R-13 Insulation Rolls
Wholesale fiberglass R-13 in 3.625" thickness. The economy choice for 2x4 framing — and the IECC minimum for walls in Climate Zones 1 and 2.
What Is R-13 Insulation?
R-13 insulation is fiberglass batt or roll insulation rated at R-13 thermal resistance under ASTM C518, the U.S. testing standard for insulation performance. The number 13 represents resistance to heat transfer: higher numbers insulate better, lower numbers cost less. R-13 sits at the entry point of the residential and light-commercial R-value range, just above the condensation-control products (R-8 through R-11) and below R-19, R-25, and R-30.
R-13 is the most economical fiberglass insulation in widespread use, primarily because the 3.625-inch nominal thickness fits 2x4 stud framing exactly. 2x4 walls were the dominant U.S. residential construction standard from the 1950s through the 1990s and remain common in renovation and light-commercial work today. Any project using 2x4 framing should start the spec conversation with R-13 unless there is a specific reason to go higher.
At Insulation Overstock, R-13 fiberglass insulation is available with every NAIMA-certified facing in the catalog: VR-R Plus, WMP-10, WMP-30, WMP-50, foil-faced, black-faced variants, and unfaced. Wholesale pricing runs $0.65 to $0.75 per square foot — the lowest of any R-value in the standard line.
R-13 Insulation Thickness and Composition
R-13 Nominal Thickness
R-13 fiberglass insulation has a nominal installed thickness of 3.625 inches. That dimension is engineered to match the actual cavity depth of standard 2x4 framing (a nominal 2x4 measures 1.5" by 3.5"; with sheathing depth, the effective cavity is 3.625"). The full thickness is required to deliver rated R-13 performance — compressing the batt loses thermal performance proportionally.
R-13 Roll Dimensions
R-13 rolls ship in 4-foot, 5-foot, and 6-foot widths. WMP-30 is also available in 8-foot wide rolls, which speeds installation on commercial and large pole barn projects. Roll lengths range from 16 to 100+ feet.
Facing Options for R-13 Rolls
Facing selection for R-13 is driven by application, not R-value. The same facing options described in the facing comparison guide are available in R-13.
Where R-13 Insulation Works Best
R-13 Insulation by IECC Climate Zone
R-13 is the IECC-recommended wall insulation minimum for warm climate zones and remains common as a wall spec for unconditioned outbuildings in any zone.
| IECC Zone | Example States | R-13 Used For |
|---|---|---|
| Zone 1 | Southern FL, HI | Walls (minimum) |
| Zone 2 | FL, southern TX, southern LA | Walls (minimum) |
| Zone 3 | TX, GA, NC, AZ, CA | Unconditioned walls (R-19 preferred conditioned) |
| Zone 4 | VA, TN, KY, MO, OK | Unconditioned only (R-19 for conditioned) |
| Zone 5+ | CO, OH, IL, MN, ME | Interior partitions only |
For a complete R-value breakdown across all climate zones, see the R-Value Guide by Climate Zone.
R-13 Insulation Cost Per Square Foot
Wholesale R-13 fiberglass insulation pricing at Insulation Overstock runs $0.65 to $0.75 per square foot — the lowest of any R-value in the standard line. The differential between facings is about 10 cents per square foot.
- VR-R Plus (vinyl-reinforced PSP): $0.65 / sq ft
- WMP-10 / WMP-30 / WMP-50: $0.71 / sq ft
- Black-faced variants: $0.69 to $0.75 / sq ft
The fastest way to see your total R-13 cost is the Insulation Calculator: enter square footage, facing, R-13, and your state, and the calculator returns material, freight, and service fee as separate line items. For larger orders, see Bulk Insulation for the $250 volume discount.
Available Facings for R-13 Rolls
Every facing in the Insulation Overstock catalog is available in R-13.
VR-R Plus (PSP) — Most Economical
VR-R Plus is the vinyl-reinforced general-purpose facing — the value-priced choice for residential, agricultural, and light-commercial projects.
WMP-10 (PSK-STD) — Standard Metal Building
WMP-10 carries a 10-perm rating — the standard for metal building wall systems in dry climates.
WMP-30 (PSK-HD) — Heavy-Duty, 8-Foot Available
WMP-30 is the heavy-duty 30-perm version, the only R-13 facing available in 8-foot wide rolls.
WMP-50 (PSKP) — Premium Metalized
WMP-50 is the premium 50-perm facing with metalized polyester backing — the highest tensile strength in the line.
Black-Faced Variants
Black-faced fiberglass insulation in R-13 is available with VR Black, WMP-10 Black, and WMP-50 Black facings for aesthetic preference or low-glare interior environments.
R-13 vs Other R-Values
| R-Value | Thickness | Best For | Wholesale Price/Sq Ft |
|---|---|---|---|
| R-13 | 3.625" | 2x4 walls, Zone 1-2 walls | $0.65 – $0.75 |
| R-19 | 6.25" | 2x6 walls, Zone 3-4 walls | $0.90 – $1.00 |
| R-25 | 8.0" | Zone 5+ walls, ceilings | $1.13 – $1.23 |
| R-30 | 9.5" | Zone 4+ ceilings, attics | $1.36 – $1.42 |
Choose R-13 when: framing is 2x4, building is in Climate Zone 1 or 2, the space is unconditioned or seasonally heated, or budget is the primary constraint.
Upgrade to R-19 when: framing is 2x6, building is in Zone 3 or 4 and conditioned, or year-round HVAC is planned.
Upgrade to R-25 or R-30 when: building is in Zone 5 or above, or insulating ceilings/attics where deeper material physically fits.
R-13 Insulation FAQ
What is R-13 insulation?
R-13 insulation is fiberglass batt or roll insulation rated at R-13 thermal resistance per ASTM C518. It is the standard insulation depth for 2x4 framing and the IECC minimum for walls in Climate Zones 1 and 2.
How thick is R-13 fiberglass insulation?
R-13 fiberglass insulation is 3.625 inches thick at nominal installed depth, matching the actual cavity depth of standard 2x4 wall framing.
How much does R-13 insulation cost per square foot?
Wholesale R-13 fiberglass insulation runs $0.65 to $0.75 per square foot at Insulation Overstock, depending on facing. It is the most economical R-value in the standard product line.
Is R-13 enough for a metal building in cold climates?
Can I install R-13 in a 2x6 wall?
R-13 physically fits in a 2x6 cavity but leaves a 2-inch air gap behind it that reduces overall wall performance. For 2x6 framing, R-19 is dimensionally correct and rated to perform fully.
What is the difference between R-13 and R-15?
R-15 is a higher-density fiberglass batt that delivers slightly better R-value in the same 3.5-inch 2x4 cavity. The performance improvement is small (about 15 percent), and R-15 typically costs 30-40 percent more than R-13. R-13 is the more economical choice for most 2x4 applications.
Order R-13 Fiberglass Insulation
Wholesale R-13 with every facing available. Material, freight, and service fee itemized separately.
Price Calculator
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