Running pipes in unheated garage ceiling

Reply

  #1  
Old 12-23-13, 10:29 AM
M
Member
Thread Starter
Join Date: Jan 2010
Location: Chicago
Posts: 333
Received 0 Votes on 0 Posts
Running pipes in unheated garage ceiling

I am renovating my kitchen and moving the sink to an island. The kitchen is over the unheated garage (it is a townhouse). The only place to run the copper or pex is in the garage ceiling/kitchen floor. The garage ceiling has double dry wall and 6-8 inches of insulation with a vapor barrier and then 6 inches of air (where there is no pipes/ductwork). It is truss construction.

It is 16 degrees here today. It is 36-38 degrees in the ceiling above the insulation now.

My question is is it safe running copper here? Should I put heat tapes on the pipes? Pex would be easier to run, but seems like it would be more susceptible to freezing.

There are already drain pipes and heating ducts in the ceiling, but no copper.
 
Sponsored Links
  #2  
Old 12-23-13, 12:28 PM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 22,810
Received 495 Votes on 455 Posts
Why would PEX be more susceptible to freezing? If it's cold and the water is not moving they both will freeze. Copper will actually freeze sooner since it conducts heat better. The big difference is that PEX piping can expand and contract repeatedly without issue while copper may survive for a while but the stresses work harden the metal until it eventually cracks. Best would be to run PEX continuous and avoid any fittings in the unheated space.

Here in NC we go through freeze thaw cycles almost daily for several months and in my rental houses PEX has proven to be the #1 choice. In winter when my rental houses are vacant the heat is off and I leave them to freeze without draining the pipes and PEX survives year after year.
 
  #3  
Old 12-23-13, 12:35 PM
M
Member
Thread Starter
Join Date: Jan 2010
Location: Chicago
Posts: 333
Received 0 Votes on 0 Posts
The only downside I see to Pex is I don't think you can use heat tapes on them (but I'm not sure).

The upside is I would have to rip up a whole less drywall.

This is going to my kitchen, so the chances of it not being used for long periods is small. If it is 36 in there today, I am kind of concerned though. What will it be if it is 5 outside? That might put it into the freezing area.
 
  #4  
Old 12-23-13, 12:37 PM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,545
Received 93 Votes on 82 Posts
If you have trusses and 6" of empty space on top of the insulation, that is where I'd want my pipes.
 
  #5  
Old 12-23-13, 12:56 PM
M
Member
Thread Starter
Join Date: Jan 2010
Location: Chicago
Posts: 333
Received 0 Votes on 0 Posts
That is where they'd go.

Maybe this is crazy, but since the area is insulated and the only thing between it and my kitchen is plywood and hardwood, I was thinking I could put a small vent. There is already ductwork. I could add a small diverter on the vent in the kitchen floor possibly or on one of the heating vents in the trusses above the insulation to get the temp up a few degrees in really cold weather.
 
  #6  
Old 12-23-13, 01:00 PM
S
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,545
Received 93 Votes on 82 Posts
Dang - I just noticed you said above the insulation originally and that it's just above freezing in there.

Sorry, I ended up being no help.
 
  #7  
Old 12-24-13, 05:40 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 22,810
Received 495 Votes on 455 Posts
I would still go with PEX. Many people are nervous of heat tape for fire concerns but I don't like it because it's one or two more things to go wrong. If the thermostat fails or the tape goes bad you're left with a freezing pipe. If the PEX freezes the flow of water will stop. When it thaws you've got your kitchen sink back with no harm done.

Also, since it's only 36f on the warm side of the insulation then you must have cold feet and I would look carefully for gaps in the insulation. Look especially close around the perimeter at the rim joists. Renting a thermal camera is also an easy way to spot insulation problems. A half day's rental is all you'd need and while you have the camera you can check over the rest of your house.
 
Reply
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: