Insulating Steam Heat Pipes

Category: Do it Yourself

Although our gas usage has decreased from this time last year, our energy bill has not.  Rising gas prices have cancelled out any savings I was hoping for, but at least we're not paying MORE this year (yet) which is a relief.

Part of that is due to the insulation on the second floor, some credit goes to the weatherstripping and insulation around the windows, but I am still not satisfied.  Our basement was far, FAR too warm last year from the steam heat pipes running hither and yon.  Since we don't live in the basement, I selfishly wanted that heat for upstairs.  So, I decided to insulate the pipes.


Before I could purchase insulation, I had to measure all of the exposed pipe to determine its diameter and the length of insulation I would need for each exposed run of pipe.  I drew a little sketch of the exposed pipe in the basement and how long each run was.

Just that activity tired me out.  Seven months pregnant and sharing things like lungs and other organs with the kidlet make me feel like I am living at high altitudes now.  I still had more steps to accomplish, even though I was already exhausted.

On to figuring out the different diameters of to determine that?  My eyes blurry with fatigue, I grabbed a piece of string and a measuring tape.  Then I wrapped the string around different pipes, figured out the amount of string that would wrap around the pipe once, and then I measured the string.  In a daze, I guessed that let me off of the hook and went immediately to bed.

Day two and I'm at one of my absolutely favorite hardware stores in Chicago, Clark-Devon Hardware.  (Also a favorite with Chicago Two-Flat.)  Why is it my favorite?  You can get anything there...anything.  I swear to you.  Need an ancient, obscure part for your steam radiator/1920's toilet/ancient wood storm windows?  Yeah, they have it.  And they know what to do with it, too.

So, I hit the counter, all ready with my drawings and calculations and excited to begin.  The helpful hardware guru looks at my paper and asks, "Are you SURE that these pipes are 6.5 inches in diameter?!"

Um, no.  That would be circumference.  And my father, reading this, is now clutching at his heart in agony.  "No, no, no!"  Because I was supposed to be the math geek and now I'm standing in a hardware store, belly out to "yar", with a brain addled by mom-nesia.  What is the calculation again?  How can I calculate diameter from circumference?  Where is my calculator?  What is pi again?  HAS ANYONE SEEN MY BRAIN?!  Anyone?  Bueller?

The guys behind the counter were very busy and I was on my own to figure it out.  So, I borrowed  a pen and paper, and got to work trying to salvage my dignity.  Um...this wasn't working.  Because the material that a pipe is made of is thicker than a circle on a page in a math book.  So, while the INTERNAL diameter of a pipe may be 1.5 inches, this does not match up neatly with its EXTERNAL circumference using pi and my nifty calculations.  Finally, I borrowed a twist tie and a folding ruler, and just headed into the plumbing aisle with my twist tie to figure out which pipe had the circumference I was using.  Sometimes, you just gotta punt.

Installing the insulation wasn't as difficult as calculating the diameter of the pipe.


Fiberglass pipe insulation is made from inorganic glass fibers bonded with a thermosetting resin.  It is jacketed with a high intensity white kraft paper bonded to a metallized polyester film reinforced with tri-directional fiberglass.  It comes in larger sizes than the polyethylene or neoprene foam pipe sleeves in most big box hardware stores.  (Those sizes are terrific for hot water pipes.  Also handy for making lightsabers, apparently.) 

You just measure, cut to fit with a straight edge, and wrap the fiberglass around the pipe.  The jacket comes with an adhesive strip that seals everything up neatly.


 Now, I'm actually hoping that the basement is colder than the first floor.  I'm also anxious to see how much this works!  Now, on to blanketing the hot water heater.

p.s. Please don't ask me about my personal circumference.  I would need a MUCH bigger piece of string.

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Bad news, mommy-brain is not completely cured by childbirth! Sorry.

We'll be heading to one of the big box stores this weekend to purchase more insulation for our attic ... gotta keep that heat inside!

With Miss Pink only 13 months old, I remember, very well, how you're feeling these days--and I certainly wasn't doing anything as labor-intensive (no pun intended) as insulating pipes.

Just remember, this too shall pass and someday you'll actually be nostalgic for how big you were. But, sadly, the mommy brain never really goes away. I still have a major fog half the time. But it's worth it for the sticky kisses!

