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Reuben Saltzman

Salt-Filled Pantyhose On Ice Dams: Not That Great

Ever since I was a teenager working at a hardware store, I’ve heard of people filling up pantyhose with salt and tossing them on their roof to create drainage channels in ice dams.  After hearing about this so many times and even seeing this method of creating drainage channels in ice dams on the news, I began to believe this actually worked.

Nevertheless, I tend to question everything, and last year I finally got around to testing this method on my own.  Instead of laying the pantyhose perpendicular to the ice dam, I laid them parallel to the ice dam in an attempt to get rid of the ice dam entirely.  As I mentioned in my blog about how to remove ice dams, this didn’t work well at all.

Several readers suggested I place the pantyhose the way everyone else does (does everyone else really do this?), perpendicular to the ice dams.  The whole idea of placing them perpendicular to the ice dams is to create drainage channels for water, so water doesn’t back up in to your house.

I tried this on a cold January day at my neighbors house (thanks for being a willing participant, Jonathan).  I was also curious as to what magical properties the pantyhose possessed.  How do pantyhose make salt so much more effective than salt alone?   Wouldn’t it work a lot faster to just put salt directly on to the ice dam?  As it turns out, yes.  This works way better.

The photos from my little experiment are below.  I filled one of the pantyhose up with “Ice Melt”, which contained a blend of calcium chloride and rock salt.  I filled the other pantyhose with an ice melting salt that didn’t have the contents labeled – I suspect it was just rock salt.  I also poured the Ice Melt in a perpendicular line along the ice dam, using far less salt than I used in either of the pantyhose.

10:00 AM (Start Time)

Salt Filled Pantyhose 10am Salt On Roof 10am

2:00 PM

Salt Filled Pantyhose 2pm Salt On Roof 2pm

4:00 PM

Salt Filled Pantyhose 4pm Salt On Roof 4pm

Hmm… it looks like we have a winner.  If you’re going to put salt on your roof, I don’t understand what the purpose of using pantyhose is.  The obvious thing here is that salt applied directly to an ice dam is far more effective than salt in a pantyhose.  So you can run and tell that.

Reuben Saltzman, Structure Tech Home Inspections – Email – Minneapolis Home Inspections

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No responses to “Salt-Filled Pantyhose On Ice Dams: Not That Great”

  1. Jim Allhiser
    January 11, 2011, 7:36 am

    Thats great Reuben!
    I love your diagnostic blogs.
    I do have a question; in your original post you wrote about how some of the techniques could damage the roofing, what about salt/ice melt?
    In my area we have to control moss, not ice. One of the popular ‘old time’ ways to kill moss is with laundry detergent. This stuff is very hard on asphalt based roofs due to the degreasers.
    I was just wondering if salt would wear the shingles in a similar manner. It is definitely hard on vehicles!

  2. Reuben C. (not the Inspector)
    January 11, 2011, 9:59 am

    This is a good data point, but I think you need to recreate the experiment in approximately 30 degree weather. I would expect the pantyhose to perform better if the water was already flowing a little bit allowing water to seep in and out of the hose. If it’s too cold out, I could see the pantyhose just acting as a barrier keeping the salt away from the ice. If it’s warmer, the existing moisture might draw the salt out. Sounds like a topic for another post!

  3. Jeff Garvey
    January 11, 2011, 12:16 pm

    I did this on my roof and I got the panty hose wet before I put them on the roof to get the salt moving. Also – I thought the reason was so that the wind would not blow the salt off – if it is in something like socks or panty hose it will still remain on the roof. If it is just thrown up there the wind could blow it off.

  4. Reuben Saltzman
    January 11, 2011, 2:27 pm

    Jim – I’ve heard people say that salt can damage roofs, but I asked another home inspector who serves on some type of roof advisory council, and he told me the salt is completely harmless. Even if it does cause damage to the roofing material, I have to think that it would be better than water coming in.

    Reuben C – (lol) I’m sure you’re right. I may try this again on a warmer day. If I do, I’ll be sure to share the results.

    Jeff – I did this experiment on a fairly windy day, but it didn’t seem to matter much.

  5. How To Get Rid Of Ice Dams | Reuben's Home Inspection Blog
    January 14, 2011, 3:08 pm

    […] to try them out and blog about it. The methods I’m going to discuss involve axes, ice picks, pantyhose, salt, heat cables, and a blowtorch.  Of course, the most effective and safe way of getting rid of […]

  6. Jamie
    January 16, 2011, 7:06 pm

    I did about 20 minute or research on Ice Dams, went out to buy a ladder, a bunch of salt and some stockings. After seeing your experiment, I feel like an idiot. I had an ice pick in my drawer the whole time…But I did need the ladder.

  7. Reuben Saltzman
    January 17, 2011, 11:26 am

    Jamie – be very careful…

  8. Peter
    January 25, 2011, 9:34 am

    My understanding of the reason for using the panty hose is not that it helps melt the ice, rather that it contains the salt-preventing runoff so that you do not need to reapply for an entire season.
    You do seem to have proven that the panty hose will slow down how quickly the salt melts ice, so probably better for a quick fix. Hopefully panty hose contained salt will eventually melt all the ice around it and prevent new ice from forming in its place winter.

