Water pipes in exterior wall

saikosis

The previous owners of our house hired someone to renovate the kitchen and a bathroom that's above the kitchen. Both the bathroom and the kitchen are served with water by the same branch. The hot line and the cold line come from the basement into a crawlspace under the kitchen. From the crawlspace, the hot and cold go up through an interior wall to the bathroom on the second floor. From the bathroom, they go back down to the first floor through an interior wall, but then they go into an exterior wall over to the kitchen sink and dishwasher.

The insulation (if any) on the lines in that exterior wall is not sufficient to prevent them from freezing when the temperature outside is in the teens or below. The bathroom water flows fine because it's all interior so nothing freezes, but the kitchen freezes thanks to that last run in the exterior wall. The contractor didn't care enough to do it right. The inspector didn't care that it was done right. The homeowners weren't paying attention enough to notice it wasn't done right.

If I didn't have the bathroom in the middle, the fix would be pretty easy, I think. I could just cut the existing lines and then run new insulated lines directly to the kitchen sink through the crawlspace. The bathroom in the middle complicates things though. Even if I run new lines for the kitchen, I still need to cap the existing lines after they serve the bathroom but before they head into the exterior wall. Otherwise, I'd still have pipes connected to the main in that exterior wall that could freeze and burst.

The bathroom sink is on the interior wall where the water lines come up from the crawlspace, but the shower and tub (which are separate from each other) are served through lines under the bathroom's tile floor. I don't know how things in the bathroom are connected. I also don't know exactly where the lines come back down into the kitchen walls or exactly what route they take to the exterior wall. The previous homeowners left us some pictures of the renovation, but they don't show the important bits. They were "look at our new kitchen" kind of pictures, not "I'm going to document exactly where everything is so I can fix problems later" kind of pictures.

I'd have to rip off the siding on the exterior wall or rip apart the interior wall or rip up the bathroom floor to find a place to cut the lines after the stuff in the bathroom but before the lines go off to the kitchen. Once the bathroom lines were capped in an interior place, I wouldn't have to worry about the now-dead lines in the exterior wall. Then, I could run new lines to the kitchen through the crawlspace. I'm worried though that finding a place to cut would be expensive and destructive. There's tile floors and antique wood floors and custom cabinets and countertops.

One idea I had was to add a circulator. If I added lines from under the kitchen sink down through the floor into the crawlspace and back to the basement, I could keep the water circulating in a loop from the basement to the bathroom to the kitchen and back to the basement. I think that would probably prevent freezing. This would also have the benefit of keeping hot water in the lines so that we didn't have to wait as long for the water in the shower or the kitchen sink to get hot.

What do you think? Would a slow circulator prevent freezing? Would it be less expensive that exploratory demolition to find the water lines? Would it be code compliant?

109A_5

Hello saikosis,

If they are copper or galvanized, you may have a flood, PEX may survive. I would get them in an inside wall. Abandon the part that is in the outside wall. Find another path for the ones that went through the outside wall. If the crawlspace ones can freeze too I would insulate under them to the warmer kitchen floor.

If the pump fails at a bad time you are back to frozen pipes and possible damage.

Until it gets resolved let the faucet drip when it is too cold outside.

Jamie Hall

Well… leave the inspector out of it. If the work met code, he had to pass it — and there's nothing in code to prevent putting pipes in the exterior walls.

Now. Circulation may be your best bet, with a proviso: you will need to arrange the circulation, with a pump and a mixing valve, so that the return temperature from the hot and cold loop in the outside wall stays above 40 F. It would be nice to think that just moving the water would prevent freezing — but it won't. I'd really have to look over all the plumbing to figure out just where to put the needed cross connections from hot to cold, and where to put a pump and what valves were needed so that you could circulate enough hot to the kitchen and then back through the kitchen cold water line, but still get cold water when you needed it. It can be done, but it's going to take some ingenuity…

EBEBRATT-Ed

Pumps would probably fix it but anything mechanical can quit.

Don't know your location but how often do you get into freezing situations?

