I've written about how to prevent ice dams by fixing attic air leaks and insulation, as well as several hack methods showing how to remove ice dams, but I still get a lot of questions about ice dam prevention.  For homeowners with a one-and-one-half story house or a house with a vaulted ceiling and no true attic space, correcting attic air leaks and insulation can be an extremely expensive project.

In these cases, it's not always cost effective to fix the problems that are causing the ice dams - the 'repairs' might outweigh the costs of controlling the ice dams, and even if the repairs make economic sense, it's not always in the homeowner's budget.  In those cases, I recommend ice dam control from the exterior.

Remove The Snow

Raking a roof

Pulling snow off the roof with a roof rake will keep ice dams to a minimum. This becomes a constant chore, but it's better than dealing with water leaking in to the house.  Just raking the first several feet of snow from the eaves is typically enough to prevent the formation of ice dams, but in some cases, this will cause ice dams to form higher up on the roof.  The trick is to get the shingles exposed to the sun; once that happens, the sun will warm the shingles enough to prevent ice from accumulating.

Raking snow off the roof with a roof rake is a safe way of removing snow, as long as you don't get too close to your overhead power lines.  In theory, a roof rake could cause some premature wearing of shingles by removing the aggregate, but I've never seen any real life evidence of this.  Some roof rakes have little wheels at the bottom that prevent the rake head from actually rubbing on the shingles.

While the roof rake pictured above is the most common type, there are many other variations of this designed to make the work easier - one such version is the MinnSnowta Roof Razor®.

Removing snow from the eaves is an effective way to prevent ice dams, but it won't work 100% of the time.  Two years ago, I inspected several houses with ice dams forming right where the snow stopped being removed.  This is not typical, but it can happen during especially cold, snowy winters. When this happens, people start to get depressed and wonder why they live in Minnesota.

The fix for this is to have all of the snow removed.

For 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.

De-Icing Cables

Roof de-icing cables, also known as heat cables or heat tape, should be considered a last resort when it comes to preventing roof leaks from ice dams.  De-icing cables themselves aren't cheap, it costs money to have them professionally installed, and they'll cost money to operate - between five and eight watts per foot.  I've also heard that they can damage shingles, but I've never seen any evidence of this.

On the flip side, de-icing cables are very effective.  When de-icing cables are properly installed and operational, ice dams won't cause leakage.   De-icing cables won't prevent the formation of ice at the eaves, but they'll keep enough ice melted to create drainage channels for water. 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.  It's like comparing a photo of a fast-food burger to the burger that actually comes in the fast-food bag.

If fixing the causes of ice dams isn't a possibility and safe removal of snow isn't possible, de-icing cables or de-icing panels may be a good choice.  Sometimes this is the most cost-effective way to prevent roof leakage from ice dams. 

Reuben Saltzman, Structure Tech Home Inspections

Who inspects the attic insulation in new construction homes?  Probably just the person that put it in.  Nobody else.

When new houses are built in Minnesota, the municipal inspection departments typically never even stick their head up in to the attic after the insulation gets blown in.  I know this because I started asking about it.

A disturbing trend?

At two recent new construction inspections in Plymouth, we received notice from the builders giving us explicit instructions NOT to open the attic access panels during the inspection.  It's their house, so they can do as they want.  Heck, home builders can choose to not allow buyers to have home inspections at all... but what do they have to hide?  As I've written about before, builders should be proud to have their houses inspected.

Case #1: We were scheduled to perform the new construction home inspection on a Friday, and we received the following email on Monday:

"Please note: Please do not go into the attic on this home. The attic access is not meant to be gone into for inspections. It ruins the sealed envelope of the home. This is considered invasive and is not allowed per the purchase agreement."

The buyer fought tooth and nail to get permission for us to go in to the attic to inspect it, but the builder never backed down.  Of course, we respected the builders wishes and left the attic access panel alone.  That's how that story ends.  The buyer may have us come back out to inspect the attic after they own the house, but it hasn't happened yet.

