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Residential Energy Efficiency Blog

Saturday, November 07 2020
How Much Does it Cost for Attic Insulation?  A Comprehensive Pricing Breakdown

If you are interested in figuring out how much attic insulation costs, there might not be any better way than to look at a project than through the eyes of a certified home energy auditor - such as myself.

I set out into Maryland communities every day to perform comprehensive home energy audits for BGE and Pepco utility energy customers by inspecting their attics, crawl spaces and basements and then providing them with solutions and attic insulation costs and returns on their potential investment.

Each home energy audit requires that a specific set of data points for the house get collected. During that process, it is an auditors job to determine what "opportunities" exist for low cost insulation improvements, also known as retrofits. 

Retrofitting is the work that goes into Home Performance.  Making a real impact on your comfort and overall energy efficiency is the goal of the comprehensive home energy assessment and the subsequent retrofitting. 

Home Performance vs. Attic Insulation

In additon to the bottom line cost of attic insulation another thing you must consider is the two different ways you can go about getting insulation pricing and how they differ.  This way, you will not miss key techniques that make a big difference in your final results.

1. Typical Insulation Quote

Most people tend to get an insulation cost estimate the familiar way which is to call ABC Insulation Company and have a rep come out, take a look in the attic and give them a price. 

After all, it is only insulation and it is in the attic.  How hard can it really be?

2. Getting a Home Energy Audit

An energy audit has a primary goal: to evaluate your home as a complete system and report back to you.  A comprehensive home energy audit takes a whole-house approach and it comes with measurable results. 

This means that you are able to sit in the driver's seat when deciding how to improve comfort and efficiency. 

Another key benefit of getting the audit done is knowing that all of the possible insulation costs will be uncovered in advance for accurate pricing and budgeting.

Think About Home Insulation in Three-Dimensional Ways

Common Insulation Misperceptions

Most homeowners think that the more insulation you have the more efficient you are and the more comfortable you will be.

But, if you miss the opportunity to insulate your home correctly, then it could leave you scratching your head about why it is not more comfortable in the house and why the energy bill has not gone down.

What does it mean to insulate effectively?  

Establish a Pressure & Thermal Boundary

If you have had a typical insulation quote recently and the representative did not mention the pressure and thermal boundary then you might be on a path to an incorrectly installed insulation project.

Most insulation, alone, will not stop the flow of air.

Insulation is similar to a jacket.  If a jacket is not zipped up, the air flows inside and around resulting in loss of body heat and comfort woes. 

If insulation (thermal boundary) has nothing stopping the flow of air (pressure boundary), then your home loses energy and you feel drafts.

Building Envelope

Identifying your house's envelope or "shell" is important for a properly estimated and installed insulation project.

Knowing where insulation is needed at every turn and what type of insulation is best for the job is an energy auditor's assignment.

Pressure dynamics inside your house create infiltration (air coming in) and exfiltration (air going out) in places that will get missed if building science principles are not applied during a typical insulation quote.

Incorrect Diagnosis

A typical insulation quote may provide information about insulation for walls which is costly and will undoubtedly yield little to no results. 

An energy audit is a great way to gain a new perspective on how your home is actually losing energy. 


Did you know that a properly installed insulation project around the house is likely to yield measurable results compared to window and door projects that tend to cost more?

For starters, an energy audit will perform an air leakage test (blower door test) and each window and door can be checked.

The blower door test is not something you would get with a typical insulation quote. 

The test can show how ceilings, walls, floors and basement areas all lead to as much as 40% of a home's air leakage compared to only 10% for windows and doors.

The Attic Insulation Technician - Required Skills

Determining how much attic insulation will cost will depend on the solution's complexity. Each home is quite different and getting measurable results requires hiring skilled technicians that are properly trained on how to do the job right.

Sealing and insulating a building shell requires technicians to work in tight spaces. Crews must be in good physical condition.

Watch this skilled technician install a baffle at the attic low point.

Often times similar houses in the same development have different problems. Through the years, different owners make changes to the building shell. Each property owner had their own "vision" along the way.

For the best results, technicians must have good general knowledge of residential building construction. Otherwise, important measures required to make the job effective, may not get completed.

The quality of the workmanship should and does factor into the cost of an attic insulation job.


