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Thread: Question on Fixing a roof

  1. #1
    Join Date
    Aug 2007
    Reno NV

    Question on Fixing a roof

    Our back patio roof leaks like crazy when we get any rain or snow. The decking under the shingles is showing signs of rotting and the leaks seem to move all around.

    It just seems to me that with the way the roof lines come off the garage that it just basically shoots water under the shingles, or that it's just too flat to really keep the water out.

    I want to keep the basic structure, as the rafters seem pretty sound.

    What I'd like to do is:

    1) tear off the shingles
    2) replace the decking
    3) put on a metal roof.
    4) Get rid of this weird little 'alcove' where they left the patio roof on when they built on the garage. That alcove is very attractive to pack rats and they like to fill it up with all kinds of debris.

    So, Just thought I'd post a couple of pictures and see what comments or advice you all might have.


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    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash

  2. #2
    Join Date
    Nov 2015
    Central North Carolina
    That porch roof looks awfully flat. Is it wood shingled or asphalt?

    I have a wide dormer roof across the back roof of my house that just had shingles and asphalt paper on it when I bought the house. It barely has a 3" pitch to it and faces roughly South. It leaked almost everywhere whenever a wind driven rain came from the South, but didn't leak when it came from any other direction. Shortly after buying the house I had the whole house re-shingled and specified that they use a certain self sealing peel and stick rubber membrane under the shingles on the dormer. None of the roofers that I talked to around here even knew what I was talking about.

    When I lived in NY State, we used this membrane material along the bottom edge of our roofs to prevent ice dams (formed when a little snow melts and then re-freezes at the bottom edge of the roof where the roof extends out over unheated soffits). When this happens every night for several weeks, sufficient ice builds up to prevent melted snow from running off the edge of the roof and it builds up behind this ice dam enough to start running up under the shingles and into the house. Adding this 3' wide self sealing rubber membrane along the edge of the roof, under the shingles prevented this from happening, yet kept the shingled appearance of the roof all the way to the roof edge. The nails that held the shingles on were just driven through this membrane and it sealed around them. It was also frequently used under the shingles in the roof valleys where snow would build up and remain for extended periods.

    I ended up calling every roofing supplier in this area of North Carolina and finally found one 25 miles away who not only knew what I was talking about, but had some in stock. I went there and bought enough to completely cover the dormer and had the roofer put it on before putting the shingles on. The dormer hasn't leaked a drop since, and that was about 20 years ago. He is now a believer and has now used this membrane material on many of his roofing jobs. From memory, I think it added about $120 plus labor to the cost of my roof. I'm certain that it will cost more now, but the cost of this in my 50 square (5,000 sq ft) roofing job was quite insignificant.

    Unfortunately, I don't remember the name or manufacturer, but if you specify that you want it covered by a "peel and stick self sealing membrane" before the shingles are applied, they should do it for you. I will try to find the name and manufacturer and add it to this thread, if I can find it.


  3. #3
    Join Date
    Jun 2008
    GTA Ontario Canada
    The guy that i can think of that knows about these things is old grey beard and he has been there so let's hope he chimes in or pm him. He was actually fixing a roof on his bday.

  4. #4
    Join Date
    Aug 2007
    Reno NV
    Thanks Charley,

    Yeah, it is awfully flat. So flat that with I actually think the way the shingles are laid that the water rolls up and underneath! LOL

    I'm sure there is just tar paper under it, and it probably rotted long ago. That membrane sounds like the kind of thing that should have been used.
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash

  5. #5
    Join Date
    Jul 2011
    The Gorge Area, Oregon
    We used that membrane stuff on my buddies ~about as flat as Brents maybe worse~ roof in Hawaii and it was the cats meow. Used it over the whole roof and it was watertight before we put down the shingles even.

    However (there's always a "but" in there somewhere) it doesn't breath at all. Which is why in colder places they only use it for the bottom row or two and perhaps the gullies (at least under shingles) otherwise you end up with moisture buildup under it due to the temperature differential and you're roof deck will rot out.

    Having said that I have zero experience with it and metal roofs, presumably you're going to use furring strips/battens underneath the roofing? That adds another air gap and may well make it hunky dory for all that but that gets a bit past my level of knowing anything - I think it depends more on how well the attic space is ventilated at that point but..

    Speaking of ventilation - in you're hot country a batten/counter batten (horizontal/vertical) to provide an above deck airflow space might well be advantageous enough to justify the cost - I remember seeing something about this when I was working at the lab - I think? this is the article (or at least a summary of it) from ORNL.

    There are some wind load considerations that are probably relevant to you, but I believe they're less concerning with solid metal roofs than shingles... double check all that though.

    Ah here's an updated report and some references

    and an energy savings calculator for different roof types.
    Love thy neighbor, yet pull down not thy hedge.

  6. #6
    Join Date
    Jan 2009
    Had the same water leakage years ago when I added a patio cover. Nothing seemed to work. Finally rubber membrane was installed on lower tier.
    Problem solved. Firm believer in the stuff. Don't need it all over just in pitch transitions.
    Good luck.

  7. #7
    Join Date
    May 2007
    Kansas City, Missouri
    As others have said, consider the ice/water shield membrane. I'd probably not change the structure of the alcove, maybe just frame it out and seal it off to keep the rats out?

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  8. #8
    Join Date
    Mar 2007
    Escondido, CA
    My Strawberry house in Arizona had rotting fascias because some idjit failed to put up drip edges and trimmed the shingles flush with the fascia. Repaired with metal drip edges and ice/water shield membrane 3 feet wide. That cured that. Was called Ice & Water Shield.

    Some say the land of milk and honey; others say the land of fruits and nuts. All together my sort of heaven.

    Power is not taken. It is given. Who have you given yours to? Hmmmm?

    Carol Reed

  9. #9
    Join Date
    Dec 2006
    Yorktown, Virginia
    I've been using Grace Ice and Water shield as a liner on my raised planter beds to isolate the pressure treated lumber from the planting soil. I think it's the membrane being talked about. Got it at Lowe's. Very sticky stuff. I'm not sure whether it will do what I want it to do for the planting beds, but I can see where it would be very effective under the new metal roof on your deck. How do you plan to handle the transition between metal and shingles?

  10. #10
    Join Date
    Aug 2007
    Reno NV
    Sounds like that membrane is the right way to go.

    Wasn't sure on the whole transition. Figured it would involve butting up the metal to the existing roofline and weaving some shingles under the shingled roof and on top of the metal.

    Based on advice I've been getting it seems like maybe the metal roof is not the way to go.

    Now I just have to find some matching shingles.
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash

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