/zeelock.htm

Here is the SMACNA link also:

smacna.org/


#6

thats a little elaborate, cerberus.
all i know is metal panels with a ton of screws in em (stainless),
is the toughest thing out there on slopes.
torchdown on anythig under 3/12/p.
i dont care what ya put under em.
i dont roof under my roof.

gweedo.


#7

lol cerberus definetly has typing skills :wink:


#8

Come on now Q, give me a break! :wink:

You realize, when I’m not on roofs inspecting installation or performing surveys, I’m in the office typing up reports or specs on my laptop.

As for gweedo’s comment about roofing under his roof. It should also be noted that as a consultant I’m going to specify a top-notch system that is guaranteed to last and perform. I’ve spoken to some about things they can do to reduce the price of a job, because I realize that not everyone can afford a top of the line roof. Still, I stand by my previous remarks about adding ice & water shield beneath metal. It is the way to go, but if you can’t afford to do that the alternative would be to install 2 layers of 30# felt. The added cost of the extra layer of felt is well worth it when compared to trouble-shooting a leaky roof and possibly removing and re-installing metal panels.

Also guys, I don’t know how many of you have run across a consultant before, but those of you that have should know that I’m going to recommend things be done correctly and I’m going to recommend added measures to ensure a top-quality roof. It should also be noted that unlike most consultants that are book educated, I actually installed roofing for over 10-years before becoming a consultant. That can be a blessing and a curse to contractors I work with, as I will cut them slack on things that you have to deal with in the real world, but it is also hard to b.s. me. :mrgreen:


#9

It sounds to me like if you hire Cerberus to install your roof don’t go with metal. Because he is telling you in advance that he guarantees the metal roof he installs will leak your better off going with just the ice and water shield and not the metal. At least then the screws won’t penetrate the roof that he’s counting keeping you dry. I can tell you horror stories about every type of roofing system that has age on it. As far as mbci metal there is no better metal in my opinion. My company is a master contractor with mbci. Also a good customer of ours Walmart/Samsclub tested metal roofs years ago and they are currently installing mbci metal roofs which are put on to mbci’s specs. In fact thier inspector is on site during the entire installation. And not mention the engineer that Walmart hired is on site at least once a week and guess what were not using ice and water shield and thier still getting a 20year leak free warranty on both labor and materials with no limit. If it leaks we’ll fix it no questions.


#10

I agree that MBCI is the way to go. Now, ask your MBCI rep if he thinks ice & water shield beneath the system is a better way to go. He would be a fool if he says no. Once again, I realize that ice & water shield is an added expense that some can’t afford, but it is the classic case of belt-and-suspenders. One of the school districts here use to not go with the ice & water shield, and now they do after having multiple problems with several of their metal roofs.

As for me putting on leaky roofs? Nope, doesn’t happen, but then again I’ve been out of the contractor end for around 15 years. I will say that I have helped several people out with their leaky metal roofs, i.e., Washington Tennis Center (Washington, D.C.), Metal Container Plant (Newburgh, New York), Anheuser-Busch (Houston, Texas), just to name a few.

Trust me Frank, I know my roofing! I’ve worked on JFK Airport, Miami Beach Convention Center, Chicago Fire Stations, Anheuser-Busch (Newark, Williamsburg, Houston), Children’s Hospital Philadelphia, etc. The largest roofing job I worked on was as a foreman for a roofing contractor, and we put the roof on the Nissan Truck Manufacturing Plant in Smyrna, Tennessee. The entire project was 36,000 squares, and yes I mean 3.6 million square feet of 4-ply coal tar pitch on two layers of fiberglass insulation and slag surfaced. Hey, you may not agree with things I say from time to time, but trust me when I say I’m pretty well versed in roofing. There are some systems that aren’t my strong suit, but I really know BUR, EPDM, Mod Bit, and Metal well.

Don’t worry, I expect people to disagree with me from time to time. But I’ll tell you one thing, I’d put my workmanship on a roof up against anyone. That is not to say your system will leak and mine won’t, I’m sure you put on a nice roof yourself.


#11

i think its obvious, the amount of knowledge one cerberus holds.
i think all of us are impressed and maybe somewhat jealous.
so an occasional wise crack is in order.

gweedo.


#12

It comes with age my man! Heck, I’m 45 years old and have been around the block a few times. I’d gladly trade some experience and knowledge if I could turn back the hands of time. Plus, as a consultant I have a library of manuals that I have studied over the years. I don’t look at them as much as I used to, but I still reference them frequently.


#13

When I worked for a union comapny a few years ago we installed 2 layers one inch iso vapor barrier underneath that osb screwed in ice and water shield on top of that and then metal deck. This was installed on a middle school.


