Insulation - The Most Underestimated Aspect of Construction

Insulation is one of the most interesting and fascinating construction components from a building science perspective. It serves multiple purposes - helps to maintain the temperature within a building, reduce energy costs, soundproof a structure, and ensure a comfortable living or working environment. In this article, we will discuss the importance of insulation in California, the benefits of proper insulation, and the various types of insulation available on the market currently.

California is known for its hot summers and cool, damp winters. Even during the day temperature can fluctuate by as much as 40 degrees Fahrenheit. Without proper insulation, a building can experience significant temperature fluctuations, making it uncomfortable and costly to maintain a consistent indoor temperature. Moreover, poor insulation can lead to energy inefficiency, resulting in high energy bills and increased carbon emissions. Well-insulated buildings do not let the heat escape when it gets cold outside and block the heat coming in from the outside on a hot day.

When evaluating a particular type of insulation, first indicator people look at is the R value. Essentially the R value determines how well a material can resist an increase in temperature resulting from an exterior heat influx. For reference, R value for wood varies from 0.40 to 1.41 based on its nature, poured concrete - 1.33, and fiberglass insulation - 4.3. Clearly building a house from just studs and concrete would not be sufficient to provide high enough levels of thermal insulation.

California's Title 24 provisions require that exterior walls are insulated at R15 and roof at R30. Given these requirements and known R values per inch for different insulation types, one can arrive at the value of batt thickness required to meet Title 24 regulations.

Proper insulation has numerous benefits for both residential and commercial properties in California. Some of the benefits of proper insulation are discussed below:

1. Energy efficiency: Insulation helps to reduce the amount of energy required to maintain a comfortable indoor temperature, which can lead to significant cost savings on energy bills. Energy Star, a leading authority on energy savings, claims that an average US household can save about 15% on energy costs from properly insulating and sealing their homes. Similarly, insulation can reduce the carbon footprint of a building by reducing the amount of energy required to heat or cool it.

2. Improved indoor air quality: Insulation can help to reduce the amount of moisture and condensation that accumulates on surfaces, which can promote the growth of mold and mildew. This, in turn, can help to improve indoor air quality by reducing the presence of allergens and other pollutants. For illustration purposes, imagine San Fernando valley at 3pm on a hot September day when temperatures hover around 105 degrees Fahrenheit. There is a lot of moisture contained in that air. When it penetrates the facade of a poorly insulated home and collides with cool conditioned air, condensation is inevitable. Condensed moisture can cause mold on drywall surfaces.

To avoid that, make sure your home is properly insulated and ventilated. Bathroom fans and

kitchen ranges are good at extracting any hot and humid air from interior spaces. Larger spaces may now include a continuous fan that operates 24/7 and removes excess moisture from the air.

3. Noise reduction: Insulation can help to reduce noise pollution by absorbing sound waves

and reducing the transmission of sound from outside the building. This can lead to a quieter, more comfortable living or working environment. Your typical fiberglass insulation has pretty good sound-proofing characteristics, but there are other superior products that do it better. For example, insulation made from mineral wool, sold under a brand name Rockwool, not only has excellent soundproofing qualities, but also is fire and mold resistant. This type of product can be useful when you are building an attached ADU and want an extra layer of sound separation between the two units. It can also be used in cavity space between floors of a wood-framed building.

There are several types of insulation available, each with its own unique benefits, drawbacks and R-values. The most common types of insulation used in California are discussed below:

1. Fiberglass insulation (R-value: 4.3/ inch): Fiberglass insulation is made of tiny glass fibers that are spun into thin strands and woven into a blanket-like material. It is one of the most commonly used types of insulation in California due to its low cost, ease of installation, and effectiveness at reducing the heat loss. It also possesses fire-resistant characteristics. Some fiberglass batts have paper facing on them, which acts as a vapor barrier. While fiberglass is not a great breeding ground for mold, paper-containing insulation products can easily develop mold after a minor water intrusion. In-wall vapor barrier protection is not typically installed in a Californian climate, so there is no reason to go with paper-faced insulation for your next construction project.

Installation process poses risks to health if proper protection is not worn. Typically, the

installer will wear a respirator and a coverall suit to protect themselves. Tiny fibers of fiberglass can irritate skin and lungs upon contact.