Case #2: A builders rep gave notice to the home buyer that we were not to open the attic access panel.  The home buyer, who spoke English as a second language, relayed this information to me.  I called the builders rep myself to ask about getting in to the attic, and he was quite insistent that I not open the attic access panel.  He even sent a follow-up email to the buyer reiterating this:

"I just spoke with your home inspector – I let him know he cannot cut the access open to the attic. This is standard protocol for us, we never allow the attic seal to be broken while we own the home. Most home home [sic] inspectors understand this is how it works with new construction. The City of Plymouth has done an Insulation Inspection and have signed off on it. (The Certificate is likely hanging on your garage wall)."

I have a hard time believing most home inspectors understand "this is how it works with new construction".  All of the best home inspectors I know open the attic access panel to inspect it, even if it means popping open the attic access panel that has been incidentally covered over with a finished surface.  Sealed-schmealed.  All it takes to 'seal' the attic access panel is about twenty-five cents worth of white caulk.

Despite what the builder said, the attic insulation was never inspected by the city, and never does get inspected by the city.  They don't look in the attic after the insulation has been installed.  When the municipal inspector signs off on the insulation in the attic,  it's standard operating procedure for them to only look at the card in the basement that states the insulation value.  That's it.  That's all.  They're trusting the insulation contractor to get it right.  This isn't a knock against Plymouth; this happens all over the Twin Cities.

It gets better.  Thankfully, the attic in the garage was open to the attic in the rest of the house, and the access to the garage attic was wide open.  Well, almost wide open.  It was easy enough for me to set a ladder up and climb through.

Before inspecting the attic, I checked the card in the basement to find what insulation value was supposed to be present in the attic.  It said R-44.

To determine how much insulation is needed to achieve an insulation value for R-44, I checked the attic insulation card.  This particular type of insulation requires a minimum depth of 14.75" to achieve R-44.  Not maximum depth, not average depth.  Minimum.

Here's a close-up.  Notice the two numbers given - "Minimum Thickness" and "Minimum Settled Thickness."  They're the same.  The footnote for the minimum settled thickness says "This product shows negligible settling."  I've had many people try to explain to me that the depth I'm reporting isn't relevant because insulation settles so much.  That might have been partially true with older insulation, but not the new stuff installed today.

I climbed in to the upper attic and found the same thing I find on almost every new construction home that I inspect; insufficient insulation.  Far less than 14.75".  What was a little different about this attic was that the insulation installer didn't even bother to 'mound up' the insulation around the depth markers to make it look like the proper amount of insulation was used.

By the way, the Minnesota energy code requires those depth markers to be placed in every 100 sf of attic space (N1101.4.1.1), and they all need to face the attic opening.  The code was written in a way that makes it easy for building inspectors to inspect the attic insulation depth... so why doesn't it happen?

I also found a few major attic air leaks, which were allowing for frost to accumulate in the attic, and had already started to turn the sheathing black.

If the garage attic hadn't been open to the rest of the attic, how would I have found out about these issues?  I'm sure I wouldn't have.  This just would have gone on and on until it made a nasty enough mess that there was evidence of it inside the house, and the builder would probably need to deal with it then, many years down the road.

The Solution

It's not tough to make the attic access panel accessible.  I've inspected many new construction homes done by local, custom, high-end builders who take the extra time and spend a small amount of extra money to get this detail right.  For example, w.b. builders uses a product called SkuttleTight, shown below, left.  For comparison, the standard attic access cover installed by most large builders is shown below, right.

Hmm, which one would you prefer to have on your own house, from an aesthetic standpoint alone?  From a functionality standpoint, this product is also far superior to standard attic covers.   It makes a nice tight fit at the walls, it has R-40 insulation, and it's weatherstripped to prevent air leaking.  The cover can easily be lifted up so the attic can be accessed, and then placed back down and made tight again.  It seems to be pretty dummy-proof.  All this for about $150, and it's available all over Minnesota.

I asked Tim Brandvold at w.b. builders why he uses this system for attics when he could save $150 by just doing what all of the big builders do.  He said he does this because it's pretty much a given that someone is going to go in to the attic, and $150 is a drop in the bucket compared to the price of the house.

