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Prashun Patel
01-02-2018, 12:03 PM
My bathroom is above my garage. The water pipes have frozen and I'd like to have the ceiling in the garage better insulated. I'm getting conflicting information:

Some say to insulate the ceiling below the pipes so that the pipes retain the heat from the interior of the house.

Others say this is hogwash, and that heat rises, and that the best (for a finished ceiling) is to blow in cellulose and block all air movemement, thereby insulating the pipes from everything.

Thoughts from the experts?

I'm also planning to install a 220v electric heater as extra insurance (excuse to run 220 to my garage for some tools).

Harry Hagan
01-02-2018, 12:15 PM
1. Your first priority is to make sure the pipes haven't burst from the freezing and if so, turn off the water supply so that you can mitigate the ensuing water damage.

2. If you keep your garage heated, don't insulate the ceiling. If you don't, insulate!

Pat Barry
01-02-2018, 12:20 PM
Insulate below the pipes. You want them protected from the cold garage environment. Question: do your floors feel cold in the space above the garage? If so, they are not very well insulated. If they feel warm and your pipes are freezing, then the pipes are exposed too much and not getting any beneficial heat loss through the floor to keep your pipes from freezing.

Dave Anderson NH
01-02-2018, 12:37 PM
One of the best insulations for pipes is the type made of closed cell foam which slips around a pipe. These typically come in 6 foot or 8 foot lengths. The most common color is a light gray. You slip them over the pipe and then use duct tape along the seam which runs the length of the insulation. I also used them at one time to insulate cold water pipes in my basement to prevent condensation drips during the summer months. After using the pipe insulation you can then add further insurance by using fiberglass in between the floor joists.

Perry Hilbert Jr
01-02-2018, 1:24 PM
Had idiots for clients that left a basement window open for the cat. Every pipe froze and burst leaving me with 7 inches of water on the floor. If you need to replace the pipes, use pex with the crimps. It can take some freezing without bursting. Insulate the pipes from any cold source. Above, below or to the side. If heat from the house gets to the pipes, fine. If they are isolated from the heat, nothing will help stop freezing, but might delay it. Leave the fixtures drip in suc cold, the constant supply of water helps prevent freezing.

Prashun Patel
01-02-2018, 1:31 PM
Thanks, guys. The contractors are telling me they suggest blow-in insulation from below. Least invasive, and effective. I am inclined to do that. Anyone have experience?

I've also heard that the reason this happens over time is that batt insulation settles opening up space to above it which will then be exposed to an uninsulated wall. Blow in will fill the space and prevent this.

I have foam around the pipes. It has not helped. Pipes burst once. I don't mind spending the money to mitigate the problem and make the upstairs space more comfortable, but I want to be smart about it.

Tom M King
01-02-2018, 3:14 PM
Hot air rises over colder air, but heat flows from warm to cold. Heat does not rise. Blow in should be some better, but may still not be enough. For an upstairs bathroom that we seldom use, I plumbed it so the pipes can be drained. For any cutoff, or bypass, I like quarter turn ball valves better than the old washer type.

Pat Barry
01-02-2018, 3:21 PM
Hot air rises over colder air, but heat flows from warm to cold. Heat does not rise. Blow in should be some better, but may still not be enough. For an upstairs bathroom that we seldom use, I plumbed it so the pipes can be drained. For any cutoff, or bypass, I like quarter turn ball valves better than the old washer type.
This is one of the reasons I suggested insulation BELOW the pipes. Insulating around the pipes might be less effective. Another idea is to install heating wires on the pipes. These have a built in temperature sensor and only turn on the heat if the temperature is below 37F or something like that. I installed these at my cabin and they have been beneficial in preventing frozen pipes. These heat tapes come in various lengths and they don't suck a lot of current as I recall. Insulating with the heat tape might be the ticket for you.

roger wiegand
01-02-2018, 3:29 PM
Assuming an unheated garage, I'd insulate the ceiling below the pipes, shooting for R21 or better -- 4" of polyiso foam, or 6" of EPS. Insulation just slows the passage of heat , doesn't stop it so your perfectly insulated space will eventually equilibrate to below freezing. In a worst case scenario I'd cut a floor register into the space from above to provide some conditioned air circulation into the bay with the pipes.