Do you think it just freezes under the sink or in the wall?

I guess the most difficult part would be to find out where to cut and cap the existing

Maybe a IR thermometer would help find the hot water pie the cold is probably near it.

That is a tough one.

hot_rod

it may cost a bit of energy to circulate hot water through a cold space, it becomes a hydronic loop. But it may be the lesser of two problems.

How much redundancy is enough? If the pump fails for even a few hours you may still freeze up.

I'd do all you can to reroute lines to warm spaces.

saikosis

No code that prevents an uninsulated or underinsulated pipe in an exterior wall in Massachusetts? Okay, then I retract my ire at the inspector and instead direct it at the code writers. Regardless…

After the pipes froze the first time and I got a rough idea of the extent of the problem from the old renovation photos, I realized that a proper fix was going to be complicated and expensive. As a temporary fix, I spliced in a pair of shutoff values and male quick coupler nipple on each line just before they go into the crawlspace. When we're expecting really cold weather, I'll shut off the valve for water supply, open the valve for the nipple, and use an air compressor to blow out the lines before we go to bed for the night. I leave the sink and nipples wide open overnight so any residual water has space to expand if it freezes. In the morning, I close the valve for the nipple and open the valve for the supply. The rush of fresh, above-freezing water from the basement into the lines in the morning clears out anything that froze in the pipes overnight. It's a hassle, but it works, and it's much cheaper than the demo required to do it right.

When it's going to be below freezing but not super cold, I don't bother with the compressor and just leave the cabinets open in the kitchen. I thought I could get away with the cabinet thing last night, but it was colder than expected and the cold line froze. I put a space heater under the cabinets and the water is running again. No burst, thankfully, but who knows what condition the pipe is in.

I would love to fix this properly. I think that would mean separating the bathroom and kitchen supply. The bathroom should have a set of lines that go through the interior walls. The kitchen should have its own set of insulated lines through the crawlspace, maybe with some heat wrap for extra precaution. The crawlspace isn't heated. However, it does have some uninsulated steam pipes that serve the kitchen, bathroom, and bedroom above. It's also open to the basement which has some warm air from the boiler and steam pipes. And the crawlspace walls and kitchen floor are spray foamed. It's cold, but not as cold as that exterior wall.

I was thinking the circulator might be more convenient than having to shut off the water overnight. I see what you're saying though about maybe having to mix in some hot water to keep the circulated water above freezing. I was thinking that keeping it running would be enough, but, if the loop isn't exposed to some warm water, it's going to keep dropping in temperature and could still freeze.

I may need to just get through this winter and then tackle this when it's warmer out. I guess I can start with the drywall and hope I get lucky finding a good place to make the cut. After drywall, the next easiest thing might be to remove the kitchen cabinets? Tile floor is maybe next? After that, I think I'd have to start praying that I can get the counters off without breaking them. Using an IR gun now is probably smart. Hopefully the contrast between cold weather outside and hot pipe inside will let me find the path in the exterior wall.

109A_5

Now I have not seen your situation but disturbing Siding, Tile flooring, Kitchen cabinets, Kitchen counters seems like a lot of drama. I would try to find a warm path that just deals with drywall. More like surgery not a bulldozer.

Pipes in an outside wall is just a problem waiting to happen, severely cold weather and high winds will find your pipes if they are not in an inside wall.

saikosis

Drywall would be easiest, but I may not get lucky. There's a small patch in the kitchen ceiling that's directly under the bathroom. If the pipes aren't there, then that means they're above the kitchen cabinets / under the bathroom tile floor, or behind the tiled bathroom wall / behind the builtins in the bedroom, etc.

pecmsg

Code is minimum standard.
Sometimes pipes need to be run that way.
Just take the necessary precautions.
As close to the interior as possible

Spray foam insulation in that cavity

Install the hot and cold close together and insulate as one

Heat tape and plug in if needed

hot_rod

We have run H&C lines under cabinet kick spaces also if you cabinets are configured to get the lines into them without going through a cold space? A L shape cabinet layout perhaps.