I like his style.  If I had my way, every attic access opening would be accessible.  I heard a rumor that this requirement will be coming with the newest building code changes in Minnesota.  If so, wonderful.

Reuben Saltzman, Structure Tech Home Inspections

When there's a long period of sub-zero temperatures in Minnesota, plumbing vents often stop working.  The problem is that plumbing vents can get completely blocked shut with frost when it's very cold outside for a long period of time.  I've seen this at a lot of home inspections this winter.  I wrote about why houses need plumbing vents last month, which should help to explain why this stuff matters.

This first photo shows how the frost begins to form.  This is a 3" steel vent pipe at an old house in Minneapolis.  Frost was just beginning to form at the top, and could actually be seen from the ground.

This next photo shows a 4" cast iron vent pipe at a multi-family home in Saint Paul.  It wasn't completely blocked with frost... yet.

As the frost keeps accumulating with very cold temperatures, eventually the vents get completely blocked with frost, which prevents them from 'venting'.   I've included several photos here to show that all types of vents can be subject to frost closure, given the right weather conditions.

This one just looked like it could use a cherry on top.

The way to prevent plumbing vents from getting covered over with frost is to increase the size of the vent before it protrudes through the roof.  Here in Minnesota, the smallest size vent that can penetrate the roof surface is 2", according to Minnesota Plumbing Code section 4715.2530, Subp.2.

Keep in mind, however, that this is the minimum requirement.  That's all the code is; a minimum requirement.  As you can see from the photos above, this isn't necessarily a formula for success.  Many old-school plumbers in Minneapolis and Saint Paul knew about this problem, and it was common for old houses to have vents that were significantly increased in size before penetrating the roof, just to help prevent the vents from getting blocked by frost.

The photos below show how this looks in real life.

Another way to help prevent plumbing vents from getting covered over with frost is to keep them short.  The plumbing code requires plumbing vents to terminate at least 12" above the surface of the roof to help prevent the vents from getting blocked with snow, but the higher the vent the greater the potential for getting blocked with frost.

In other words, the best height for a plumbing vent is 12" above the surface of the roof, and the wider the pipe the better.  If you look up at your roof from the ground and you can see frost accumulation at the plumbing vents, don't get too worried about it.   The frost will go away as soon as it warms up a little - maybe later in the day, definitely by April.

Reuben Saltzman, Structure Tech Home Inspections

With the recent snow storm we received in Minnesota and the crazy snow storm that dumped several feet of snow on the east coast, there will be plenty of people dealing with leaking roofs from ice dams.  I have already blogged about how to prevent ice dams from happening, but I get far more inquiries about how to remove ice dams.   There are plenty of 'hack' methods of removing ice dams, so I decided to discuss them.  The methods I'm going to discuss involve an axe, ice pick, pantyhose, salt, heat cables, a pressure washer, and even a blowtorch... just for fun.

Let me repeat - these are all hack methods.  I don't advise any of these methods, but when people have water leaking in to their home, these DIY methods are what people turn to.  Hopefully I can talk people out of doing most of these.  The most effective and safe way to remove an ice dam is to hire a professional ice dam removal company that will use steam.

Axe

The most obvious way to get rid of ice dams is to 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, cumbersome, and you'll wreak your roof.   I had to 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.  I've inspected dozens of roofs where someone got crazy with an axe at the eaves.  It's a great way to ruin your roof.

Verdict: This is a high risk, yet fast and effective way of getting rid of a lot of ice, but leaves the job incomplete.  You'll probably damage your roof doing this, and you might hurt yourself too.

Ice Pick

This sounds like a natural choice, doesn't it?  I actually used my awl, but close enough.  I gave it my all.  <insert crickets chirping>

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 worked quite well... but again, you'll probably poke a bunch of holes in your roof doing this.

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 well 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 in 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.  The instructions said to put them higher up on the roof, but I wanted to make some holes in this ice dam.

By day two, I had some pretty dramatic results - the tablets had melted all the way through the ice dam.  By the way, 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.  Some channels were created for water to drain through, which might be enough to prevent leakage at your roof.

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 might prevent leakage from ice dams if enough channels are created for water to drain through, but you're still left with a huge ice dam.