Mac McQuinn
01-02-2018, 3:45 PM
A couple years ago during a cold spell, I had a pipe freeze although did not burst. It was in the basement above a insulated ceiling tile. I pulled the tile for access, the pipe was wrapped with fiberglass which evidently didn't quite do the job. Ironically the line was not along outer edge of house, it was between second and third joist in. I stuck a fan under the tile opening and tilted it upwards, I open up a ceiling register nearby to create a warmer area near the opening and after 1/2 hour the water started to flow.
After the cold spell, I closed the tile although anytime it gets down to single digits, I open it. Good luck.

Mac

Jerome Stanek
01-02-2018, 4:07 PM
A couple years ago during a cold spell, I had a pipe freeze although did not burst. It was in the basement above a insulated ceiling tile. I pulled the tile for access, the pipe was wrapped with fiberglass which evidently didn't quite do the job. Ironically the line was not along outer edge of house, it was between second and third joist in. I stuck a fan under the tile opening and tilted it upwards, I open up a ceiling register nearby to create a warmer area near the opening and after 1/2 hour the water started to flow.
After the cold spell, I closed the tile although anytime it gets down to single digits, I open it. Good luck.

Mac

Why not replace the tile with a piece of egg crate to let the heat go up

Adam Herman
01-02-2018, 4:55 PM
I would open it up and take a look. the pipe could be run very close to the ceiling with no room for insulation to go under it. if this is the case it should not be too hard to re-plumb that section with PEX and move it up closer to the floor. blown in will be better than batts nearly every time and in every situation.

Al Launier
01-02-2018, 5:17 PM
Thanks, guys. The contractors are telling me they suggest blow-in insulation from below. Least invasive, and effective. I am inclined to do that. Anyone have experience?

I've also heard that the reason this happens over time is that batt insulation settles opening up space to above it which will then be exposed to an uninsulated wall. Blow in will fill the space and prevent this.

I have foam around the pipes. It has not helped. Pipes burst once. I don't mind spending the money to mitigate the problem and make the upstairs space more comfortable, but I want to be smart about it.

I've used the BIBS (Blown In Blanket System) insulation system throughout my house & highly recommend it. I used to think my previous 4 homes were well insulated, but definitely not well as this. Its fragmented fiberglass insulation mixed with a vapor adhesive that allows it to stick to everything, especially around piping, outlet boxes, etc. The adhesive allows it to hold onto walls, rafters & does not sag like the batts do.
"The BIBS system is a high performance insulation system that forms a seamless blanket of dense-packed fiberglass insulation that completely fills around pipes, wires and other objects inside the cavity to maximize thermal efficiency. This unique process helps eliminate costly voids and air gaps, saving you heating and cooling energy. The BIBS system provides you with the highest, full cavity effective R-values attainable on the market today."
http://www.bibs.com/overview/faqs/#toggle-id-1

Bob Bouis
01-02-2018, 6:02 PM
Why not insulate the garage instead?

Bill Jobe
01-02-2018, 7:19 PM
Hot air rises over colder air, but heat flows from warm to cold. Heat does not rise. Blow in should be some better, but may still not be enough. For an upstairs bathroom that we seldom use, I plumbed it so the pipes can be drained. For any cutoff, or bypass, I like quarter turn ball valves better than the old washer type.

I second Tim's opinion on ball valves. I never use anything else.

Mac McQuinn
01-02-2018, 8:02 PM
Why not replace the tile with a piece of egg crate to let the heat go up

Good idea, I'll check around and determine if it's available in my tile size, thanks.
Mac

Lee Schierer
01-02-2018, 9:48 PM
Insulation just slows the passage of heat , doesn't stop it so your perfectly insulated space will eventually equilibrate to below freezing. In a worst case scenario I'd cut a floor register into the space from above to provide some conditioned air circulation into the bay with the pipes.

This is not accurate. If the space above is heated continuously, the heat flow will continue as long as there is a temperature differential. As far as cutting in a floor register, unless your provide an air return, zero air flow will occur.

