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Energy Auditor


Eric Gans
Certified Energy Auditor


Residential Comfort & Energy Efficiency

Sunday, November 29 2020
Why is My House So Cold?  The Real Reasons


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.

If your house is cold there are likely several reasons for the problem. 

The reason most think their home is cold: windows, doors and HVAC.

But, if you really want a more comfortable and energy efficient home then the places you really want to look are not where you might think. 

Take it from an energy auditor with over 1000 energy audits and blower door tests completed - these are the things that will actually give you the very best return on investment.

More Focus on HVAC Ducts Rather than Replacement

Every homeoewner should familiarize themselves with their HVAC duct system.  A disconnected duct can not only cause a room to be cold, but it can disrupt temperatures throughout your entire home.

Air Pressure

If you stop and think about it, so many things in our lives are working for us because of air pressure.  For example, tires.  Air pressure inflates the tire so that driving, riding, mowing etc. can happen with good performance and comfort.  No air - no good!

Inside our homes, air pressure is used in a variety of ways.  One example is plumbing.  What happens when too many people try to take a shower at one time?  The air pressure drops with so many open taps so the overall pressure of the water decreases as a result.

Air Pressure and Comfort

Air pressure is also used to heat and cool our homes. If you have air ducts, there is a whole lot happening inside the duct system each and every time the unit is running.

The ducts are the primary mode of transportation for the warm air to flow and service the rooms it was mathematically sized to do.

In an HVAC system that uses air ducts the blower pushes the air through at a specific velocity or flow.  The size of the ducts relies on the force of the blower to get the air to where it needs to go. 

So, similar to a train arriving to an place where the track has been removed and not being able to get any further - if there is a disruption to a portion of the duct system - the air will not get to where it needs to go.

Ducts in Attics and Crawl Spaces

Although it is entirely possible, it is highly unlikely that the rigid ducts that run through your walls and inside the "envelope" of your home are or ever will be disconnected.  As an example, the ducts in the unfinished part of your basement (inside envelope) have likely been there since the beginning and they have not collapsed under their own weight!

The ducts that give the most problems are those that are in the attic or crawl space.  The two main things that I see that contribute to the issue are:

1. The use of flexible ducts that branch off of the main supply plenum are much less forgiving when moved, bumped or subjected to some of the harsh temperatures in an attic.

2. Poor workmanship likely due to the pure simple fact that working in an attic or crawl space is not pleasant and it is human nature to want to get the job done and get the heck out!

Disconnected Ducts or Poorly Sealed Ducts

When you happen to be walking around in a part of your home that has an attic above you - look up.  If you have air vent supply registers in the ceiling then the chances are very high that you have HVAC ducts in an attic space.

The next questions you should be thinking if you do have vents in the ceiling is when is the last time you went to the attic and had the ducts inspected?

This attic inspection during a home energy audit in Maryland demonstrates the importance of having attic and crawl space ducts routinely inspected.

Why Does it Go Unnoticed?

The first idea that comes to most people's minds when a room in the house is not quite as comfortable as other areas or rooms is that the windows are bad.  

In fact, it is not uncommon to do a home energy audit for a mechanical engineer that knows pretty much everything there is to know about an HVAC system, but they did not realize that the duct above their head might be the reason that they are having a comfort issue, rather than need to dense pack insulate a finished southern facing exterior wall.

The Impacts a Loose or Disconnected Duct Can Have

If a duct is disconnected it is not delivering the air to the location that it is supposed to.  Obviously, that particular location suffers.

Due to static pressure, the entire duct system is effected when one duct is disconnected or if all ducts are very loose!  When the pressure inside your duct system is radically changed, with a disconnected duct as one example, it can cause temperature variances in other parts of the house.

What Can You Do?

The best thing to do is take advantage of any home assessment program in your state that includes the technician going into your attic or crawl space as part of the inspection process.