  9. Matt Brodeur
    January 31, 2011, 3:27 pm

    I think the whole point of the panty hose is to be able to toss them up on the roof without needing a ladder. I just tried one myself tied to a rope so I can pull it back down again. Waiting to see how well it works for me. If it works I’m doing a whole bunch more.

  10. Dave
    February 1, 2011, 11:47 am

    The purpose of the pantyhose is to provide a way of gradually releasing the Ice melt.

    Sure, just pouring salt in a channel works quicker but it will soon wash off and the ice dam will begin building again whereas the pantyhose might not have to be refilled before spring time, so unless you like climbing ladders up to the roof every couple days it’s actually the more efficient method.

    BTW don’t use Salt, use Magnesium Chloride ice melt. It’s much less damaging to concrete side walks, front steps and foundations, not to mention roofing shingle nails.

  11. juanitogan
    February 4, 2011, 8:44 am

    Last night my tools of choice on a 7″ tall by 16″ deep ice dam was a rip hand saw and a rip claw hammer. The saw is ancient and dull but worked just fine in the ice. No doubt a bow saw would have been even faster (perhaps too fast). Anyhow, I made cuts in the dam about 3″ apart and picked out the ice with the rip claw. It was much faster and easier than my six-prong ice pick. I tried just the claw alone as well just to see the effect, but making the cuts first is definitely the easy way to go.

    I cut six channels into 37.5′ of ice dam. Salted the channels because I left at least an inch of ice in the bottom of them (it was dark and I could not see well enough to go deeper). Then put salt-stuffed stockings in four of the channels (the heavy, up-to-the-knee stockings). Overall, the hardest part was handling the ladder in the several feet of snow. From set up through tear down it took 1.5 hours.

    It was 12 degrees out and dropping so there was not much immediate response to the salt. But I’ll see today if it works and the leaks stop as the temperature is expected to creep above freezing.

    By the way, the stockings are absolutely necessary if you have to put salt on a steep slope. I don’t recommend “real” salt either but all I had last night was a sodium chloride / magnesium chloride mixture.

    This is a new house for me as of last November and I will definitely be adding much more insulation to what is probably only R6 in the attic to minimize the ice damming. There was de-icing cable installed but it looks very old and is not working and needs replacing when the weather clears.

  12. juanitogan
    February 7, 2011, 9:02 am

    An update to my previous post. The leaks had slowed significantly the morning after I cut the channels in the ice dam. The leaks stopped entirely after things warmed up and started melting more rapidly. The channels with stockings in them were completely clear of ice whereas the channels with only loose salt were not. To sum it up, this has been a success.

  13. Steve B.
    February 8, 2011, 8:07 pm

    I fail to see how a single afternoon test is proof for or against a concept. It may take days or weeks to prove one method is superior.
    Personally, I’ve thrown Calcium Chloride salt on the roof to great effect. It hasn’t eliminated the dam but eroded it rapidly. Of course it came back in the next few snowfalls. So my loose salt tests are a bandaid at best.
    My dams are too well developed to prove for or against salt in hose. Perhaps next winter I’ll try that.

  14. Tweets that mention Salt-Filled Pantyhose On Ice Dams: Not That Great | Reuben's Home Inspection Blog -- Topsy.com
    February 9, 2011, 10:09 am

    […] This post was mentioned on Twitter by Dennis N. Duce and DennisDuce, Michelle Drenckhahn. Michelle Drenckhahn said: via: @linkedin – Maybe not… http://ow.ly/3SMBX @steveminne @Micropterus: Panty hose work best. #icedams #minnesota […]

  15. barb
    February 9, 2011, 9:26 pm

    I filled knee high nylon socks with Morton action melt salt, laid them perpendicular on the ice dam
    & within 2 days a nice channel was created. Will
    it do the trick? If not, I know I will have to hire a
    steam crew to work their ” magic.” Those highly advertised salt ” pucks ” were a waste of time & $.

  16. Terry
    February 11, 2011, 4:09 pm

    Focus on the problem not the band aid. Stop the heatloss to your attics and you will not get ice dams. Air seal, insulate, and proper ventilation. No need for all the gimicks.

  17. Reuben Saltzman
    February 12, 2011, 9:20 pm

    Terry – I’ve written about how to prevent ice dams already. This post is for people who have ice dams and have been told to use salt-filled pantyhose.

  18. Reuben Saltzman
    February 12, 2011, 9:10 pm

    Peter – thanks for the input. I left that salt-filled pantyhose in place, and it currently buried in the middle of the ice dam. Maybe I was using the wrong type of pantyhose.

    Matt – very possible. That’s a good theory.

