PREVENTING ICE DAMS FROM THE EXTERIOR

I’ve been doing a lot of attic inspections for Minneapolis homeowners with water leaking in to their houses, and in almost every case I find obvious problems in the attic that should be addressed to either prevent or significantly reduce ice dams.  I mentioned most of the stuff that I look for in last week’s blog about preventing ice dams.

Occasionally I’ll come across a house with no attic space in the areas where heat loss is occurring, or there isn’t access to the attic areas.  In these cases, it probably isn’t cost effective to fix the problems that are causing the ice dams – the ‘repairs’ would outweigh the costs of controlling the ice dams.  In those cases, I recommend ice dam control from the exterior.

Remove The Snow

If you rake the snow off your roof, you’ll keep ice dams to a minimum.  This becomes a constant chore, but it’s better than dealing with water leaking in to your house.  Just raking the first several feet of snow from the eaves is usually enough to prevent the formation of ice dams, but in some cases, this will cause ice dams to form higher up on the roof.

I have one very low-sloped section of roof at my own house where even closed-cell foam wasn’t enough to prevent the formation of ice dams, so I get out there with a roof rake and pull the snow off my roof.  This is a perfectly safe way of removing snow, as long as you don’t get too close to your overhead power lines.

This is also a very effective way of preventing ice dams, but it won’t work 100% of the time.  This year,  for the first time ever, I actually had another ice dam begin to form higher up on my roof just past where I had stopped raking.  That was crazy.  I ended up removing almost all the snow on my roof with a super-long roof rake, and that worked very well.

For owners with two-story homes where using a roof rake from the ground isn’t practical or possible, the options are to risk your life getting up on an icy roof to shovel the snow off, hire someone else to risk their life, or install roof de-icing cables as a preventative measure.  I say go with the de-icing cables.

De-Icing Cables

Roof de-icing cables, also known as heat cables or heat tape, should be a last resort when it comes to preventing leakage from ice dams.  De-icing cables themselves aren’t cheap, it’ll cost money to have them professionally installed, and they’ll cost money to operate – between five and eight watts per foot.  On the flip side, they’re very effective; it’s pretty much a guarantee against leakage from ice dams.  They won’t prevent ice dams, but they’ll keep enough ice melted to create drainage channels for water, if installed properly.

If you choose to install roof de-icing cables yourself, here are a few tips:

• Measure the areas where you need to install your de-icing cables first, and buy appropriately sized cables.  For a simple 15′ section of roof with no overhang, a gutter, and one downspout with an extension, you will need a 60′ heating cable.
•  The cables should extend 6″ up the roof past the exterior wall line, through the gutters and downspouts, and 2/3 of the way up the valleys.
• Don’t bother removing the snow from your roof; you could damage your cables, and you could potentially create another ice dam higher up on the roof, defeating the purpose of the heating cables.
• Don’t expect the snow and ice to melt the way it does in the promotional photo above.  The photo at right, which I took at a real house, is what this stuff is going to look like.  Don’t worry, this is normal.

If fixing the causes of your ice dams isn’t a possibility and you can’t safely remove snow from your roof, install some de-icing cables or de-icing panels.  This is oftentimes the most cost-effective way to prevent leakage.

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

    

How To Get Rid Of Ice Dams

Last year at about this time I wrote a blog about ice dams, covering what needs to be done to prevent ice dams from happening, both on the inside and outside of the house.   This year I'll discuss a bunch of different ways to get rid of ice dams.  The methods involve axes, ice picks, pantyhose, salt, and heat cables.

Axe

The most obvious way to get rid of ice dams would be to just take a blunt instrument and hack away at the ice dams.  I tried an axe.

Pros: Fast results - I hacked through several feet of six-inch thick ice dams in a matter of minutes.
Cons: Unsafe and cumbersome.   I had a set up a ladder on the icy ground and swing an axe while standing on a ladder.  The ice also really flew in my face - I should have been wearing goggles!  I was only able to remove the ice down to the gutter, and only able to get close to the surface of the roof without risking damage to the shingles.
Verdict: This is a high risk, but fast and effective way of getting rid of a lot of ice, but leaves the job incomplete.

Ice Pick

Sounds like a natural choice, doesn't it?  I actually used my awl, but close enough.

