metal valley..appropriate or risky on 3/12 pitch?

Discussion in 'Roofing and Siding' started by bill's quest, Aug 10, 2009.

  1. Aug 10, 2009 #1

    bill's quest

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    I expect to be meeting with the "supervisor" of the roofing job, and I would find it helpful to judge an earlier comment by him. As some may know...(i've posted enough lately) my roof is three over twelve. The supervisor talked me out of my request for metal valleys. I wanted them because on the last installation I saw a lot of organic debris gather in the valley and how easily it worked its way under the shingles. Even though this would be an add on to the job which I was willing to pay the supervisor insisted that valleys on a low pitch roof was a bad idea....despite that there was going to be ice and water shield underneath it. He said that he felt certain that within three years I would have a leak because of water working its way underneath the shingles and that I would have water dripping through my windows. Maybe I heard him wrong...but I gave in thinking that maybe his crew did not have the expertise in metal valleys and that I should not force this. I was under the impression that metal vallyes are fine if they are done right. Another possibility is that he did not have the correct metal on hand (which was true) and that this would upset his schedule.

    Was the supervisor's position to reasonable? If not, I feel more careful to question his creditability in the future.
     
  2. Aug 10, 2009 #2

    inspectorD

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    Metal valley's are always better than any others "if " they are installed correctly.This is for the northeast.
    They need a bend at the edges and in the center so the water will not wash up the other side in heavy rains or Ice backups. Google metal valley.
    Ice and water is the best thing for a roof since sliced bread. So even if water did get under the metal while freeze ups occur or heavy rain, it will not get past the Ice and water shield.
    I recommend copper as the other metals will deteriorate quicker.

    Always read up on as much material you can before getting any work done, or hire another professional to keep them honest and look at thier work.
     
  3. Aug 10, 2009 #3

    bill's quest

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    fwiw..i did a lot of the homework on the internet...and knew many of the features for how a metal should be done...but I admit they wore me out on their resistance at the very last minute when the roof was scheduled and i neglected this resource...but it is still not too late for negotiations..I have not paid them


    just to be sure....in the real world...as this contractor would say...how sure are you that a metal valley is appropriate for a low pitch roof....?
     
  4. Aug 10, 2009 #4

    CraigFL

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    Last edited: Aug 10, 2009
  5. Aug 10, 2009 #5

    bill's quest

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    craigfl,

    Not a good sign, could not register to log in...many many attempts....i assume that there is not a post there already dealing with my question....and that I would have to initiate the question
     
  6. Aug 10, 2009 #6

    CraigFL

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    Try the new link...

    Sorry for the bad one.
     
  7. Aug 11, 2009 #7

    Nestor_Kelebay

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    CraigFL:

    The poster is concerned about how the valleys of his roof are done. He wants galvanized metal bent to fit the valleys of his roof before the shingles are put on. Your link is to a web site about metal roofing. That would include roofs that have metal shingles and "copper roofs" that are typically only installed on the most expensive of homes.

    Bill's Quest:

    I'm no expert on roofing, but I did act as the "general contractor" when my sister's house needed new shingles. (Basically, the family relied on me to make all the decisions on what to do, and the Bank of Dad paid for it.) That's because it's not really possible to hang around DIY Q&A forums for years and not learn a little bit about everything, including shingle roofs. I haven't responded because I was hoping a roofer would be answering your questions, and a roofing contractor would know vastly more than I.

    I think you may be forming an opinion on metal flashing based on insufficient or incorrect information. Where I live, roofing contractors don't use galvanized metal in the valleys hardly at all anymore.

    Standard practice years ago was to cover the valley with tar paper, nail your galvanized metal down and shingle up to the valley from both sides, typically leaving a 2 inch gap or so between the shingles. The problem with this system is that if leaves and stuff accumulate in the valley, the compost that forms up there can plug up the valley so that water ends up flowing laterally sideways under the shingles. You have to remember that the galvanized metal is typically only 16 inches wide, and water will flow laterally 8 inches under the shingles. And if the water sits on the tar paper too long, it can start to leak through it.

    The other problem with the galvanized valley is that if water gets between the shingles and the galvanized metal, and subsequently freezes, it's going to expand. Since the roof is covered by tarpaper when you shingle, and most roofers use pneumatic nailers, they can neither see what they're nailing into, nor can they get any "feel" from the pneumatic nailer that the nail is driven solidly home like you can from a hammer. So, if it just so happens that they put a nail right into an old nail hole, they have no way of knowing that they've just created a potential roof leak.

    If water gets under the shingles there, and expands, it's going to push the shingle up and pull the nail outward a tad. That nail hole will then leak water if water gets under that shingle again.