For example, in Maryland a BGE or Pepco customer (power utilities) can get a comprehensive home energy audit for $100 which includes a detailed inspection of the entire thermal envelope of the home.  As part of the energy audit, HVAC ducts are assessed and testing can also be done, if necessary, to determine how leaky the ducts are when the system is running.

If You are Cold Always Think Attic and Basement First

One lesser known place compared to windows and doors to get air leakage sealing done and earn big savings is at the attic floor and in the basement.  Because heat rises and other pressure dynamics inside of your home, most of a the warm air leaves through the ceiling and into the attic (outside).  And, most of the cold air infiltration occurs in the basement or at the foundation level.


Basement Rim Joist Air SealingCold leaky rim joist

Simple sealing and insulation can go a long way in the right places in a basement.  Often times the first instinct is to insulate the walls of the basement.  But, the rim joist is much leakier and will yield much bigger gains when treated - for much less cost.

If you are not familiar with the rim joist in your basement, take a look at the walkthrough video below. 


If you have an unfinished area of your basement look at the top of the foundation wall for the rim joist area.  Here is a tip:  if you see spider webs dangling around then chances are you have air leakage in the general vicinity.

How Does My Basement Leak Cold Air?

A good way to understand why a basement or lower point in a home is more likely to leak cold air is to think about the Empire State Building.  Whether you have been there or not, you might recognize that any larger building has some type of a revolving door at the entrance.  In many cases, buildings have a double door solution where you open a door walk five steps and then open another door.

The reason for these solutions is because of pressure due to the stack effect or chimney effect.  On certain days, the door might not be able to be opened or could blow off due to pressure dynamics inside and outside of the building.

Stack Effect

The stack effect can be simply understood by thinking about a wood burning fireplace.  When the fire is going, the smoke and heat rises up and out at the top.  That is a positive pressure dynamic.  At the base of the fire, the fire is "sucking" up oxygen - the negative pressure.

In a building, the dynamics are similar.  The warm air rises and escapes through cracks and crevices creating a positive pressure dynamic - similar to the stack effect.  Downstairs, in the basement, where there are cracks and crevices, particularly at the rim joist, cold air is drawn or "sucked" in.

For this reason we will recommend to air seal the attic floor and the basement rim joist every day all day over windows and doors.  If you follow the science and try this out in your own house on a clear, dry mid range temperature day.  Open the upstairs windows and watch the curtains get sucked against the screen wanting to flow out and open a first floor or basement window and watch curtains flap towards the inside from the air being drawn in.


If your home is perpetually cold then take note of where your HVAC ducts traverse through your "building's shell" and where perhaps there could be room for issue or improvement.  Delivery of the air is equally important to the creation of the air.  And, everyone must pay close attention to the details of their attic floor.  Creating a continuous air-barrier (not to allow any air to pass through) is critical to a comfortable and energy efficient home.


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

Thursday, November 19 2020
Crawl Space Encapsulation: The Basics

Let's face the facts about crawl spaces.  They leave a lot to be desired.  

Most crawl spaces are difficult to access in most cases they are stuffy, dusty and full of insects.

To make matters more complicated there are so many questions about how to properly seal and insulate an open crawl space.  For example:

When should crawl space vents be open?
Does an encapsulated crawl space need isulation at the ceiling?
How much does it cost to insulate a crawl space?
What is the best way to encapsulate a crawl space?
Do I need a vapor barrier in my crawl space?
What does it mean to seal a crawl space?

As an energy auditor, certified through the local Maryland utility, it is important to properly examine a crawl space in a number of different scenarios which can be complicated.  My method of simplifying the way I think helps me figure out the right solutions and explain them in easy to understand ways to the the homeowner.  

The information below are common insights required to make an informed decision about how to properly treat your crawl space.


Old School Thinking:  I See Insulation Everything is Fine

If you live in a home on a crawl space there is a very good chance that you think that this just is the way it is and there is not much you can do.

When you first moved in you ambitiously went into the crawl and you saw insulation below the floor.  Everything seemed fine.    

Maybe you have never looked in the direction of your crawl space, or any crawl space for that matter, and have no ideas on what one may look like.

