Understanding Vapor Barriers

Understanding Vapor Barriers

In our line of work, we come across many “interesting” insulation jobs. But, before you start any project, understanding vapor barriers is a must. Then, the insulation will be installed correctly.

We see work completed by the homeowner who wants to save money. Additionally, we come across some that were completed by licensed professionals who haven’t been educated on proper installation. Similarly, the biggest mistake we see is people installing a double vapor barrier—installing a covering (usually plastic) over an already existing vapor barrier.

Understanding vapor barriers

In the first place, “the function of a vapor barrier is to retard the migration of water vapor. Furthermore, vapor barriers are not typically intended to retard the migration of air. That is the function of air barriers.”[1]

Moreover, a vapor barrier is any material used for damp proofing, typically a plastic or foil sheet. Additionally, these sheets resists diffusion of moisture through the wall, floor, ceiling, or roof assemblies of buildings.[2]

What does a vapor barrier do?

Vapor barriers are installed along, in, or around walls, ceilings, and floors. Of course this is done to prevent moisture from spreading and potentially causing water damage. Additionally, a true vapor barrier is one that completely prevents moisture from passing through its material, as measured by the “moisture vapor transmission rate.” If the material has any porousness, but the barrier still provides protection from moisture, it is called a vapor diffusion retarder.[3] Furthermore, vapor retarders also are commonly referred to simply as vapor barriers. The barrier terminology is less accurate because, in most cases, the products don’t completely barricade the vapor.

What can I use as a vapor barrier?

There are a wide number of materials available to create effective vapor barriers, including:

  • Elastomeric coatings
  • Aluminum foil
  • Paper-backed aluminum
  • Polyethylene plastic sheet
  • Asphalt-coated Kraft paper
  • Metallized film
  • Vapor retarder paints
  • Extruded polystyrene or foil-faced foam board insulation
  • Exterior grade plywood
  • Sheet-type roofing membranes
  • Glass and metal sheets[4]

Map of US weather zones for green cocoon insulation

Photo courtesy of energy.gov

Where do I need a vapor barrier?

The IRC divides North America into eight climate areas. This is done for the purposes of determining when a vapor barrier might be needed in a building. Additionally, the IRC recommends builders install a Class-I or -II vapor barrier on the interior side of homes in climate zones 5 and above, and in the Marine 4 zone. However, if you air condition your house in the summer, you might trap condensation in your roof or walls for part of the year. If this is the case, be sure to use a Class-II vapor barrier on the interior of the wall. Moreover, you can use a Class-III vapor barrier on the interior. Pair that with spray foam insulation on the interior of the wall or roof. Furthermore, when building in hot, humid climates (zones 1 to 3), you should not have a vapor barrier on the interior side of the wall.[5]

Major Problem

Incorrect use of vapor barriers is leading to an increase in moisture-related problems. Vapor barriers were originally intended to prevent assemblies from getting wet. However, they often prevent assemblies from drying. In like manor, vapor barriers installed on the interior of assemblies prevent assemblies from drying inward. This can be a problem in any air-conditioned enclosure, below grade space, or a vapor barrier on the exterior. Additionally, a problem can occur where brick is installed over building paper and vapor permeable sheathing.[6]

Building in a Cold Climate While Adhering to Building Codes

Is a vapor barrier required in New England? Yes! Not to mention that as a builder your first step is to consult your local and state building codes. In many colder North American climates, vapor barriers are a required part of building construction.

You may find that vapor barriers are often not required in warmer climates. And, if installed in the wrong climate or on the wrong side of building materials, a vapor barrier can cause more harm than good. By the same token, this circumstance may prevent water vapor from drying, which in turn can cause rot and mold.[7]

If you don’t know the building requirements for your area, ask an expert!

Double Vapor Barrier – Don’t Do It!

What is a double vapor barrier? The insulation in Photo A was installed by an inexperienced insulation installer. Additionally, the brown paper on the fiberglass is a vapor barrier. By putting poly plastic over everything, the installers created a double vapor barrier. Not to mention that this type of installation creates future moisture, mold, and rot problems.  Moreover, in Photo B the cellulose netting is not strapped and it is starting to sag. Furthermore, the staples are ripping out and the ceiling could come down at any time!

An example of a double vapor barrier

The Green Cocoon shows an example of a double vapor barrier

In conclusion, if you need insulation don’t wonder what type you need. Let us do the thinking for you. Call us today!

[1] Building Science (2011). BSD-106: Understanding Vapor Barriers. Retrieved from buildingscience.com.
[2] Wikipedia (2019). Vapor Barrier. Retrieved from en.wikipedia.org.
[3] Energy.gov (2019). Vapor Barriers or Vapor Diffusion Retarders. Retrieved from energy.gov.
[4] Energy.gov. Vapor Barrier
[5] Fine Home Building (2009). How It Works: Vapor Drive. Retrieved from finehomebuilding.com.
[6] Building Science, BSD-106.
[7] IKO Commercial, (2019). An Introduction to Vapour Barriers and Vapour Retarders. Retrieved from iko.com.