    Nowadays, what they do is put ice and water shield down in the valley first. (I don't know if they put tar paper over the ice and water shield or not, but it's irrelevent to the discussion.) That ice and water shield is a sticky bitumen strip 36 or 42 inches wide, so it extends a lot further from the valley than galvanized metal would. So, the liklihood of water spreading out under the shingles as far as the tar paper is very much less.

    Also, the bitumen is a soft material and on a hot day it becomse a very viscous liquid and flows around things like nails to seal off nail holes from leaking water. So, if the same thing happens, the bitumen ice and water shield will seal up around that nail on the next swelteringly hot day to plug that leaking hole.

    Basically, if your roofer installed your roof the way it's being done in Winnipeg now, your roof valleys are more waterproof than they would be with galvanized metal in them.

    My feeling is that your roofer simply didn't understand why using ice and water shield made for a more waterproof valley than galvanized metal, but was aware that it did. He certainly didn't want to say: "Yeah, but then there's a much better chance your roof will leak." cuz then you'd be losing sleep. But, he was probably aware that they way they're doing it now is better, but didn't understand why.

    PS:
    Don't go there. You need to know about something called a "builder's lien". If someone does work on your house, and doesn't get paid in full afterward, they can put a lien against your house. That means that if you ever sell your house, the buyer's lawyer will check to see if there are any liens against the house. If so, then the person holding the lien is legally entitled to get paid before you get what's left of the purchase price. So, refusing to pay or haggling with your contractor over price is not a great idea. If you both dig in your heels, and you end up with a lien on your house, then he's gonna get paid eventually anyhow. And, there could be interest accruing on that lien, so it could end up costing you a lot more than it will to pay up now.

    Whenever I have a tenant moving out on me because they've bought a house, the chances double that they're gonna skip out on me without paying the last month's rent and not lift a finger to clean before leaving. They think that once they're in their own house, I can't do squat. It's only when they find out I've put a lien on their house that's accumulating interest that they realize I have them over a barrel. Every experienced contractor worth his salt will know his way around the law courts building in your town just like every experienced landlord will.
     
    Last edited: Aug 11, 2009
  8. Aug 11, 2009 #8

    oldognewtrick

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    Bill, Nestor and InspectorD have hit most of the points on a metal valley. In my opinion either a closed valley or a metal valley will be a functional option IF installed correctly. Either one can fail if not properly installed. Metal valleys should NEVER, I mean NEVER be nailed directly into the valley material. When we form a valley pan "W" we turn the outside edge back onto itself and use a clip to secure the edge. Galvanized is not a suitable material option for valleys, at a minimum a painted galvalume with a Kynar finish and a 3" head lap.

    Closed valleys with ice and water will last the life of your shingle. The big things about valleys are what we call "tipping" the valley shingles. This means cutting the point of the shingle under the coarse that is visible. This stops water and debris from catching the top edge and running across the course, damming debris and causing a potential leak. This should be done on shingles and in a metal valley.

    When metal valleys are installed in a shingle roof you have a material that will generate a lot of heat, I have seen ice and water become runny and ooze at the fascia. There is a similar product made by Tamko "Metal and Tile" underlayment that will withstand the heat generated by metal valleys. Certainteed also make a high temp SA underlayment.
     
  9. Aug 11, 2009 #9

    Nestor_Kelebay

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    Olddog/Newtrick:

    You seem to be very knowledgeable about roofing, so I was hoping you could explain some things in your post:

    1.
    Is this done to accomodate thermal expansion of the metal valley. That is, the "U" shaped edge of the metal valley can slide up and down inside that clip. Do the clips stick up much so that stepping on a clip would damage the shingle? I worked out that for a -40 deg. C to +40 deg. C temperature change from summer to winter, you can expect to see a change in length of 3/16ths of an inch in a 15 foot long valley.

    2.
    This was the first time I've heard of "galvalume" and Kynar, so I googled them to find out what they were:

    www.mcelroymetal.com/elements/files/MM620option.pdf
    Galvalume is similar to galvanized sheet metal, except that instead of having a pure zinc coating on both sides of the steel, galvalume has a coating that's about 55% aluminum, 43.5 percent zinc and 1.5 percent silicone. Apparantly, this alloy is more durable than pure zinc on steel, so galvalume coatings protect the steel much longer than the zinc coatings on galvanized steel.

    Kynar 500 paint
    Kynar Homepage
    Kynar 500 is a high end paint that's used on metals to protect the surface of the metal to exposure to the elements. It uses a binder that's made from a plastic called "polyvinylidene flouride", and can be purchased in spray cans and in pint, quart and gallon size paint cans. "Polyvinylidene flouride" or PVDF is a cross breed between polyethylene and teflon cuz it looks like:

    ...|
    H-C-H
    ...|
    F-C-F
    ...|
    H-C-H
    ...|
    F-C-F
    ...|
    H-C-H
    ...|
    F-C-F
    ...|
    H-C-H
    ...|
    F-C-F
    ...|

    (pardon the periods)

    If all the flourine atoms were hydrogen atoms, it would be polyethylene. If all the hydrogen atoms were flourine atoms, it would be teflon.

