My house has some decent runs of water supply pipe in the crawlspace, and one goes to the kitchen. I am planning to insulate the pipes but wanted to see the general concensus on using rubber or PVC foam.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story

The crew discusses finding rot when remodeling, challenges installing custom shower panels, and how to prevent subs and suppliers from sabotaging builds.
Featured Video
Builder’s Advocate: An Interview With ViewrailHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
Rubber and PE insulations have comparable R values, different but not extreme. Rubber has a higher max. temperature rating, but you won't approach either one's limit in household use (unless there is a steam generator/shower). PE insulation is considerably cheaper.
Household hot water use tends to be intermittent; you don't run hot water continuously all day long. So the purpose of the insulation is to slow the loss of heat to extend the time of usefully available hot water. IMO, PE does this more cost effectively.
If it ain't broke, don't fix it, just open it up to see how it works!
Edited 12/12/2007 11:26 am ET by formula1
Not to highjack this thread but i'm planning on installing a hot water circulating loop and would like to insulate it really well. I understand that a complete, tight coverage is essential but am interested in a high performance insulation if there is such a product. Is a good installation of foam good enough? I plan on using 3/4" pex for the loop. As far as using foam. Would a tight fit around the tubing be the way to go or is an air space acceptable? Or better?
What are you trying to accomplish?
Insulating pipes in a crawlspace is always good, but if you are trying to prtect them from freezing, it is sometimes not enough. Heat trace is the sure savior of pipes in cold condtions.
Trying to keep the hot water hot ? Insulation is way down the efficiencey scale on that one IMO. A circulating loop, point of use HWH, or a small instant HWH will give you better results than the insulation. With just insulation you still have to empty the hot water pipe of cold water when your use is infrequent. BTDT, insulation didn't make a diddly's differance, and that was in a conditioned basement. Added a 5 gal. 120v HWH under the sink in the kitchen (longest run frum main HWH). Problem solved.
I could have added a circulating loop, but the point of use HWH was cheaper in labor for the HO, so he opted for that fix. We also have used that fix in several places in the commercial office facility where I work.
Dave
I've got a new plumbing installation coming up on my own house and was just thinking about pipe insulation today.
I don't plan to have a circ. loop so I am wondering if there's any benefit to me to have insulation around the HW supply lines. I know that some energy bleeds out while the hot water is traveling from the WH to the fixture, but is it enough to really make a difference?
I would think that you would maintain the heat in the lines after extended use a little longer, IE your water would be lukewarm after 15 minutes with insulation as compared to 10 minutes with no insulation.
So, in a conditioned space with no loop, is it worth the price of insulation or should that $50 be put somewhere else?
Jon Blakemore
RappahannockINC.com Fredericksburg, VA
Drop a heat vent down there. I do this in all my crawl space houses. Seal the vents, put plastic down for vapor barrier and if you're feeling real ambitious, run rigid insulation along the exterior walls covered in drywall for fire protection.
pipe insulation improvement
I am finally getting around to copper re-piping my house. While running the hot water lines I got to thinking about the insulation I am using and comments I read about heat loss. I am running a thermal loop so it is important that I do insulate. In an effort to increase the life span and thermal efficiency of the polyethylene foam, I came up with an idea that might help. I wrapped the pipe with two layers of fiberglass drywall tape which adds a small air space between the pipe and insulation. I wound the tape in a steep spiral so there was little overlapping and less tape was needed. The second layer I wound the opposite direction. On long straight runs, I wrapped the pipe before hanging and soldering. I just pulled back the tape while soldering and finished it up when the pipe cooled. The adhesive on the tape is just righ to hold it in place, though I did use sparay adhesive at times on the ends.
Anal? Maybe, but it was quick and cheap and could only help.