Salt Filled Pantyhose 

Take off your pantyhose, fill 'em up with calcium chloride or something similar, and toss 'em on your roof perpendicular to the ice dams.  The idea is that the salt will leak through the pantyhose and create channels for the water to drain through, preventing water from leaking in to your house.

I filled one pantyhose leg with "Ice Melt", which contained a blend of calcium chloride and rock salt.  I filled another 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.  I did this just to compare the results.

10:00 AM (Start Time)

2:00 PM

4:00 PM

The pantyhose were a bit of a bust for me.  With salt alone being so effective, why bother with the pantyhose?  I've heard several opinions on this:

• The pantyhose will contain the salt and prevent runoff.  The idea is apparently to leave the pantyhose there all winter.
• The pantyhose can be 'flung' on to the roof with a rope - no need for a ladder.  After the work is done, you pull the pantyhose back down.
• The pantyhose will gradually release the salt.
• The pantyhose method works much faster if you start by pouring water on the pantyhose.  I didn't try this myself.
• When salt alone is used, it will wash out within a week and the ice channel will freeze over again.

Pros: If you fling the stockings on to your roof from the ground, it's pretty safe.

Cons: This takes a long time.  After a week of near-zero temps, the pantyhose looked just the same.  They hadn't even made a dent. I don't think I would have the patience to do this if I had water leaking in to my house.  Also, this could lead to damaged gutters.

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 owned in Saint Louis Park... so I took pictures.  These photos all show the heat cables after about one day.

Pros: Gets the job done eventually, I suppose.

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.

Verdict: Don't do this.  Seriously.

Blowtorch

I received a request to use a blowtorch on an ice dam, so I tried it.  This video was taken about four years ago. Sorry for the poor audio.

Pros: You can tell your wife you tried everything, even a blowtorch.

Cons: Cold fingers, waste of propane, waste of time, dangerous, etc.

Verdict: I think you get the picture.

High-Temperature Pressure Washer

A pressure washer will certainly remove ice dams, but it will create a ridiculous ice mess below, and will surely damage the shingles.   This was one method that I didn't even test.  The photo below shows what can happen to a roof after a pressure washer or high-temp pressure washer is used on a roof.

There is a big difference between a steamer and high-temperature pressure washer.  In the video below, Steve Kuhl discusses the difference with me.

Conclusion

Ice dams are no fun. As I mentioned at the beginning of this blog, hiring a pro to steam the ice dams off is the only thing I recommend.

Oh, and one more piece of advice: if you know someone who has water leaking in to their house from ice dams, don't tell them to "stop focusing on how to get rid of the ice dam, and spend your time fixing what caused it."  It's like telling someone with a gash in their finger to be more careful around knives.  "Great, thanks, now please pass the bandages."

Reuben Saltzman, Structure Tech Home Inspections

This is a guest blog post by Steve Schirber, of Cocoon.

Re-insulating an existing home properly is a complicated task.  A house is a system; a bunch of smaller parts that make up systems, that make up larger systems.  The tighter the house, the more a house tends to behave like a system. This means that when you change something in the house, such as adding more insulation, that change can affect the homes performance. In most cases, this is the intended outcome.

If insulation and air sealing is performed in an attic, it might make the rooms below feel warmer, reduce heating costs during the winter, and help to prevent snow from melting on the roof, in turn eliminating ice dams.  That's great, but what else changed that wasn't supposed to?  Here's a list of possible unintended consequences.

Back Drafting

When air is pulled out of a house, the house will draw outside air back into the house.  The amount of air coming in equals the amount of air being pulled out. Simple. This exchange of air happens when you run your bath fans, range hood, or clothes dryer.  Depressurization occurs when there is more air leaving the house than coming in. Depressurization can cause a handful of problems, but I will focus on back drafting.

Back drafting occurs when a combustion appliance, such as a water heater, can’t generate enough draft to vent the combustion gases up the flue. When back drafting happens, these gases spill into the house, causing a potential buildup of carbon monoxide.  Unintentional carbon monoxide exposure accounts for an estimated 15,000 emergency department visits and 500 unintentional deaths in the United States each year. (Source: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5650a1.htm).

