Roof Health Archives - The Green Cocoon

Ice Dams and How to Prevent Them

Building Science, Home Maintenance, Insulation, R-Value, Roof Health

Does your house have icicles hanging from the roof during the winter? If so, there is something going on that could potentially cost you thousands of dollars. It is called an ice dam and here’s how to prevent them.

What is an ice dam?

If the attic isn’t properly insulated, during the winter the warm air will escape and melt the first layer of snow on your roof. Many uneducated contractors will tell you to increase your attic insulation to prevent ice dams. While this may slow down the buildup of ice dams, it will essentially increase the speed of your heat loss. Consequently, the heat loss will make your home less efficient.

DIYers (do-it-yourself) like to solve the problem by putting heat tape on the roof, but that can be incredibly damaging to the shingles. Furthermore, the tape does not solve the problem, which is inefficient insulation and heat loss.

The layer of snow that is against the roof will melt and run down the roof shingles. You can’t see this happening because it is under the pile of snow. Once the water reaches the overhang where it is colder, an ice dam starts to form. This process happens over and over; the ice dam gets bigger; and the water gets higher. Eventually, water will get under the shingles!

As the melting continues, the ice dam and water lift the shingle more and more. Eventually, it hits the top of the shingle. That is when water can get into your house, and potentially cause thousands of dollars in damage.

How to prevent ice dams

Whether you are creating a conditioned or unconditioned attic, we recommend the same things.

Seal the gaps – First you need to air seal any gaps or holes in the floor or roof. There are several products that we suggest you use. Please contact us so we can help you decide which product is best for you.
Use correct R-value – Make sure you have enough R-value. Remember, fiberglass doesn’t have a constant R-value so we don’t recommend it. In southern New Hampshire, you need a minimum of an R-49.
Ventilate the attic – If you plan to insulate the attic floor, make sure to allow for proper ventilation to prevent condensation. If you are not sure you have adequate insulation, give us a call and we will come out and take a look.

Using a spray foam in the attic is the best choice because it fills the holes and crevices. We recommend closed cell spray foam for several reasons:

It has a higher R-value per inch than open cell spray foam.
Closed cell spray foam is a vapor barrier and water can’t permeate it.
It sticks to the walls and fills all the crevices and holes.

Learn more about Closed Cell Spray Foam by watching a video on our website. Contact us with questions.

Polyurethane Foam Used as a High-Performance Adhesive

Building Science, Insulation, Roof Health, Save Money

In the insulation industry, we all know why spray polyurethane foam works so well as an insulation and air barrier for buildings. Most also know that polyurethane is used to make many everyday objects in your automobile and around the house. But, most don’t know that polyurethane foam is used a lot as a high-performance adhesive.

Closed Cell Spray Foam Strongest

If you mix the A and B sides of polyurethane foam together, the curing liquid sticks to everything. This creates a strong bond with most any type of surface. In a foam form, the curing polyurethane adhesive rises to fill small gaps between irregular surfaces. This is closed cell spray foam. It reduces excess waste and energy consumption in buildings by up to 50% while adding strength—R-value (7 per inch).

Used in Construction Industry

This high-performance polyurethane adhesive has found a permanent home in the construction industry. Roofing contractors regularly use polyurethane adhesives to attach various roofing materials to substrates (see SPFA-142).

Polyurethane adhesives are also used to bond gypsum board to framing, especially in manufactured housing applications. Two inches of closed cell spray foam between wall stud framing can provide nearly the same racking strength as a half inch of oriented strand board (OSB) sheathing, according to sprayfoam.com. The same application of closed cell foam below the roof deck, between the rafters and trusses (new construction or retrofit), can increase the wind uplift resistance by a factor of three. It can also provide a secondary water barrier if the roof shingles fail.

The Insurance Institute for Business and Home Safety (IBHS) recognizes the structural benefits of closed cell foam insulation and polyurethane adhesives in their Fortified Construction Standards program.

Homeowners Save Money

Understanding all of the benefits of closed cell spray foam is key for homeowners. The knowledge helps them make better decisions regarding insulation choice when building or remodeling their home. Moreover, as we strive to construct more resilient and eco-friendly buildings, we encourage the use of spray foam in most of our projects.

Monitor the Health of Your Roof During the Winter

Energy Efficiency, Insulation, Roof Health, Save Money

Many cities across the country were hit with a major winter storm last week, and for some, it was the first big one of the season. One area of the house that gets hit the hardest during a winter storm is the roof. Make sure to monitor the health of your roof during the winter to make sure it is strong enough to take the brunt of bad weather. If the snow isn’t melting quickly, it means that heat from your home isn’t escaping through your attic floors and then transferring from your roof to the exteriors. That means your roof is doing its job!

Bare spots and icicles mean heat is escaping

If your roof gets a decent amount of snow on it, make sure it’s not melting in specific spots. That means there’s heat loss likely due to poor insulation and/or ventilation in the attic. If that is the case, give us a call once the snow melts.

After a snowfall, every homeowner should take a look at their roof and check for hot spots—areas on the roof where the snow has melted. It’s normal for some melting around venting and fireplace exhausts, but you shouldn’t see any bare patches on your roof. A snow-covered roof means your insulation is doing its job.[1] If not, it’s time for a new insulation package!

Also, keep an eye out for icicles—another sign of heat loss. If your roof is warm enough to melt the snow but it’s cold enough outside for snow to refreeze, your roof is losing heat. That’s not healthy for your energy bills or the environment.

Remove some snow if it gets too deep

What about the weight of snow? If there’s ice too, that can be a heavy load. Add the weight of two layers of shingles and that’s one roof no one would want over their head. Generally, most roofs max out at about 20 pounds of snow per square foot, which translates to around two feet of wet snow or up to four feet of light, fluffy snow.[2]

Once you start hitting those levels, you may want to think about removing the snow. Otherwise, it could potentially cause your roof to cave in, which is a terrible experience in any weather, but particularly during subzero temperatures. Still, you can’t exactly get on top of your roof with a snow shovel. If you have an asphalt roof, you run the risk of doing serious damage to your shingles, which can cause your roof to leak afterwards—and all kinds of havoc as a consequence.²

If you don’t have the proper equipment to remove the snow yourself, hire a roofing contractor to safely handle the removal for you. It generally only costs about $100 to $300, and it will save your roof a lot of wear and tear.[3]

Install an ice and water shield

We suggest you install an ice and water shield over the first four feet of roof, on top of the sheathing—not just along the edges near gutters. This adds a second layer of protection against leaks and moisture where ice dams may occur, so if water gets in below the shingles the sheathing is watertight.

Another reason to add an ice and water shield is it seals around nails, unlike tar paper, roofing felt, or asphalt paper. If you have shingles on your roof, as most North American homes do, for every nail that goes through the tar paper there’s a tiny hole — an open invitation for water in your attic.

Check your attic (and garage) after a storm too. If you see frost on the sheathing it’s not a good sign. It means your attic isn’t properly vented for your specific insulation type or it is lacking insulation all together, which could lead to mold or rot. If you see any signs of mold or rot in your roof, call a professional remediation company.

Your roof and attic are crucial when it comes to protecting your home over the winter. Please contact us to schedule an appointment to make sure your insulation package is up-to-date.

[1] National Post (Feb. 7, 2015). Snow piling up on your house is a good indicator of the roof's condition. Retrieved from nationalpost.com.

[2] Modernize (2019). Is Snow Good or Bad for Your Roof? Retrieved from modernize.com.

[3] Cost Owl (2019). How Much Does Roof Snow Removal Cost? Retrieved from costowl.com.