Insulate Your Home and Save Money

Insulate Your Home and Save Money

The fall has officially arrived in New England and winter is approaching quickly! With temperatures already slipping below freezing in some areas, the thought of high heating costs is on our minds. Insulate your home and save money. By adding or upgrading your insulation can save money on heating costs, thus making your home more energy efficient. By using Efficiency Maine, you can save up to $3,000 by upgrading the insulation in your home!

The Green Cocoon is located just over the border in Massachusetts, but we also service our sister states like Maine. Maine is known for its diverse landscapes, lighthouses, and its delicious bounty from the sea. However, it is also known for its harsh winters. And, that has many homeowners bracing themselves for indoor drafts, cold floors, and hard-to-heat rooms. What if you didn’t have to put up with these home comfort pains this winter?

Why Upgrade My Home’s Insulation?

Many Maine homeowners don’t realize just how effective insulation can be at making their homes more comfortable and efficient. Insulation in key areas like the attic, basement, and exterior walls slows heat transfer into and out of the home. This means that in the winter, that valuable heat you’ve paid for stays inside your home, right where you want it. Cellulose and spray foam insulation are especially effective insulation materials (which is why we install them in homes here in Maine!)

With the right insulation upgrades, you can expect benefits like:

  • Fewer drafts and cold spots
  • Warmer floors
  • Lower annual heating/cooling costs
  • Enhanced overall comfort
  • Greater home energy efficiency
  • Reduced outside noise

When insulation is paired with proper air sealing to eliminate air leaks, the benefits go even further!

Insulate & Save up to $3,800 with Efficiency Maine Rebates

While an insulation upgrade does have an upfront investment, there are valuable local incentives available through Efficiency Maine to offset that cost. As a matter of fact, upgraded insulation helps you save money on your heating bills over time, and insulation has a remarkably short payback period.

Currently, you can receive up to $3,000 on an insulation rebate, $400 on an energy assessment and another $400 when you air seal troubled spots.  The Department of Energy graphic below has a useful cross-section diagram illustrating the most common air leakage spots.

Take Advantage of Efficiency Maine Rebates with The Green Cocoon

As a Residential Registered Vendor with Efficiency Maine, we’re here to help homeowners on the southern coast of Maine save on their next insulation project. In addition to assessing the unique insulation needs of your home, we’ll help you determine the rebates for which you qualify.

The Green Cocoon would love to help you. We are just a phone call away at (978) 462-0082.

Farmers’ Almanac Says Get Ready for a “Polar Coaster” Winter

Farmers’ Almanac Says Get Ready for a “Polar Coaster” Winter

According to Farmers’ Almanac (Almanac), we are in for a “Polar Coaster” winter. The term was inspired by the ups and downs that are predicted on the thermometer. Consequently, we may not be able to get off “the ride” until April!  Moreover, now is a great time to start thinking about saving money by making your home more energy-efficient with The Green Cocoon’s eco-friendly building insulation.

Saving Money

How do you save money with The Green Cocoon? Let us explain.

In our blog post, “Invest in Insulation,” we analyzed the average heating and electricity bills in Massachusetts (where we are located). Furthermore, we wanted to give our readers an estimate of how much money they would save by investing in insulation. And, the answer is approximately $1,284 annually!

Additionally, here’s what you can do with $1,284:

  1. You can buy an average of three months’ worth of groceries for a family of four.
  2. You and your significant other could take a one-week cruise to the southern Caribbean from Boston.
  3. Fill the gas tank in your car for almost one year. Of course, this depends on car size and miles travelled.
  4. Invest it every year and after 30 years you would have over $100,000!

New Hampshire Known for Crazy Weather

If you live in New Hampshire, you are no stranger to crazy winter weather. According to NOAA’s National Centers for Environmental Information, the coldest temperature on record in New Hampshire  (-50°F) was on January 22, 1885. That was at the summit of Mount Washington. Likewise, many winters in New Hampshire bring snow, rain, ice, and chilly temps, which many of us enjoy! If you are an outdoor enthusiast, it means a lot of exciting outdoor winter activities.

Almanac’s editor Peter Geiger, said “Our extended forecast is calling for yet another freezing, frigid, and frosty winter for two-thirds of the country.” What does that mean for us this winter? We will experience colder than normal temperatures, and significant precipitation.

Use Eco-Friendly Building Insulation

In conclusion, don’t keep throwing your money out the window. The Green Cocoon has eco-friendly building insulation that comes in various forms. Contact us to learn more!

Invest in Insulation

Invest in Insulation


One question we always get asked here at The Green Cocoon is, “What is the R.O.I. (return on investment) on insulation?” Consumers want to know if the upfront cost is worth it and more importantly, how long it takes to see the payback. Let’s break this down and find out!

Energy Costs Analyzed

Energy costs vary per state, and since we are located in Massachusetts, we will use that state. The average winter heating bill for oil (most popular) is about $2,083 per year[i]. The average yearly electric bill is around $1,128[ii], and much higher in the summer months due to the use of air conditioners.  That comes to a moderate total of $3,211 annually.