While the Minnesota Fuel Gas Code has specific installation requirements for gas water heaters, just following all of these rules doesn't mean a water heater will draft properly.  Even with a proper installation, there are three common home improvements that can cause problems with existing water heaters.

• Tightening the enclosure. This is done by air sealing gaps or cracks in the exterior of the house, adding insulation or weather stripping, and replacing windows or siding.
• Adding ventilation appliances such as bath fans, larger cooktop vent hoods or whole house ventilation fans.
• Replacing the furnace. When older furnaces are replaced with newer sealed combustion units, the water heater vent often becomes “orphaned”.  It used to share a large flue with the old furnace, but now it's left to fend for itself to produce a draft.  The relatively small burner on a water heater doesn't always product enough draft to work properly by itself, so it back drafts.

Back drafting can be prevented by not having open combustion appliances - this often means replacing the old natural draft water heater with a powervent water heater. Performing a worst case depressurization test can determine if back drafting is occurring already, and can help predict if it will occur when the home is made tighter.

Condensation Problems

I often hear people say “...they build houses too tight. You gotta let them breathe.”  A leaky house may be uncomfortable and may have high utility bills, but is always well ventilated. This is why most 100 year old homes don’t have mold or moisture problems. They “breathe”.  When houses are made tighter, they need to breathe through an intentional hole at a controlled rate. We have to pay close attention to this as we go into a house to perform air sealing measures or add insulation. These changes can tighten the house, effectively eliminating a source of ventilation. These changes in ventilation rates can have undesirable consequences such as elevated moisture levels in the house, condensation on windows, or mold growth.

Any of the changes made to a house that can cause depressurization can also change the ventilation rate. Another common ventilation change that isn't so obvious happens when when old furnaces are replaced with new high efficiency furnaces.  The older units produced a draft that pulled air from the house up the flue, providing a source of ventilation. Replace the old furnace... take away the source of ventilation.

Every house has its own prescribed ventilation requirement. This can be calculated along with a blower door test to determine if the house is "breathing" properly.  The fix most commonly consists of adding new ventilation equipment that can be programmed to ventilate the correct amount of air.

Increased Radon Levels

Radon is a naturally occurring radioactive gas that is present in soil. It is odorless, colorless, and tasteless. Radon is the second leading cause of lung cancer and is responsible for an estimated 21,000 deaths per year.  Radon is literally drawn up into the house by a form of depressurization called stack effect.

Houses that are leaky and have low levels of radon will often see an increase in radon levels after the building enclosure is tightened. This is due to a change in the natural air change rate, which dilutes radon levels.  Once this source of ventilation is removed, radon levels increase. Any change to the natural ventilation rate in a house can cause a change in the radon levels.

What To Do

To minimize the potential for unintended consequences when adding insulation to a home and making it tighter, the first step should be to have a home diagnostic test performed.  I'm not talking about the energy audits where you get a low-flow aerator for your sink, a tube of caulk, and a few CFL light bulbs.  I'm talking about a comprehensive set of tests that includes the use of a blower door, an infrared scan, testing of the exhaust fans, and possibly even a radon test.

The benefit of having a diagnostic test is

1. Thoroughly understanding the opportunities to improve the performance of you house
2. An accurate scope of work designed to have intended results
3. Testing after the work is done can measure if the work was done correctly
4. Unintended consequences can be identified before they become problems

For the best possible results on your next insulation project, be sure to work with a company that takes a holistic approach to your home envelope, and guarantees the results, not just the work.

Steve Schirber is the Principal and G.M. of Cocoon. As a diagnostic testing, envelope modification, and Insulation contractor, Cocoon provides solutions to home owners with tangible results in the area of health, safety, comfort, and energy efficiency.

His unique knowledge comes from 20 years of service in the construction industry, specializing in residential building assemblies, delivery systems and building performance.  Steve has a BCE in Structural Engineering from the University of MN. Steve is an NRPP Radon measurement specialist/mitigation provider and is a BPI Building Analyst and Envelope Professional.