    I'm presuming that a "3 inch head lap" simply means that each galvalume "W" shaped valley overlaps the one below it by 3 inches.

    So, what we have is galvanized steel on steroids coated with paint on steroids.

    Why would you call this a "minimum"? This galvalume sheet metal coated with Kynar 500 paint is what's used for the metal cladding on buildings and is super durable to exposure to weather. I'm thinking the only two metals that would outlast this would be stainless steel and copper.
    So, why wouldn't ordinary galvanized steel be the "minimum" protection you can have in a shingle roof valley, bare galvalume a step up, and galvalume painted with Kynar 500, another step up, and then copper and stainless steel? I'm learning that galvalume painted with Kynar 500 is already a Cadillac flashing to have on a shingle roof, so I'm curious about your claiming it's the "minimum" you need.

    3.
    I found almost nothing about this "tipping" on Google. Is it also called something else, and can you link to a web site that explains how the shingles are cut at the valley and why cutting them that way is beneficial?
     
    Last edited: Aug 11, 2009
  10. Aug 11, 2009 #10

    oldognewtrick

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    Nestor,you don't have holes in the valley pan when you use a clip. A clip is merely a piece of valley metal that we cut about 1 inch wide and 3 inches long, you make a bend at the end of the strip and hook it over the edge of the valley pan, then you nail the clip to the roof deck. This will allow for thermal expansion, leave no penetrations in the valley material and will lay flat under the shingles. The valley pans are overlapped and not secured out in the open area. Securing them will pop the joints. I see people try and solder copper valley lap joints and the solder joints will pop under thermal expansion. If you pop rivet them pop rivets will also fail.

    By using a painted metal for a valley pan you create a flashing that will last longer than the shingles. Remember galvanized garbage cans? You don't see them much anymore because they rust. Galvanized gutters will last a long time, IF they are coated inside and out with a red oxide primmer and painted. When you get into your heavy weight or lifetime shingles, the MFG require non-corrosive flashings. This is so that the flashings out preform the roof system they are protecting.

    3" head laps are pretty much standard on any of your hard surface roofing installation specs.

    As far as tipping valleys let me see what I can come up with.
     
  11. Aug 11, 2009 #11

    oldognewtrick

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    If you go to gaf.com and click on the residential section, on the left side click on Installation Guide and Video. Scroll down to How To Do Valleys and watch the video. It shows how valleys are installed and what we call tipping a valley and why its important. If I knew how to just post a link to the video it would be a lot easier for y'all. The shingle Mfg have a lot of info designed to educate not only installers but homeowners. The better informed a consumer is, the better choice they can make in choosing a contractor to install their roof.

    When I meet with a homeowner I'll spend as much time as they want to educate them on the installation of their new roof. Most people only but 1 maybe 2 roofs in their lifetime and we take the approach of being an educator rather than a salesperson. A roof that will last its maximum life expectancy is more than just a shingle but it's a system that has to work together.

    Hope this helps.
     
  12. Aug 11, 2009 #12

    inspectorD

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    I'm sorry, I forgot to mention the clips...:eek:
    And when we do metal roofs ,we use 24 inch copper cut at 8 foot lengths, gasketed at the seam, basically a piece of thin tubed rubber.It works.
    I have not had any issues "yet" with Grace ice and water human fly paper.:rofl:
    And Old dog is right on the money with his advice,it is the system of shingles and ventilation and deck that makes the roof last, maybe he could consult over the phone.:D
     
  13. Aug 11, 2009 #13

    bill's quest

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    oldog/newtrick et al...

    Thanks for the commentary...for clarity on my part....hat's done is what's done re the valley....i am not trying to have that re-done. ...no way....what does interest me is getting a grip on the contractor's level of knowledge and how he handles customer requests/issues. BUT, I will go inspect how he did the shingles in the valley....and if he did it in a way to minimize debris damming. I'll take a picture if i can download it here.

    I thought that I had a legitimate request...go w/ metal valley because there is significantly less debris damming.... and what I am asking the board....Do you think that it was legitimate to the point that there is reason to be extra cautious about how the contractor attempts to manage the customer in other areas of the job? And, was the contractor's rationale to insist not to the metal valley flawed...he climed that leaking was a high risk with a low pitch roof This is the main point.

    Going forward, the contractor is suppose to finish some things that are in the contract and re-do some things due to poor workmanship and having a deaf hear to what I verbally requested. None of this involves work on the valley.


