At a Glance

Coverage Area: 32 (sq ft)

Water Resistant

Use Location: Indoor/Outdoor

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Kingspan Insulation R- 5 , 1-in x 4-ft x 8-ft Unfaced Foam Board Insulation

Name: Kingspan Insulation R- 5 , 1-in x 4-ft x 8-ft Unfaced Foam Board Insulation
Brand: Kingspan Insulation
SKU: 5001939653
Rating: 4.7 (168 reviews)

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4.7

168

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For use as general purpose insulation for roofing, wall, and foundation applications requiring a minimum compressive strength of 25 psi. With its closed-cell structure, it is the most capable foam insulation for direct to ground contact of commonly available insulations. XPS insulation can be used as continuous insulation on interior or exterior walls to help increase the R-value of the walls, and improve the energy efficiency of the entire home or building.

XPS (Extruded Polystyrene) rigid foam board insulation with 25 psi minimum compressive strength
High R-value of 5
Lightweight, durable, easy to use and more moisture resistant than standard EPS insulation
Premium insulation value of R-5
Durable, yet easy to cut and shape, no loose beads
Retains integrity and insulating properties over time
Blowing agent blend GWP (Global Warming Potential) of less than 50, low ODP (Ozone Depletion Potential)
Meets and exceeds all ASTM C578 Type IV and Type X specifications
GreenGuard Insulation Board cannot be left exposed in an interior application and must be covered with an approved 15 minute thermal barrier

General
Package Quantity	1	Insulation Type	Foam
Use Location	Indoor/Outdoor

Dimensions
Actual Length (Feet)	8	Common Width (Feet)	4
Actual Thickness (Inches)	1	Coverage Area (Sq. Feet)	32
Actual Width (Feet)	4	Package Weight (lbs.)	5.5
Common Length (Feet)	8	R-Value per Inch	5
Common Thickness (Inches)	1	Maximum R-Value	5

Features
Fire Resistant	No	Sound Barrier	No
Formaldehyde Free	Yes	Vapor Retardant	Yes
Mold Resistant	No	Water Resistant	Yes
Paintable/Stainable	Paintable	Facing Material	Unfaced

Certifications
CA Residents: Prop 65 Warning(s)	No	ENERGY STAR Certified	No

Warranty
Warranty	None

Compatibility
For Use in Basements	Yes	For Use in Floors	Yes
For Use in Crawlspaces	Yes	For Use in Garage Doors	No
For Use on Plastic	No	For Use in Masonry	Yes
For Use on Metal	No	For Use in Plumbing	No
For Use on Wood	Yes	For Use in Vents	No
For Use in Ceilings	Yes	For Use in Walls	Yes
For Use on Insulation	Yes	For Use in Windows	No
For Use in Attics	Yes	Fits 2 x 4 Walls	Yes
For Use in Doors	No	Fits 2 x 6 Walls	Yes
For Use in Duct	No	For Use on Glass	No
For Use in Electrical	No

Miscellaneous
UNSPSC	30141500

Check out the Best Selling Board Insulation on Lowes.com

Review

4.7 out of 5

168 Reviews

96% Recommend this product

Ratings may include incentivized customer reviews.

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What Customers Are Saying

Customers overwhelmingly praise this foam board insulation for exceptional ease of cutting and installation using basic tools like knives and jigsaws, with clean cuts and minimal mess compared to cheaper alternatives. Reviewers consistently report reliable thermal performance for basements, garages, and ceilings, noting it provides effective insulation without significant bulk or weight. Many highlight its versatility beyond traditional uses, including craft projects, stage props, and decorative applications, with customers appreciating how well it accepts paint. A few mention occasional brittleness under stress or wish for additional features, though these concerns are rare and most consider it a solid value choice.

Customer review summary generated by AI, including incentivized reviews.

168 Customer Reviews

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Great for outdoor holiday yard props

Would Recommend

Purchased these foam boards to make Halloween and Christmas yard props. It is the best material to work with.

DMartinPAugust 28, 2026
Verified Purchaser

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Used to make a backer board for cutting sheet good

Would Recommend

I bought this to use as a backer board for cutting sheet goods with my track and circular saws. It's the right thickness for durability without taking up too much space -- I cut into fourths and used metal tape for connecting the sections in an accordion fold. I would have given it a 5-star but the back had an unusual pattern (maybe from the way the foam was extruded?) as I would have preferred to make that my cutting side but it was a bit odd.

MarkBJuly 17, 2026
Verified Purchaser

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16 Questions

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Kingspan Insulation R- 5 , 1-in x 4-ft x 8-ft Unfaced Foam Board Insulation

What tape should be used for the seams when putting two boards next to each other?

Will insects tunnel and/or nest in this foam?

Would this be durable in an exposed exterior application?

Is it water proof

Can this be glued to a hardboard wood panel, In lieu of pulling the hard board down and putting the insulation between the block and hardboard.

Can this be used to insulate rectangular hvac ducts?

Kingspan Insulation: Featured Videos

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		Name	Current Item Kingspan InsulationR- 5 , 1-in x 4-ft x 8-ft Unfaced Foam Board Insulation
		Ratings	168
		Water Resistant
		Maximum R-Value	5
		Insulation Type	Foam
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5	10	9.3	6	4.8	6.3	7.5	0.9	10
Polystyrene	Foam	Polyisocyanurate	Polyisocyanurate	Polystyrene	Mineral wool	Foam	Foam	Polystyrene