If that is the case, have a look at this video taken during a BGE energy audit of a typical open crawl space.


When Should Crawl Space Vents be Open?

Open Crawl Space Vent Example

If possible, crawl space vents should always be blocked and sealed.  Crawl space vents provide virtually no benefit by being open.

Creating vent openings in the foundation wall were designed to allow "fresh" air into the crawl space for ventilation.  Millions of homes have been built using this method.

The problem is that you can't control what air moves into the crawl space and when it turns hot and humid or cold and dry, the open vent solution is not the best for climates that have seasonal changes like Maryland.

You cannot count on enough dry, average temperature days in a row to sufficiently dry out the crawl space.  Additionally, considering the vents are typically not nearly large enough or often times obstructed, your crawl space does not stand much of a chance for success and as a result, your indoor comfort and air quality suffer and your energy bills are high.

Check out one common issue due to open crawl space vents.

Open Crawl Spaces: Two Seasonal Problems

Summer Humidity

Inside look at a crawl space vent.Open vents allow humid air into the space, or worse streaming water, which tends to get trapped and migrate to unwanted places. 

So many of us plug up our dehumidifier in the summer to keep the basement dry. 

Those with open crawl spaces likely have two machines working and they may not be able to keep up with the high humidity. 

Open vents in a crawl space can have a significant impact on indoor air quality and are main factors in high indoor humidity levels.

Eighty percent of crawl spaces in humid climates have insulation that has fallen. Wood structural flooring components should not be subjected to moist, humid conditions for long periods of time.


  Get a comprehensive home energy audit today!


Winter Issues and How Physics Plays a Role

During winter months, cold winter air is actually pulled into the vents due to physical dynamics that are at play - known as the stack effect, or chimney effect.  Insulation is unable to prevent infiltration through the floor.

Negative pressure is created in a crawl space when it is connected to the living space above.  As warm air rises and finds places to escape, it tugs the cold air from below right on in as seen in the diagram to the right.

Unconditioned cold air that migrates into the crawl space through the vents is then conveyed up through the floor and walls and into your living space.  

Therefore, as a result of this physical characteristic of most buildings, having an open crawl space is not a good solution if you live in a location with a cold season.



If You Have a Crawl Space – You Have an Energy Efficiency "Point of Weakness"

Big problems with comfort and high energy bills stem from irregularities in the building shell.  Twists and turns in a home’s design create more complex treatment solutions in locations such as:

  • Porches
  • Roof Overhangs
  • Shafts for Chimneys & Pipes
  • Protruding Windows & Doors
  • Indented Windows & Doors
  • Cantilevers
  • Garages
  • Knee Walls
  • Open Basements
  • Open Crawl Spaces

Most of the largest leaks in homes occur where framing (such as floor joists or wall studs) span from an area inside conditioned space to an unconditioned or vented space, such as the attic,crawlspace, garage, or roof. Appropriate blocking is needed in these instances and it requires a team that knows home performance techniques and solutions to do it right.

Does A Crawl Space Need a Vapor Barrier?


Your crawl space needs a properly sealed vapor barrier.  Ground moisture will wreak havoc on your wood flooring, joists and indoor air quality if left un-checked.  A fully encapsulated crawl space will always include a sealed vapor barrier.

Watch: Properly Installed Crawl Space Vapor Barrier


What to Look for In Order to Prescribe the Proper Treatment for an Open Crawl Space

No general rule should be applied to how to treat a crawl space. 

These three factors should be considered first:

1. Climate
2. Ground Dampness
3. Presence of Ducts in the Space

In Maryland we tend to have hot, humid summers and sometimes it can be damp well into the fall.  The winters bring cold snaps, some longer than others, that can put a significant load on any HVAC system. 

Seasonal changes make sealing crawl spaces in our region a good option.  Typically, ducts are in crawl spaces in homes where this foundation type exists.

Crawl space inspections will require defining the best place to establish or re-establish the thermal boundary.