Pros: Very fast results, very little effort.  It's as though this tool was made for picking at ice.  Oh, wait...  Still, I was genuinely surprised at how fast and accurate this method was.
Cons: Unsafe.  Again, I was jabbing at ice dams while standing on a ladder, which was sitting on the icy ground.  I also had to be very careful to not damage the roof.
Verdict: This is definitely my method of choice.  Nothing else worked nearly as well.

Roof Tablets

Yes, this is a product designed specifically for preventing damage from ice dams.  Contrary to the name on the container, the product doesn't actually melt your roof (whew).  The instructions say to toss the tablets on to your roof and they'll melt through the ice dams, allowing for "water to drain safely".



I tried tossing the tablets on the roof like the instructions said to do, but it didn't work out very well.  I consider my tablet tossing skills to be above average, but I still couldn't get the tablets to end up in a good location - they all just slid together in one place.  If I didn't get a ladder out to take pictures, I never would have known that the tablets didn't end up a good spot.

Just to give the roof melt tablets the best possible chance for success, I hand-placed them on the ice dam and I used about four times as much as the directions called for.

By day two, I had some pretty dramatic results - the tablets had melted all the way through the ice dam.  btw - for anyone in a southern climate that might be reading this blog, that white stuff on the ice is snow, from a very light snowfall the night before.

By the third day, not much change.  There were definite holes in the ice dam, and some channels had formed for water to drain through, but the majority of the ice was still there.
 
Pros: If you had perfect aim and tablets didn't move after you tossed them on to the roof, this would be very safe.
Cons: The tablets don't stay where they land, which negates the whole safety thing - I still had to set up a ladder on the icy ground and move the tablets around myself.  This method was also pretty ineffective - it created a bunch of holes in the ice dam, but so what?  Most of the ice dam was still there in the end.
Verdict: This might be a nice way to get down to the roof surface, and it would be nice to follow up with an ice pick after a day or two, but the tablets alone aren't great.  Sure, it's safe... but so is sitting inside a warm house.  Neither gets the job done.

Salt Filled Pantyhose

This is a simple, straight-forward approach.  Take off your pantyhose, fill 'em up with ice melt (calcium chloride or something similar), and toss 'em on your roof.  The idea is that the salt will leak through the pantyhose and eventually melt the ice dams away to nothing.   This is supposed to work better than just putting salt directly on the roof, because salt applied directly to the roof will just melt a bunch of tiny holes, much the same way the tablets melted large holes.

By day two, there were several tiny holes in the ice dam.  Whoop-de-doo.  Salt alone would have done this.

By day three, the pantyhose had started to melt in to the ice dam, and had completely melted down to the roof.   The part that hadn't melted down to the roof basically had a hard, crusty layer of salt(?) formed on the bottom of the pantyhose, and nothing else was happening.  I picked up the pantyhose, broke up all the chunks of stuck together salt, and placed it back down.
 
On day four, I tried moving the pantyhose again to loosen up the stuck together chunks of salt, and the pantyhose ripped apart, leaving a big mess of salt on the roof.  Yuck.


Pros: This is pretty safe.
Cons: Took way too long and didn't do much.  Waste of time.  I wonder if I can return the pantyhose to Walgreens?
Verdict: Better than nothing.

Heat Cables

For the record, heat cables aren't supposed to be placed directly on ice dams, but some people might try it anyway.  My friend did this at a house he owns in Saint Louis Park... so I took pictures.  These photos all show the heat cables after about one day.

Note the creative way of keeping the cables from touching each other.  Pretty cool, huh?



Pros: Gets the job done, and will prevent the formation of ice dams throughout the rest of the year.
Cons: Heat cables aren't made for this, and I'm sure the manufacturer would tell you that this poses some type of safety hazard.  Stringing up the cable was also very unsafe.  It's a good thing my friend owns a jet pack.
Verdict: Don't do this.

Summary

An ounce of prevention is worth a pound of cure.  My favorite method was definitely the ice pick, but this was also very unsafe, and there's a good chance that the roof surface could get damaged this way.  I'd rather not have to deal with ice dams at all.

After a good snowfall, rake the snow off your roof.   This definitely takes the least amount of effort and it's safe.  I've been asked whether a roof rake will damage the roof, and the answer is definitely no.  A good roof rake will have little wheels at the bottom of the rake , which prevents the bottom of the rake from even touching the surface of the roof.  Rake away.



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

    


RELATED POST: How To Prevent Ice Dams