'Radiant Above Sheathing Ventilation™'How it Works

'RASV™' is an abbreviated term used to describe Radiant Above Sheathing Ventilation.

• First Vertical Metal Riser Battens are installed over sheathing between the soffit and the  ridge. 
  
• Next, Horizontal Metal Battens  are applied on top of the  Vertical Metal Riser Battens (to which stone coated steel roof panels or roof tiles are applied) 
• This forms an air gap referred to as  'Above Sheathing Ventilation' (or ASV) between the roof sheathing and the roof panels. 
• The lower surface of this ventilation channel is covered in a radiant foil vapor barrier that deflects 97% of radiant energy from entering the roof attic. 
• The upper surface of the ventilation channel is formed by the unpainted  galvalume metal underside of the stone coated steel roofing panels. 
• Solar radiation absorbed by the metal roof panels is dissipated in the radiant sheathing ventilation channel and buoyant heated air is channeled by convection from the soffit to the ridge, where it is vented back in to the atmosphere via a concealed ridge vent. 
• The number of air exchanges occurring within the ventilated cavity averages 20–100 ACH (air changes per hour) and prevails almost 80% of the time.  
• Buoyant heated air exiting the ventilation' cavity  via the double ridge vent (and prevailing winds) form negative stack pressure at the ridge which assists in drawing fresh cool air in to the roof attic via the soffits. This highly effective ventilation system can save homeowners up to 25% in Summer Cooling Costs and 10% in Winter Heating costs compared to a regular black asphalt shingle roof.    

A Radiant Ventilated Cool Roof System harnesses 3 proven technologies known to create thermal resistance and reduce heat conduction within  steep slope roof deck assemblies; 

1-  Above Sheathing Ventilation (ASV) - using metal battens and counter battens to create an optimized convection and drainage plane between between the roof sheathing and roof substrate.  

2-  Radiant Barriers installed within the ASV assembly that prevent  97% of radiant energy from entering the attic space. 

3- Sheathing Vents  installed in the sub tile ventilation cavity that draw heated attic air into the sheathing ventilation system and improve attic ventilation.   

A Radiant Cool Roof Saves up to 25% in Summer Cooling Costs and 5%-10% in Winter Heating Costs  

Installing a metal roof with  'Radiant Above Sheathing Ventilation' ('RASV') can save you up to 25% in Summer Cooling Costs and 5%-10% in Winter Heating costs compared to a regular asphalt shingle roof. 

Radiant Ventilated Cool Roofs Come in 3 Styles and over half a dozen colours

• Cool roof Tiles
• Cool Roof Shakes
• Cool Roof Shingles

 
 A Radiant ASV Cool Roof complies with Title 24 California Building Standards, Section 152, and NAHB Green Building Standard, Chapter 7,  which both state that roofs installed with radiant barriers and an appropriate air gap are considered equivalent to the prescriptive definition of a cool roof (i.e cool pigment roofs)-  regardless of the roof color and it's associated solar reflectance.   

The combined effects of solar reflectance afforded by the radiant vapor barrier and the above-sheathing ventilation channel support a 70% reduction in the heat flow penetrating the ceiling into conditioned attic space.  

'Radiant Above-Sheathing Ventilation™' improves the
summer performance of the attic assembly and also
reduces the heat losses by night-sky radiation during the winter.

Installing a metal roof with  'Radiant Above Sheathing Ventilation™' (RASV™) saves up to 25% in Summer Cooling Costs and 10% in Winter Heating Costs  compared to a regular black asphalt shingle roof. 






Above Sheathing Ventilation (ASV) Meets Code Requirements for 'Cool Roof' Certification

 A Radiant ASV Cool Roof complies with Title 24 California Building Standards, Section 152, and NAHB Green Building Standard, Chapter 7,  which both state that roofs installed with an appropriate air gap are considered equivalent to the prescriptive definition of a cool roof  (i.e. cool pigment on a metal roof)- regardless of  solar reflectance. 

• The Cool Roof Batten Riser™  is a 'patent pending'  Metal Batten Riser  for  stone coated steel roofing panels.
  
  
•   The  Cool Roof Batten Riser™  forms an optimized Above Sheathing  Ventilation and drainage plane beneath stone coated steel roofing panels.  The number of air exchanges occurring within this ventilated cavity averages 20–100 ACH (air changes per hour) and prevails almost 80% of the time. 
  
  
• The  Cool Roof Batten Riser™   simplifies stone coated steel roof installation because it is pre-flanged to accommodate either metal or wood battens at the precise batten spacing required for stone coated steel  roof panels.    
  
  
• The  Cool Roof Batten Riser™  facilitates the use of radiant barriers within in the  Above Sheathing  Ventilation cavity. 
  

The Cool Roof Batten Riser is designed to work with Wood Roof  Battens and Metal Roof Battens  

A  wooden roof batten ventilation sub-assembly costs significantly less than an "all metal" roof  ventilation sub-assembly. Wooden roof battens support the proven benefits of 'above sheathing ventilation and are fully compatible with radiant barriers.The disadvantage of wood battens is that they tend to warp split, and crack over time.      

The quality of wood roof battens can vary significantly from batch to batch and ultimately will determine how long both the battens and your new metal roof  will last. 
    

Investing in an 'all metal' roof batten sub-assembly costs more than a wooden batten sub-assembly.   In areas subject to high wind conditions and ongoing fire hazards, we recommend investing in the 'all metal' batten system which is totally fire resistant, corrosion resistant and will never rot, crack, split or break-  even if you walk on the roof.

Every horizontal metal batten is fastened to our  Cool Roof Riser Battens™  with two 1.5 Inch  corrosion resistant screws which  penetrate both the metal riser and the roof sheathing below ensuring a virtually indestructible roof.   

An all metal batten system will last as long as your new stone coated metal roof -guaranteed! 
    

The  Cool Roof Batten Riser™  forms an optimized Above Sheathing  Ventilation and drainage plane beneath stone coated steel roofing panels.  The number of air exchanges occurring within this ventilated cavity averages 20–100 ACH (air changes per hour) and prevails almost 80% of the time.  

The Cool Roof Batten Riser™ comes in 3 different riser height sizes 

• 0.75 Inch
• 1.5 Inch
• 2.25 Inch