Does it really reach R-21?

Only as a radiant barrier with an air space on the foil face, measured in a closed assembly. In contact with a surface or buried in a cavity it performs far lower.

Can it go behind drywall or under siding?

It can, but foil needs an air gap to reflect heat. Direct contact with drywall or sheathing loses most of the radiant benefit.

It is rated Class 1/Class A with flame index 0 and smoke development 15, and the maker says it is non-toxic. Keep foil faces away from direct flame and check local code for exposed foam.

How do I seal the seams?

Use foil tape on butt joints and edges. Overlap edges slightly and press the tape flat so moisture and air do not get behind the foil.

What widths and lengths come in the roll?

Rolls run 50 ft long in 2, 3, 4 and 6 ft widths, plus a 4 ft by 100 ft roll.

Will it stop condensation on RV skirting?

The closed-cell foam is waterproof and does not promote mold, so it blocks drafts and radiant heat. Ventilate the space behind it so trapped moisture can escape.

SmartSHIELD 1/4 Inch Reflective Foam Price History: Lowest $149.95

Q: Where is the SmartSHIELD 1/4 Inch Reflective Foam Insulation Roll - Black / Foil cheapest?

At Insulation MarketPlace, for $149.95, as of our latest check.

Q: What do buyers say about the SmartSHIELD 1/4 Inch Reflective Foam Insulation Roll - Black / Foil?

Rated 5 out of 5 from 1 ratings. Buyers like: Black and silver finish looks made for RV skirting; Called a game changer by a reviewer.

What reviewers say

Buyers are few but positive. One calls it a game changer, and another likes the black and silver finish for RV skirting.

What people mention

InstallationPraisedBuyers say it is easy to cut and put up.
AppearancePraisedThe black and silver foil finish is liked for RV skirting.
ValuePraisedOne reviewer calls it a game changer for the job.

From Insulation MarketPlace

Closed-cell polyethylene foam core with double-sided engineered foil reflects up to 97% of radiant heat
R-values from R-15.67 to R-21.10 for high thermal resistance
Class 1/Class A fire resistance rating
Waterproof and resistant to mold growth
Lightweight, flexible and easy to cut and install for DIY or professional use
Non-toxic composition, safe for indoor use without skin or respiratory irritation

Sizes: 2ft x 50ft, 3ft x 50ft, 4ft x 50ft, 6ft x 50ft, 4ft x 100ft
Materials: Closed-cell polyethylene foam wrapped in two layers of premium engineered foil, with a protective black plastic film
Guarantee: 10 years warranty; 60-day money-back guarantee
Returns: 60-day money-back guarantee
Shipping: Same day FREE shipping
In the box: Comes in a compact roll for easy handling

About the SmartSHIELD 1/4 Inch Reflective Foam Insulation Roll - Black / Foil

This is a 1/4 inch (6mm) reflective foam insulation roll with a closed-cell polyethylene foam core. The core is wrapped in two layers of engineered foil and covered with a protective black plastic film. The foil reflects up to 97% of radiant heat.

R-values range from R-15.67 to R-21.10, which helps reduce energy loss and stabilize indoor temperatures. The material is waterproof, resists mold growth and carries a Class 1/Class A fire rating. It does not delaminate.

The roll is lightweight and flexible, and it is easy to cut and install. It suits DIY and professional use. The composition is non-toxic and does not irritate skin or the respiratory system.

Thickness: 6mm (1/4 inch)
Roll sizes: 2ft x 50ft, 3ft x 50ft, 4ft x 50ft, 6ft x 50ft, 4ft x 100ft
Material: Closed-cell polyethylene foam wrapped in two layers of engineered foil, with a black plastic film
R-value: R-15.67 to R-21.10 (A: 15.67; B: 21.10, ft²·h·°F/Btu, ASTM C-236)
Radiant heat: Reflects up to 97%
Emittance: 0.03 (ASTM C-1371-98)
Fire resistance: Class 1/Class A
Flame index: 0 (ASTM E-84)
Smoke development: 15 (ASTM E-84)
Moisture: Waterproof; closed-cell structure
Vapor permeability: 0.033 g/m²·h·kPa (0.05 perms) (ASTM E-96/IRAM 1735)
Mold resistance: Resists and does not promote fungal growth (ASTM C-1338)