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Question DetailsAsked on 8/26/2013

How much should it cost to insulate my attic with R30 fiberglass insulation for 1485 square feet.

The attic already has R8. I want the roll in type of insulation

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5 Answers


Am not willing to give cost estimate since I reccomend a different approach. Make sure you have shutes that will keep the soffit vents open. (They can be purchased at big box stores ie Menards Lowes etc) Make sure you have adequate ceiling ventilation. Best choice a continious ridge vent. Installed by a roofer if you can get shingles to match your current roof. The ridge vent pulls air thru the attic and exhausts the heated air and even more importantly the moisture that builds up in the winter attic. Yes you can substitute flat 505 vents or turbines but they are not as effective. Cut new soffit vents to feed your ridge vent. Then and only then consider cellulose (ground up paper treated with boron , to kill insects and fireproof it) to be blown as a cap over existing insulation. It has a higher R value and restricts the flow of air (convective heat loss) that fiberglass does not. Two men one tearing the bags and feeding a hopper the other climbing around the attic, The blower is a free rental from big boxes if you buy enough insulation. Viola lower energy bills and lower investment cost.

Before insulating you can take a plastic rake and move the fiberglass out of the way to seal air leaks from your home below. This is called air sealing.

Jim Casper Old Energy Conservation Guru

ps for a idea on radiant barriers see my blogs

Source: www.heartlandmastershield,.com

Answered 7 years ago by jccasper


I too am not able to give you the information you want because we do not install batts unless the drywall is down and we can properly install the batts. The earlier reply is correct in discussing proper ventilation since attics can become very, very hot without proper ventilation.

Building Performance Services offers a program called "Fiberglass Plus" that includes pressure testing all the duct work and repairing leaks prior to blowing in fiberglass which could potentially bury problems. The Department of Energy says duct repair is the most cost effective energy improvement.

Please take a look at our website for information purposes. We charge $1.25 for the "Fiberglass Plus" program which includes 16-18" of fiberglass, the miniumum recommended for our climate in south Florida.

Source: http://www.buildingperformanceservice...

Answered 7 years ago by Beaucastle


If you read the questions that you will find under your question (below the answers), that should help you some.

Ballpark number - assuming you have done all the sealing around penetrations and ensured the existing vapor barrier is intact and sealed, then about $1.50-1.75/SF for roll fiberglass insulation.

Be sure the eave / soffit vent baffles or chutes are in place to maintain air flow to your ridge vent first, it is a good idea to map out where ducts and wires are for future reference (or photo before covering, if overlying your R-8), and don't forget sealing and insulating the access hatch or door too. Be sure to block out around any devices that need air circulation to operate - fans, furnace, A/C, fireplace chimney, etc.

Be sure to use UNFACED insulation, you do not want intermediate vapor barriers in the middle of the insulation. For best results, use two layer rather than one thick one, criss-crossed so the joints in one layer are covered over by the batts going the other way, leaving only very small joint intersections to leak air, and end of roll joints should land in the middle of the underlying layer width.

Answered 7 years ago by LCD


When folks call in and ask this question, we usually offer them a free attic inspection and quote for what they actually need to solve their particular problem. Most of the time, the quote we give does not match the original price request. Every attic is different and once the inspection is complete and, the customer's objectives are revealed, what is really required to meet those objectives is usually not what the customer thought they needed.

That's the value of having an insulation professional, who offers all the various insulations available, come to your home to inspect and help you design a cost effective solution to meet your specific needs. Go to Angie's List to find that professional and double check at to find a true professional in your area.

Steve Anderson

Progressive Insulation & Windows

Chatsworth, CA

Source: and

Answered 7 years ago by Steve Anderson


If you're in the central florida area you NEED to look up Bright Energy! They do awesome work. They blow home depot and all the major competitors out of the water with pricing and do just as good a job. They offer radiant barrier, r30 fiberlass insulation, batt, water heaters etc. LOOK THEM UP is all I'm saying. good luck with your search in the mean time!!


Answered 6 years ago by IamAJ

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