Combining two different types of roof vents in the same roof/attic like in the picture above, is the wrong approach. Air Takes the path of least resistance and the roof vents will draw from each other instead of drawing from the overhang like the picture below.
Balanced Attic Ventilation System
Research has shown that the best way to ventilate an attic is with a system that provides continuous airflow along the entire underside of the roof sheathing. Achieving this desired airflow requires a balanced system of intake ventilation low at the roof’s edge or in the soffit/undereaves and exhaust ventilation at the ridge.
During the winter when you think you have a leaky roof, the trouble may be excess condensation in your attic, this moisture comes from poorly ventilated bathroom exhaust fans, washing machines, dishwashers and driers.
This moisture enters through bypasses and penetrations that lead into the attic, The most common are:
- Attic hatches
- Recessed lights (also known as pot lights)
- Plumbing stacks
- Electrical wires
The moisture can migrate into the attic during the cold dry season and will form condensation on the underside of the roof surface which can then lead to mold and wood rot.
Poor ventilation is also one of the biggest reasons for premature roof failure. Many people think adding vents to the roof can solve their ventilation problem. Proper roof ventilation requires a system approach.
Almost every roof and attic is different and should be evaluated and treated on an individual basis.
Indications that your attic might have a ventilation problem include:
- Wet or compressed insulation
- Rusty nails or rust spots that have dripped onto your insulation PIC
- Blackened roof board or plywood, mold or mildew inside your attic
- Curling or cracking shingles
- Uneven snow melt
- Icicles at the roof edge
A well-ventilated attic extends the life of your roof. Trapped heat and moisture increases energy costs, cause ice dams and will damage not only your roof but also insulation, and roof structure.
Some of the most common attic/roof ventilation mistakes are:
- Failing to know or use the correct formula to calculate how much venting is required
- Neglecting to balance the attic ventilation with an equal amount of intake and exhaust vents
- Short circuiting the system by combining two different types of roof exhaust vents in the same attic.
- Installing additional insulation that ends up blocking the intake venting
- Adding aluminum soffit panels without enough venting holes or removing the wood soffit
- Venting a bath fan improperly or directly into the attic
Juffs Roofing will evaluate the best solution to your ventilation problem. We also determine what kind of intake or eaves ventilation and exhaust systems will suit your roof design.
We can help! Contact Juffs Roofing with your questions about attic ventilation and condensation.