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Roofing underlayment

Irishjoe | Posted in General Discussion on March 6, 2005 11:34am

My neighbor is acting as his own GC on a new house so the build is going slowly. My question for you guys is…The trusses were recently installed and he is planning to sheath and cover with some underlayment that may be left exposed for a short while. Any suggestions as to what to use and the best way to install it. He is concerned about cupping etc that you sometimes see. We are in upstate N.Y. and winter is still in full swing here. He is using 5/8 in plywood over trusses on 24 in centers with a 7/12 pitch. Thank You in advance for any insight or links that would be helpful.

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  1. gdavis62 | Mar 06, 2005 11:46pm | #1

    30 pound building felt paper will work just fine.

    I am in way upstate NY, Lake Placid, and all the lumberyards stock and sell 2" diameter light gage sheet metal "washers."  We use them when fastening felt to sheathing.  The lumberyards call them "discos."

    Shoot a roofing nail right through your discos.

    If you are really concerned about wind ripping the felt off the roof, take string and nail a continuous piece of string a couple inches up along each downhill edge.  Place the disco over the taut string, then fire away to fasten.

    1. Irishjoe | Mar 06, 2005 11:52pm | #3

      Hey Gene thanks for the reply, You are in L Placid so you know what we're up against. Is there other materials out there that you have seen used? The HO said he heard about a different material (supposedly better and cheaper) than 30# felt.

      1. User avater
        Sphere | Mar 07, 2005 01:12am | #6

        We have used Titanium UDL. Neat stuff. Kinda like a plastic but walkable. IIRC its about the same cost or a bit higher than felt. 

        Spheramid Enterprises Architectural Woodworks

        Restoring, Remodeling, Reclaiming The Quality..

      2. gdavis62 | Mar 07, 2005 01:21am | #7

        There is 15# felt.  It's cheaper, but it won't lay and stay as flat as 30#.

        Now, others here will tell you about other products, like Roof Guard II, but they are more costly than plain old (and tried and proven) felt.

    2. blue_eyed_devil | Mar 08, 2005 04:17pm | #26

      Gene, that's a good tip...the string thing...I'll remember that one.

      blueJust because you can, doesn't mean you should!

      Warning! Be cautious when taking any framing advice from me. There are some in here who think I'm a hackmeister...they might be right! Of course, they might be wrong too!

  2. Piffin | Mar 06, 2005 11:52pm | #2

    I have gone to using the new breed, RooftopgaurdII. A roll is five feet wide, so it covers faster, saving labor. It is ripstop protected so only needing to do it once saves labour. once it is nailed down, I have had two jobs where it lasted five months of winter before getting shingled, letting me work in better weather, so it saves labor. Oh, and you can walk easy on it up to 6/12 and not hard to walk at 8/12 so it saves labor costs.

    Yep, there is no doubt that the product is expensive to buy but did I mention how it saves labour cost?

    I nail it with plasticap nails every 18" or closer every diagonal direction and laps 12"oc

     

     

    Welcome to the
    Taunton University of
    Knowledge FHB Campus at Breaktime.
     where ...
    Excellence is its own reward!

    1. Irishjoe | Mar 07, 2005 12:09am | #4

      Who is the Manufacturer? Is it a lot more than felt?

    2. gdavis62 | Mar 07, 2005 04:28am | #13

      I might as well ask you right on this thread. 

      <Sorry, Mister Thread-Initiator, for the hijack>

      Does RTG II substitute for I&WS?  In other words, can I do my valleys and eaves in RTG II, and forego the Grace?

      And how about under my copper at the eyebrow dormer?

      1. Schelling | Mar 07, 2005 05:11am | #14

        "Does RTG II substitute for I&WS?  In other words, can I do my valleys and eaves in RTG II, and forego the Grace?

        And how about under my copper at the eyebrow dormer?"

         

        It says so on the package, but there is no way that I would trust it in an situation where I thought there might be an ice dam problem.  Like you I will probably stick to felt in most situations but am leaning toward RTGII for winter applications where felt is so brittle.

        We used RTGII under the metal (steel, copper, and lead coated copper) on the house we are currently building. The roofers requested that we fasten it with roofing nails only, no caps, as the caps can telegraph through. The product stayed perfectly fastened with only roofing nails for 3 months.

        1. User avater
          RichBeckman | Mar 07, 2005 05:38am | #15

          "The roofers requested that we fasten it with roofing nails only, no caps, as the caps can telegraph through."I'd love to see that. I've done several roofs always using the plastic caps and I've never seen a hint of telegraphing.Edit: When I posted this I missed the fact that the post I am replying to is discussing metal roofs. Please ignore me. Thanks.Rich BeckmanAnother day, another tool.

