Will it freeze?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Zinski1911, Oct 25, 2013.

  1. Zinski1911

    Zinski1911 New Member

    Messages:
    6
    Location:
    Montpelier, OH
    I just purchased a foreclosure and spent the summer renovating from top to bottom. I am planning to live in this house. Its on a slab, and all of the copper was stripped out of the house before we bought it. We ran pex through the walls. There is one area where we had to run the pex overhead. There is a 7 foot section above the ceiling of the back room that we had no other option but to run the pex through. That room has a flat roof above it. The entire home is insulated, except the 7 foot by 1 foot path where the pex runs through the ceiling. The path had blown in insulation, but that fell out when my guy cut the ceiling to run the pipe through. He finished the drywall after, but failed to put insulation back(unbeknownst to me). I am scheduled to move this week, and he dropped this little number on me yesterday. I live in Northwest Ohio, and we get a fair bit of cold weather here. So, what are the opinions? Will this short run be a problem, or will I most likely not have to worry about it? Thanks
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,522
    Location:
    Cave Creek, Arizona
    No way to tell. If the water in the pipe reaches 32 degrees, or so, it WILL freeze. But, we do not know if the heat in the room will be enough to overcome the cold weather above the pipe. In any case, insulation does NOT stop freezing, it only slows the process down, if conditions are right.
  3. Zinski1911

    Zinski1911 New Member

    Messages:
    6
    Location:
    Montpelier, OH
    By insulation, I mean actual fiberglass insulation above the pipes. I thought about cutting a vent into the finished ceiling to allow heat into the cavity. I'm worried about heat loss too. I may be doing some emergency drywall work this weekend.
  4. DonL

    DonL Banned

    Messages:
    3,979
    Location:
    Houston, TX

    Just heat the room when it gets super cold.

    Cutting a vent sounds a bit overkill. And all of your heat will get out.


    Was this install Inspected ?
  5. Zinski1911

    Zinski1911 New Member

    Messages:
    6
    Location:
    Montpelier, OH
    The room will be heated continually.
  6. Zinski1911

    Zinski1911 New Member

    Messages:
    6
    Location:
    Montpelier, OH
    and yes on the inspection
  7. Reach4

    Reach4 Active Member

    Messages:
    2,130
    Location:
    IL
    I would try to fit foam board pieces into the area above the pipes, and then fill insulation holes with expanding foam. Keeping water flowing slowly through a pipe can keep it from freezing.

    You could also put the "outdoor" sensor from one of those wireless thermometers near the the side or top of the pipe until you know how the freezing situation works out.
  8. Zinski1911

    Zinski1911 New Member

    Messages:
    6
    Location:
    Montpelier, OH
    Yeah my issue is whether or not to cut into the drywall. If I do, I'll insulate the heck out of it. I have movers scheduled to start early next week, and was hoping to avoid any drywall work. Thanks for the suggestions though
  9. DonL

    DonL Banned

    Messages:
    3,979
    Location:
    Houston, TX

    You can also use a Service Thermometer poked thru the drywall.

    That is a nail size hole to patch.
    Last edited: Oct 25, 2013
  10. Dana

    Dana In the trades

    Messages:
    2,812
    Location:
    01609
    Neglecting to re-install insulation above the plumbing is a degree of professional negligence that is totally inexcusable. You have about R0.5 of gypsum between the PEX and the room, and about R0.5 of roof deck + shingles above that, and an unknown amount of air leakage into the cavity. Assuming a 70F ceiling and NO air leakage the plumbing will hit the freeze point at about -6F, a rare but not unheard of outdoor temp in Montpelier according to Weatherspark datasets. If the cavity is vented to the outdoors or simply leaks a lot of air, all bets are off- it could freeze even at much higher outdoor temps with optimally bad wind direction/strength.

    To meet code with only fiber insulation you need to maintain at least a 1" gap between the top of the insulation and the roof deck, and on a flat roof 2" is definitely better, and you would need to install a semi-permeable water-vapor retarder on the interior side (kraft facers on batts are OK, foil facers or polyethylene sheeting are not.)

    If you want to stuff the cavity full to the roof deck, in that climate (US climate zone 5) you need at least R20 of air-impermeable insulation such as rigid foam in contact with the roof deck and air-sealed at the edges. To avoid creating a moisture trap for the roof deck wood between the roofing and foam it's best to use a modestly water-vapor permeable foam as the air-impermeable layer, such as unfaced EPS (the white beaded stuff of cheap coolers and coffee cups), and it would take 5" to hit R20. Cutting it with a loose enough fit that it has 1/4-1/2" of clearance between the foam and joists makes it possible to reliably air seal it with can-foam (Dow Great Stuff or similar.) You can then fill the cavity with fiber- unfaced rock wool is probably the best, but unfaced fiberglass would be OK, and you would not need anything more vapor retardent than latex ceiling paint as the interior side vapor retarder.
  11. Zinski1911

    Zinski1911 New Member

    Messages:
    6
    Location:
    Montpelier, OH
    I agree on the inexcusable negligence. This is the 8th house I've hired him on though, and he's been flawless each other time(figures this is the one foreclosure that I bought to actually live in). As far as the roof above, its a flat, rubber coated(brand new as of June) roof. The underside does have batts and was done by a professional insulation company that I hired out to. That's quite a good amount of information you're giving me. I appreciate all of the replies so far. Truly a wealth of information. I think I'm going to bite the bullet and cut into the ceiling. Its going to cost a little more, but I'll be able to sleep better for sure. Thanks everyone!
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,522
    Location:
    Cave Creek, Arizona
    quote; This is the 8th house I've hired him on though, and he's been flawless each other

    I do NOT do insulation. If it did and something froze and broke, I would be liable, even if I did a "good" job of insulating.IN fact my insurance company might ask WHY I did it since it is outside the scope of my jurisdiction/parameters. I let someone else take responsibility.
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