Fiberglass Batt Insulation Cost Guide 2026

Quick Answer: Fiberglass batt insulation typically runs $0.50 to $1.50 per square foot as of 2026, with the spread driven by R value, width, facing, and brand. R-13 and R-15 wall batts sit at the low end, R-30 and R-38 attic batts sit in the middle, and high density cathedral and sound batts sit at the high end. Prices move with the commodity glass and resin market, region, and supplier volume, so treat the range as a planning number and pull live quotes for bid day.

What Drives the Price

Six variables move the price of a fiberglass batt, and you should read them off the insulation schedule before you quote.

R value. Higher R value means more glass fiber packed into the same thickness, and that is the single biggest driver. R-13 and R-15 are commodity wall batts. R-19, R-21, and R-30 are floor and attic batts with more material. R-38 and R-49 high density batts carry a premium because they pack more R into a thinner cavity.
Width and cavity fit. Batts come in 15 inch, 23 inch, and 16 inch and 24 inch on center widths. A 23 inch batt for 24 inch on center framing costs a touch more than the 15 inch because of the wider roll, and the wrong width is a field mistake that costs labor, not material, but you price the right width the first time.
Facing. Unfaced batts are the base price. Kraft faced batts with the vapor retarder attached run 10 to 15 percent more. Faced batts with a flange for stapling to the face of the stud cost a little more again. Foil faced and vinyl faced specialty batts run higher for moisture control.
Density and grade. Standard density batts are builder grade. High density batts, sometimes labeled cathedral or sound attenuation, pack more fiber and cost 20 to 35 percent more. Sound batts with the same R value as a wall batt but rated for sound transmission carry a similar premium.
Brand and packaging. The major manufacturers all run a commodity line and a premium line. Packaged rolls and bagged batts price differently, and bulk pallets of bagged batts get the best volume break. Brand matters less than the R and width, but it does move price 5 to 10 percent at the same spec.
Region and volume. Northern markets run more R value per house and more batts per job, so volume discounts show up there first. Freight from regional warehouses adds 3 to 8 percent in remote markets. Pallet pricing beats single bag pricing every time.

Typical Price Ranges by Type

These are supply house price ranges as of 2026, per square foot installed material only, before tax and freight. Your local market will move these numbers, so use them to frame the bid and refresh on quote day.

R-13 kraft faced, 2x4 wall: $0.50 to $0.75 per SF. The most common residential wall batt.
R-15 kraft faced, 2x4 wall, high density: $0.65 to $0.90 per SF. Better R in the same cavity.
R-19 kraft faced, 2x6 wall: $0.70 to $0.95 per SF. Common in newer framed homes.
R-21 unfaced, 2x6 wall, high density: $0.85 to $1.10 per SF. Premium wall R value.
R-30 kraft faced, attic: $0.90 to $1.20 per SF. Attic and floor over unconditioned space.
R-38 high density, cathedral: $1.10 to $1.40 per SF. Vaulted ceilings, tight rafter cavities.
R-49 attic, high density: $1.20 to $1.50 per SF. Cold climate code minimum attics.
Sound attenuation batt, 3.5 inch: $0.70 to $1.00 per SF. Interior walls, party walls, multifamily.

Price the facing the schedule calls for. An unfaced batt priced as kraft faced will look cheaper on the bid and lose the job when the vapor retarder is missing at inspection.

How to Calculate the Quantity You Need

Take insulated square footage by R value off the insulation notes or the wall and ceiling assemblies. For walls, take the gross framed wall area and subtract the openings, because batts do not go behind windows and doors. For ceilings, take the framed ceiling area, not the floor area, because a vaulted ceiling runs more square feet than the floor below it.

For each assembly, note the R value, the cavity depth, and the facing requirement. A 2x6 wall with R-21 unfaced is a different line than a 2x6 wall with R-19 kraft faced, and you price them separate. Apply a 5 percent waste factor to the measured square footage, because batts get cut to fit around outlets, plumbing, and framing quirks, and a tight waste factor beats a generous one when the unit price is low.

Round each line to a full package, because batts ship in bags and bags ship on pallets. A bag of R-13 commonly holds 88 to 120 square feet, and partial bag pricing is the worst pricing. Tie every count to the sheet and assembly it came from so the bid is defensible in review.

How to Buy Smarter

Pull three quotes on bid day. Supply house pricing on the same R and width can vary 10 to 25 percent between branches. The R value and width are the leveler, quote the same spec everywhere.
Buy by the pallet, not the bag. Pallet pricing on a tract of homes beats single bag pulls every time. Ask for the volume break up front, not after you place the order.
Lock the quote for 30 to 60 days. Glass fiber and resin prices move with the commodity index. A 30 day hold protects a longer bid cycle.
Match the facing to the assembly. Kraft faced goes on exterior walls in cold climates, unfaced goes on interior walls and where a separate vapor retarder is called for. Read the notes before you price the facing.
Check the cavity depth. A 2x6 wall with R-19 is not the same as a 2x6 wall with R-21. The deeper R costs more and the schedule is the source, not the plan view.

Where Estimators Get It Wrong

The classic mistake is taking the gross wall area without subtracting openings. Batts do not go behind windows and doors, and a 12 percent opening factor on a typical wall will swing the bid materially. Subtract the openings or you overbuy and the waste factor eats the difference.

The second mistake is mixing R values on a wall assembly. A 2x6 wall can carry R-19, R-21, or R-23, and the schedule tells you which. Priced wrong, the bid is off by 20 percent on that line and the takeoff looks sloppy in review.

The third is forgetting the vapor retarder and the facing. A kraft faced batt is a different product than an unfaced batt with a separate poly sheet, and they are priced separate. Read the notes for the retarder, not the plan view.

Putting It Together

Read the insulation notes, take the square footage by assembly, subtract the openings, and apply the 5 percent waste factor. Price each line by R value, width, and facing with the matching product. Get three quotes on bid day, lock them for the bid window, and round to full pallets. A wall batt priced at $0.65 per square foot can become a $0.75 line by the time waste and partial bags land, and the estimator who prices only the unit misses that gap. Keep the count tied to the sheet, keep the quotes dated, and the bid holds up in review.