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  • Flashing a shed dormer - help!

    Building a shed dormer for the first time and I am unsure of how to do the flashing at the top of the dormer where it meets the main roof (pitch change).

    Pictured is the change of pitch flashing sitting roughly in position, then there will be an apron flashing (not pictured) which runs up the side of the dormer, and finally a barge cap flashing that runs along the edge of the dormer eave (also not pictured).

    How does one normally flash this part of the dormer? Can someone run through the basics with me?

    I'm totally lost. For instance - does the change of pitch flashing finish in line with the dormer wall? Or does it extend out to the edge of the dormer eave?...or maybe even beyond it? Then how do you avoid creating a leak where the edge of the change of pitch flashing meets the metal roofing? A whole lot of caulk??
    Short piece of roofing on right just there temporarily to help me figure this out. Short piece of roofing on right just there temporarily to help me figure this out. Something like this is where I am trying to get to

  • #2
    Good questions.
    Related question: effective flashing-seal at join between dormer's raked eave/soffit with the main body roofing plane?

    Comment


    • #3
      Originally posted by aptbldr View Post
      Good questions.
      Related question: effective flashing-seal at join between dormer's raked eave/soffit with the main body roofing plane?
      Actually - you've articulated it better than me....that's what I want to know! Any thoughts?

      Comment


      • #4
        The metal roof mfg hopefully has a detail available that shows how to do.

        I've never worked with that material in such a way but at the dormer side to main roof customarily step - flashing is used in some way. Possibly another pre - fab piece by the mfg is used there that accepts the roof material while flashing the area.

        The ridge to top of dormer it's the dormer roof tucked / let in under the main roof. There may be pre - fab metal from the mfg that is half flat -- half corrugated that makes the transition.

        There are a lot of metal roof instructions out there.
        Steve

        "Get three coffins ready" - A Fistful of Dollars 1964

        http://youtu.be/KZ_7br_3y54

        Comment


        • #5
          Originally posted by gooseberry View Post
          Actually - you've articulated it better than me....that's what I want to know! Any thoughts?
          Gooseberry, I can try to help you, as I mostly do metal roofing...although I use a different profile than in your picture. If I have done a shed dormer in metal, it has been awhile, but some of it isn't much different than doing a gambrel roof. Usually, under the the bottom of the transition flashing and on top of the metal, there are outside closures that match the profile of the metal. These stick right to the metal and are screwed through the top, into a major rib. At the top of the transition flashing, you would use inside closures on top of the flashing and under the metal. There is also a product called M-seal that will expand slowly and do the same thing. Usually the flashing extends beyond the pitch change to protect the rake / soffit area. Outside closures up under the rake, would help. Just remember to always run rake trim, sidewall, and end wall trim/ flashing over the top of the metal or it will leak. I often fix roofs where this is done backwards.

          Up the rakes, I usually use rake trim that goes down the side of the rake (however much you want) and then up over the top of the metal, which is supposed to sit outside of a major rib. The rib keeps the water from backing under the trim. If there isn't a rib, then you have to bend one. Putting some buytl

          But I think your roof maybe somewhat more challenging, as the roof looks strapped and I usually only would do that on a barn or some other outbuilding. Here is a link to an install guide from my metal roofing supplier : http://everlastroofing.com/application-guides Go to the one that says "Light Gauge Application Guide" It has some good pictures and it can only help.

          I hope that helps and I hope that I didn't forget anything thing. Enjoy your roof!
          Jason Laws
          Plain In Maine
          Amity, Maine
          plaininmaine.houzz.com



          " ... I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock" (Matthew 7:24-25 KJV).

          Comment


          • #6
            Might as well start at the beginning

            http://www.atas.com/ATAS/media/ATAS/...ullLinking.pdf
            Steve

            "Get three coffins ready" - A Fistful of Dollars 1964

            http://youtu.be/KZ_7br_3y54

            Comment


            • #7
              Pretty good jason better than what i posted
              Steve

              "Get three coffins ready" - A Fistful of Dollars 1964

              http://youtu.be/KZ_7br_3y54

              Comment


              • #8
                Originally posted by Happy Home View Post
                Pretty good jason better than what i posted
                I don't think that what I posted is better than anything you did. Everyone's input is worth something, I think. I like that link that you posted - good reading!
                Last edited by Jason Laws; 04-18-2016, 06:28 PM.
                Jason Laws
                Plain In Maine
                Amity, Maine
                plaininmaine.houzz.com



                " ... I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock" (Matthew 7:24-25 KJV).

                Comment


                • #9
                  Thanks so much for all your help so far every one.

                  Here's what we've attempted to far (first picture just gives you a bit of context):


                  IMG_20160419_162528.jpg

                  IMG_20160419_162112.jpg


                  Jason/others I am not sure if we followed what you said or not...please let me know. Notice we have notched the roofing sheet around the change of pitch flashing. This is seems the main area of concern. We intend to fill that notch up with caulk (Jason - closure/M-seal is not available here it seems) to stop the rain. In your honest opinions is this an acceptable solution? Is it usually done like this? If it is no good I am happy to pull it off now and fix it before we go on (we've only done one side of the dormer so far).

                  Not shown in the photo is the rake trim, which will slide up under the change of pitch flashing; and the sidewall trim, which will slide up under everything.
                  Last edited by gooseberry; 04-20-2016, 01:33 AM.

                  Comment


                  • #10
                    Goosebery, I'm not sure that I am following everything exactly either - hence the problem of not being right there.

