Roof Ventilation

Ventilation Information


Q. Why Ventilate Your Roof?

A-1  Helps reduce heat build-up in the summer, making living areas more comfortable and reducing air conditioning usage.

A-2 Helps eliminate trapped moisture that can cause mold, mildew and wood rot.

A-3 Keeps roof deck uniformly cool in the winter to help protect from ICE DAMS.

A-4 Extends roof shingle life

Q. What temperature should my attic be in the winter time?

A-1 The temperature of the attic in winter should be as close to the outside temperature as possible…to protect from ICE DAM  (This can be accomplished by installing proper attic ventilation…soffit vents and a good ridge vent system)

Q. What is the best type of attic ventilation?

A-1 Tests show that ridge vents with balanced soffit vents are the superior venting system. (A house with 42 feet of ridge vent would need 15 gravity vents or 5 roof turbines to provide the same amount of ventilation)

The principal source of attic heat is direct sunlight on the roof of the home. In an unventilated attic, the temperature will reach 160 degrees or more, when the outside temperature is in the 90 plus degree range.In cold climates, a combination of high humidity (40% or more) with low outside temperature will cause frost to accumulate on the underside of the roof sheathing.


One of these forces is called Thermal Effect. The thermal effect results in a difference in air temperature in the attic, and that of the outside, combined with the difference of the elevation be-
tween  the lowest and highest vent opening. In other words, hot air rises and collects at the peak of the roof. Thermal effect is utilized primarily at low wind speed.
The other force is Wind Speed Pressure. The wind flowing over the building will create areas of vacuum in the building which will result in negative pressure areas on the windward side and positive pressure areas as it passes the downwind side. Ventila-
tion air moves into the attic through the vents in a positive pressure area and exhausts through the vent opening located in negative pressure areas.


Proper roof venting is critical to good construction practices and maintenance. The purpose of roof venting is to reduce temperature build-up inside the roof cavity during the summer months and to reduce fungal wood rot and other problems associated with condensation in the roof cavity during the cooler months of the year.

A good venting system allows for a continuous flow of air which enters the roof cavity at a low spot in the roof (for example, under the eave) and exits the roof at a high spot (for example, at or near the ridge of the roof). As a general rule, there is no need to provide for any sort of mechanical assistance, fans, or other devices to the roof venting system. A good venting system works adequately by means of a natural convection current where warm air rises and pulls the cooler, drier air behind it. A good roof venting system must also be designed in such a way as to provide for proper air flow at all portions of the roof.

Improperly vented roofs often result in premature deterioration of the roofing material and fungal wood rot in the roof framing and decking. It is not uncommon to find an improperly vented fifteen-year-old roof with badly curled (and thus non-functional) roofing material and advanced fungal wood rot on the lower side of the roof decking. With the introduction of more insulation and weather sealing, as well as other building techniques which reduce venting, proper roof venting techniques are even more critical than in the past.


Ridgevent pic 1

New roofs or even in existing roofs, we highly suggest the complete ridge vent system.

Ridegevent pic 2

After cutting out the peak, normally 3″ on each side from peak or atleast 1.5″ opening if truss header is in place as seen above. Simply use 2.5 inch roofing nails to install the 4ft pieces of rigid vent and start the new shingle caps over the vent system.

Our Location

  • 524 S. Hafner
  • Stillwater, OK 74074
  • Local: (405) 372-7645 or call us Toll Free: (800) 475-2612