The normal approach is to move the pipes as close to the heated area as possible and then insulate below and around them with adequate insulation. Insulate the entire floor (ceiling) area, nit just the bay with the pipes. The higher the R value the better. You also need to insure that you seal off any air flow from the cold space so that air flow does not negate the insulation.

Jim Huelskoetter
01-02-2018, 10:06 PM
I would consider pulling the ceiling and getting closed cell foam sprayed, giving better insulation and an air barrier from exhaust gasses. But that might be tough to get done quickly during a cold spell

The existing structure has some insulation value, even if there is only the garage ceiling and floor with no insulation. The temperature at any point between the ceiling and floor will be proportional to the thermal resistance up to that point, vs the total resistance of the structure. So, if half the thermal resistance is below the pipe, then the pipe will be at half the temp difference between the ceiling and floor. That calculation shows that insulation added between the ceiling and pipe will be most effective at preventing freezing of the pipe, as others have said. Completely filling the cavity with insulation would save energy cost but insulation above the pipe would increase freezing risk.

Jim Andrew
01-03-2018, 8:27 PM
I built a house once with a bath over the garage. The plumbers put the water lines really close to the lower edge of the joists. I put the pipe insulation on the pipes, and put as much insulation under the pipes as possible, but looking back should probably have put furring strips on the joists before finishing the insulation. The plumbing froze up, and the plumber fixed it, and told the homeowner it was my fault. Nobody called me. Plumber told me about it later.

Peter Christensen
01-03-2018, 9:29 PM
If you can plumb in a second set of pipes back to the Utiliy room and put in a couple little recirculating pumps the lines will never freeze and the hot water will be instantaneous. Only need to turn it on for winters.

roger wiegand
01-04-2018, 9:01 AM
I didn't make my point clearly. I think you want to bring the pipes inside the conditioned envelope of the house, which means putting the insulation on the cold side and allowing heat transfer by whatever means into the space where the pipes are. Conduction and radiation may be sufficient, an opening will allow convection, albeit limited, as well. Burying the pipes in insulation doesn't accomplish this in an effective way. It can work, especially for copper pipes which are good conductors, if the conditions aren't very extreme, but I don't think it's the best or safest long term solution.

Prashun Patel
01-04-2018, 9:49 AM
The easiest would be to just blow insulation into the cavity without having to re-plumb. I am going to do that, and am already installing a thermostatic space heater mounted on the ceiling.

I think this is the best compromise.

Wade Lippman
01-04-2018, 5:32 PM
The easiest would be to just blow insulation into the cavity without having to re-plumb. I am going to do that, and am already installing a thermostatic space heater mounted on the ceiling.

I think this is the best compromise.

Obviously you have made your decision, but I have some questions...

This seems like a disaster waiting to happen... How long has it been like this? Has it frozen in the past.
Is your garage insulated? If not, I can't see insulating the ceiling helping much. It is more likely to prevent heat from moving down from the bathroom as preventing cold from moving up from the garage.

A friend put a pipe for a pot filler in the insulated wall between their kitchen and garage. It froze the first year and they had to put heat tape around it. Your situation is much worse.

Prashun Patel
01-04-2018, 5:49 PM
I take your point and am not being cavalier about this. The pipe has burst once in 17 years. The theory that the batt insulation under the pipe settled and allowed air flow through the cavity seems sound. If we fill the cavity with insulation that does not settle then the airflow will cease.

The suspenders to the above belt is the electric heater that I am putting in the space. So I am blocking the entry of any cold air from the side and making sure the above and below are always above freezing.

I am going into this with eyes wider open becaus of this thoughtful advice here.

Thanks.

Myk Rian
01-05-2018, 12:18 PM
Some say to insulate the ceiling below the pipes so that the pipes retain the heat from the interior of the house.
Others say this is hogwash, and that heat rises, and that the best (for a finished ceiling) is to blow in cellulose and block all air movemement, thereby insulating the pipes from everything.
Not only is it hogwash, it doesn't make any kind of sense. Leave the pipes exposed?


I'm also planning to install a 220v electric heater as extra insurance (excuse to run 220 to my garage for some tools).
I have a Dayton heater in my garage. Something like 14k-17k BTU. I keep it at 45-50.