    Dave – I find that most people who do the salt-filled pantyhose thing are doing so because they have water leaking in to their house and they’re looking for a fix. If I were looking for a quick fix, I’d dump salt on my roof before using pantyhose 🙂

  19. Reuben Saltzman
    February 12, 2011, 9:15 pm

    juanitogan – thank you for the detailed account. I’m sorry to hear about your problems.

    Steve B – seriously? If you have water leaking in to your house and you want to provide a drainage channel, I think it’s quite obvious that straight-up salt (calcium chloride, or whatever) works much faster.

    If you spend days or weeks testing this and come up with any different results, please let me know.

    Barb – how’d it go?

  20. Ryan Parsons
    November 9, 2011, 9:31 am

    We experienced a terrible winter last year and have already had an October snow. We did a ton of ice dam & snow removal. Thanks for the panty hose comparison shot. We had a lot of clients asking about that, and we were not sure of the answer.

  21. juanitogan
    November 22, 2011, 9:48 am

    To stocking or not to stocking? The answer really depends on the situation. My testing last year (read my previous posts) definitely proved that stockings were beneficial in my particular situation. But I did not use stockings alone either. I used the claw of a rip hammer and loose salt to help clear the channel — but stockings were definitely required to clear the channel completely and to keep it clear for the rest of the season. I later added stockings to my non-stockinged channels after initial testing because it became stupidly obvious that loose salt washes away too quickly to maintain the channel.

    Still, it is apparent to me that the correct solution still depends on the weather and the amount of heat escaping the roof. For the stocking to be effective, there must be a way to leach the salt out of it. The only way to really do that is to keep the stocking wet. The only way to keep the stocking wet is to start the ice melting somehow. Also, powdery salts may leach better because the powder can escape the stocking easier to kick-start the process. Furthermore, different salts work differently at various temperatures which changes the game as well.

    Anyhow, back to the stocking and whether or not it works. True, if you throw a stocking of _any_ kind of salt on a block of ice in -20F weather, it is probably not going to do anything (too cold to melt with most kinds of salt). If you throw a stocking of _table_ salt on a block of ice in 0-degree weather, it is probably not going to do anything either (table salt stops working at around 0 degrees). Now imagine a stocking of salt that happens to be filled in such a way that no salt powders are escaping, and throw that on a block of ice in 25-degree weather and — guess what? — it still probably won’t do anything because there is nothing to kick start the salt leaching out of the stocking.

    Now throw a stocking of any kind of salt on a block of ice that is already wet from melting (due to either warmer weather or salt poured directly on the ice) and that stocking of salt will help cut through the ice as long as conditions remain right for the stocking to stay wet and continue leaching salt. Would loose salt melt through a block of ice faster than a stocking of salt? Sure, but only if you are lucking enough to keep the loose salt from washing away too quickly.

    Get the picture yet? If your roof is warm enough to melt snow and create just enough runoff to run down and refreeze into an ice dam at the edge, then your roof should also be warm enough to keep a salt stocking wet enough to keep it working and to keep the channel under it clear. If you don’t use a salt stocking to keep a channel clear then you would have to refill the channel several times a day with loose salt due to the runoff.

    Now… How do you create a drainage channel in a dam that has already formed? Is a salt stocking enough? Perhaps, in some cases such as if the weather is above freezing or if the sun is melting the ice — perhaps, if the stocking has lots of salt powder falling out of it — but probably not if the weather is far below freezing. In most situations, I would probably recommend loose salt to kick start the melting process and then throw a stocking on top of it to keep it going. If you can, chisel out most of the channel to help the process. Refill the stockings when needed. Then, insulate your attic better so this doesn’t happen again next year.

  22. How to Repair a Roof In the Winter - Roofing Tutor
    November 27, 2011, 10:51 am

    […] lay the legs perpendicular to the ice damn. I have to admit many folks say this doesnt work like Reubens Blog but I have used this trick many times with good results and a few giggles from the neighbors. If […]

  23. JamesR
    September 25, 2012, 5:46 am

    Using Salt? Replace your gutters and downspouts after they corrode. I have started using a recently new product called the Ice Dam Blaster (TM) Invented by a company with 30 years experience in non-corrosive airport deicing applications. There are 3 products to use depending on the severity. I have a v shape valley between house and garage that always freezes up. Put a few along there and the chemical slowly dissolves and creates the much needed brine to prevent the dam in the first place. Now available at http://www.powericemelt.com and several hardware stores.

  24. Reuben Saltzman
    September 26, 2012, 4:01 am

    JamesR – that certainly sounds better than pantyhose… and it’s a lot more expensive too. I’d love to try that product out on my old neighbor’s house.

  25. JamesR
    January 8, 2013, 6:18 am

    The old adage somehow still applies, you get what you pay for. Sure it costs a little more up front, but if it works without ruining the building materials and killing the vegetation, I’m all for it. Salt? Check your gutters and nails after several years and see if “saving” a few bucks is really going to save you anything. I’ve got better things to do than worry about some frozen gutters, the Ice Dam Blaster has solved the recurring problem once and for all!

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