          Edited 3/7/2005 8:54 pm ET by Rich Beckman

          1. gdavis62 | Mar 07, 2005 05:58am | #16

            How much steel, copper, and lead roofing have you done over the caps, and not seen telegraphing?

          2. User avater
            RichBeckman | Mar 08, 2005 02:57am | #24

            "How much steel, copper, and lead roofing have you done over the caps, and not seen telegraphing?"My bad. I failed to realize that suddenly a copper roof was being discussed.I've not done any steel, copper, or lead roofing over the caps or over anything else!Rich BeckmanAnother day, another tool.

        2. seeyou | Mar 08, 2005 12:54am | #22

          I've used RTGII and Titanium and I like Titanium better. I use a lot of I&WS, but it's just to protect the inside of the house during re-roofing. On pitches less than 3/12 I would normally use I&WS, while on anything greater, I use Titanium (or RTGII). If the roof will be recovered quickly with asphalt shingles, I use #30 felt. If it has to stand for a while or if it's a copper roof, I use Titanium. I've never had any trouble with plastic caps telegraphing thru copper. As far as the economics, RTGII or Titanium cost about twice as much per square foot, but they go down about twice as fast and use less nails. I can also skip the rosin paper under copper. They'll still be there long after the felt has blown off. I'd say the cost is about the same for the hitech stuff and the felt.

          edit: Oh yeah, one 10 sq roll weighs less than 1 one 2 sq roll of felt. Less trips up and down.

          You're almost as paranoid as the people that're trying to kill me.

          Edited 3/7/2005 4:56 pm ET by greencu

      2. Piffin | Mar 07, 2005 07:08am | #17

        In some cases, yes. IMO
        On a decent pitch with new sheathing instead of old baording baords and gaps etc, I would trust it. They even provide a detail for roll lapping a ehm into the lap to prevent backup, and it is heavy enough to resist wear and tear. The back of uit is slightly gummy for a modest self seal around anils. 

         

        Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

        1. gdavis62 | Mar 07, 2005 07:16am | #18

          On a pitch of 4-1/2 in 12?

          1. Piffin | Mar 07, 2005 08:05am | #19

            With asphalt shingles? 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

          2. Piffin | Mar 07, 2005 08:21am | #20

            Gene, On a new house, I would expect not to find any apprecuiable icve damning, because the insulation, ventilation, and VB pachage would be right, right? In certain locations I might still use the I&Ws, like at joints of the copper eyebrow, but if the RTGII is judicious ly placed, i would feelconfident in it. but it depends on the roofer. that bituthene covers a lot of sins.For a metal roof, the cap nails will telegraph but tin tabs won't. On asphalt, neither do. 

             

            Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

  3. FrankB89 | Mar 07, 2005 12:19am | #5

    I use TriFlex....similar to what Pif mentioned....  comes in 10 sq. (1000 sq. ft.)rolls.  It's tough, lays flat and goes on quickly.  (About $105 per roll last time I bought some).

     

  4. dIrishInMe | Mar 07, 2005 01:21am | #8

    Another product I like is Roofers Select from certainteed:

    http://www.certainteed.com/NR/rdonlyres/E2BF07E5-0D1E-4DED-8B09-A96B4585553D/0/RS.PDF

    It's basically just a highbred felt.  Runs about the same cost per sq ft as 30# felt but it weathers better with less of the wrinkling that normally results from temperature and moisture level fluctuations on regular felt.  Only down side is that it has fiberglass in it so working in shorts can be problematic - although it doesn't sound like you all have to worry about that... :-)
     

    Matt
  5. User avater
    xxPaulCPxx | Mar 07, 2005 02:38am | #9

    The Titanium or Roofgaurd (or similar) is probably where he want's to go.  Most people will recommend what they have been working with for 20 years (asphalt felt), rather that what might be a better product (multiple ply plastic).  I had to convince a guy at the local roofing supply to even look for the stuff.  When I mentioned that even thought it was more expensive it was a better product, he said "Well it wasn't too long ago we didn't even use an underlayment between the shingles and the deck!" - Ya, thanks grandpa - all of us current homeowners are paying for those mistakes you made back then.  SHEESH!

    Rebuilding my home in Cypress, CA

    Also a CRX fanatic!

    1. dIrishInMe | Mar 07, 2005 04:01am | #10

      I'd like to see how these different products price out. Matt

      1. gdavis62 | Mar 07, 2005 04:26am | #12

        I figure about $4 per square for 30# felt.  My next roof needs a net of 65 squares of material, and as I recall, the RTG II premium was too much to bear.

        A few factors come into play, though.  It's a 4-1/2 pitch roof, I'll probably cover it with "helper" wages, rather than "journeyman" costs.  We'll probably paper it by August, and get the roofer in to finish everything before the leaves all fall off the trees, so there's really no "exposure factor."

        I think I'll revisit it one more time, and run the numbers.  I recall seeing that it can eliminate the need for I&WS, and if it does, I'll need to factor in the savings for that.

