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Reuben Saltzman: Stop throwing pantyhose on your roof!

Reuben Saltzman: January 14, 2011

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.

This post was written by Reuben Saltzman and originally published on Reuben's Structure Tech Home Inspection Blog.

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Comments (4)

Didn't you say anything other than professional steam removal is a hack method?

I am confused: (Or maybe Reuben Saltzman is confused?)

The title of the article is "Stop throwing pantyhose on your roof!"

In the article the conclusion from the experiment is "Hmm… it looks like we have a winner."

Yeah sure he does not get the purpose of the pantyhose - but he misleads everyone with the title!

The purpose: well, I can think of several reasons... One of them: Keep the salt together in a lump so you can throw the pantyhose onto the roof. No need to climb, no need to haul ladders, and all that other risky stuff.

C-L

Looks to me like Eric demonstrated pretty clearly that the panyhose method doesn't work. Looking at the pictures it doesn't seem to be melting the ice or creating a channel. Maybe it just takes longer with the panyhose. I can see the advantage of not using a ladder etc. Maybe what we need is some kind of deal on a pole that will deliver the ice on the ice dam that will eliminate the need for ladders or pantyhose.

Joe - yes, I did say anything other than steam removal is hack work. I'm not advocating the use of salt or pantyhose on the roof; I'm just comparing these two hack methods for anyone interested. I love reading about this kind of stuff, so I'm guessing there must be other people that do too.

Chagri - I didn't write that post title. My original post title was "Salt-Filled pantyhose on ice dams: not that great."