We need to put some plumbing up against an exterior wall. We are told this is usually avoided but we have no choice. We live in a cold climate (very cold winters in Toronto) so we want to take every precaution to ensure the pipes never burst. We were told to put up a vapour barrier, then insulation, then another vapour barrier. However, when we asked at a local home depot, the pro said that you should only have a vapour barrier on ‘warm’ side of a house or closest to the inside. But does anyone know the best way? Where would the pipes go? Does anyone have some insight? The pipes are for a shower and tub (separately). Thanks!
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The HD guy was right.
Vapour barrier should only go on the warm side. Putting two layers will cause moisture to be trapped between them.
I too live in Ontario (just outside London) and have installed plumbing like you are. I installed the vapour barrier on the warm side and have never had a problem with the water lines.
Thanks so much lefty. You've restored my confidence, especially since you're a Canuck!!! Appreciate your time!
Sue
You want to keep the pipes on the warm side of the insulation. So you run insulation behind the piping only. The vapor barrier goes behind the pipes, in front of the insulation. For several reasons, including that you don't want to create a penetration in the vapor barrier for the pipes, especially in a humid room, which a room with plumbing is likely to be. Try to keep the pipes close to the inside of the wall so you can get the most insulation behind.
Be careful you protect the pipes from little hidden cold spots. Sometimes the wall is insulated, but not the rim joist between floors and you get freezing there. Or just a little breeze of cold air, such as a crack in a crawlspace or top of a basement wall is just enough to freeze a couple of inches of pipe.
If you are plumbing a vanity, consider coming up through the floor rather than in the wall.
Hi Sue : Use the highest rated insulation in your cavity. ( I'm assuming wood framing) In this case rigid xps or eps board will achieve R-5 per inch thickness.
Place as thick as possible allowing for your pipes. Foam all loose fits, make airtight.
Use air foam pipe insulation on your hot and cold.(cheap to buy)
Finish around pipes, in front of rigid insulation board with Roxul or equal.
Place super six vapor barrier in front, and drywall !
No drafts, or other exterior wall penetrations allowed nearby !
>> Use air foam pipe insulation on your hot and cold.(cheap to buy)
>> Finish around pipes, in front of rigid insulation board with Roxul or equal.I think I understand the point you're making, but in this particular situation, I really don't think you want any insulation between the pipe and the heated room. Nothing but air and sheetrock, and as little air as possible.
If it would be possible to have the supply water pipes exposed, ie. in front of the
gyprock, with the drains and venting within the wall cavity, this would be better.
Do you agree uncle dunc?
In the sense that there is less risk of drains freezing as compared to supply lines, yes. But less risk is not the same as no risk. The last time we discussed this at Breaktime, just a week or two back, several people told about drains in exterior walls freezing.
Yah, Mr Dunc, they will freeze if you insulate poorly and allow draughts to enter the cavity.
The purpose of this discussion was to show a way for Mrs Homebuilder to circumvent this problem, which has been done.
Personally, we build ICF homes, which are totally draught free and superinsulated.
We have no issues with plumbing on exterior walls, because of the system's superiority. Cheers.
thank you all for your feedback, it's really appreciated!!! I'll let you know how it goes...
I agree with what is being said. Always try to come up through the floor if possible or for a shower or tub, can you flip the tub or shower around so the plumbing is on an inside wall? Also, insulate the pipe with pipe insulation, tape the seems with insulation tape, etc. 10' in Mass is $5.
Is this shower going to be used daily, or is it a guest shower? If it is a guest shower I would be much more concerned.
Hi DDay
Thank you for your feedback. We decided to build a wall and put the plumbing up through it. This shower is our main ensuite shower so we wanted to ensure everything worked well. Thanks for your advice, much appreciated.
Sue,
Last week I had a line freeze when our temperatures dipped below zero for a few days. With this experience, I'd never put a line in an exterior wall. The pipe was insulated. The cavity was insulated, and the pipe was placed close to the interior wall. In the future I'd come up through the floor. Why worry about the possibility of frozen pipes?
Jeff
You obviously have a heat loss/air infiltration issue that you have not successfully
cured, and probably accounts for some lost $ on your heating bill.
Safe play to come up thru the floor, in your case.
Yes, but I'm puzzled since the line only runs for 3 feet on the exterior wall. My guess is the Z flashing is where the cold enters.