I swear at age 40-something now looking back at my pregnancys 16-19 years ago I realize my brain has been in permanent fog. This has something to do with being a mother all these years. Of course, it's worth it all the way. Coffee helps. Good for you insulating those pipes!

Insulation on the Brain..

I am currently insulating the gap between the house and foundation in an effort to not repeat the $125 gas bill for October.. (it was warm in October) Trashy Plastic on the windows, thermal drapes, I am willing to trade aestetics (sp?) for saving money on heat.

WE also used to make those lightsabers. I got the pattern from a friend of mine. We would use the pipe insulations and sew a fabric sleeve for it, with a different color for the handle, we left the pipe out of the middle. They were about 3 feet long and the kids loved them for the pirate themed birthday party I made them for. You can beat on somebody merciless with them and it doesn't hurt.. It looks merciless but it doesn't hurt. Great way to take out agressions!

I notice from the photo that you were handling these fiberglass pipe insulation without gloves or a dust mask of any sort? Did that work out ok, or did you end up getting irritated by the fiberglass?

I'm about to go through this myself (though my wife is the one who is pregnant, 5.5 months in her case).

Well, I would always advise people to play it more safe than I do. Better safe than sorry.

In other news, I was protected from the fiberglass on hands thing by the tape wrapped around the insulation. I was just careful not to touch it. And the insulation was pre-cut to 3 foot lengths that open like a hinge...not very much cutting of fiberglass meant that I was not (knowingly) irritated "lung-wise". However, in hindsight, I wish I had worn a mask, if only to make sure.

Faith, our energy usage has gone down but it could also be attributed to milder weather than usual, the new insulation in the attic and better weatherstripping on the windows! Since we just insulated the steam pipes, I'm not sure how long it will take for us to figure out how much the insulation is contributing. We definitely have been able to keep the thermostat turned down more this year than last year. There is less "banging" in the pipes in the basement (knocking is caused by colder condensation meeting warm steam in the pipes).

I guess the only indication of "is it working?" this soon is that the basement ISN'T toasty warm like it was last year. Which indicates to me that the heat is going somewhere OTHER than the basement, when it goes anywhere at all. Strangely, this has ALSO coincided with us escaping the "smelly basement syndrome" we had when standing water in the basement drains was evaporating last year and letting sewer gases in. Perhaps less heat in the basement has slowed down the evaporation process in the drains...all good for me.

Good luck with whatever you decide to do.

Aren't those fiber glass insulators dangerous to inhale? I certainly wouldn't want my children playing w/light sabres made of fiber glass. You all should read these articles...

Thanks for posting your work with insulating your steam pipes. I've found very little practical info on 'do it yourself' refitting.

Did you tackle insulating the pipe elbows or just leave them exposed?

i'm so happy i found your blog - i've been beating my google search senseless looking for foam insullation sleaves with a diameter large enough for my boiler --> radiator pipes. is there a specific brand of insulation you used?


How fantastic that you did this. This will be one of our first home improvement projects after we close on our 1920s Bungalow. Glad to see that it can be done and that we, as fairly inexperienced homeowners, might have no problem doing it. :) thankyou!

Hi, I'm about to do this too, our basement is about 90 degrees in the winter! Have you noticed any significant savings from putting the insulation on the pipes?

GREAT info. Now I want to know about your attic insulation. Do you have a "regular" attic that you walk up stairs to get to? Or, is it a crowl space?

Have you saved the heat like expected?


Thanks for sharing your experience! We are working on insulating our steam pipes with fiberglass but can't figure out a system for insulating the corners and T's. I've heard that you can buy pre-cut but that they are very expensive. Did you insulate your corners or just the straight-aways? If so, how did you do it? I would love any advice you have! Thanks! Rachel

For those asking about the corners, here is a site that shows what you do there. It's a flexible PVC shell that goes over a piece of flexible insulation that wraps the corner. They are sized to the pipes you're insulating. You can get a white vinyl tape to cover the edges and if you take your time you can have a very professional looking and performing job when finished. And yes, It can make a huge temperature difference in the basement. The lower temps down there really are proof of it!

Check out:

Good luck, Rich L


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