# Rigid XPS + Pipes, electical and Great Stuff?



## Windows on Wash (Aug 30, 2011)

It should be fine but keep in mind that any insulation that you put up on warmside wall will keep that interstitial space from getting warmed up and therefore colder and more subject to freezing.


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## Gary in WA (Mar 11, 2009)

No, you could easily have future problems. 
"I have several places where there is plumbing (1/2" copper) strapped to the wall, as well as some electrical. Based on my searches, it sounds like it should be fine to get the XPS tight to the copper, wrap in split foam, and finish the voids off with Great Stuff. Please, correct me if I am wrong...' ----- once you cut off the basement heat from the supply lines, they will/are *conducting cold* from the CMU's. With the new insulation -insulating- them from the heated side, they could easily freeze, especially at the above-grade portions of wall. With insulation/drywall in front of them, the dew-point temperature will be lowered to condense moisture more easily. depending on local conditions, the wood 2x4 will stay wet during the winter months and into summer before drying, due to new drywall/insulation. Best to put them in a frame wall or under furring, in front of required thickness of XPS to stop condensation per location for your basement; http://energycode.pnl.gov/EnergyCodeReqs/index.jsp

Gary


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## Windows on Wash (Aug 30, 2011)

He did say he would be wrapping them with split foam and then spraying them. I am assuming, perhaps foolishly, that the wrap will be all the way around. If you are just trying to clamshell it from the front and the wall side will be uninsulated, all the disastrous stuff that Gary mentioned would happen. 

Where is the house again?


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## Gary in WA (Mar 11, 2009)

Toronto...

Maybe I understood it wrong...
"fine to get the *XPS tight to the copper*, wrap in split foam"--- not tight to the split foam.

Gary


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## Windows on Wash (Aug 30, 2011)

Gary in WA said:


> Toronto...
> 
> Maybe I understood it wrong...
> "fine to get the *XPS tight to the copper*, wrap in split foam"--- not tight to the split foam.
> ...


How did you figure out he is in Toronto? Did I miss that somewhere? 

Hopefully the poster is still around to clarify his plan.


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## Gary in WA (Mar 11, 2009)

Lol; http://www.diychatroom.com/f5/ditra-osb-directly-floorboards-leave-old-underlayment-138266/

Gary


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## Windows on Wash (Aug 30, 2011)

Holy smokes...2012. I am guessing you searched that vs. remembered it.


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## domh (Jan 20, 2012)

Wow, thanks for the responses, guys. I have been on vacation and missed the replies. 

Good sleuthing... Indeed, I am in Toronto. As for clamshelling the pipes, nope I would definitely make sure to get the foam pipe wrap all the way around with the split facing the warm side.

Very little of the basement is above grade. It's almost entirely below. It is actually very temperate (nice and cool in summer and maintains a comfortable temperature in. winter, even if the heat is turned off).

But even still, if I insulate the pipes but leave them where they are, they are going to be pretty snug against the CMU. And since I am using 2" XPS, that leaves them much close to the CMU than the warm side...

For the amount of work required to move the network of pipes over and get the electrical moved (heck there'll be a new framed wall anyway) I might as well just do it. As for XPS insulation, I'm going to be posting something shortly begging for advice haha.


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## Windows on Wash (Aug 30, 2011)

Unless you get those things insulated, inside 2 inches of XPS foam, they're going to get mighty, mighty cold


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## domh (Jan 20, 2012)

Windows on Wash said:


> Unless you get those things insulated, inside 2 inches of XPS foam, they're going to get mighty, mighty cold


Oh, for sure. There's no way they're NOT getting insulated. It's more a matter of whether or not I can keep them INSIDE the 2" of insulation, as opposed to have to move them into the framed space (between the drywall and XPS).


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## domh (Jan 20, 2012)

Pipes and electrical all moved now. Next stop: insulation town. Thanks again fellas!


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## Gary in WA (Mar 11, 2009)

You're welcome, we appreciate the business!

Be sure to use unfaced XPS on the walls so as not to drive the moisture to the mud sill for rot there, or scaling on the concrete at the minimal area above-grade as you said. Use foil-faced on the wood rims to prevent summertime moisture at rim/board interface. Caulk/seal the wood joints (plate-joist-rim) before board ins. to prevent air infiltration between those. check with us on installing boards...

Gary


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## domh (Jan 20, 2012)

Gary in WA said:


> You're welcome, we appreciate the business!
> 
> Be sure to use unfaced XPS on the walls so as not to drive the moisture to the mud sill for rot there, or scaling on the concrete at the minimal area above-grade as you said. Use foil-faced on the wood rims to prevent summertime moisture at rim/board interface. Caulk/seal the wood joints (plate-joist-rim) before board ins. to prevent air infiltration between those. check with us on installing boards...
> 
> Gary


Well, here's the thing... the house is cinderblock/masonry wall atop the foundation (it was built in '67). So while I do have rim joists, they are actually flush in some places or extending a bit into the basement interior in others. I am pretty sure I can spray foam in the gaps, but since the rim joists have the masonry separating them from the exterior, is it necessary to use foil-faced?

The reason I ask is because my boards are 96". The height from the floor to the top of the rim joists is 96-3/4"... Would it be acceptable in this case to simply use the full length of the board and then spray foam the remaining gap?

Pics attached. Thanks for your advice!


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## Windows on Wash (Aug 30, 2011)

Yes on the board length. Most are left a bit short and then foamed at the top anyway.


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## Gary in WA (Mar 11, 2009)

Use canned foam at bottom/top to air seal. *Use foil-faced *on both concrete/wood rims to prevent summer/winter time moisture issues, scroll to bottom- last paragraph; http://www.buildingfoundation.umn.edu/RimJoist/rimjoistphenom.htm

Gary


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