      2. User avater
        xxPaulCPxx | Mar 07, 2005 08:45pm | #21

        I got a 10 sq roll of Titanium from Home Depot for about $129. Rebuilding my home in Cypress, CA

        Also a CRX fanatic!

      3. MikeSmith | Mar 08, 2005 01:10am | #23

        Matt.. i've used 15# felt

        Roofer's Select

        30# felt

        TriFlex 30    [  41.5" x 300'  (10 sq. @ $ 115 )]

        and RoofTopGuard II   [  60" x 200'  (10 sq. @   $135 )]

         

        the only one we use now is the last one  RTGII.. we put it on with tins and roofing guns.. and we've left the roof that way for entire winters...no leaks, no tear offs..Mike Smith Rhode Island : Design / Build / Repair / Restore

        1. dIrishInMe | Mar 08, 2005 03:52pm | #25

          Let me complete Mike's chart  - although we will now have prices mixed in from another locality...

          15# felt        [3' x 144' = 432 sq ft (3 rolls = $45 (~10 sq))]         $42             Roofer's Select [3' x 144' = 432 sq ft (3 rolls = $60 (~10 sq))]       $60        30# felt      [3' x 72' = 432 sq ft (5 rolls = $45 (~10 sq))]             $84TriFlex 30    [  41.5" x 300'  (10 sq. @ $ 115 )]                          $115RoofTopGuard II   [  60" x 200'  (10 sq. @   $135 )]                    $135

          So, we see that premium products can be as much as 3x the expense as the minimal product (15# felt).  The above is for 10 squares which would be more in the range of what would be needed for an addition.  For a whole house roof of say, 20 squares, then your price spread goes from $84/$270.  My personal home has 65 squares on it (large steep pitch ranch), which would be ~$ 210/$900.   The idea being that sure, there are better products available, but the price difference can be significant.   The above numbers do not account for lappage, and waste, but you get the idea, and the question is, how much do these products add to the value of the house?  Matt

          1. MikeSmith | Mar 08, 2005 05:24pm | #27

            matt , it adds almost nothing to the value of the house..

            it cuts labor significantly , and almost completely covers us in terms of liability  which we can get into when we do a strip and reroof

            i like to  get rooftop deliveries..

             that assumes that all of the paper is already in place..

            when we use 15#   or 30# felt.. i always sweat wind and rain.. and potential leaks before we can get the final roofing in place

             

            now, i sweat nothing.. the RTGII is almost like having a second roof under the first roof

            it may or may not suit you for new construction..

             but it certinly fits with our way of doing things and the sequence we like to follow

            and one 10 sq. roll really does weigh less than one 2 sq. roll of 15# felt

            and  it's 5' wide

            to me the benny is saved labor and peace of mindMike Smith Rhode Island : Design / Build / Repair / Restore

          2. timkline | Mar 08, 2005 05:34pm | #28

            Mike,

            Why the choice of RTG over TriFlex  ?   Is it just the roll width being wider ?

             carpenter in transition

          3. MikeSmith | Mar 08, 2005 10:36pm | #29

            tim.. that's a big part of it..  we usually do steep roofs.. 8/12 & over  so we can't walk them.. we stage it all the way up  and then stock our roof on the staging..

             

            5' between staging  is just  about ideal.. as opposed to the tri-flex, which is just over 3'

             Mike Smith Rhode Island : Design / Build / Repair / Restore

          4. dIrishInMe | Mar 09, 2005 02:21am | #30

            I can definitely see the advantages in a re-roof or addition situation where roof leakage is not tolerable.  On the other hand, in new construction, a *fairly* waterproof roof for 3 or 4 weeks or so until all the siding, rough-ins, exterior painting, etc are done is perfectly acceptable as there is no finish items in the house.  I wish I could justify the additional expense, but just can't.

            Matt

            Edited 3/8/2005 6:32 pm ET by DIRISHINME

  6. Darin | Mar 07, 2005 04:17am | #11

    joec1,  I used Tri-Flex 30 on my own home renovation and some of it was exposed for almost 9 months through the winter of 2003 in New Jersey.  I used "silver dollars" (tin discs) with roofing nails to hold it down.  Not one tear and virtually no leaks except for one or two places where we had small leaks around the nails.  I would say we had almost every conceivable weather event over those nine months and I was more than satisfied.  I don't think I would consider anything else.  We installed the Tri-Flex on my garage addition in Oct. 2003 and did not install shingles on the roof until July/Aug 2004.  I talked to the manufacturer and they recommend covering within 3-6 months, but they told me that I would not have a problem up to 1 year exposure.  Except for looking a little dirty and worn from walking in certain areas, I don't think you could have ripped the stuff off, the nails would have pulled.  Here is a picture.

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