HOW TO PREVENT ICE DAMS

We’ve received over 34″ of snow in Minnesota in the last 25 days, which makes this the snowiest December on record.  While the snow turns our state in to a beautiful white winter wonderland, it also causes nasty ice dams that wreak havoc on homes like never before.

The heavy amount of snowfall and temperatures in the teens have been the perfect conditions to create ice dams.  Water leakage from ice dams is an epidemic in Minnesota right now.  I have friends, neighbors, and family members with water leaking in to their homes.  It’s everywhere.  I’ve taken all of the photos below within the last two weeks.

The two things that everyone wants to know is how to get rid of ice dams and how to prevent ice dams.  As I mentioned in a previous blog, the only completely safe and effective way to get rid of ice dams is to hire a professional ice dam removal company; they’ll use steam, which will completely remove the ice dam.  Anything else is a hack method.

The best way to prevent ice dams from forming is to address the three factors in your attic that contribute to ice dams; insulation, ventilation, and attic bypasses.

Attic Bypasses (air leakage)

This is the largest contributor to ice dams.  In almost every house that I inspect to determine the cause of ice dams, I find attic bypasses directly below the beginnings of the ice dams.  Attic bypasses are passageways for warmed air to enter in to the attic space, and traditional insulation won’t fix this.  The photos below show some common attic bypasses that I can find in just about any older house.

This first photo shows one of the largest and most common bypasses – the space around the furnace and / or water heater vent.  Sometimes these are huge. The one shown below is quite small.

In the photo below, you can see several holes in the top plate of a wall that were drilled for wires to pass through.  These holes could all be easily filled with spray foam, but finding these holes all over the attic would be a challenge without first removing the insulation.

With additions, the transitions between the ‘new’ and ‘old’ construction seem to always be sources of attic bypasses.  I had to dig through a lot of insulation to find this gap, but I wasn’t surprised at what I found.

When plumbing vents enter in to the attic, the space around the vents needs to be sealed.  This one obviously wasn’t.

Some older houses have whole-house fans that are designed to run on hot summer nights; these fans are gigantic sources of heat loss, because they’re usually not insulated or sealed up.  I took the photo below from inside the attic without a flash on my camera.  There’s some crazy heat loss occurring there, and as you might imagine, there was a huge ice dam nearby.

What makes most of these attic bypasses so difficult to locate is that they’re almost always buried in insulation.  Finding these buried air leaks turns in to an educated guessing game.  Lately I’ve been using an infrared camera while doing ice dam inspections, and I’ve found it to be very useful for finding these hidden passageways.

If you plan to have more insulation added to your attic, it’s probably a worthwhile investment to have all of the existing insulation completely removed and the bypasses sealed up before you re-insulate.  There’s just no way to find all the bypasses if you don’t do this.  If your home is over 20 years old, it’s almost a guarantee that you’ll have attic bypasses that need to be sealed.  It’s a shame that so many insulation contractors just add insulation on top of what’s already there without sealing the bypasses.

I also practice what I preach; I’m such a firm believer in removing insulation and sealing bypasses before re-insulating that I did this at my own house, my parents had this done at their house, and my sister had this done at her house.  It makes a big difference.

Insulation

This is a basic concept that everyone understands; you need insulation in your attic.  If there are voids in the insulation, they need to be fixed.

My first choice would be to have about two inches of closed-cell foam insulation applied to the attic floor, and then have several inches of cellulose installed on top of that.  The closed cell foam would seal up every bypass, and the cellulose would be a cost effective way to get the insulation level up to current requirements.  The drawback with this method is cost; closed cell foam ain’t cheap.

My next choice of insulation would be all cellulose insulation, with all of the bypasses sealed first.  I prefer cellulose to loose-fill fiberglass because it has a higher insulating value per inch, it seems to do a better job of stopping air leakage, and it’s not itchy fiberglass.  I’ve been digging through a lot of fiberglass covered attics lately, and my arms start getting itchy just thinking about it.

My last choice of insulation would be loose-fill fiberglass insulation… not that there’s anything wrong with it.  I personally just don’t like dealing with fiberglass.

What about fiberglass batts?  You know, those big rolls of fiberglass?  No way, Jose.  That stuff is impossible to install properly.  Fiberglass batts leave gaps all over the place that add up to an exponential level of heat loss.  I’m pretty sure that fiberglass batts are installed in attics exclusively by handy homeowners.

Ventilation

Having adequate ventilation for the attic space will help to keep the roof surface cold, which will help to prevent snow from melting, which will help to prevent ice dams.  The best way to ventilate an attic space is with continuous soffit vents and continuous ridge vents, but this isn’t always possible.

If you don’t have enough soffit vents, add more.  If you don’t have enough roof vents, add more.  You can’t have too much ventilation.  If your soffit vents are dirty, clean ‘em or replace the grills if they’re painted shut.  Grills are cheap.  If your soffit vents are blocked with insulation, you need air chutes installed at the eaves to prevent the insulation from blocking the vents.

When all else fails…

If you’ve already done everything you can think of to fix your ice dams but they keep coming back, or you’ve hired a contractor to fix your ice dams but they seem to be scratching their head a lot or coming up with a bunch of different guesses, call a home inspector.  We look at this stuff every day, and some of us even specialize in ice dam inspections.