Some of our customers have seen reductions in their heating and cooling bills of up to 75 percent, but for the sake of this example, let’s just say that by insulating your home you save 40 percent. That is a savings of $1,284 per year! If the average insulation job for a medium-sized home is around $6,000 (give or take a few thousand depending on size and material), it would take just under five years to get the return on your investment. After that, you are pocketing an extra $1,284 per year. Think of all of the things you could do with that money! What does that money equal?

What You Can Do With Savings

Here’s what you can do with $1,284:

  1. You can buy three months’ worth of groceries for a family of four.
  2. You and your significant other could take a one-week cruise to the southern Caribbean from Boston.
  3. Fill the gas tank in your car for almost one year (depending on car size and miles travelled).
  4. Invest it every year and after 30 years you would have over $100,000!

As you can see, insulation is well worth the investment. The question isn’t, “Can I afford it?” The question is, “How can you not?”

If you don’t have the money upfront for insulation, there’s no need to wait to start saving. Ask us about our interest-free financing options.


[i] Commonwealth of Massachusetts (2019). Household Heating Costs. Retrieved from mass.gov.
[ii] Electricity Local (2019). Residential Electricity Rates & Consumption in Massachusetts. Retrieved from electricitylocal.com.

Hurricane Season Is Upon Us!

The hurricane season in New England is defined as June 1st to November 30th. However, 75% of the 40 tropical systems that have impacted our region in the past century have struck during the months of August and September. The last severe hurricane to hit Massachusetts was Hurricane Bob in August 1991. Bob, a Category 2 Hurricane, with winds between 91 and 110 mph, caused almost $1 billion in damage. Other hurricanes like Eduardo (1996), Bonnie (1998) and Bill (2009), threatened the Bay State, but veered out into the Atlantic as they traveled up the coast (www.mass.gov).

hurricane-roof-damageEvery year as storm season rolls around, millions fear for the safety of their family as well as the safety of their home. Now, with Demilec USA’s Heatlok XT spray foam insulation, you can rest assured that your home is protected by the strength of a hurricane adhesive. It has been tested to have bonding strengths up to two times that of Florida’s code minimum! Heatlok XT can provide the following benefits to your home:

  • Reduce Storm Damage
  • Increases Wind Uplift Resistance
  • Create a More Solid Structure

Demilec USA’s Heatlok XT Spray Foam and hurricane adhesive product bonds the roof deck and trusses together. As a result, it meets and exceeds the requirements of the state of Florida, a state known for its destructive hurricanes (www.demilec.com).

You worked hard to put the roof over your family’s head. Don’t let a storm carry it away! Give us a call and ask how you can get Heatlok XT in your home today!

Insulation of the Future: The Green Cocoon Investigates Hemp

Insulation of the Future: The Green Cocoon Investigates Hemp

The United States demand for insulation is estimated to rise 3.7 percent per year to approximately $9.5 billion by 2021.[i] And with so much demand, new types of insulation are being tested for the future. We will focus on one—Hemp.

According to Green Building Advisor, “Two North American companies are producing insulation for residential construction from locally sourced hemp fiber. This gives builders an alternative to fiberglass, plastic foams, and other more conventional materials.”[ii]

Europe Has More Access to Hemp

In Europe, builders have access to hemp insulation, but availability has been limited in the U.S.  Some U.S. builders have toyed with a mix of hemp fibers and lime called “hempcrete.” But, because of U.S. laws, extensive use of industrial hemp has been blocked.

Hemp Batt Wall Insulation

One Canadian company capable of producing threadlike hemp insulation on a commercial scale is Montreal-based MEM Inc.  Not far behind producing hemp fiber insulation is a biomaterials supplier in Louisville, Kentucky, called Sunstrand. And, new on the scene is Nature Fibres, a Canadian company based in Quebec. [iii] The interesting fact about Nature Fibres is they moved into Asbestos, Quebec, to start up their business. The town was named after asbestos because of the former industry in town. But, due to the associated health risks, those manufacturing facilities are closing their doors.

Benefits of Using Hemp

The benefits of using Hemp for insulation are many. It is biodegradable and has a very long service life. “Walls opened up in France 50 years after construction showed hemp insulation looking essentially brand new.”ii Hemp is composed mostly of a natural fiber (88% hemp fiber and 12% polyester fiber) with no chemical binders and no VOC (volatile organic compounds) off-gassing. As a result, it allows water vapor to pass through it. and is naturally repellant to rodents and insects.

It is clear that with all the changes in the market and with regulations, the insulation industry needs to keep up with demand and changing times. The Green Cocoon is a company that looks to help people lower their carbon footprint by increasing their home’s efficiency. We do this while using the greenest products available on the market.

[i] Walls & Ceilings (2019, August 6). An Optimistic Look into the Insulation Future. Retrieved from wconline.com.
[ii] Green Building Advisor (2018, March 8). Hemp Insulation Comes to North America. Retrieved from greenbuildingadvisor.com
[iii] Eco Home (2018, October 19). Hemp Insulation in Canada & USA – Insulating Naturally Is an Eco-Friendly Alternative. Retrieved from ecohome.net.