Replies

1. Expert Member
   MALCOLM TAYLOR | Jan 10, 2016 05:56pm | #1

   Brian, You insulation plan is fine. Don't put that duct in though. You don't want or need to pressurize that joist space. If R-50 insulation doesn't keep those supply lines warm enough you must live on the the dark side of the moon.

2. 
   charlie_sullivan | Jan 10, 2016 07:58pm | #2

   Brian,

   As Malcolm says this is overkill. Making sure things work well is always good, but the spray foam won't actually give you any better performance than cellulose, because the thermal performance is limited by the thermal bridging through the joists. So it's a waste of money to use spray foam there, and irresponsible to use it given its high global warming impact.

   Unless you are in fact on the moon, in which case some atmospheric greenhouse effect might be welcome.

   As long as the pipe is much closer to the floor above than to the outdoors, it will be fine, even without the open air space and air supply. Specific est

   But that looks like just a water supply line. What about the drains? A shower trap usually drops pretty low into the floor. Do you need that in the overhang area?

3. 
   gioberg | Jan 10, 2016 09:12pm | #3

   Charlie and Malcolm - Thank you for the feedback.

   The area described is directly on Lake Erie where winter weather tends to be more harsh, including gusty, driving winds. While I realize R-50 may be overkill I'd rather be safe than sorry.

   Charlie - yes there will be bathtub drain I just didn't include it in my drawing.

   Thanks again for your responses.

4. Expert Member
   MALCOLM TAYLOR | Jan 10, 2016 09:54pm | #4

   Brian,
   I didn't mean to sound like the insulation was excessive. I'd do much as you suggest. The last thing you want to do is poke around replacing cracked pipes. I'd just avoid trying to heat the space with a duct. Good luck!

5. 
   charlie_sullivan | Jan 10, 2016 10:37pm | #5

   The bathtub drain will be more of a challenge. I'm not very knowledgeable about plumbing code for drains, so I'd consult with a plumber sooner rather than later, but I think you need a p-trap close to right under the tub, and unless you want to elevate the tub, the bottom of it will be pretty low in the joist cavity. Unless you come up with a different plumbing solution, you might need to leave most of that joist cavity empty, and just lay a mineral wool batt in the bottom of it, and then have thick EPS insulation below the joists--something like 4" to 8" instead of the 2" you have shown. Avoiding the spray foam will save plenty of money to pay for the thick EPS. Unless that creates a headroom issue for the deck below.