Why Do I Have Icicles Around My Roof Line and My Neighbor Doesn't?

Although icicles in the winter are a beautiful sight to see, they can be an indication that something may be wrong with the insulation in your home.  You will notice that some homes have icicles around the rooflines and some don't, and that is with good reason.

When you see icicles form on your gutters and eaves, it is an indication that ice dams are building up on your roof.  These ice dams can cause damage to the interior and exterior of your home, and should be addressed sooner than later.  Furthermore, if an ice dam breaks free, it can pull shingles and gutters off with it, damaging anything that it falls onto.  When roof sheathing gets wet, it can form mildew and rot, and cause further damage to your roof.  

Ice damming occurs once snow accumulates on your roof, and the cycle of snow melting and refreezing begins, creating a buildup of ice.  In a perfect world, snow falls, it melts, enters your gutters and flows away from your roofline.  Or the snow evaporates or melts from the heat of the sun during daylight, assuming the outdoor temperature remains above freezing. With ice damming, the dam creates a blockage and causes water and ice to remain at the edges of your roof.

There are two determining factors that contribute to ice damming; the outside temperature and the inside temperature of your attic.  The warmer your attic is, the easier it will be for the snow to melt on the surface of your roof, whereby increasing the chances of re-freezing when the outdoor temperatures fall below 32 degrees.  This growing heap of ice blocks the path of melted snow and causes an increased buildup of ice, creating an ice dam.

When ice damming occurs, water can pool up and leak through your roof shingles and into your home.  Worse yet, this thick band of ice can dislodge roof shingles or pull gutters away from the roofline. On a roof with a low slope, even a small ice dam can cause water damage inside your home.

To help prevent ice damming, although considerably physical and potentially dangerous, is to remove the snow from the roofline when there is considerable accumulation. On very low-sloped or flat roofs, especially in the snowbelt, some homeowners actually remove all the snow from their roofs.  On a roof with a greater pitch, snow can be removed about 3 or 4 feet from the roof line.  This will eliminate or at least slow down the build-up of ice and allow for the snow to melt and discharge through the gutter system more effectively.    

The best way to prevent ice damming is to keep your attic cool in the winter.  Although this may seem counter-productive, it is important to keep the heat within the occupied portion of your home and away from your attic.  This can be achieved by properly insulating the space between the ceiling of your home and your attic. 

Installing additional insulation on the floor of your attic is not a difficult task.  Whether laying additional batts across your existing insulation or blowing more insulation between the joists, providing an insulating barrier will assist in keeping the heat inside your home and out of your attic.  When applying additional insulation, be careful of exposed recessed light fixtures or vent fans that are installed through the attic floor.  Some of these fixtures are not designed to be covered with insulation.

In cases where you have already reached the maximum R-value (the rating used to measure the insulation value of the material), additional insulation will not help prevent heat from entering your attic.  At that point, you may want to consider applying weather stripping around attic access areas or stairways, or replacing the attic stairs with a new insulated model.

Even with proper insulation, there is still heat that can seep into the attic.  That is where proper ventilation of your attic comes into play. Without proper ventilation, heat will build up in your attic, even if you have taken every precaution against it.  

The equation for properly venting your attic is to provide 1 square foot of ventilation for every 150 square feet of attic space.  Newly built homes have to meet code requirements that require proper ventilation, however older homes did not have to meet these mandates.  

If your home has a small louvered window at either end of the attic, known as a gable vent, you may want to consult with a professional contractor to assess if the ventilation is adequate for the space.   If not, you may want to consider replacing them with larger louvers, or identify other effective options.  A properly ventilated attic not only reduces the likelihood that ice damming will occur, but also removes water vapor, which can condense in the attic and cause dry rot on wood and rust on metal building materials.

If your roof extends beyond the exterior walls of your home, you may want to consider adding vents in the soffits.  To provide a complete ventilation system for your attic, you can add a ridge vent at the peak of your roof to allow the cold air entering your attic at the soffit to rise up through the space to the vent, providing cooling and removing moisture. Installing a ridge vent at the peak of your roof is typically done when replacing your roof, as that is when it is most cost effective and less intrusive. 

If you have seen icicles around your roofline or if you have interior damage to your walls or ceilings as a result of an aged or faulty roof, and you are considering installing a new roof, it is important that you choose a contractor that can correct these issues.  Not only does a faulty roof installation waste time and money, it can also create situations that didn't exist before the work was done.

A quality roof installation should include proper flashing, an ice and water barrier installed on all edges and valleys of the roof, a rolled asphalt underlayment and quality roof shingles, installed pursuant to the manufacturer's recommendations. When hiring a roofing contractor, you should also ask for references from other customers that may have experienced ice damming.  This will ensure that the company has experience in resolving this type of issue, and is capable of providing a permanent solution. 

Max Mannino, President – Tri-Star Construction & Home Improvement

(718) 815-1800         www.tri-starconstruction.com