I am finally getting ready to tackle a project I have been dragging my feet on for a while.

I need to replace the 1950 old galvanized supply pipe that runs to a unit on the other side of the building. That run is about 50' long.

However it is an extremely difficult path because of concrete driveways and a lot of tree roots along the way. If I do it below ground I will need to do a lot of hard digging, saw cutting concrete, jetting under concrete walkways, chopping off lots of tree roots etc...

I am contemplating a plan B, which is to run the pipe UP the exterior wall, then enter the attic, shoot across the ENTIRE attic, exits the attic to the other side of the exterior wall, and down to meet where the original pipe enters the house.

Is this a bad idea? If so, why?

with the exception of critters chewing on the pipe, it sounds good to me.

If the supply line will be supplying a different unit than the one you're running the attic pipe in I suggest going as large of pipe as you can afford due to not having your tenants who live in the unit below the pipes having to hear water running. The larger the pipe the slower the travel speed of the water which means less sound. Also I recommend insulating the pipes in the attic

Of course the outside pipes going up the wall will not look good and as you know any water pipes exposed to the sun need to be metal or protected from uv rays.

I would go thru the attic, but Vic is right -- noise may be a consideration. Holdrite makes an isolation strap. They might help. Reaming the pipe might help a little too.

[holdrite.com]



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I didn't think of the potential noise issue. Thanks vic for the heads up.

I have a better sketch of the layout to explain things further. In the diagram below, the water meter is at the property corner. There is a newer 1" pipe that runs from the meter to the corner, where there is a tee. Then the 1" runs to the right side and changes to 3/4" copper before it enters UNIT A. Unit A is getting good volume and pressure. That blue line 1" PVC is about a 30' run total.

At the property corner the branch of the tee reduces to 3/4", and ties to the old original 1950 3/4" galvanized line (in green) that runs across the front the turns to the left wall and transitions to 3/4" copper before entering Unit B. That run from the tee to the riser is about 50' long. It is under 4" of concrete. Much of the front of the property is under concrete. Where it's not concrete, it's planters with plants that must be all torn out to dig down.



The red line represents my thinking of how it may work. I can abandon the green line completely, and add a tee to run up the wall, across the attic, and down the wall again to connect to where the pipe enters Unit B. That will lengthen the run from 50' to about 70'. A 20' increase. So the longer run is a concern.

The noise is also a concern since it will be running past Unit A above to get to Unit B.

A third concern is what kind of pipes do I use. I think I HAVE to use copper. Either 3/4" or 1". Either way, that means I have to solder inside the attic. At this time, the attic in a Miami house is about 130 degrees. It is full of blown insulation, and it's tight and low head room. I seriously wonder if I could start a fire in here.



I could consider soldering outside. In other words, drill a hole on the exterior wall, slide a 10' long pipe inside, then solder on another 10' piece on a ladder, I will have to rig up some contraption to support the second piece horizontally as I solder, once done, slide the section in, and repeat. It's cumbersome, and I have to run to the attic and back to the outside multiple times, but it's doable, I think.

If I am to pass the pipe through the attic, should I go high (mount near the hip of the roof framing) or low (mount over the bottom rafters)? Will mounting higher reduce the noise? That may also have the benefit of less likely for someone to step on the pipe while working in the attic and break a joint.



Of course, I can also consider soft tubing so a joint is not needed, but I have had problems before trying to uncoil and straighten 3/4" tubing before, let alone 1". I think 1" soft tubing 60' lengths would be VERY expensive. I haven't checked yet.



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If you run it high you will be supplying VERY warm water.



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

copper up the wall and into the building. Then transition to 1" PEX off a roll or 20 ft. lengths.

Always use type L copper.

Do you have any experience soldering brass PEX adapter to copper? There's very little room for error in the procedure.



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I am hesitant to use PEX in attics. We have cases of rodents chewing through PEX.

one of my lines to my customers is that a rodent infestation is worse than a water leak.

I would suggest you seal off the building properly, kill any rodent residents and run PEX pipe. 1" Uponor wall is fairly thick and if you properly insulate with 1" wall insulation they would have their work cut out to cut into pipe. BUT again there shouldn't be rodents in your attic. bad in so many ways.

I guess if you don't have that many solder joints copper might not be a bad option. Just don't burn down that place doing it or invest in a copper crimping method.

NP16, I don't mean I have rodents now. I don't. I just mean I feel nervous about PEX inside attics because I hear about rodents chewing through them.

If I have rodents inside, and I did have a property that had some rodents inside due to a soffit vent screening being damaged, and all that was needed was a bait placed inside the attic, which they told me once ingested would cause the rodent to want to drink a lot of water, which causes the rodent to get out of the attic to find a water source, and eventually die outside of the house. But a damaged PEX would cause a burst and then we have leaks from ceilings, walls, ruined insulation, molds remediation and all that will be much more costly then rodents. Of course, copper could burst too if someone walks on a joint or drill a hole from below to mount something and hit the copper without knowing.

One thing I am curious is my understanding that PEX cannot be used in the exterior, in my case, going from OUTSIDE -> INSIDE > OUTSIDE...is that stretch of pipe inside the attic considered part of the "OUTSIDE RUN" or inside technically?

OK so these are the potential issues with going through the attic:

Noise over unit A when unit B is using water
The water sitting inside the pipe will be very warm
Potential fire hazard if copper pipes are used when soldering inside the attic with very flammable insulation

That seems to sum (no pun intended) it up. Only other issue I can think of is that it might be (for others reading this post and possibly taking it out of context) is that if unit A and B are not on the same legal lot and at no time in the future could the units become stand-alone properties that could be sold seperately.

Vic, I don't think the two units may be standalone units (condo conversion) in the future. However even if that were to happen, attics are considered common space (at least down here in FL), there are existing wiring, coax cables, CAT5 cables, even the main power cables from the meter to the panel of unit B runs through the attic space above unit A.

That being said, I think even though there isn't a "show stopper" issue, all the lesser issues, when considered all together, does add up to a bigger big con. I think I am now leaning towards doing it the conventional way, put it underground, even if it means I will be cutting up a concrete driveway in two places.

"I think I am now leaning towards doing it the conventional way, put it underground, even if it means I will be cutting up a concrete driveway in two places" I totally agree with this recommendation.