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Armacell AP Self-Adhesive Sheet Insulation vs Owens Corning FOAMULAR NGX 250

These are different tools for different jobs. The Armacell AP sheet is a flexible, self-adhesive nitrile/PVC elastomeric sheet at 1 inch thick and R4.2, made for wrapping ducts, pipes and equipment where you want a peel-and-stick surface that bends around curves. The Owens Corning FOAMULAR NGX 250 is a rigid XPS board at 3 inches thick and R5 per inch, made for walls, foundations and below-grade work where compressive strength and moisture resistance matter. Buy the Armacell for duct and equipment wrapping; buy the FOAMULAR for structural sheathing and ground-contact insulation.

  • Choose the Armacell AP sheet if you are insulating ducts, pipes or irregular equipment and want a self-adhering flexible sheet that conforms to curves.
  • Choose the Owens Corning FOAMULAR NGX 250 if you need rigid board for walls, foundations or below-grade use where compressive strength and moisture resistance matter.

Prices

  • Armacell AP Self-Adhesive Sheet Insulation: $58.69 at eBay (last seen Nov 8)
  • Owens Corning FOAMULAR NGX 250: $50.32 at Insulation4US (last seen Nov 9)
  • Difference: the Owens Corning FOAMULAR NGX 250 is $8.37 cheaper than the Armacell AP Self-Adhesive Sheet Insulation at the latest prices (Nov 8 and Nov 9)
Armacell
Armacell AP Self-Adhesive Sheet Insulation 36" x 48" x 1" SAS10043

Armacell AP Self-Adhesive Sheet Insulation

Armacell AP Self-Adhesive Sheet Insulation 36" x 48" x 1" SAS10043

4.8(1 rating)
$58.69at eBayChecked Nov 8
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Pros
  • Self-adhesive backing saves time on ducts and equipment
  • Flexible sheet conforms to curves and irregular shapes
  • Wide temperature range down to -297°F
  • 25/50 flame and smoke rating
Cons
  • Lower R-value per inch than XPS
  • Not rated for compressive loads or below-grade use
  • Not UV resistant, so it needs a jacket or coating outdoors
Owens Corning
Owens Corning FOAMULAR NGX 250 Insulation Board

Owens Corning FOAMULAR NGX 250

Owens Corning FOAMULAR NGX 250 Insulation Board

$50.32at Insulation4USChecked 19 h ago
See all prices and details
Visit Insulation4US
Pros
  • R5 per inch, higher thermal resistance than the Armacell sheet
  • 25 psi compressive strength for walls, slabs and foundations
  • Retains R-value after water and wet-soil exposure
  • Made without HFC-134a, with a 90% lower GWP blowing agent
Cons
  • Rigid board does not wrap ducts or pipes
  • No self-adhesive backing, so it needs fasteners or adhesive
  • Thicker 3 in board takes more space in tight assemblies

What separates them

Armacell AP Self-Adhesive Sheet InsulationOwens Corning FOAMULAR NGX 250
Form and stiffnessFlexible elastomeric sheet, 36 x 48 in, 1 in thickRigid XPS board, 24 x 96 in, 3 in thick
R-valueR4.2 at 1 inR5.0 per inch
InstallationSelf-adhering peel-and-stick backingScore and cut with a utility knife, no adhesive backing
Moisture resistanceClosed-cell nitrile/PVC, but no published wet-soil ratingLow water absorption, retains R-value after standing water and wet soil
Compressive strengthNot rated for load-bearing25 psi, suitable under slabs and behind walls
Temperature range-297°F to 220°FNot published for extreme service temperatures
Flame/smoke rating25/50 ratedNot stated in the listing
Environmental profileNitrile/PVC composition, no GWP claimHFC-134a-free blowing agent, 90% lower GWP over 100 years

Price history

$252.19$52.00
Nov 7Nov 10
  • Armacell AP Self-Adhesive Sheet Insulation: lowest $252.19 on Nov 9 at DK Hardware; $252.19 on Nov 10.
  • Owens Corning FOAMULAR NGX 250: lowest $52.00 on Nov 7 at MyHackerTech; $79.97 on Nov 10.

Prices at every store

Armacell AP Self-Adhesive Sheet Insulation

  • DK HardwareNew

    In stock

    $252.19+ $20.25 shippingChecked 4 h ago
    Visit DK Hardware
  • eBayNew

    Availability unknownSold by zorotools (99.9% positive, 1,400,000 ratings)Returns: Set by the eBay seller; the eBay Money Back Guarantee covers an item that doesn't arrive or isn't as described.

