R-Value needed

What is the R-Value of insulation needed between plumbing and outside wall if plumbing is running in an exterior wall?

This is in Michigan.

Thanks in advance.

I don't consider it a true exterior wall. It separates the insulated garage from the rest of the house.

I have 2 inches between the plumbing and where the inside of the drywall will be. Would it be code to spray foam (r-7 per inch) that one stud space to get r-14 or according to the inspector I have to either make that one stud space thicker or move the pex to a different wall. I really don't want to change the thickness of the wall as that will not look so nice in the garage.

r value

At this point it is not a code issue, it is an inspector issue, so you have to run it by him. If you do it and he doesn't like it you will still have to move the PEX or change the wall.

Keep in mind that insulation does not stop heat movement, it only slows it down nor does it make heat. If it is a really cold day, you leave the gargage door open, it's windy, etc., or go away and lower the thermostat, the pipes in an exterior wall may freeze - then, when they thaw, big problems.

jadnashua said:

Keep in mind that insulation does not stop heat movement, it only slows it down nor does it make heat. If it is a really cold day, you leave the gargage door open, it's windy, etc., or go away and lower the thermostat, the pipes in an exterior wall may freeze - then, when they thaw, big problems.

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At least I am using pex and not copper

hj said:

At this point it is not a code issue, it is an inspector issue, so you have to run it by him. If you do it and he doesn't like it you will still have to move the PEX or change the wall.

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Shouldn't there be a code for the amount of r-value needed rather than just pleasing a guy who does not do his job right? This inspector signed the inspection sheet stating the drains passed a water test when he did not have me test them? I had all the equipment on site to either water test or air test. I water tested before hand so I know it holds water but he did not even ask.

In my book signing that document they tested good is FRAUD!!! I guess I should not expect anything more from a city worker. I will have to wait to get my green sticker before bringing that issue up to the city.

I agree.

HJ is also right too.

Jadnashua is also right.

Do the best job of insulating that you can, and remember that insulation doesn't keep pipes warm -- it slows the transfer of heat towards cold areas, and cold towards warmer areas, and nothing more.

R values often have little bearing on real life applications. I have posted about this before. At some time far in the future human society will have evolved to the point where we can produce heat-transfer metrics that are reliable in real life situations, as well as code requirements that define well enough what to do in what situation, that all this will be meaningful and reliable. Our civilization is still years away from this, as far as heat-transfer insulation is concerned. This is one subject I know enough about, to say this in this way.

Do the best you can and don't sweat it after that. You have 2 inches of space and the garage is on the other side so that is great.


David

contrary to popular belief, insulation does not keep pipes from freezing. It just slows down the process. If you don't have an adequate heat source to keep the pipe from freezing, it's going to. We never put pipes in outside walls. As for it being a garage wall, what happens when the door gets left open and it's 10 degrees outside?

I have never managed to get my KT-200 to thaw a PEX tube yet...
Seems I can't get a good connection for some reason...

Redwood said:

I have never managed to get my HT-200 to thaw a PEX tube yet...
Seems I can't get a good connection for some reason...

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What is an HT-200?



All good points...I'll add the 2x4s and get r-19.

Thanks for the advice.

Sorry I typo'd... Its KT-200!



PEX is non-conductive so the KT-200 will not work on it. If PEX is frozen there is no indirect way to thaw it.

I would instead bring the supplies up through the floor to avoid possible freezing. Drains may go in the wall as they drain dry after use so they will not normally freeze.

thawer

That is because you are using the METAL alligator clips. PEX tubing requires the PLASTIC ones. If the code mandated an R value for insulation and the pipes froze you would have a good case for damages, except for the fact that they stamp the plans relieving themselves of any liability if they approved something erroneously.

I'll have to find some of those plastic alligator clip before this winter. I believe the current oil prices will have us in for a bonus year on pipe thawing and I'd hate to miss out on thawing PEX. LOL