In some cases, it’s not cost effective to control ice dams from inside.  Next week I’ll be blogging about controlling ice dams from the exterior.

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

    

Don't Ruin Your Furnace

When I think of homeowner maintenance, the first thing I think of is changing the furnace filter. Most homeowners know about this regular chore, and at least one out of five homeowners is diligent about doing this.  As for the rest of you...

Do you really know why you're supposed to change your furnace filter?  Hopefully your dad, your real estate agent, or your home inspector lectured told you about doing this regularly.  There are a couple obvious reasons to change your furnace filter - your heating or cooling system will run more efficiently and the air in the ducts will hopefully be cleaner, but those aren't the most important reasons for changing your furnace filter.

The most important reason for changing your furnace filter is to preserve the life of your furnace.

To make it very simple, your furnace works by passing relatively cool household air over a big hunk of metal, which is called your heat exchanger.  As the cool air passes over the heat exchanger, it gets warmed, which dissipates heat from the heat exchanger.  This warm air gets distributed throughout the entire home, and this is what keeps the indoor air temperature at 70 degrees when it's -10 degrees outside.  That heat exchanger is responsible for transferring a lot of heat to the rest of the house.

Now think about what would happen to that heat exchanger if it couldn't transfer it's heat to the rest of the house:  it would get extremely hot, much hotter than it was ever supposed to get, and it would probably fail (i.e. -crack) prematurely.

When you operate your furnace with a dirty filter, this is what you're doing to your furnace.  You're preventing the cool household air from passing over the heat exchanger, heat doesn't get dissipated the way that it should, and the life of your furnace gets reduced... besides costing you more money in heating bills.

In other words, don't forget to change your furnace filter.  It's not just about indoor air quality.


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

Why Is There Frost In My Attic?

At the last four home inspections that I've done, every home had frost problems in the attic. Have you checked for frost in your attic yet this year?  If you live in Minnesota or a similarly cool climate, now is a good time to check your attic for frost.

Temperatures in Minnesota have been in the teens lately, which is plenty cool enough for frost to develop in attics.  Once we get a week of sub-zero temperatures, frost will really start to accumulate in attics.  The colder it is outside, the more frost will accumulate in an attic.   If you already have frost in your attic, I can assure you that it's only going to get worse - winter is still two weeks away.
 

Please excuse me while I digress for a moment.  Who the heck decides when the seasons change?  Yes, I know what the winter solstice is, but what a silly indicator of winter.  Winter in Minnesota should officially start on December 1st or after the first snow fall, whichever comes first.  Half the leaves were still on the tree in my back yard when we got our first snow this year, which happened on November 13th.   That wasn't a light dusting either.  When the ground gets covered with snow, fall is over in my book, no matter what the calendar says.

Frost doesn't do much damage to roofs while it remains frost, but when it melts, it makes a big mess. When the frost melts, there is often enough water to saturate the insulation in the attic and leave stains all over the ceilings.   This is the short-term problem with frost in attics.  The long term problem is that this continual saturation of the roof decking can cause the plywood on the roof decking to delaminate; when this happens, it loses a lot of it's strength and nails are much more prone to pulling out.  The fix for delaminated roof decking is to replace it.

The photos below all show roofs with delaminated plywood; this is caused by frost in the attic.  The last picture is especially nasty.  Click on any of the photos for a larger version.







The way to prevent frost from accumulating in an attic is to prevent warm, moisture-laden air from getting there in the first place.  There are two basics ways of doing this.

Seal attic bypasses  

Attic bypasses are passageways for warm air to leak in to the attic.  A few common places to find these gaps are around furnace vents, plumbing vents, electrical boxes, and electrical wires coming in to the attic.  Any bath fans, kitchen fans, or dryers venting in to the attic space will absolutely wreak havoc.  Even small gaps in any of these vents can bring a lot of moisture in to the attic.  For more tips on locating attic air leaks and sealing them, download this handout.

Lower the humidity in your home

 I find frost problems in almost every single attic where someone uses a whole house humidifier.  That's why I don't like whole house humidifiers.  It's nearly impossible to seal every little bypass to an attic, but when interior humidity levels are kept fairly low, sealing most attic bypasses is good enough.  Here are a few ways to lower humidity levels in your home:

• Turn off your whole house humidifier (duh)
• If you have one, use your kitchen exhaust fan when you're cooking.  Gas ovens add a considerable amount of moisture to the air.
• If you have a crawl space, make sure that a proper vapor barrier is installed on the crawl space floor.
• Turn on your bathroom exhaust fan during showers and leave them on for a half hour after every shower.  If you don't have a bathroom exhaust fan, get one.  While the building code allows an openable window as a substitute for a fan, I don't ;-)
• Install an HRV or a continuous exhaust fan.  Either one of these will dramatically lower humidity levels in a home.

Will adding more ventilation to an attic prevent frost?  No, this won't do squat.  I've been in tons of attics that were completely covered in frost, yet had fantastic ventilation.  To fix the frost in your freezing attic, focus on forbidding the moisture from getting there in the first place.

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