R-Values

Use these values as starting points while designing and checking energy performance of structures and assemblies. Always consult product specifications for exact R-Values and verify numbers prior to final documentation.

• These values should be used as a starting place, and not the end result.
• Code and Energy Guidelines may present guidelines or other requirements to follow.

R-Value Degradation

R-Values may degrade over time due to settling, chemical changes (rust, staining), dust, or other issues.

*Air Gaps & Film

Air Spaces (Air Gap)

Air spaces are particularly difficult to estimate values of the R-Value as they depend on numerous factors, including size and shape of the surfaces, orientation, reflectivity of the surfaces facing the airspace, heat and airflow in/out of the airspace (air changes per hour), and other factors.

ICC A9.4.2 Air Spaces

ICC Ashrae TA9.4.2 Air Spaces Has been created to help deal with the difficulty of how to estimate air space values. Note that all air spaces under .5” thick are stated to have zero R-Value.

Air Film (Adjacent to Assemblies)

Air against a wall has an insulative property and is known as ‘air film’. Interior and Exterior accepted values are shown in the chart, and are generally used throughout various textbooks.

R-Value Charts

R-Value Per Inch

Category	Component	Low	~Mid	High
Barrier	Foil Faced Barrier	0.50	1.00	1.30
Finish	Gypsum Drywall	–	0.90	–
Finish	Glass (Single Pane)	2.50	3.60	4.00
Insulation	Fiberglass (Batts)	2.90	3.40	3.80
Insulation	Cotton (Batts)	3.00	3.60	4.30
Insulation	Plastic Fiber (Batts)	3.80	4.00	4.30
Insulation	Mineral Wool (Semi-Rigid)	4.00	4.10	4.30
Insulation	Fiberglass (Semi-Rigid)	4.00	4.10	4.30
Insulation	Polystyrene (EPS & XPS) (Rigid)	3.80	5.00	6.50
Insulation	PolyIso (Rigid)	6.00	6.20	6.50
Insulation	Polyurethane (Rigid)	3.70	4.00	4.50
Insulation	Compressed Straw (Rigid)	0.90	1.50	2.40
Insulation	Cellulose (Spray In)	3.10	3.50	3.80
Insulation	Fiberglass (Blown)	2.20	2.50	2.90
Insulation	Mineral Wool (Rockwool) (Blown)	3.00	3.30	3.50
Insulation	Spray Foam (Closed Cell)	5.00	6.00	7.00
Insulation	Spray Foam (Open Cell)	3.00	3.50	4.00
Masonry	Concrete (In Situ)	0.08	0.10	0.20
Masonry	Mortar (Thinset)	0.30	0.40	0.50
Masonry	Brick (Solid)	2.00	2.25	2.50
Space	AIr Film (Exterior)	–	0.17	–
Space	Air Film (Interior)	–	0.68	–
Space	Air Gap (Typical)*	–	0.26	–
Space	Air Gap (Reflective)*	–	0.30	–
Wood	Plywood Board (Construction Grade)	1.00	1.10	1.20
Wood	Oriented Strand Board (OSB)	1.20	1.40	1.50

~Mid Value * Standard Widths

Category	Component	~Mid	1/4″ (.25″)	1/2″ (.50″)	5/8″ (.625″)	3/4″ (.75″)	1.0″	2.0″	3.5″ (_x4)	5.5″ (_x6)	7.25″ (_x8)	9.25 (_x10)	11.25 (_x12)
Barrier	Foil Faced Barrier	1	0.25	0.50	0.63	0.75	1.00	2.00	3.50	5.50	7.25	9.25	11.25
Finish	Gypsum Drywall	0.9	0.23	0.45	0.5625	0.675	0.90	1.80	3.15	4.95	6.53	8.33	10.13
Finish	Glass (Single Pane)	3.6	0.90	1.80	2.25	2.70	3.60	7.20	12.60	19.80	26.10	33.30	40.50
Insulation	Fiberglass (Batts)	3.4	0.85	1.70	2.13	2.55	3.40	6.80	11.9	18.70	24.65	31.45	38.25
Insulation	Cotton (Batts)	3.6	0.90	1.80	2.25	2.70	3.60	7.20	12.6	19.80	26.10	33.30	40.50
Insulation	Plastic Fiber (Batts)	4	1.00	2.00	2.50	3.00	4.00	8.00	14	22.00	29.00	37.00	45.00
Insulation	Mineral Wool (Semi-Rigid)	4.1	1.03	2.05	2.56	3.08	4.10	8.20	14.35	22.55	29.73	37.93	46.13
Insulation	Fiberglass (Semi-Rigid)	4.1	1.03	2.05	2.56	3.08	4.10	8.20	14.35	22.55	29.73	37.93	46.13
Insulation	Polystyrene (EPS & XPS) (Rigid)	5	1.25	2.50	3.13	3.75	5.00	10.00	17.5	27.50	36.25	46.25	56.25
Insulation	PolyIso (Rigid)	6.2	1.55	3.10	3.88	4.65	6.20	12.40	21.7	34.10	44.95	57.35	69.75
Insulation	Polyurethane (Rigid)	4	1.00	2.00	2.50	3.00	4.00	8.00	14	22.00	29.00	37.00	45.00
Insulation	Compressed Straw (Rigid)	1.5	0.38	0.75	0.94	1.13	1.50	3.00	5.25	8.25	10.88	13.88	16.88
Insulation	Cellulose (Spray In)	3.5	0.88	1.75	2.19	2.63	3.50	7.00	12.25	19.25	25.38	32.38	39.38
Insulation	Fiberglass (Blown)	2.5	0.63	1.25	1.56	1.88	2.50	5.00	8.75	13.75	18.13	23.13	28.13
Insulation	Mineral Wool (Rockwool) (Blown)	3.3	0.83	1.65	2.06	2.48	3.30	6.60	11.55	18.15	23.93	30.53	37.13
Insulation	Spray Foam (Closed Cell)	6	1.50	3.00	3.75	4.50	6.00	12.00	21	33.00	43.50	55.50	67.50
Insulation	Spray Foam (Open Cell)	3.5	0.88	1.75	2.19	2.63	3.50	7.00	12.25	19.25	25.38	32.38	39.38
Masonry	Concrete (In Situ)	0.1	0.03	0.05	0.06	0.08	0.10	0.20	0.35	0.55	0.73	0.93	1.13
Masonry	Mortar (Thinset)	0.4	0.10	0.20	0.25	0.30	0.40	0.80	1.40	2.20	2.90	3.70	4.50
Masonry	Brick (Solid)	2.25	0.56	1.13	1.41	1.69	2.25	4.50	7.88	12.38	16.31	20.81	25.31
Space	AIr Film (Exterior)	0.17	–	–	–	–	–	–	–	–	–	–	–
Space	Air Film (Interior)	0.68	–	–	–	–	–	–	–	–	–	–	–
Space	Air Gap (Typical)*	0.26	0.07	0.13	0.16	0.20	0.26	0.52	0.91	1.43	1.89	2.41	2.93
Space	Air Gap (Reflective)*	0.3	0.08	0.15	0.19	0.23	0.30	0.60	1.05	1.65	2.18	2.78	3.38
Wood	Plywood Board (Construction Grade)	1.1	0.28	0.55	0.69	0.825	1.10	2.20	3.85	6.05	7.98	10.18	12.38
Wood	Oriented Strand Board (OSB)	1.4	0.35	0.7	0.88	1.05	1.40	2.80	4.90	7.70	10.15	12.95	15.75