                    Again, you are using a totally different metal profile, which throws me off when I look at it. And I agree, that where the flashing and the roof join there is somewhat difficult. THe way that you are doing it looks about normal. I would have extended the flashing maybe to the next rib, but you already cut your transition flashing. With the way that you have it now, can you put some butyl tape behind everything, at least (3) rows. Just don't only use caulk - the metal moves so much that it won't last. This is where closures come in handy, as you can back almost anything with it. I always try to end cuts at a major rib, or in your case, the next rib.As I said, I haven't do a shed dormer in metal for awhile and usually I try to make it start under the ridge cap.
                    This is almost as fun as installing flashing for a metal chimney - the metal flashing most people use is really only for shingle roofs and can leak wonderfully - a rubber boot should be used.

                    By the way, are you going to sheath the dormer sidewalls or is everything just strapped? It is hard to sheath a sidewall with the metal mostly on.

                    I hope that I haven't hurt more than helped - I just don't do shed dormers very often, especially metal.
                    Jason Laws
                    Plain In Maine
                    Amity, Maine
                    plaininmaine.houzz.com



                    " ... I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock" (Matthew 7:24-25 KJV).

                    Comment


                    • #11
                      Actually, we havent cut the transition flashing yet! So we've now extended it out to the next ridge. We also cut it a wedge shape so there is less of a gap to fill. How does this look? Is this what you were thinking?

                      IMG_20160421_114150.jpg

                      When you say closures - we can purchase a foam "infill strip" like this locally. Is this what you mean?


                      corro-infill-strip.png

                      Comment


                      • #12
                        What are you using the building - dormer for ?

                        Is that corrugated the plastic type ? Whats the foil ? You have insulation then Strapping for the roofing ?

                        What type of insulation on the roof ?
                        Steve

                        "Get three coffins ready" - A Fistful of Dollars 1964

                        http://youtu.be/KZ_7br_3y54

                        Comment


                        • #13
                          Originally posted by Happy Home View Post
                          What are you using the building - dormer for ?

                          Is that corrugated the plastic type ? Whats the foil ? You have insulation then Strapping for the roofing ?

                          What type of insulation on the roof ?

                          Hi Happy Home.

                          Dormer to be used for bed room of residential home.

                          It's a corrugated sheet metal roof product that is popular over here manufactured by a company called "Colorbond".

                          The foil primarily relects the sun's heat but also helps to protect the house from moisture. We'll be adding glasswool insulation to the walls and ceilings also.

                          We mainly use the steel strapping for tie-down and bracing in high wind / cyclone areas. Norfolk Island occasionally get's low severity cyclones, so homes are usually built to the Australian cyclone specification/standard. I understand that in the US most homes are fully sheathed in some kind of OSB/plywood product? I love the sound of this approach but this is rare on Norfolk and in Australia. A house may have some of it's walls sheathed for bracing in higher-wind areas, which is the case with this house, but I haven't heard of anyone sheathing everything where I am from. The dormer side walls were not going to be sheathed in this case, however the front walls are (those either side of the dormer window).

                          Comment


                          • #14
                            Originally posted by gooseberry View Post
                            Actually, we havent cut the transition flashing yet! So we've now extended it out to the next ridge. We also cut it a wedge shape so there is less of a gap to fill. How does this look? Is this what you were thinking?

                            [ATTACH=CONFIG]n1062250[/ATTACH]

                            When you say closures - we can purchase a foam "infill strip" like this locally. Is this what you mean?


                            [ATTACH=CONFIG]n1062251[/ATTACH]
                            Looks great, Gooseberry!

                            As far as your infill strip, that is what I would call a closure - same idea. And by the looks of it and the look of the metal profile, one closure may work the same in and out. In my area, I can buy inside and outside closures, plus I can buy a vented closure if I want a ridge vent (which don't really work in my cold climate). Usually the bottom is sticky so that it won't fly away at the wrong moment - don't panic if it doesn't come that way, though.

                            Jason Laws
                            Plain In Maine
                            Amity, Maine
                            plaininmaine.houzz.com



                            " ... I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock" (Matthew 7:24-25 KJV).

                            Comment


                            • #15
                              Originally posted by gooseberry View Post


                              Hi Happy Home.

                              Dormer to be used for bed room of residential home.

                              It's a corrugated sheet metal roof product that is popular over here manufactured by a company called "Colorbond".

                              The foil primarily relects the sun's heat but also helps to protect the house from moisture. We'll be adding glasswool insulation to the walls and ceilings also.

                              We mainly use the steel strapping for tie-down and bracing in high wind / cyclone areas. Norfolk Island occasionally get's low severity cyclones, so homes are usually built to the Australian cyclone specification/standard. I understand that in the US most homes are fully sheathed in some kind of OSB/plywood product? I love the sound of this approach but this is rare on Norfolk and in Australia. A house may have some of it's walls sheathed for bracing in higher-wind areas, which is the case with this house, but I haven't heard of anyone sheathing everything where I am from. The dormer side walls were not going to be sheathed in this case, however the front walls are (those either side of the dormer window).
                              What is "glasswool" insulation? Is that the same as fiberglass insulation?

                              That metal profile that you use is one that used to be installed many years ago around here and I find them mainly on older buildings. The one I use now has the major ribs about 9" O.C. and the panels are about 3' wide.

                              How does your bracing method down there hold up? Is there much structural damage after a big storm?
                              Jason Laws
                              Plain In Maine
                              Amity, Maine
                              plaininmaine.houzz.com



                              " ... I will liken him unto a wise man, which built his house upon a rock: And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock" (Matthew 7:24-25 KJV).

                              Comment

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