Proper Measurements Are Key to Providing an Accurate Attic Insulation Cost Analysis

Houses that need pricing for attic insulation usually have lots of twists and turns.  This is not because the insulation is different or because the house is older, rather it is a simple fact that all houses are complicated. Knowing how to evaluate things from all six sides when determining the proper treatment is key to accurate insulation pricing.

Missing a measurement or a location where insulation is required could be the difference between not only an accurately priced job but also a job that will yield the desired results. 

Similarly, if you don't seal all of the holes in a leaky boat then you might as well not seal any cause you're still gonna sink!


The Size and Style of Home Impacts Overall Costscost of attic insulation

In all cases, insulation around a home must be contiguous with an air barrier. That is that the insulation and the air barrier must be together wherever the boundary between inside and outside exists.

When considering how much attic insulation costs, it should be understood that the price depends on the style and size of the home.

If a home has high ceilings in a bedroom and a standard ceiling in the hallway, there could be higher costs. This configuration creates a knee wall which also needs insulation.

If a house has a crawl space foundation and also has high ceilings on upper floors, then the cost will be higher than a home that does not have those features.

A good general way to figure out the cost comparison of two insulation jobs is to determine the overall square footage of the home's envelope or building shell.

Do You Need to Have Your Existing Insulation Removed?

Cost of Attic InsulationIn most home renovation projects it is customary to get rid of the old.  For example, during a replacement roofing project, the old shingles are stripped off the roof and thrown into a dumpster not to be used again.  The old shingles have no value.  In fact, adding shingles over top of old shingles will actually lower the value of the project and the overall value of the home.

Insulation, on the other hand, is different.  The insulation in your attic, believe it or not, does have some value.  For example, if you have 10 inches of fiberglass rolled batting insulation at your attic floor, the R-Value is calculated at 10 inches by a factor of 2.1 to get the R-Value of the material.  So, in essence, the insulation is giving you back some insulating qualities.

Unfortunately, as in the scenario above, there is not enough insulation to adequately separate the living space from the outside.  But, there is no reason to get rid of the value that you do have.  For example, if the R-Value of your existing insulation is calculated at R-20 and the recommended value should be R-49, then you only need R-29 to get where you need to be.

Removing existing insulation actually gets you further away from the mark you need to hit and will end up costing you more.

Here is one key thing to always remember: there is virtually no reason to remove existing insulation at the attic floor.  Insulation is on the "outside" of your home. 

Insulation that has been subjected to mold growth will not be a threat to your health if the issue causing the mold growth is stopped.  Therefore, throwing away insulation that has mold on it once the problem is resolved is a waste of resources.

Once you stop a moisture issue in an attic that is leading to mold, it is not necessary to remove the dirty insulation.

What Are the Typical Insulation Solutions and How Much do They Cost?

**Pricing listed in this article is based on information gathered in the Maryland market.

There is an expression in team sports like football and basketball.  It goes something like this: "let's take what the defense is giving us".  Essentially, what the team is saying is let's go after the places that the other team is not guarding.  The path of least resistance, so to speak.

In preexisting homes, it is a similar game plan.  We have to "take what the house is giving us".  This means that careful consideration should be given to treating the areas that are accessible compared to the areas that cannot be reached.  This approach will have a significant impact on overall cost.  

As a general rule, when you are dealing with a Home Performance contractor, the overall goal is to find the opportunities that: 


Take a 5 minute tour through an attic.
Get a little more insight into what things need to be addressed.


Insulation Cost Analysis

Let's take a look at what items are on the retrofit list and figure out a little more about each type of project including what is involved with treatment and how much each insulation solution costs.

Cost for Rim Joist Air Sealing & Insulation

The cost of an attic insulation job should also include easy to access areas in the basement or at the foundation area.  Great opportunities to seal the basement exist at the top of the foundation wall.  Basement work in tandem with attic work will yield the best overall results. 

The price:  $5.25 per linear foot.


Watch before and after treatment to the basement rim and band joist.


Knee Walls Insulation Treatments and Costs

Generally, a knee wall is much like an exterior wall.  The difference - it is accessible from an attic area.  Knee walls are usually insulated, however not well and as a result, they are major sources of energy loss and comfort complaints.  To properly "button" up a knee wall, you can expect to pay for air sealing, new insulation and some type of air-barrier (sheathing) .

The price:  $4.25 per square foot.

Block & Seal Knee Wall Attic Floor Gaps - A big issue that many homeowners don't address is the space between floors.  The space between the floors is only accessible if certain types of residential home construction, commonly referred to as Cape Cod

The price:  $3.50 per linear foot.


