Froze pipes in attic...replace all with pex?

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ms1780

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carterville, missouri
I am buying a HUD reposession in South West Missour. The coldest it gets here is about -5 and that is seldom seen. The house is a slab house and all the water lines are cpvc in the attic. There are several short sections, about 3' that have obviously froze in the past and been replaced with pex. I had my inspector come and as soon as we kicked on the well pump it was obvious the company that did the winterization did a very poor job. The ball valve in the main line coming in was split. I replaced that and then found another pice of 1/2" cpvc in the attic that had froze and split nearly in half long ways. The current lines run on top of the 2 x 4 ceiling joist, not thru them and the blow in is not very thick. I don't think there are very many more leaks in the cpvc or at least I did not find anymore wet insulation. I am considering replacing all the cpvc, mostly 3/4" main line with 1/2" branch lines, with pex because I have heard it will not break nearly as easy as plastic. So, do you pros think this is worth the cost and time or do you think the plastic will be okay if I add blow in and we ocupy the house? Also, if I do the pex should I drill holes in the 2 x 4 ceiling joists and put the pex closer to the sheetrock? One more thing, should I wrap the pipes, hot and/or cold with pipe insulation before I add blow in?

Thanks,

Mike
 
I only have limited experience with PEX pipe, and almost no experience with freeze proofing, as I live in Florida.

But I have heard that the PEX pipe itself is someone more resistant to splitting if it freezes than solid piping, but then there are still the metal fittings to worry about, and those will crack.

I would NOT drill holes in the ceiling joists. If this is the type of framing that I am used to, those joists carry a lot of weight from the roof, and weakening them is a really bad idea. At the best, drilling the type of joists I am thinking of could cause the ceiling to sag, and at the worst, drilling enough of them could cause a roof collapse. Not to belabor the point, but I think it is important to say once more, don't drill, notch, etc, ceiling joists if there is the slightest chance that they carry the load of the roof.

As far as insulation, more blown insulation can't hurt, and can only lower you heating bills. Wrapping the pipes with insulation might be a bit of overkill if you add attic insulation, but it does provide another line of defense against freezing, and will help you get slightly hotter hot water and slightly colder cold water at the faucets, so I would probably go that extra mile.
 
I would just like to add that your concern with the pipes bursting should be secondary to the pipes freezing. No matter what is installed (copper, cpvc,pex) a frozen water line is useless. A guess would be that maybe 1 in 5 of my frozen water line service calls also involve a burst pipie once the lines are thawed. If the plastic water lines freeze it becomes more labor intensive to thaw them out. So be thorough in insulating.
I would respond with the same enthusiasm as phishfood with regard to not drilling 2x4 joists. Would it be possible to strap the new water lines to the bottom of the joists and install a drop ceiling? Just throwing it out there.
 
Thanks for your responses. I agree, I should not notch the ceiling joists. The roof is constructed of what we call pre-enginered trusses. I think once we ocupy the house and have the heat on in the winter and I take some other precautions like extra blow in and pipe insulation, after we do that I think the cpvc pipes will be fine. The house is about 10 years old and only a few pipes have actually froze and been replaced and all those may have been after it was repossesed. There are also two large covered porches on the house that have vented soffet. I think I will lay batt insullation over the vented soffet in the winter and that should help too.

Thanks,

Mike
 
You could install heat tracing wire in the space that would kick on when the temperature drops below a set point, it would require an electrician to do, but It would Guarantee no burst/frozen pipes.. here in the great north Heat trace wire is used allong with insulation pipe wrap in spaces that can be exposed to elements such as attics and partitions between condo's. They are regulated with a thermostat so they dont operate all the time.

this is your best bet. Our codes dont allow use to install water lines in any exterior partition unless accompany'd by this tracer wire, and we are Not at all allowed to install water or drainage lines in exterior walls.
 
Thanks for your replies! I think I will replace the broken sections of cpvc, then wrap all the lines in the insulation pipe wrap, then wrap that with batt insulation, leaving the bottom open to allow the heat from the house to come up into it, then I will blow in celulose insullation on top of that. I will then make sure to cover the vented soffets over the large porches in the winter and the first winter I will put a thermometer up there that will store the coldest temp and keep an eye on it, maybe even leave the faucets drip on the really cold nights. We VERY seldom get below about 10 deg. F. here. Let me know if you think this is sufficient.
 
static water is most dense a 4' Celcious, it expands a little even before it freezes, so If you get even down to -4 you are looking at possiblility of pipes freezing. heat tracer wire with pipe wrap insulation would ensure no freezing and be your best bet. Remember that water in non-compressiblle, so it takes Very little expansion to cause a rupture. Insulation alone is not going to necesarrilly solve the problem, unless accompanyd by someting to heat in the event of a cold snap.

I'll point out that the R Rating of something is the time it takes in minutes to lose 1 btu of heat through 1 square inch of the material So, again if there is no heat then The insulation does little.

doing as you have said will llikely be enough, But not For SURE.

IF i were going the insulation route, Assuming now that the heat from the house will rise and keep the pipes thawed, I would buold a frost box over them. This is done up here between Separated Row houses and condos on occasion. A box is made out of plywood and 2x6 to house the pipe runs, it is lined with styrofoam basement insulation, the pipes are then wrapped in insulation, loose fill insulation to fill the voids and over the insulated pipe, and the top screwed down with insulation ( styrofoam ) over. This is buiried under frost level ( usually under 3 feet ) in the ground...... Ocasionally if the residences are not in use and there is a VERY cold stretch pipes will freeze and burst, but not often.

I would build something like that in your attic, and hope there was suficciant heat rising to do the job .

:)
 
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