Attic Insulation 101 Types Cost and R-Value

Kevin Brown

Attic Insulation: Types, Cost, and R-Value

Attic insulation is a critical part of a building’s energy efficiency. By properly insulating your attic, you can significantly lower the amount of heat lost during the winter and the amount of heat gained during the summer. This can result in reduced energy bills and a more comfortable living space.

When it comes to attic insulation, there are various types to consider. The most common types include fiberglass, cellulose, and spray foam insulation. Each type has its advantages and disadvantages, so it’s crucial to choose the right one for your needs.

Firstly, fiberglass insulation is the most widely used type. It comes in batts or rolls and is relatively easy to install. Additionally, fiberglass is fire-resistant and has a high insulating capacity.

Secondly, cellulose insulation is made from recycled materials, making it an eco-friendly choice. It is blown into the attic and forms a dense layer, providing effective insulation. However, it may settle over time and lose some of its insulating properties.

Lastly, spray foam insulation provides superior insulation and eliminates air leakage. It can be installed in hard-to-reach areas and effectively seals any cracks or gaps. However, it is more expensive than other types of insulation.

When considering the cost of attic insulation, several factors should be taken into account. These include the size of the attic, the type of insulation chosen, and the labor costs involved. It is best to consult with a professional insulation contractor to get an accurate estimate for your specific needs.

In conclusion, attic insulation is vital for maintaining energy efficiency in your home. By understanding the different types of insulation available and considering the associated costs, you can make an informed decision regarding which type is best suited to your needs. Remember that proper attic insulation is an investment that pays off in the form of increased energy savings and a more comfortable living environment.

Attic Insulation 101 Types Cost and R-Value

Attic insulation increases energy efficiency and prevents mold-causing humidity. There are five common types, and the best choice depends on the local climate, your home’s architectural type, and your budget.

Attic Insulation 101 Types Cost and R-Value

Insulating the attic is essential because the majority of US houses are not adequately insulated, leading to about a quarter of home heat being lost through the attic. Proper insulation in the attic helps to retain this heat, resulting in lower energy bills.

As warm air naturally rises, without insulation, it will escape through leaks and cracks in the attic, causing your HVAC system to work harder. This can also increase the risk of mold or moisture problems in the attic.

Attic insulation is not just for cold climates. Heat moves to cooler areas, and on hot days, attic temperatures can be 20 – 30 degrees higher than outside temperatures. This high attic heat can transfer through the ceiling into living areas through conduction.

Heat can also seep through gaps or cracks, making air conditioning systems work harder.

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How much attic insulation is enough? All insulation has an R-value rating, which measures the thermal resistance of a product. Each type of insulation has a different R-value per inch.

Once you choose the insulation type, thickness becomes important.

The map below depicts US climate zones and recommended attic R-values for each zone. The suggestions for hot and cold zones are similar. The map, chart, and insulation R-values provide an answer to the question of how much insulation is needed.

Cost is another factor to consider when determining attic insulation. Ten inches of spray foam is more expensive than ten inches of cellulose, and the R-values also differ.

Recommended insulation levels for retrofitting existing wood-framed buildings are as follows:

Attics are a key area to focus on when it comes to adding insulation to your home. By doing so, you can greatly improve energy efficiency and reduce heating and cooling costs. In fact, a well-insulated attic can save you up to 20% on your energy bills.

There are several types of attic insulation to choose from, depending on your needs and budget. One common type is batt or blanket insulation, which comes in rolls or sheets. It is made of fiberglass, mineral wool, or cotton and can be installed between the attic joists or over them.

This type of insulation is versatile and relatively easy to install.

Another option is loose-fill insulation, which is made of small particles of various materials, such as fiberglass or cellulose. It is blown into the attic space using a special machine. Loose-fill insulation is a great choice for attics with irregular shapes or hard-to-reach areas.

Spray foam insulation is another popular option for attics. It is applied as a liquid and expands to fill and seal any gaps or cracks in the attic. This type of insulation provides excellent thermal and moisture resistance, making it a great choice for attics in humid climates or areas prone to moisture issues.

Lastly, there is radiant barrier insulation, which is designed to reflect heat radiation away from the attic and keep it cooler. It is typically installed directly under the roof, either on the attic floor or on the underside of the roof rafters. Radiant barrier insulation is particularly effective in hot climates where the attic can become extremely hot.

When choosing the right attic insulation, it’s important to consider factors such as your climate, budget, and the condition of your attic. It is also a good idea to consult with a professional insulation contractor who can assess your attic and recommend the best insulation options for your specific needs.

In conclusion, adding insulation to your attic is a cost-effective way to improve energy efficiency and reduce heating and cooling costs. Whether you opt for batt, loose-fill, spray foam, or radiant barrier insulation, each type has its own advantages and considerations. By making the right choice, you can create a more comfortable and energy-efficient home.

