The higher the r value the greater the insulation performance.
													
																	Roof insulation r value per inch. 
									
		
	
	
		
	
	
		
	
	
		
	
																	Know exactly how much you need with our project calculators. 
																	All these have r values ranging from r 3 2 to r 3 8 per inch. 
																	Contractors often use it to insulate under slabs ceilings walls and roofs. 
																	The r value of closed cell foam is r 6 5 7 per inch. 
															
													
									
		
	
	
		
	
	
		
	
	
		
	
																	Does not consider presence absence of reflective barriers. 
																	To convert rsi to r value multiply the rsi by 5 67826. 
																	To convert the r value of a specific thickness of a material to rsi divide the r value by 5 67826. 
																	The r 0 87 value for the first value in this air r value table subsection. 
															
													
									
		
	
	
		
	
	
		
	
	
		
	
																	Closed cell spray foam has a far better r value per inch than other less effective insulations like cellulose fiberglass or even open cell foam. 
																	Air gap or air film 3 4 air space insulating properties. 
																	R value measures how well certain building insulation materials can resist heat.