    $58.69+ $5.99 shippingChecked Nov 8
    Visit eBay

Store links may earn us a commission.

All 2 stores and price history →

Owens Corning FOAMULAR NGX 250

  • Insulation4USNew

    In stockReturn policy

    $50.32Checked 19 h ago
    Visit Insulation4US
  • Roofing4USNew

    In stockReturn policy

    $50.32Checked 19 h ago
    Visit Roofing4US
  • ManuNew

    In stockReturn policy

    $50.32Checked 19 h ago
    Visit Manu
  • MyHackerTechNew

    In stockReturn policy

    $52.00Checked 19 h ago
    Visit MyHackerTech

Also available at

  • MyHackerTechCheck price at MyHackerTech
All 5 stores and price history →

Specs compared

SpecArmacell AP Self-Adhesive Sheet InsulationOwens Corning FOAMULAR NGX 250
Thickness1"—
Width36—
Length48—
R-ValueR4.2—
Temperature Range-297°F to 220°F (-182.78°C to 104.44°C)—
Flame/Smoke Rating25/50—
CompositionNitrile, PVC—
Weight28.07—
UV ResistantNo—
Country of OriginUSA—
FormSheet—
Product TypeInsulation Sheet—
Show all 21 specsShow fewer specs
SpecArmacell AP Self-Adhesive Sheet InsulationOwens Corning FOAMULAR NGX 250
Insulated PlasterboardNo—
Coverage Area144 square feet (Per Carton)—
Material Compositioncotton: 35%, isSubjective):false,—
Installation MethodSelf-Adhering—
Thermal Resistance R-Value—5.0 (0.88)
Compressive Strength—25 (172)
Board Width—24
Board Length—96
Board Thickness—3

What reviewers say

Armacell AP Self-Adhesive Sheet Insulation

Owners and installers generally find the peel-and-stick backing a real time saver on ducts and tanks, and the closed-cell foam holds up in damp spots. Complaints center on adhesive grip on cold or dusty surfaces and on the need to cover it outdoors.

What people mention
  • AdhesiveMixedInstallers say the peel-and-stick backing saves time but can lift if the surface is cold, damp or dusty.
  • Moisture resistancePraisedOwners like that the closed-cell foam does not absorb water the way fiberglass does.
  • Outdoor useCriticisedReviewers note it is not UV resistant and must be painted or jacketed when exposed.
  • InstallationPraisedThe sheet cuts cleanly and conforms to curved ducts and tanks.

Owens Corning FOAMULAR NGX 250

Owners and contractors describe FOAMULAR boards as easy to cut and dependable in damp below-grade use. Complaints center on price and on the bulk of thick boards.

What people mention
  • CuttingPraisedOwners say it scores and snaps easily with a utility knife.
  • MoisturePraisedReviewers report it keeps its R-value in wet ground and standing water.
  • Compressive strengthPraisedThe 25 psi board stays firm under slabs and soil backfill.
  • PriceCriticisedBuyers note XPS costs more per R-value than polyiso or EPS.

Questions and answers

Which is better for insulating ducts?
The Armacell AP sheet. Its self-adhesive backing and flexibility let it wrap ducts and fittings, and its 25/50 flame/smoke rating suits that use. FOAMULAR is rigid board and is not made for wrapping ducts.
Which lasts longer underground?
FOAMULAR NGX 250. It is rated for wet soil and standing water and keeps its R-value, with 25 psi compressive strength for below-grade loads. The Armacell sheet is not rated for ground contact.
Is the FOAMULAR worth stepping up to over the Armacell sheet?
Only if you are insulating walls, slabs or foundations. For those jobs the higher R-value per inch, compressive strength and moisture resistance justify it. For duct and pipe wrapping, the Armacell sheet is the right product.
Can I use the Armacell sheet outdoors?
Not exposed. It is not UV resistant, so it needs a protective jacket or coating outdoors. The FOAMULAR board is also typically covered or faced when exposed.
Which gives more R-value per inch?
FOAMULAR NGX 250 at R5 per inch versus R4.2 for the 1 inch Armacell sheet. The gap is small per inch, but the 3 inch FOAMULAR board reaches much higher total R.
Do either need special tools?
The FOAMULAR board scores and cuts with a utility knife, no special tools. The Armacell sheet cuts with a knife too, and its self-adhesive backing removes the need for separate adhesive on clean surfaces.

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