#14

[quote=“Cerberus”]I agree that MBCI is the way to go. Now, ask your MBCI rep if he thinks ice & water shield beneath the system is a better way to go. He would be a fool if he says no. Once again, I realize that ice & water shield is an added expense that some can’t afford, but it is the classic case of belt-and-suspenders. One of the school districts here use to not go with the ice & water shield, and now they do after having multiple problems with several of their metal roofs.

As for me putting on leaky roofs? Nope, doesn’t happen, but then again I’ve been out of the contractor end for around 15 years. I will say that I have helped several people out with their leaky metal roofs, i.e., Washington Tennis Center (Washington, D.C.), Metal Container Plant (Newburgh, New York), Anheuser-Busch (Houston, Texas), just to name a few.

Trust me Frank, I know my roofing! I’ve worked on JFK Airport, Miami Beach Convention Center, Chicago Fire Stations, Anheuser-Busch (Newark, Williamsburg, Houston), Children’s Hospital Philadelphia, etc. The largest roofing job I worked on was as a foreman for a roofing contractor, and we put the roof on the Nissan Truck Manufacturing Plant in Smyrna, Tennessee. The entire project was 36,000 squares, and yes I mean 3.6 million square feet of 4-ply coal tar pitch on two layers of fiberglass insulation and slag surfaced. Hey, you may not agree with things I say from time to time, but trust me when I say I’m pretty well versed in roofing. There are some systems that aren’t my strong suit, but I really know BUR, EPDM, Mod Bit, and Metal well.

Don’t worry, I expect people to disagree with me from time to time. But I’ll tell you one thing, I’d put my workmanship on a roof up against anyone. That is not to say your system will leak and mine won’t, I’m sure you put on a nice roof yourself.[/quote]

I asked the rep he said if a customer is installing a mbci roof and it’s installed properly there is no need for ice/water shield(“it’s an uneeded added expense it would be like changing your engine oil every 1000 miles.”) . If it were needed it would required and in the spec book. They would then manufacture there own ice and water shield. If the contractor can’t put on the system without it leaking then they shouldn’t be roofing. We have put on thousands of squares of metal without ice and water shield and none of them leak(even on flat).


#15

I realized after I told you to go ask the rep, what he would say. Of course, he isn’t going to recommend ice & water shield, because that would be like saying his product is prone to leaking. With that said, I’ve never had an MBCI rep tell me the ice & water shield installed beneath their roof system was not needed and was just an added expense. Also, why do you suppose Tamko makes an ice & water shield product called TW Tile and Metal?

Anyway, I’m glad that you’ve never ever had any of your roofs leak in the past 20 years. I don’t know where you are located, maybe Arizona or Nevada? I guess it all depends on where you live, but here in Houston where we get rain like you’ve never seen, along with straight-line winds, if you don’t install ice & water shield beneath your metal system you are asking for trouble. It is the industry standard here, not the exception.


#16

Cerberus, Have you ever considered running for a political office. i have served on the local school board and I am currently on several commitees. The way some of those guys talk and fanigle words, that’s what you remind me of.LOL
Anyways ice and water shield is a good selling point for a contractor because it means more money and less chance of it leaking and for the customer it’s like supplemental insurance you pay for it and may or may not need it. I understand that if all your doing is consulting then you almost have to over recommend because you are not the one personnely installing the roofing system that you’ve recommended. So to cover yourself and your reputation you are most likely going to recommend something that. We have an office in Norht East Ohio and in Florida so we deal with the same weather you do. Any company that cares to can put on roofs that don’t leak. Every company has leaks or problems at one time or another. All I am saying is that for us it’s not major problem. When our company was started it was 2 guys working out of a pickup. Now we employ over a hundred roofers that share the same vision I do. When we bid a pitched metal roof there would be several options including using ice and water shield around the perimeter or even the entire roof. However, we will always explain to the customer that we can install the roof without the ice and water shield and still make it watertight. We provide every customer with several options no matter what. We currently have a traveling crew that is doing tear off shingle roofs on a certain denomination of churches with buildings that are 12/12 or steeper. The specs are 2 layers of ice and water shield in the valleys. With tar paper over lapping the ice/watershield then that being stripped in w/ ice/water shield, then copper valley metal over top with no punctures within 12" of eithier side of the center of the valley. There is a 2 sided seam tape that runs along the valley on each side to secure the shingles to the copper. You and I both know that all that is overkill and any good roofer can keep it fron leaking with just onel ayer of ice/water shield then the metal but, the customers chose that system with those specs and that’s what there getting.


