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Top Prospects for Alternative Insulation in the Home

Keep Your New Home Warm in Winter and Cool in Summer 


As you think about building a new home from house plans, insulation is obviously a critical aspect the constricton process. But as it stands, the traditional types of thermally protective barriers are far from perfect. For example:

• Fiberglass batts are readily available but are very harmful to work with, have low R-value, and require a vapor barrier from moisture.

• Concrete-and-foam forms are energy efficient when insulated but can only be used in new construction.

• Rigid foam boards use hydrochlorofluorocarbons (HCFCs) in production, which is harmful to the environment.

• Blown in cellulose is environmentally friendly but is also susceptible to mold among many other issues.

• Spray polystyrene foam of a closed-cell type is very expensive while open cell absorbs moisture.

It's not hard to see that there's a real industry gap for what many would consider the perfect insulating material. If a product could be affordable, environmentally friendly, convenient to work with, and offer an unprecedented R-Value then it could corner the insulation market – almost easily.

But before we look at alternative insulation materials, let's look at the basic job that insulation is intended to do.


Installing Insulation Properly

Depending on the climate in the region in which you live, insulation for a home plan provides a protective barrier between your home and the outdoors. The United States Department of Energy has good, clear advice – with easy to review diagrams – making it really easy to understand how to insulate your house. The information was designed to help you reduce your home's heating and cooling costs through proper insulation and air sealing techniques and to make you more comfortable. Insulating a home properly will also save money.

A house plan needs to have the proper specifications to be properly insulated from the foundation to the roof for optimal energy efficiency. Factors also include moisture and air leakage control in each area of your house. While in the design phase of planning a new home, think about doing structural insulated panels, insulating concrete forms, and insulated concrete blocks. These materials literally have insulation built in, and houses built using these products often have superior insulating qualities and minimal thermal bridging.

When installing insulation, always consult with your general contractor, and/or a local insulation professional. Following are the considerations:



Typically a loose-fill or batt insulation is used in an attic as it offers better coverage and is less expensive.  Make sure that vertical walls with attic space behind are insulated. Attic decking with an added platform for a heating or cooling unit, or hot water tank, is raised above the ceiling joists to leave room for the insulation. Finally, if you live in a hot climate, radiant barriers can also be installed in an attic to reduce heat.



When building a new home, make sure the ducts are placed in the conditioned space to avoid the energy losses associated with duct systems. If the ducts are in unconditioned space, seal them and then insulate.


Exterior Walls

In an existing home, think about using blow-in insulation installed with the dense pack technique, because it provides significant air sealing. With advanced wall framing techniques, thermal bridging can be reduced and you can maximize the insulated wall area. It provides a continuous layer of insulation, reducing thermal bridging through wood studs, improving comfort and helping to save energy and improving comfort.


Floors above Unheated Garages

Make sure to seal all possible sources of air leakage, which minimizing the danger of contaminants caused by car exhaust, paints, solvents, and other supplies, etc.


Foundation Insulation

A properly insulated foundation helps keep below-grade rooms more comfortable and also prevents insect infestation, radon infiltration, and even moisture problems. Plus it reduces heating costs. For insulating a new homes, seek construction techniques that provide both foundation structure and insulation, such as insulating concrete forms and insulating concrete blocks. Optimal foundation insulation materials and placement vary by climate.

Crawlspaces. Check to see if it is ventilated or unventilated. Most building codes require vents to help remove any moisture from the crawlspace. If you have or will have an unventilated crawlspace, seal and insulate the foundation walls rather than the floor between the crawlspace and the house. This keeps piping and ductwork within the conditioned volume of the house so these building components don't require insulation for energy efficiency or protection against a freeze.

Slab-On-Grade. Insulated slab are easier to heat, and placing the mass of the slab within your home’s thermal envelope helps moderate indoor temperatures. Installing slab insulation during the construction process is very straightforward. However, construction details vary widely, so it’s best to consult a building professional in your area.


Cathedral Ceilings

Insulation for cathedral ceilings enables ceiling temperatures to remain closer to room temperatures, and also provides an even temperature distribution throughout the home. Cathedral ceilings must provide space between the roof deck and home’s ceiling for adequate ventilation. Foil-faced batt insulation is often used in cathedral ceilings as it offers the permeability rating often required for use in ceilings without attics.


