Insulation FAQs at Southland Insulators in Northern VA Residential & Commercial Insulation Services in Northern, VA

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Insulation FAQs at Southland Insulators in Northern VA

Insulation - Southland Insulators
Can I add new insulation on top of old insulation?
Yes, you can add new insulation on top of old insulation, unless it is wet. Wet insulation can lead to mold, mildew or even rotting of your ceiling roof rafters. If it is wet or appears it has previously been wet, you should look for the cause and repair it to prevent a reoccurrence. If the insulation needs to be removed, we can do this for you.

How much insulation should I add to my attic?
The recommended level (by the U.S. Department of Energy) for Zone 4 (the Mid-Atlantic) is to insulate to R-38, or about 12 to 15 inches, depending on the insulation type. Please note that the E.P.A. is recommending R-49.

What is R-value?
R-value is a measure of the insulation’s ability to resist heat flow. The higher the R-value the better the thermal performance of the insulation.

Why do I need to seal my attic if I’m adding insulation?
Fibrous insulations (fiberglass and cellulose) are not air barriers, and as such, they allow air to move through them. This results in increased energy use. Air sealing stops the escape of air from the home.

Where are the big leaks in my attic?
Typically, the biggest attic leaks are found where the walls meet the attic floor, above drop ceilings and overhangs, and behind attic walls. Look for dirty or discolored insulation to find the leaks. This indicates that air is moving through the insulation materials. There are many other “holes” in the attic ceiling that should also be sealed, such as recessed “can” lights, plumbing stacks, electrical wires, attic hatches or doors, around chimneys or flues, and duct chases. We have certified solutions for all of these areas.

Can I over seal my home or make it too tight?
While it is possible to seal a house too tightly, it is very unlikely in older homes. In new homes where we install spray foam insulation, we often recommend an energy recovery ventilation system be added. While this is an added cost, the reduction in tonnage needed to heat and cool the home can offset most or all of the cost. A certain amount of fresh air is needed for good indoor air quality and there are specifications that set the minimum amount of fresh air needed for a house. Our BPI Certified building analyst using diagnostic tools can make sure your combustion appliances are operating properly (see

Are you licensed and insured?
Yes, we have been in business over 23 years and are licensed in all the Mid-Atlantic states (Virginia, Maryland, Delaware, Washington D.C., West Virginia and Pennsylvania). Insurance certificates will be provided upon request for your job or jobs.

Do you give free estimates? How long before someone returns my call?
We do give free estimates. You should receive a return call or e-mail to set up an appointment within 24 hours of your request.

Do you warranty your work?
Yes, for 12 months from completion of the job.

Do you accept credit cards?
Yes. We accept Visa, Mastercard, Discover, and American Express.

How much is attic insulation per square foot?
Because every job and condition is different, it is impossible to give square foot prices over the phone. We focus on energy efficiency and simply adding inches of insulation to your attic may not be the solution to your issues of high energy bills and comfort. We would be happy to provide a free estimate and energy analysis of your particular situation.

Do you sell material or only install it?
We both sell and install. While many times insulation is portrayed as do-it-yourself friendly, this is not always the case. Building science has evolved to the point where just adding insulation is not the only or the best solution. However, we do sell insulation at competitive prices.

Is insulation flammable?
Unfaced and loose-fill insulations are a Class-A non-combustible building product. Kraft facings on some insulation will burn and need to be covered with a flame spread barrier. We have certain insulation with a flame spread covering which can be left exposed should our job require such a product.

What is the difference between cellulose and fiberglass?
Cellulose is made by grinding up old newspaper and treated to be fire retardant. Fiberglass is made from melted sand, which is spun much like cotton candy and cut into sizes to fit in framing, or made as loose fill to be blown into attics.

What R-values do I need to meet county requirements?
R-value requirements vary from county to county, and it depends upon which year code your house was permitted under. The county requirements are the legal minimum, and we stress with higher energy cost, one should insulate above the legal minimum. Our staff of trained building analysts can give you both the minimum and options to save you money forever on your energy bills.

What is the R-value of spray foam?
Spray foam has an R-value of 3.7 per inch, which is comparable to fiberglass. The difference with spray foam is that it is an air barrier which stops the movement of cool air into warm areas, thereby preventing moisture problems. As an air barrier, spray foam prevents the leakage of air that fibrous materials allow. This saves energy, up to 25% in a typical home.

Why is spray foam more expensive than fiberglass?
While both are insulations, their physical characteristics are entirely different. Fiberglass is not an air barrier and lets energy escape. Spray foam fills every space in the framing, and seals the house while insulating it. The fact that Spray foam is worth it resonates in our testimonial letters.

Can spray foam be sprayed in an existing home?
Yes, with certain conditions. Every home is different. We are happy to provide you with detailed options as to where and how spray foam can be used to improve your thermal performance and comfort level.

What is the difference between open cell and closed cell foam?
Open Cell foam is identified as a 0.5 pounds per cubic foot. It is made up of tiny cells of foam that are not completely closed. The cells are broken and air fills all of the “open” space inside of the material. This makes the foam have a soft feeling. Open Cell foam has an R-value of 3.4 to 4.5 per inch.
Closed Cell foam is a 2.0 pounds per cubic foot. The cells are closed and packed tight together. They are filled with gas that helps the foam rise and expand. Closed Cell foam is a greater insulator due to its denser properties. Closed Cell foam has an R-value of 5.4 to 7.2 per inch.

How is spray foam better than traditional fiberglass?
Spray foam is applied in a liquid form, and then expands. As the foam is expanding it conforms to and fills every single nook, cranny, crevice, hole, crack and gap to create a continued thermal envelope. Spray foam insulation adheres to any clean, dry surface and will not shrink, settle or disintegrate over time.

Does spray foam support bacteria or fungal growth?
Open cell and closed cell offer no food value, and is an inert substance; therefore if does not support bacteria or fungal growth.

At what point during a construction project is spray foam applied?
Spray foam is applied after the windows, doors and roof, after the framing, plumbing, and electrical inspections are complete, and after any other systems located behind drywall is installed. Foam is the last installation to take place before drywall.

Can anyone install spray foam?
Only trained, certified and licensed applicators can apply spray foam.

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