#17

Cerberus, Have you ever considered running for a political office. i have served on the local school board and I am currently on several commitees. The way some of those guys talk and fanigle words, that’s what you remind me of.LOL
Anyways ice and water shield is a good selling point for a contractor because it means more money and less chance of it leaking and for the customer it’s like supplemental insurance you pay for it and may or may not need it. I understand that if all your doing is consulting then you almost have to over recommend because you are not the one personnely installing the roofing system that you’ve recommended. So to cover yourself and your reputation you are most likely going to recommend something that. We have an office in Norht East Ohio and in Florida so we deal with the same weather you do. Any company that cares to can put on roofs that don’t leak. Every company has leaks or problems at one time or another. All I am saying is that for us it’s not major problem. When our company was started it was 2 guys working out of a pickup. Now we employ over a hundred roofers that share the same vision I do. When we bid a pitched metal roof there would be several options including using ice and water shield around the perimeter or even the entire roof. However, we will always explain to the customer that we can install the roof without the ice and water shield and still make it watertight. We provide every customer with several options no matter what. We currently have a traveling crew that is doing tear off shingle roofs on a certain denomination of churches with buildings that are 12/12 or steeper. The specs are 2 layers of ice and water shield in the valleys. With tar paper over lapping the ice/watershield then that being stripped in w/ ice/water shield, then copper valley metal over top with no punctures within 12" of eithier side of the center of the valley. There is a 2 sided seam tape that runs along the valley on each side to secure the shingles to the copper. You and I both know that all that is overkill and any good roofer can keep it fron leaking with just onel ayer of ice/water shield then the metal but, the customers chose that system with those specs and that’s what there getting.


#18

You are correct in that I will only specify a roof I have the utmost confidence won’t leak. Is ice & water shield an unnecessary expense? It could be if you have a perfect installation and the weather conditions don’t ever expose any deficiencies in workmanship. However, with many of the clients I deal with leaks are unacceptable, so we design a roof that won’t leak, and if it does it won’t leak inside. For example, if you put a metal roof over the Anheuser-Busch control room for their brewery, which is all computerized, wouldn’t you feel better using ice & water shield? Afterall, one leak over their computerized brewing equipment could cost them and you hundreds of thousands of dollars. One of the most recent MBCI jobs I dealt with used Tamko’s TW Tile and Metal underlayment, it was the field house for one of the local school districts. The field house has an indoor swimming pool, basketball courts with hardwoods flooring, and offices. Needless to say, if the roof were to leak onto the basketball floors over a weekend or the summer break, the cost of the ice & water shield would be nothing compared to the cost of a new hardwood basketball court. Also, it should be noted that the ice & water shield provided the general contractor a temporarily dried-in roof that allowed them to work on the interior while the roofing was being installed.

Now, with that all said, yes I too have installed metal roofs without ice & water shield. And I like you, don’t like leaks. In fact, I can’t remember any of my roofs ever leaking because of workmanship, but I’ve had my share caused by other trades. In fact, I think the worst leaks on any of my roofs was the EPDM roof I installed on FedEx’s corporate HQ in Memphis. Every now and then someone would puncture the roof membrane, and it always seemed to be over their computer room. They used to complain because it was a 4-hour drive to the job from middle-TN, I’d find the leak in about 30 minutes and have it fixed, and then drive back to middle-TN. So, FedEx would get a bill for 8.5 hours to fix a leak caused by others, but what really pissed them off was the $50,000 worth of Halon gas that would discharge when there was a leak in the computer room. Talk about your expensive roof leaks. Obviously, it goes without saying they were foolish to install an EPDM roof on that particular building, and I suspect by now they got a completely different roof since we’re talking over 20-years ago.


#19

Hi!

I have an existing 10-year-old shingle roof that had wind damages. A few plywood pieces buckled so there are waves on the roof but there are no leaks…yet.

I want to know if I can put a metal roof on top of the existing roof – without taking the old shingles off. The roof contractors I talked to said that they will put 2x4 posts on the existing roof then attach the metal on top.

Is this a good way to go? Will this roof be too heavy? What kind of metal do I need to get? What kind of screws, etc.


#20

I would not recommend putting a metal roof system overtop of your existing shingle roof system. First of all, there is the weight issue like you mentioned. Second, if the metal roof were to leak, you might not know about it because of the shingles, and that might lead to unseen damage. Third, if the metal roof ever does leak, the entrapped moisture may promote mold. Fourth, you would create a dead-air space between the two roof systems that likely would not be addressed with the ventilation…Just go ahead and have the shingles removed, and then have a metal roof properly installed.