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Batt insulation is popular because it’s easy to install. The installation consists of fitting the first layer of insulation between the trusses or joists onto the drywall and a second layer perpendicular to the first. Keep this insulation away from heat-emitting electrical fixtures such as pot lights, regardless of the fire-retardant properties of the batts.

Many attic spaces are home to plumbing pipes, HVAC ducts, and electrical wiring, making batts difficult to install and inefficient when not properly placed. Some insulation contractors recommend against installing batts in attics.

In an unvented attic, blanket insulation can go between the rafters. The friction fit properties hold the insulation in place initially, but you’ll need strapping to keep them there.

Batt or blanket insulation types:

    Fiberglass: Available unfaced or with kraft paper on one side, serving as a vapor barrier. Costs between $0.40 and $1.20 per square foot, depending on thickness. R-value between R-3.1 and R-3.4 per inch.

    Mineral Wool: R-15 mineral wool costs approximately $0.80 per square foot. R-value between R-3.0 and R-3.85 per inch. More rigid and difficult to cut and place compared to fiberglass, but better soundproofing.

    Denim: Not always available. R-3.5 per inch. Inconsistent batt sizes.

    Approximately twice the cost of fiberglass. Easily absorbs moisture and therefore requires a vapor barrier.

    Loose-Fill Insulation

    Loose-fill insulation provides thick coverage on attic floors, filling gaps and cracks. It can be installed by professionals or through DIY options. Some home improvement outlets supply loose-fill insulation machines when you purchase the material from them.

    Alternatively, you can pour loose-fill insulation from bags into the attic and smooth it out, though this may result in inconsistent application.

    Loose-fill covers the entire attic floor with insulation, filling around obstructions like wires, pipes, and ducting. It is inexpensive, easy to install, fire retardant, and has a good R-value.

    Blown-in insulation may block soffit vents if not installed carefully, especially in older homes without air chutes or stops at the exterior wall. Attic ventilation is necessary to equalize air temperature.

    Loose-fill insulation types:

    – Cellulose: R-3.5 per inch. Costs $0.80 – $1.30 per square foot. Dusty during installation.

    Does not lose R-value if it settles. Absorbs moisture in humid conditions.

    – Fiberglass: R-2.2 – 2.7 per inch. Costs $1.56 – $2.72 per square foot. Has air convection problems due to lower density compared to cellulose or spray foam.

    Spray Foam Insulation:

    Spray foam insulation is popular for attics, despite its cost. It is applied to attic floors and the undersides of vaulted ceilings, adhering permanently. Foam provides complete insulation by expanding into all cracks, gaps, corners, and crevices.

    Until recently, spray foam could only be installed by professionals due to the necessary equipment. However, DIYers now have the option to rent equipment. Nevertheless, caution must be exercised as spray foam is toxic.

    Correct mixing is crucial for its effectiveness.

    Spray foam is offered in two formulations: open and closed-cell foam, each with unique properties. Both have an 80-year lifespan and provide excellent R-value.

    Open Cell Foam: R-3.8 per inch. Costs $0.25 – $0.50 per inch. Functions as an air barrier but not as a vapor barrier.

    Not recommended for the northern half of the US due to the potential 70-degree F difference between external and internal temperatures. Additionally, it is an exceptional soundproofing product. Expands approximately 3” after application, effectively reaching most gaps and cracks.

    Closed Cell Foam: R-7.0 per inch, costs $0.90 – $1.50 per inch. Provides air and vapor barrier. Expands about one inch.

    May require multiple layers for desired R-value. Reflective Insulation: Reflects heat in hot climates but not effective in colder climates. Prevents solar heat gain. Most effective installed on undersides of rafters with one-inch air space on reflective side. Installing on top of joists is less effective but keeps most heat away from living spaces.

    Rigid Foam Board Insulation:

    Rigid foam boards are difficult to install between trusses or rafters but are a good option for unvented vaulted ceilings. Using foam board insulation between studs and rafters is a way to insulate the attic without losing ceiling height. Rigid Insulation R-values range from R-3.5 – R-6.5.

    Rigid foam can go on the floor of the attic, between joists or trusses. Some products act as a vapor barrier if at least 2” thick. A perfect fit between framing members is almost impossible to achieve, so you’ll need to seal these gaps with acoustic caulking or low-expansion spray foam from cans.

    If you are considering a new roof, you can install rigid foam on the exterior before reroofing. Extruded polystyrene is the most popular product–often called Styrofoam and is available in multiple sizes and thicknesses.

    Rigid foam is difficult to install on attic floors if there are wires, plumbing, and HVAC ducting. Loose fill or spray foam are better options.

    Terry Schutz is experienced in home renovations, DIY advice, and construction topics. With over 30 years in the construction industry, Terry has gained knowledge as an installer, manager, salesperson, and business owner.

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