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Thread: Water Pipes in Attic

  1. #1

    Default Water Pipes in Attic

    Well I added a new master bath to my house and I live on a slab so i ran the cpvc water pipes through the attic. About a 30 foot run of pipe. I live in Northern Indiana and it got into negatives last couple days so it froze. I had some insulated tubing around them and had them laying in the blown insulation but it still froze. I probably should have covered them a little more then i did.

    I cut out the pipes today and i am gonna start over. Any ideas to help fight the freezing in this type of weather. I was thinking maybe it would be best to replace the run with pex?

    Next time i will tape the foam tubing on all joints and thought maybe i could wrap piece of wall insulation around the two pipes and tape it up real good or just put a 6 inch piece over the top of the pipes.. not sure yet.

    Any suggestions to keep them from freezing? I dont really want to go the heat tape route if i dont have to.

  2. #2

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    If you plan on staying in the attic then just run your pipes along the drywall, under the insulation then place extra insulation over that. This way they will be in direct contact with the heated gypsum and protected by the attic insulation.
    http://www.inspectpa.com/forum/forum.php
    My answers are based mostly on the ICC codes. Advice given is my personal opinion and every person performing work should acquire a permit from his/her jurisdiction and get the work inspected. My opinions are not directions to follow for DIYs or professionals

  3. #3

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    Thanks for response. Only negative thing about that option is the way the ceiling joists are running perpendicular and would require them to be drilled to get down to the drywall. It really is annoying living on a slab. I should of ran them through the walls i am starting to think.

  4. #4
    Forum Admin, Expert Plumber Terry's Avatar
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    Don't put any insulation around the pipes.
    Remove all insulation below the pipe, and lay fiberglass batts over them.
    Between the ceiling joists on either side, lay two more batts, keeping space open below the pipes.
    The heat from the home must be able to get to the pipes, and then you trap it.
    A pipe in an uninsulated attic will freeze otherwise.

    If you change the pipes, then PEX would be good.
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  5. #5

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    If you will be drilling between the ceiling joists, you must drill at least 2" up from the bottom. Keep the pipes as close to the ceiling as possible and do exactly what Terry is showing for those that are above the drywall inside the joist bays.
    http://www.inspectpa.com/forum/forum.php
    My answers are based mostly on the ICC codes. Advice given is my personal opinion and every person performing work should acquire a permit from his/her jurisdiction and get the work inspected. My opinions are not directions to follow for DIYs or professionals

  6. #6

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    Thanks that drawing makes sense. I have 4" ceiling joists so I could just set it on top of that.

    So should i keep the the foam wrap around it? Or keep it off so heat can get to the pipe?

  7. #7

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    Don't wrap the pipes. Otherwise you cannot take advantage of the heat between the ceiling and insulation void where the pipes are located.
    http://www.inspectpa.com/forum/forum.php
    My answers are based mostly on the ICC codes. Advice given is my personal opinion and every person performing work should acquire a permit from his/her jurisdiction and get the work inspected. My opinions are not directions to follow for DIYs or professionals

  8. #8
    Moderator & Master Plumber hj's Avatar
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    Default Icc

    My answers are based mostly on the ICC codes.

    Don't they pertain to trucking and other interstate commerce, not plumbing?
    Last edited by Terry; 12-23-2008 at 10:14 AM.

  9. #9

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    Quote Originally Posted by jar546 View Post
    Don't wrap the pipes. Otherwise you cannot take advantage of the heat between the ceiling and insulation void where the pipes are located.
    Thanks alot! I will give that a shot and see how it goes.

    I might still wrap the pex tubing with a heat tape for a situation where it might get frozen or really cold out. Should i put a seperate heat tape on each line,, or just put the two 3/4" pipes together and wrap them up together.

  10. #10
    Forum Admin, Expert Plumber Terry's Avatar
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    If you have power, there is no reason for heat tape when installed this way.
    The insulation traps the heat from below.
    This works for copper pipes too.
    The only time these pipes would freeze, is if you lost power.
    In that case, all pipes could freeze.
    If you lose power, your heat tape is useless.

  11. #11
    DIY Junior Member darylmary's Avatar
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    Unhappy My attic water pipes are frozen..again

    Quote Originally Posted by Terry View Post
    Don't put any insulation around the pipes.
    Remove all insulation below the pipe, and lay fiberglass batts over them.
    Between the ceiling joists on either side, lay two more batts, keeping space open below the pipes.
    The heat from the home must be able to get to the pipes, and then you trap it.
    A pipe in an uninsulated attic will freeze otherwise.

    If you change the pipes, then PEX would be good.
    Hi Terry,
    I just bought a home in New Brunswick and have a similar problem to the original query about water pipes in the attic. I was advised (wrongly it turns out) to put foam sleeves around the main Plastic pipe which stretches 40' across the attic, close to the eaves. We hit -12C last week and I froze up totally. A combination of warmer temps and a heater in the attic fixed that problem. A friend suggested more insulation under the eaves as the cold Atlantic wind (I am right on the ocean) blew right in. The pipes froze again last night at -18C. Now I understand from your forum that the problem is being caused because pipe is ABOVE the insulation. Like your previous poster, my pipe runs counter to the joists, basically sitting on top of them all the way across. Can I rectify this freezing problem, WITHOUT drilling holes through all the joists, by just removing the insulation around the pipes and underneath the pipes and putting a thick mound above the pipes? The way you drew your sketch it looked as though this was possible.
    I am a single senior on fixed income and can't afford major expenses at this time. I would really appreciate a speedy reply. In the mean time I have opened up the attic to the small insulated bedroom up there and am hoping enough warmth will circulate to fix the present frozen pipe problem. Thank you for any help you can offer.

  12. #12
    In the Trades Gary Swart's Avatar
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    What many people just don't grasp is that insulation does not provide heat. It only slows heat transfer. A so-called "warm coat" is not warm at all. When you put it on, it will retain your body heat longer than a light weight jacket. So you need the insulation over the top of the pipes so the heat from the floor below will be held in longer.

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