The thermal boundary can be described as the location that divides the inside living space from the outside, unconditioned space of your home.

Most crawl spaces are outfitted with insulation at the ceiling.  And, most crawl spaces are sources of energy loss and comfort problems.


If I Have Insulation in My Crawl Space Ceiling, Why is it Such a Problem?

In order to understand any high-performance crawl space insulation retrofit, you must first understand the three key things that getting results are dependent upon:

  1. Proper Installation of an Air Barrier
  2. Proper Installation of a Sturdy Vapor Barrier
  3. Proper Installation of Insulation

Typically, all three key factors are missing in a crawl space.

If not properly sealed, penetrations at the crawl space ceiling (floor inside) will lead to communication of air between the two areas.

A vapor barrier is only good if it is 100% sealed, otherwise moisture will still migrate up and into your living space.

Fiberglass batting insulation is difficult to install in almost all applications.  The thermal performance of batt insulation is heavily dependent on proper installation.  To attain maximum R-value, the batt insulation should be in continuous contact with all the surround cavity surfaces where they are installed.  They need to be cut exactly to length because if they are too long they bunch up leaving the area to be insulated exposed and if too short, spaces are created that promote convection.


Open Crawl Space vs. Encapsulated Crawl Space

Past research has shown that a conventionally vented crawl space that has been converted into an non-vented and conditioned space tends to operate similarly to houses with basements, with several benefits for the homeowner: 

• Energy savings
• Comfort
• Moisture control
• Long-term durability
• Healthier air quality

Open crawl space with insulation at the ceiling and an improperly installed vapor barrier.


Watch: Take a Look at a Completed Crawl Space Project Including Blocked and Sealed Vents

Reasons Maryland Homeowners with Crawl Spaces Might Not Choose to Encapsulate

  • Significant efforts can be made with ease to seal and insulate ducts, air handlers, water heaters, pipes etc.
  • Lacking any paid heat source, the crawl space is consistently between ground temp and outdoor temp which is typically above 32 degrees
  • The floor has had significant air sealing and insulation work performed already; some investment has taken place
  • The cost to seal and insulate the floor is considerably less then encapsulation for some reason

A Big Opportunity That Often Gets Overlooked

Too often the ducts that are running through crawl spaces are asked to do way too much. 

Not only do they need to carry conditioned air to the furthest reaches of your home, but in some cases they are expected to transport 90 degree air through a duct that is super cooled to 25 degrees on the coldest of days.

Sealing a crawl space from the outside can drastically improve the performance of your HVAC system and will contain duct leakage because the immediate barrier outside of the ducts also plays into the amount they leak.

For example, ducts that run through an open crawl space will leak much more due to the pressure dynamics compared to an encapsulated crawl space.

How to Properly Encapsulate a Crawl Space

It is important to not begin a foundation insulation retrofit project until it is well drained and dry.  Drainage should be the priority if the crawl space recurring takes on water.

Next, the crawl space should be free of debris and items that might impede the ability to install a vapor barrier.  A thick plastic vapor barrier should always be installed in crawl spaces with dirt floors.

The vapor barrier should be sealed to the walls, piers and any other penetration from the ground.

Crawl space walls should be air sealed and insulated (typically by using a rigid foam board with high R-value) all the way up to the rim joist.  The rim and band joist should be air sealed and insulated.


Do you live in Maryland and need advice on how to treat your crawl space?

If you are interested in making your home more comfortable and more efficient, give me a call.  We can discuss your situation and likely getting a BGE or Pepco Energy Audit is the way to go.  

Incentives through the program can be quite advantageous, particularly for those that know that they have to get this problem resolved once and for all. 

Furthermore, an energy audit can uncover other factors that can contribute to your specific issue as each home is different - even the same model across the street.

Give me a call!  I'd love to help you out!

energy audit maryland

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.

Saturday, November 07 2020
Attic Insulation Cost Factors & How Much Should You Pay?