2. Cellulose insulation (R-value: 3.5/ inch): this type of insulation is made from recycled newspaper and other recycled paper products that are treated with chemicals to make them fire-resistant. It is an eco-friendly option that is effective at reducing heat loss, but it can be more expensive than fiberglass insulation. Cellulose insulation can be used in walls, but its most typical application is in the attic space where its gets blown over spaces enclosed by joists. During production process it gets treated with chemicals that resist fire. It is also less hazardous during installation than the fiberglass insulation, but caution should still be exercised when working with cellulose insulation. A respirator mask should be worn at all times as cellulose dust can be a harmful irritant for the lungs.

Certain types of cellulose insulation will need to be stabilized with water during installation, which provides an effective blanket of air sealant over the attic space. Do not worry about mold since moisture content is low and can be released into the environment by evaporation through attic vent openings.

3. Spray foam insulation (R-value: 7/ inch): Spray foam insulation is a more expensive option that is effective at reducing heat loss and preventing air leakage. It is sprayed onto surfaces as a viscous fluid and then expands to fill gaps and crevices, providing a tight seal. Undoubtedly, spray foam is very effective at sealing any spaces and providing a reliable shield against air and heat. However, it has its own disadvantages. Firstly, is the cost of application. It can be twice as expensive as the fiberglass type. Second, in a case of retrofitting or taking walls apart, spray foam presents more challenges and is a lot more labor and clean-up intensive due to its highly adhesive qualities.

In addition, spray foam insulation does not let mold develop easily. Its main two health-related concerns are dust that it emits during the installation process and volatile organic compounds (VOCs) that are released in the air for the next 24-48 hours after its application. It is best to let the dwelling air out for that time period before continuing work inside.

4. Rigid board insulation: this category of insulation is made up of several products - EPS (expanded polystyrene), polyiso (polyisocyanurate), and XPS (extruded polystyrene or also known as styrofoam) insulation. Their most common applications are on roof decks, along foundation walls of basements, and at exterior walls. These types of insulation are resistant to mold, provide excellent thermal resistance, and act as an air barrier. Table below summarizes physical properties of each insulation type.

	EPS	Polyiso	XPS
Structure	Closed-cell rigid foam	Closed-cell rigid foam with facers	Closed-cell
R Value	3.6/ inch	6.5/ inch	4.7/ inch
Price point	$	$$	$$$
Performance and Application	Needs to be thicker to match R value of other products	Best at medium to high temperatures (above 50˚ F)	Best to be used in above-grade applications because it can retain moisture

It is uncommon to see exterior insulation on residential construction in Los Angeles. Most architects specify interior batt insulation for simplicity purposes. However, higher energy performance can be achieved if both exterior and interior insulation are installed. This method provides significant energy savings, but requires use of advanced ventilation systems to remove moisture from air and bring fresh air inside since this wall assembly is so air tight.

For those who strive towards more eco-friendly options that do not off gas a lot of organic compounds and/ or do not leave a large carbon footprint, there may be some products on the market that are worth looking into.

One of the most eco-friendly insulation options is wool insulation. Made from the fleece of sheep, wool insulation is an excellent choice for those who want a sustainable, natural material. Wool insulation is also incredibly effective at trapping heat, making it ideal for colder climates. Additionally, wool insulation is naturally fire-resistant, meaning that it doesn't require the addition of potentially harmful chemicals to achieve fire safety standards. Some manufacturers claim to reach an R value of up to 4.3 per inch with their blown-in wool insulation solutions, which is a really good indicator.

For those looking for a more high-tech solution, there are several eco-friendly insulation options made from recycled materials. For example, recycled denim insulation is made from old jeans, providing a sustainable and effective solution for insulation. Similarly, insulation made from recycled plastic bottles can help to reduce plastic waste while also providing excellent thermal insulation.

One of the most innovative eco-friendly insulation materials available today is aerogel insulation. Aerogel insulation is made from a gel that is dried to form a solid material with a low density. This material has an incredibly high insulating value, making it ideal for those looking to maximize energy efficiency. Additionally, aerogel insulation is made from silica, a naturally occurring mineral that is both abundant and non-toxic.

Overall, there is a variety of solutions on the market that may suit your individual needs. Most homes in California utilize standard fiberglass insulation. Your contractor will likely propose to install it too. You should consider mineral wool insulation at least for interior partition walls and floor joists to provide sound barrier between rooms and floors.