[kboorman]

I have a very small powder room that I'd like to put a pedestal sink in. The supply and the waste lines come up out of the slab floor and I'd like to move them into the wall. There is an S trap in place now which I plan to replace with a P trap that is properly vented.

My problem is that my unheated garage is on the other side of the wall and I'm concerned that the pipes will freeze even if the wall is insulated. I live near Philly and we get a few cold stretches each winter.

There would be approximately 24" of the hot and cold supplies plus the waste line and vent stack in this wall that's heated on one side and unheated on the other.

Are my concerns unwarranted? If not, what can I do to make this work?

Thanks in advance, Kirk.

 

[myworkshop]

Frozen pipes

You might want to install a circulation pump. This pump installs on the water heater (hot side) and circulates hot water to the anywhere in the house. The newer ones come with a timer so you're not using it all the time.:yes:

 

[JDC]

That drain wont present a problem. The only standing water in it will be in the trap which will be inside the bathroom.

I'd move the waterlines to a point where the come up through the slab behind the pedestal. This way they are not noticable. Putting them in a wall that has an unheated space on the other side is asking for trouble.

You could bring the waterlines up then add female adapters at floor level. At this point you'd install 1/2" X 18" chrome nipples. Get a couple of 1/2" IPS deep box escusions to cover up the transition. Add a couple of straight stops and you're set. Makes for a very nice finished look.

 

[kboorman]

The circulation pump is an interesting idea, I didn't know such a thing existed. That would actually kill two birds with one stone because we have to let our water run for a while before it gets hot.

Still wondering what to do about the cold water supply though. Could I just run the hot and cold in close proximity and insulate them together? Would the hot supply give off enough warmth to keep the cold from freezing? Or would the warm water circulating from the hot supply into the cold be enough to to do the job?

My only issue with a setup like this is that the whole idea was to allow me to install a pedestal sink and I don't think I want to be able to see the sensor valve behind the pedestal.

 

[kboorman]

Thanks for the reply JDC, I was typing and researching the circulation pump as you were posting your idea.

So you don't think the waste line in the wall will be an issue? I think moving the supplies behind the pedestal would work out nicely if done as you described.

Get a couple of 1/2" IPS deep box escusions to cover up the transition.

Can you elaborate on this? I'm not familiar with these but I assume there some type of cover the will conceal the joint?

 

[RegeSullivan]

If you keep the supply lines toward the interior and insulate behind (toward the garage) it is unlikely you will ever have a problem unless the garage is completely exposed like leaving the open doors wide open in weather well below freezing overnight. Be sure the insulation goes all the way to the top of the stud cavity. It would be even better if the insulation filled the cavity above where the supply lines are. If you suspect a lot of air infiltration seal up the holes with spray foam before you insulate.

If you do this and get concerned on one of those below zero weeks just stick one of those little instant read thermometers into the wall and see what it says. Just don't poke it past the insulation.

Rege

Rege

 

[kenmac]

if you are concerned about cost.. Put a timmer on that circulation pump. If not you will be heating water. heating water cost

 

[concretemasonry]

I have a leaky (air-wise) garage door on my tuck under garage in Minnesota. My plants that I winter survive well and nothing has ever frozen in the garage.
?Do you have any idea of what the coldest temperature is in your garage. You may be surprised at how warm it is depending on the orientation, protection and the sun. Are the rooms adjacent to the garage cold?

Just running a trickle of water is common and economical during cold times. When I lived in northern Michigan, it was suggested to run a slow trickle of cold water to prevent freezing of the buried lines. The water rates were reduced and many people ended up with a credit because water is cheap even if the dewerage charge is tied into it.

Dick

 

[luke2531]

If u have heat in the powder room u will be ok as long as u insulate the wall and the pipe.

 

[JDC]

I completely and totally disagree with those who are saying the waterlines will be fine. Perhaps they will be, but you get a real good cold snap and you'll be cussing those same people while you cut a hole in your wall to fix this. I live in Ohio and have had cases of Coke freeze in my garage....WITH an insulated steel garage door. I've had to fix NUMEROUS waterlines that have burst that people thought never would. Well guess what? It happens.

I still believe the safest bet is to keep the waterlines in a heated space. The escutcheons are nothing more than deep chrome cover plates that will hide the transition from chrome nipple to copper female adapter.

 

[al's sewer]

I agree totally with JDC. The only thing I would suggest is if your sink backs up to the garage wall cut in an access panel that can be easily removed and wrap your pipe with heat tape that can be plugged in but this can be a hassel also if your heat tape goes bad and you don't realize it. also if you watch the weather closely you could just keep your faucets dripping on the nights that you will have extreme cold weather. but again if you are out of town or forget to do it it could also be a problem. My suggestion is That i agree with jdc and come up thru the slab inside the pedestal stand, then you have no worries.

 

[clasact]

Just my two cents worth but how about putting in pex.I have it through out my home starting where the water is supplyed to the house in the utiltiy room.the furnuce went out last winter and it was 16 below or near for several nights I was on the road and couldnt do anything about it.,but when I got home not one leak or broke pipe,the stuff is great.That should solve the problem and inexpensivly too

 

[Scuba_Dave]

My 1st floor bath has the shower pipes in an outside wall with R7 insulation. Kitchen sink & feed is also on an outside wall with R7 insulation
It's been this way for over 50 years never a problem

When I redid the bath I upgraded to R13 insulation
Kitchen now has an unheated garage on the other side

 

[al's sewer]

I lived and worked in the plumbing trade in the state of Maryland for 25 yrs. (a little farther south) I can remember at least 3 instances where I had frozen pipes on a garage wall that was insulated and the room was heated. If you want to do it thier way Go for it and good luck. I am just talking through experience here.

 

[RegeSullivan]

This is not a high risk situation if you do it properly. However do not not insulate the supplies lines as fast1 suggested. You want the heat from the interior to keep the pipes warm. Be sure the insulation is between the supply lines and the cold space and keep eliminate the air infiltration. I am sure if anyone would have have seen frozen pipes it is Al and he has only seen three in 25 years. There are many homes that have pipes in garage walls. Where I live in Western PA there are 54 just in my plan and about half are on slabs and half with basements.

Rege

 

[AllanJ]

If you must put a pipe inside the wall, do not put any insulation between the pipe and the interior wall surface while putting the best possible insulation between the pipe and the exterior wall surface. The space lacking insulation should be as wide at the interior wall surface as it is deep.