Roof Insulation

Why You Should Insulate Your Roof

Insulating a home's roof is one of the most cost-effective energy conservation measures. A well-insulated roof retains heat in the winter and deflect the sun's heat in the summer. Either way, roof insulation reduces the need for constant heating and cooling, so your HVAC equipment does not run as much. That translates into lower energy costs.

The U.S Department of Energy reveals that homeowners can save between 10-20% on whole-house energy savings with proper insulation and air sealing. Besides being environmentally friendly and helping to lower your monthly utility bills, roofing insulation improves your home's comfort and overall value. It is a cost-effective home upgrade that pays for itself relatively quickly and keeps giving year after year.

Insulation manufacturers use a variety of materials, including fiberglass, cellulose, and mineral wool. The most appropriate option for your home will depend on factors such as your location, prevailing climate, and your budget. 

No doubt, insulating a roof can be tricky because insulation materials have to fit tightly around roof vents and other fixtures. Plus, there exist building codes that specify a particular way to install insulation. Some installations are within the capability of DIY enthusiasts, but others require the intervention of a competent home insulation contractor, like ourselves, Conejo Valley Home Services. 

Below is everything you need to know about insulating your roof.

Home Insulation Experience


We have a team of insulation technicians that have been in business together for over 40 years.

Conejo Valley Home Services Licensed, Insured and Bonded

We’re a reputable contractor with legitimate credentials. C-20 and General B License # 536465.

Affordable Insulation

Get in touch with us for the best and affordable insulation services in Conejo Valley and Surroundings.


What Our clients Say!

Reliable Excellence

What to Look for Before Installing Roof Insulation

If you are considering investing in roof insulation, first understand the scope of the project.


Firstly, examine the condition of your roof. If you can easily access the space, there is no sign of moisture, and you may proceed to do the job yourself. Below are circumstances when professional intervention is worth the expense:

  • If you cannot easily access your attic
  • When you notice any sign of leaks or water damage
  • Poor ventilation
  • Old wiring that may increase the risk of insulation fires

If you opt for the DIY route, remove all clutter from the space. Sealing off all gaps and air leaks will ensure the effectiveness of your new roofing insulation. Air sealing options include expanding foam and caulk. The attic will still need ventilation, and that is where the wisdom of a professional comes in.


The type of your roof will determine the tasks involved and whether to hire a home insulation expert. You may need to remove old shingles and visually inspect the deck before loading any material. If the deck is in good condition, the installation should be very straightforward. A metal roof can complicate things. You'll need to hire an expert to install a vapor barrier on the warm side before applying the insulation to counteract condensation and corrosion. 

You will need to determine the ideal type of insulation material for your roof. The most preferred option is spray foam insulation, which creates an excellent, tight seal around all the gaps and holes in your attic ceiling. It fills all the voids, creating a barrier that traps the heat during the winter and cool air during the summer. Also, you can find rolls that you must carefully cut, so they fit around all cracks and openings.

For DIY roofing insulation, acquaint yourself with your state's building codes to ensure compliance. Else, the state will hold you accountable for any code violation and subject you to any penalties. Consider also that the state may demand you redo the project, which will undoubtedly cost a considerable chunk of money. That is why we highly recommend consulting with a professional before undertaking similar projects.


Types of Insulation

Below are the top roofing insulation options to consider:

1. Spray Foam

Spray foam is among the most common and effective insulation roof materials. It is a polyurethane-based heat and sound insulation liquid foam known for its effectiveness in sealing cracks.

When applied to gaps and cracks, spray foam expands and solidifies, forming a robust air and moisture barrier. When done right, spray foam insulation can significantly reduce your energy bills and carbon footprint. You can choose between high-density closed-cell insulation foam and low-density open-cell spray foam.

With closed-cell insulation, the cells are firmly closed and pressed together for better rigidity and stability. It is ideal for larger areas and offers an R-value between R-4.9 and R-7.1 per inch.

Right Type of Attic Insulation

For open-cell insulation, the cells stay open to produce a softer and more flexible foam. It's ideal for indoor application (think soundproofing) and offers an average R-value of R-3.55 per inch.

Pros of spray foam insulation include:
  • Helps maintain comfortable indoor temperature in summer and winter months
  • Offers acoustic insulation than other insulation options
  • Can extend the longevity of your existing roof and reduce its maintenance requirements
  • Reduces wind-driven dust commonly found in the attic
  • Its high strength to low weight ratio guarantees a stronger, more stable roof
  • Keeps critters away from your home
Cons include:
  • Requires professional installation due to its chemical and flammability risks
  • Requires higher upfront costs

2. Loose-Fill Roof Insulation

Also known as blown-in insulation, loose-fill insulation comprises loose fibers of recycled materials. Installation involves blowing the material into inaccessible spaces using a blower machine that you can rent from a local hardware store. 

The main options are fiberglass and cellulose loose-fill insulation. Fiberglass' thermal value ranges between R-2.2 and R-2.7, while that of cellulose averages R-3.5 per inch. 

  • Fits easily around obstructions and between irregularly spaced joists
  • Ideal for insulating inaccessible areas
  • Light and convenient to use
  • Ideal for topping up existing roofing insulation
  • Fiberglass insulation is entirely fire-resistant
  • Cellulose insulation does not pose any health concerns
  • Cellulose is more durable, making it an excellent option for colder climates
  • Unsuitable for draughty attics
  • Glass fibers can cause health issues like respiratory conditions when inhaled.
  • Safety equipment and protective clothing required for fiberglass installation add to the upfront costs.
  • Fiberglass insulation loses up to 50% of its thermal value in cold climates.
  • Cellulose is flammable and hard to extinguish.