    If the valley was to be done w/metal, I had three choices....aluminum (I considered too vulnerable to having a puncture from nearby tree fall out); galvanized metal that was described as "powder coated". .. I was told that it would outlast the shingles but that it is vulnerable to being "scratched"---i.e. rusting); or, copper....about 25% more expensive. Whatever the choice, GAF had a strong recommendation for a hightemp underlayment and I would have insisted the contractor call GAF in order to be on the same page....with the underlayment issue as well as the quality of galvanized metal...the foreman had never heard the term-"galvalume"......this was the same process that I took with my refusal to allow them to ice and water shield the entire roof....(another story that reflects my disappointment in the roofing division of a major local contractor).

    Oldog/newtrick....would settle my obsessive mind if you would cast your opinion on the contractor's resistance to doing a metal valley. What I hear so far is that if done correctly, a metal valley is OK. Would you go further to say that a metal valley done right would handle debris better than a shingled valley done right?
     
  14. Aug 11, 2009 #14

    bill's quest

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    here are some of the valley plus others

    P1000834.jpg

    P1000856.jpg

    P1000853.jpg

    P1000842.jpg

    P1000833.jpg
     
  15. Aug 11, 2009 #15

    bill's quest

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    Olddog/newtrick

    the last pic above was to show that many/some shingles are ski sloped..either due to warped wood or improper storage

    and re the roof ridge vent....it looks better than it is re height of opening....less than 3/4 inch and almost zip when the shingles alternate from 2ply to 5ply....if that makes sense

    and added a few more pics...feel free to comment, now that I've learned how to download images

    new ones: telegraphing on one slope; wide soffit w/continuous vent; a house surrounded by trees

    P1000819.jpg

    P1000816.jpg
     
  16. Aug 11, 2009 #16

    bill's quest

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    to do what oldog/newtrick does never came on my radar....and I looked around at big and small contractors....a whole new experience getting feedback here...a number of homeowners I contacted in the area...they had a similar pitch with new roofs...they only knew no known leaks and some could not even tell me the contractor...but pleased that the roofing job only took one day...zip knowledge about installation.

    as for the whole home picture..... .I could not get it to upload.....i hope the pictures offer something...they sure take up a lot of room...
     
  17. Aug 11, 2009 #17

    glennjanie

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    Hello Bill:
    I am late in posting on this subject but I want to share my experience on the matter.
    Several years ago the manufacturer's most desired method was a woven valley and was shown on each bundle of shingles.
    Simply extend each run past the bottom of the valley by one foot and overlap the run on the other side by one foot the other way. To keep the shingles from tearing in the valley, there should be no nails in the valley or the extension tabs.
    Glenn
     
  18. Aug 11, 2009 #18

    oldognewtrick

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    Bill, to comment on your roofers ability to install metal valleys based on a few comments and pics would not be appropiate on my part. I don't know him, his company or what type of work he does. What is his warranty period for workmanship? To express an opinion would involve more than just seeing a few pictures. It does seem that there is either some decking boards that are not secured or when the underlayment was rolled out it was not streched tight. Did they strip the old shingles and reroofed back in the same day? If not moisture (morning dew) will cause roofing felts to wrinkle.

    Glad you learned to post pics, I cant even post a link. Lucky I can turn the computer on....maybe someday.

    Did they fix the ridge vent issues?

    Inspector D, be glad to offer free consultation, but remember you get just what you pay for it.;)
     
  19. Aug 12, 2009 #19

    bill's quest

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    oldog/newtrick,

    I happen to have an old picture of the house prior to the re-roofing. The "telegraphing" is in the same place but harder to notice....40 yr heavier shingles and I didn't know better. But,I'm thinking that the contractor should have taken a closer look prior to the job,and known that the line ( which is staggered across the entire slope) would be one of the more obvious places that needed new planks.

    On the valleys...can you offer a description of their technique...woven, tipping, etc ?

    And Yes, I do hope Inspector D is willing to have at it. Bottom line, I want to know what is reasonable to insist upon.
     
  20. Aug 12, 2009 #20

    oldognewtrick

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    Bill, they installed a cut valley, which is the same as we install. One slope extends up and the corresponding roof shingle extends over the other. You weave the first course only, snap a line and cut down the valley. I do not like woven valleys, if you step in the valley you can fracture the shingles on an older shingle. Not so much on your roof but on steeper roofs the valleys are the travel routes.

    Looking at the pics and seeing the uneven deck boards, in my opinion I would insist that they be fixed. They may never be a problem, but if you ever sell the house a home inspector might pick up on that. If you walk the roof does the boards have any play in them?

    My opinion(and its an opinion) I would leave the valley issue alone and insist on the deck boards being fixed.

    If you have not been there yet go to gaf.com and look at the video. It will show you about tipping the valleys. I would insist on that also. If they are a certified GAF installer and able to offer enhanced warranties they should know how to trim the top edge of the hidden shingle in the valley.
     

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