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From a Certified Pro
Certified Energy Auditor
Residential Comfort & Energy Efficiency
Thursday, July 23 2020
Written by Eric Gans, Building Analyst & Envelope Professional
The State of Maryland recommends that our attics have enough insulation to equal R-49.
If you are experiencing home comfort issues then a great place to start looking for answers is in the attic.
If your home is older than 10 years than you are likely not meeting the 2022 Maryland building code.
Existing insulation in a Maryland attic is inconsistent for a variety of reasons. Having the recommended amount of insulation is important for a healthy home.
In this article:
Tasks Required to Get Your Attic Insulation's Current R-value
Tasks Required to Get Your Attic Area
1. Measure the length and width from below for any attic area to calculate the square footage.
2. Note the exact square footage of any area that has different insulation levels (up to three). Use a laser measure to make it easy!
REQUIRED R-VALUE MARYLAND
|Ending R-value of 49 or as space allows|
|Ending R-value of 38 or as space allows|
(basement, crawl space, knee wall)
|Ending R-value of 11 or greater|
|Crawl Space Ceiling|
|Ending R-value of 25 or as space allows|
|Ending R-value of 25 or as space allows|
(top of foundation wall in basement)
|Ending R-value of 19 or greater|
Learn how to determine what type of insulation you have below the graphic...
Determine what Type of Insulation You Have
Different attic insulation materials and levels yield wide ranging R-values.
So, it is first important to determine the type of insulation that is in your attic.
Typical Insulation Materials Found in Maryland Attics
- Fiberglass batts
- Loose fill fiberglass
- Loose fill cellulose
- Mineral wool
- Two-part spray foam
Need help identifying what type of insulation exists in your attic?
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Identifying the Most Common Maryland Insulation Types
Cellulose Loose Fill
Grey in color
More dusty and clingy than other materials
Has bits of newspaper in it
Good fire/mold retarder w/ additives
Rolled Fiberglass Batt Insulation
Typically referred to as batt insulation
Has the kraft paper or aluminum foil on one side
Recognizable due to the "Pink Panther" commercials
Must be installed flawlessly (unforgiving)
Low R-value per inch if not installed properly
Fiberglass Loose Fill
Typically white shreds, pink squares or yellow shreds.
Much less dusty
Lower cold weather performance than cellulose
Determine Your Current Attic Insulation Level
The amount of insulation your attic needs will depend on how much is there now.
This can be a little tricky. Calculations can be off if the information is not gathered right. The condition, coverage and depth of the insulation is important. Accuracy will ensure the best return on your investment and that you are meeting Maryland building code.
Un-insulated Areas Play a Heavy Hand in Poor R-Values
Now lets go a little deeper and explore the impact of un-insulated surfaces. It may surprise you how important having an even blanket of insulation is for for getting a great result.
If you notice any area in your attic that does not have insulation then pay attention to the information below!
This typical Maryland attic is a great example of what the impact of missing insulation can have.
The attic area in the home pictured above is 975 square feet and flat (R-49 recommended in Maryland).
You will notice 1" of blown in fiberglass insulation and 7" of rolled fiberglass batting laid on top.
In this scenario, the attic has roughly 8" of insulation in "most" of the areas that need it. Later you will learn how to use the depth to determine the R-value. In this case, the attic is R-17...
But, there is a catch!
There are two major un-insulated areas in this attic (very common in Maryland attics).
1. A three foot by three foot push up hatch
2. A three foot by three foot whole house fan
Equaling a total of 18 square feet of un-insulated area at the attic floor.
This equates to just about 2% of the attic area (18 divided by 975).
Typical hallway push up hatch leading to an under insulated Maryland attic. Watch how a hatch gets treatment.
The hatch from the attic has a plywood cover (seen in background)
Whole house fan as seen from the attic.
With the use of the HOME ENERGY SCORE CALCULATOR we are able to calculates the impact un-insulated surfaces have on insulation performance.
The picture gets clear!
What ends up happening with this common scenario is not good. A mere 18 square feet of missing insulation has a big impact. The expected R-value reduces down from 17 to 13 for the entire attic!
That translates to hot summer nights and cold winter drafts and high energy bills to pay.
According to Dr. Allison Bailes of Energy Vanguard, the heat flows through the bare areas fast. Based on his article, the air leaves in the un-insulated ceiling area as much as 38 times faster then the insulated areas.
Be sure to measure your attic insulation in precise fashion. Different areas that have different levels should be separate. Each area will get an R-value assessment. Along with knowing the condition, this weighted average calculator can then help you determine your attic's R-value.
Back to Top
Determine Your Attic Insulation's Condition
The condition of the existing insulation in an attic is also important. Obtaining the information will assist in generating reliable return on investment reporting. Current condition can also reveal clues about future comfort gains.
R-value can be misleading if several factors are not met:
- Installation integrity
- Missing pressure boundary (air sealing around gaps/voids)
- Overall insulation coverage (distribution)
Your insulation should get a rating of "poor", "moderate" or "well" insulated.
Attic Insulation in Poor Condition
Insulation with large gaps and voids. Missing insulation greater than 2% of the insulated area.
Attic Insulation in Moderate Condition
Insulation with defects and gaps around wiring, electrical outlets, plumbing and other intrusions. Rounded edges or "shouldered". The amount of fill is incomplete, but rarely dips less than 30% of intended thickness. Gaps and spaces running clear through the insulation should be no more than 2% of the insulated area.
Well Insulated Attic Characteristics
The insulation has no any large gaps or voids around obstructions. The insulation appears to fit in any cavity side-to-side and top-to-bottom. The insulation appears to around wiring and other services in the area.
Different Insulation Types & Conditions = Different R-Values
The values for the corresponding condition of your attic insulation can be multiplied by the number of inches you have to see where your attic falls on the scale.
- Loose Fill Cellulose
New: 3.60 R-value per inch
Existing Well: 3.60
Existing Moderate: 3.13 R-value per inch
(Example: 6" = R19; 10" = R31)
Existing Poor: 2.7 R-value per inch
- Fiberglass Batt Insulation
New: 3.14 R-value per inch
Existing Well: 2.67
Existing Moderate: 2.10 R-value per inch
(Example: 6" = R13; 10" = R21)
Existing Poor: 1.26 R-value per Inch
- Loose Fill Fiberglass
New: 3.14 R-value per inch
Existing Well: 3.14
Existing Moderate: 2.73 R-value Per inch
(Example: 6" = R16; 10" = R27)
Existing Poor: 2.36
Watch a uniformly blown cellulose attic insulation job in progress!
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