3. Batt Insulation

Batt roof insulation is available in rolls of foil-backed rock, mineral, or glass fiber. The rolls are pre-cut in varying sizes to fit regular joists and rafters.

Batt insulation is DIY-friendly and easy to transport. Its applications include residential properties, public sector buildings (like schools and hospitals), and commercial premises. 

However, batt insulation has a low R-value (ranging between R-2.9-3.8 per inch), resulting in low energy efficiency. That means it performs poorly in colder climates and may need several layers to achieve the required thermal insulation. 

4. Rigid Insulation Boards

They are durable foam boards made from thick sheets of closed-cell foam and characterized by exceptional thermal insulation values. These boards can be used anywhere in a home and are available in three types:

  • Polyisocyanurate (polyiso) - Available with a radiant barrier, this polyiso-based foam has the highest price and R-value of the three options. 
  • Extruded polystyrene (XPS) - A blue/pink, water-resistant foam with a plastic surface. However, polystyrene is flammable and can deteriorate with extended exposure to UV rays.
  • Expanded polystyrene (EPS) - Has similar properties as XPS foam but has the lowest R-value and price of the three choices. 
Advantages of rigid insulation boards:
  • High insulation thermal value per unit thickness
  • Available in eco-friendly options like straw, wood, and cork 
  • DIY friendly as they are available in large, solid sheets
  • You can cover them with plasterboard to improve the overall appearance
Disadvantages include:
  • They contain a chemical flame retardant claimed to cause serious health issues such as cancer.
  • Deteriorates with prolonged exposure to sunlight

5. Structural Insulated Panels

Last in our list of insulation roof options is structural insulated panels (SIPs), prefabricated panels with a foam insulation layer sandwiched between two oriented strand boards (OSB). These panels are available in different sizes and shapes, with thickness ranging between four and eight inches.


SIPs are durable and stable and can be used in place of wood frames. High air sealing and thermal resistance properties help cut energy consumption and cost. Because SIPs are susceptible to moisture damage, they require a vapor barrier or exterior sheathing for protection against water. Additionally, installing large panels demands the expertise of an experienced contractor. 

What is the Best R-Value for Insulation?

R-value is a rating that grades insulation materials based on their ability to prevent conductive heat flow. R denotes resistance to heat flow. The R-values of roofing insulation vary depending on the material type, thickness, and density.


The higher the R-value, the higher the resistance to heat flow, which means better performance. The vice versa holds. To keep the temperature in your home consistent, you must have your roof insulated with the correct R-value. The required insulation R-values vary depending on the geographical locations, as illustrated by the Energy Star's R-value region map.


The chart divides the U.S into different zones, each with an assigned R-value range. For example, most parts of California lie in Zone 3, which requires roof insulation with an R-value ranging between 30 and 60. Generally, a colder region requires a higher R-value than hotter climates. 

Benefits of Roof Insulation

Below are the top perks to having your roof insulated:

  • Heat retention and prevention: Insulation stops heat from escaping your house through the roof, keeping warmth inside your house. If you live in a region that suffers extreme temperatures in summer, roof insulation comes in handy to prevent excess heat from entering your home. 
  • Energy savings: Insulation keeps the conditioned temperature inside your home, saving your HVAC system from having to run overtime to make your home comfortable. Resultantly, you save both energy and utility bills.
  • Extra protection: Roof insulation safeguards your home against the onslaught of long-term exposure to natural elements. It can help your roof last longer, which is a significant benefit for the resale value of your home.

What is the Average Cost of Roof Insulation?

A complete roof insulation project averages $22,000. Installers charge per square meter or hour for this type of project. Average labor cost ranges between $50 and $80 per hour or $40-$100 per square meter. 

Below are factors that influence the cost of roof insulation:

  • Accessibility: Areas with limited accessibility can complicate the insulation process, thus attracting higher fees. You may need to hire an electrician to locate obstructive electrical wiring or perform necessary adjustments, which will raise your expenses.
  • Type of insulation: Insulation roof materials have varying prices. For example, spray foam ranges between $0.35 and $2.00 per board foot, while blown-in insulation typically costs $1.00 per square foot. Reflective foil insulation will set you back $0.15-$0.30 per square foot. 
  • Replacement: Removing deteriorated insulation can be time-consuming and labor-intensive, driving up your expenses. If your existing insulation does not require replacing, you can save money by just topping it up with layers of modern insulation.

Which Type of Roof Insulation is Right for You?

The first step to determining the correct type of roofing insulation for your home is identifying your home's R-value climate zone. Use the information to source insulation products that will achieve the stipulated insulation thermal value.


Are you struggling to determine the appropriate R-value and material for your roofing insulation project? If so, have a home insulation expert evaluate your home, determine the specific insulation requirements, and recommend the most suitable options.


A premier insulation contractor in the Conejo Valley, Conejo Valley Home Services handles your home insulation project with the utmost professionalism from conception to completion. We specialize in cellulose and fiberglass blown-in insulation and fiberglass batt insulation services backed with over 41 years of industry experience. You get the confidence that you will have the right insulation installed correctly for maximum home comfort, increased energy savings, and minimal carbon emissions. Call us today at 805-499-0448.

Need Insulation Services?
Get in Touch!

Request Services

Fill the form below to Request Home and Commercial Insulation Services


scroll to top button