Alternative Insulation Materials

Building product manufacturers have noticed this opportunity for alternative insulation materials, particularly aided by the green construction movement. There are a few “exotic” insulation materials that have continually grown in popularity over the past decade:



Leading the way in the alternative insulation market is cotton. Interestingly enough cotton insulation is considered a green building product because it is largely made out of recycled blue jeans. Cotton is much safer and more convenient to work with than fiberglass, and it is formaldehyde free. Another big benefit is that cotton provides great acoustical qualities.

Insulation batts made from recycled denim

Made from all natural fibers – recycled denim – cotton batt insulation contains no irritating fiberglass and no formaldehyde (courtesy of Menards). In fact, it contains no chemical irritants and no volatile organic compounds (VOCs) and requires no warning labels compared with other traditional products. Yet is has identical thermal performance to fiberglass and as good or better sound isolation – albeit at a 3x higher price.



The reason sheep are able to live in any climate is because their wool is constructed of tightly packed fibers that trap air. These properties are what makes wool insulation such a viable option for home insulation. Wool insulation is renewable and sustainable, and it uses a fraction of the energy to produce compared with foam boards. Wool fibers are also breathable, which allows them to release moisture, and as a bonus wool is also non-combustible.

Home insulation made from wool

Wool fiber is natually "crimped," and when it is firmly packed together, it forms millions of tiny pockets that trap air, resulting in great insulating performance – keeping heat inside the insulated envelope during winter and out during summer (courtesy of Oregon Shepard). Although wool is naturally fire resistant, as a home insulating material it is treated with an all-natural solution that provides extremely high fire and vermin resistance. Cost is about twice that of traditiional fiberglass insulation.



A 100% natural product that can be harvested from the same tree every 18 years or so (using only the bark of the tree). Cork insulation sheets are moisture resistant and offer great thermal and acoustical characteristics. Expanded cork insulation is a natural material that nevertheless requires sophisticated processing to be an effective insulating material. It is naturally moisture resistant and more fire resistant than polyisocyanurate and polystyrene foam board insulation. The cost to achieve R-19, however, would be 3 to 5 times the cost of polyiscyanurate and 2.5 to 2.75 that of extruded polystyrene boards.


Soy-Based Spray Foam

One of the problems with cork boards or even wool or cotton batts is that they don't always cover the tiniest crevices in a wall or around pipes, which is why many homeowners prefer a spray foam. Soy-based spray foam is a much more eco-friendly material than traditional types of spray foam, and it is mold and moisture resistant as well as non-flammable.

Soy-based spray-foam home insulation

If you want to use a spray foam insulation in your home but are concerned about off-gassing and hydorfluorcarbons, you might consider a spray foam that is soy-based, Though not 100% soy, it reduces the amount of petroleum products used and is applied using water, so it is less toxic. The materials costs approximately 3 times more than traditional spray insulation (courtesy of International Association of Certified Home Inspectors).


With so many alternative options available (not to mention others such as recycled plastic bottles and more) it may seem dumbfounding that polystyrene foam and fiberglass are still the most common insulating options today.


Alternative Insulation a Reality?

The two main factors holding down alternative insulation materials from cornering the market are cost and availability. Approximately 9 out of 10 building contractors would prefer using wool or cotton over itchy and irritating fiberglass batts, but it's hard to pass on a price markup of two to three times to the homeowner. Using cork boards compared with polyisocyanurate foam sheets will come at a price differential that is five times higher. In addition, unfortunately, there aren't any significant increases in R-value when using one product compared with the other.

These alternative insulation types are also harder to come by than fiberglass batts, foam boards, or even blown-in cellulose, which all can be obtained at your local hardware store.

Homeowners who are striving to build their house as green as possible have been driving the market for these alternative insulation materials. For the majority, however, the cost advantages of traditional materials are too much to overcome.

It won't be like that forever, however, so don't be sad when those old jeans don't fit anymore – they may insulate your house someday. 


Footnote: the photograph at the bottom right of the lead image is of cellulose being blown into an attic space. For more information, click here.



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