Watch this video showing a knee wall attic floor gap in Cape Cod style home.


Attic Access Points

Most homes have at least one way to get to an attic space that needs to be sealed.  The best way to determine how many hatches you have is to count.  Then for each one, consider where you access the space.  If you are inside, then you need to seal the opening to disconnect from the attic.  An attic access can range in price depending on the size, type and location.

The price:  From $175 up to $300 per opening

Cost of Air Sealing

Air sealing an attic can be broken down into two main parts. 

1. General Air Sealing: includes the top plates, standard penetrations (regular light fixtures, plumbing stacks and general voids and cracks.

The price:  $1.00 per square foot. 

2. Ala Carte Air Sealing: includes items like combustion appliance flues, HVAC chase openings, staircase voids and other thermal bypasses that are created by the construction style of the home.  Cost per air sealing solution can range depending on the requirements to properly seal the area.

The price: From $50 - $200


General Air Sealing Demo

Cost of Attic Insulation

A key to determining the cost of insulation for your home is to figure out what the current R-value is in the attic and around the shell of the home.  You can use this article to determine your exact R-value and come back to see what the cost is per square foot for the R-value you are missing.

Insulation Price Matrix - Blown In Insulation Solution

$ Per Square Foot

R-13 $.75
R-19 $1.05
R-22 $1.20
R-30 $1.60
R-38 $1.85
R-44 $2.10
R-49 $2.35
R-60 $2.85

Baffle Installation Pricing 

Attic ventilation is important for the longevity of your roof, roof deck, insulation and the wood framing.  You should expect that for every foot of eave you have around your house that you will need 1/2 a baffle to improve, maintain or in some cases actually create new air intake for ventilation.  Baffles are installed in the toughest to reach places in the attic - at the lowest place the roof deck is in relation to the attic floor.

The price: Each baffle, installed, will cost $4.00 per.

cost of attic insulation
Baffles maintain a channel for air intake and good attic ventilation.


Cost of Cantilever (Overhang) Insulation

attic insulation cost

Overhangs on the front and rear of your home are wonderful because they add valuable square footage to the inside of the living space it it can really make a difference.  The problem, they are susceptible to air infiltration if not insulated properly and they are hard to get to.  Pricing for a cantilever can vary depending on many challenges, including the height at which the cantilever is positioned, the type of siding, if any, is in place and the amount of insulation required to fill the cavity.  You can expect a cantilever project to cost between $275 - $2000 and more.  Analysis should be given to the value vs. cost for a cantilever project.  A well trained energy auditor can give you guidance on this type of insulation solution and the cost.

Cost of Crawl Space Insulation/ Encapsulation - A crawl space foundation creates great opportunities for improved efficiency, comfort and indoor air quality.  On the other hand, it can escalate the overall cost of an insulation project.  Untreated crawl spaces tend to go unnoticed when homeowners are thinking about how much an attic insulation project costs, but not considering the space for treatment could be the difference between an attic insulation job that yields results and one that does not.  Crawl spaces have to be broken down into the following components of the job:

crawl space insulation cost
Crawl Space Before

cost of crawl space insulation
Crawl Space After

Typical Crawl Space Work Scope and Insulation Cost

Removal of Existing Insulation - $2.00 per sq. ft.
Floor/Vapor Barrier - $1.50 per sq. ft.
Walls (R-13) - $6.00 per sq. ft.
Closed Cell Spray Foam - $12.00 per sq. ft. (includes ignition barrier)
Rim Joist $5.25 per linear foot
Duct Sealing $2.50 per linear foot
Any Access Points - $175 - $300 each

Dense Pack Insulation Cost and Solutions - Hometrust will recommend dense pack insulation solutions for easily accessible cavities that can be properly "packed" to get the desired result.  Dense packing walls is a project that should be given a lot of consideration by any homeowner in any age home.  Pitfalls associated with improper installation techniques could render the work useless, however you may never really know.

The cost to dense pack a cavity is typically $6.00 per sq. ft.

To understand more about why sealing the top and bottom of a home are most beneficial, read this information about building science.


Written by Eric Gans
I have over 1000 energy audits under my belt in Maryland.  I like to take my personal experiences with each of my audit customers and try to get the things that concern them out into the world so others can make good home improvement decisions - in the right order - according to their needs.

I would like to hear your comments about this article.  Feel free to post something below...



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