Table of Contents

Get it Straight from an Energy Auditor

Insulation Cost Estimate Types

Three Dimensional Thinking

Contractor Required Skills

Accurate Measurements are Critical 

Impacts on Home Insulation Costs

Insulation Removal Costs

Attic Insulation Solutions

$$ Insulation Cost Analysis $$

Watch Basement Insulation Treatment

Insulation - Blocking & Sealing

Ceiling Attic Hatch Insulation Demo

General Air Sealing Demo


How do I Know this Stuff?

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, 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

You will find loose fill insulation, spray foam in different varieties, fiberglass insulation, rigid foam board, caulk, baffles and attic domes if you visited a home performance project while in progress.

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 addition 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.  You don't want to 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. Home Performance: Comprehensive Energy Audit

An energy audit has a primary goal: to evaluate your home as a complete system and report back to you.  The energy audit is actually an assessment and it uses a whole-house approach to calculate energy usage deficiencies and find ways to make everything work much, much better.  And, it comes with measurable results.

Much like the performance of your car increases with a tune-up, your home can perform better after tightening things up!  This means that you are able to sit in the driver's seat when it comes to creating better 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. -Top-

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.

Others believe that insulation is missing in their walls and it is the reason why bills are high and comfort is low.

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, the air flows inside and around the shell 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 meaningful results. 

An energy audit is a great way to gain a new perspective on how your home is actually losing energy and why the top and bottom are way more important than the sides. 


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.  -Top-

The Attic Insulation Technician - Required Skills

Determining how much attic insulation costs also 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.

X-Ray Vision

For the best results, technicians must have good general knowledge of residential building construction, including basic knowledge about the techniques that are used when building additions.

The insulation crew needs to be able to look past the boundaries that the eye can see so that sealing the right spots or not sealing the right spots is constantly being considered.

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.  -Top-

Proper Measurements Are Key Attic Insulation Cost

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!  

A detailed work scope should be provided with the specific information about the area/measurements and treatment methods. -Top-

The Size and Style of Home Impacts Insulation Costcost 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.-Top-

What are the Costs for Having 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 typically 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.-Top-

Solutions: Insulation Cost Analysis

**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: 


Watch to Get More Insight Into Attic Issues



Insulation Costs

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

$5.25 per linear foot

Air Seal and Insulate Rim Joist - 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. 


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


Knee Walls Insulation Cost and Treatment Methods

$4.25 per square foot

General Knee Wall Insulation with Air Barrier - 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) .

$3.50 per linear 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


Check out a knee wall issue and how it gets treated.

Attic Access Costs & Solution Types

From $175 up to $300 per opening

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 most commonly seen attic access points are push up hatch and pull-down stairs.  

Watch a technician treat an attic hatch in the field.


Attic Air Sealing Costs

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

$1.00 per square foot

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

Watch a technician air seal connections between the attic and inside.


From $50 - $200

2. Ala Carte Air Sealing:

A. Combustion appliance flues
B. HVAC chase openings
C. Staircase voids and other thermal bypasses that are created by the construction style of the home. 
D. Vertical wall air sealing
E. Recessed Lights
F. Chimneys
G. Plumbing Penetrations

Cost per air sealing solution can range depending on the requirements to properly seal the area.

Attic Insulation Cost

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



Watch loose fill insulation being installed.


Baffle Installation Pricing 

$4.00 Each

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. -Top-

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

Cantilever (Overhang) Insulation Costs

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.

Tip: Once you identify the location of any first floor cantilever you have, take a look to see how that aligns with any unfinished portion of the basement. If the two areas match up then the overall cost can be less since the need to remove the soffit is not necessary.

Watch spray foam being applied to this overhang with ducts.


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 space insulation cost
Crawl Space Before

cost of crawl space insulation
Crawl Space After


Crawl spaces have to be broken down into the following components of the job:


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.  



Attic Insulation Expert

Written by Eric Gans

I have over 1000 energy audits under my belt in Maryland and each scenario requires an insulation cost analysis. I am certified through the Building Performance Institute.

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


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