Roof ventilation is one of the most overlooked architectural design elements in residential construction. A poorly ventilated roof can cause dampness and damage to the interior structure and contents while also being a low-cost solution to many moisture-related problems. But before we get into that, we need to know what a roof is and how it works to design our roof vents properly.
A roof is a part of a house located over the exterior walls of the home and protects the interior from heat, cold, wetness, and wind. Without this important component, it would be impossible to have a habitable structure to spend 45-50% of our lives.
Roofs today are very similar in design to how they were built 20 years ago. However, improvements in building materials and advances in technology have made better ventilation systems possible without sacrificing the aesthetic value that our older homes possess.
What is Roofing Ventilation?
Ventilation is air circulation from the interior of a building to the exterior. Historically, roofing ventilation has been very poor, causing moisture and heat to build up in the roof assembly and eventually leading to rot, decay, and costly repairs that could have been easily prevented.
Approximately 50% of all homes are built without adequate roof ventilation. As a result, these homes become a breeding ground for mold, mildew, algae, and fungus that degrade the structure and interior contents of the home.
Signs of Poor Roof Ventilation
Poor roof ventilation can cause many problems with your home.
Including but not limited to:
- Mold, mildew, and fungus growth in attic space
- Mold and mildew growth in interior structure/walls/ceilings
- Condensation on interior walls and ceilings
- Condensation on exterior walls
- Increased energy costs due to poor insulation value of the roof assembly.
You may not be able to tell if your home is ventilated or not from the inside, but signs from the outside can sometimes help identify if it is or not.
What to Look for:
- Water stains on the exterior of your home.
- Mildew and mold growing from external walls, drywall, ceiling, and attic space.
- Puddles of water under the home porch and street lights at night.
A properly ventilated roof will allow all heat, rain, snow, and wind to pass through the roof with minimal moisture build-up at all points. Sunlight will penetrate the roof and reach into the home, keeping it naturally warm during winter months and cool in summer.
Benefits of a Properly Ventilated Roof
There are many benefits of a proper roof ventilation system.
Including but not limited to:
- Reduces moisture build-up in the structure of your home.
- Reduces condensation and mold build-up inside and outside your home.
- Reduces seasonal temperature swings inside the home.
- Improves energy efficiency by reducing heat loss in winter and increases cooling efficiency in summer.
- Prevents internal moisture damage to your home, saving on costs for repairs and maintenance.
- Protects you and your family from the harmful effects of mold, mildew, and fungus.
- Improves the interior aesthetic appeal of your home.
- Restores value to older homes.
- Reduces hydrocarbon emissions into the atmosphere and thereby reduces air pollution.
- Reduces CO2 emissions and contributes to global warming reduction by improving the insulation value of a home (a properly ventilated roof will allow more heat generated inside a home to pass through it instead of being trapped in the roof assembly).
How to Properly Ventilate a Roof
For air circulation to pass through a home properly, there are specific areas that we must ensure are open. These include roof valleys, roof vents, attic vents, ridge vents, gable vents, and bypass or stack effects.
1. Roof Vents
Roof vents are significant to a home’s proper ventilation and must be appropriately installed to ensure air can circulate into and out of your home correctly. They are often called ridge or gable end vents if located at the ends of your roof (typically at the gable ends). Roof vents must be installed with slope and pitch to allow water to run off the roof into gutters.
If your roof is very steep, it may not have enough slope for proper rain run-off. It would be recommended to install a gutter system or a modified roof vent with less pitch to prevent the accumulation of water on your roof.
2. Attic Vents
If your home doesn’t have adequate attic ventilation, there is no way for air to enter or exit your home except through windows and doors.
If you have a forced-air heating system in your home, you will have problems with moisture and mold, making your home uninhabitable.
3. Roof Valleys
Roof valleys are significant because they allow air to flow from the attic into the downstairs space and vice versa. The primary purpose of a roof valley is to allow air to flow across the top of the room that it is located in, thus eliminating dead air spaces between rooms.
4 . Ridge Vents
Ridge vents are essential because they allow air to flow from the attic into the downstairs space and vice versa. The primary purpose of a ridge vent is to allow air to flow across the top of the room that it is located in, thus eliminating dead air spaces between rooms.
5. Gable Vents
Gable vents are very important because they allow air to flow from the attic into the downstairs space and vice versa.
6. Bypass/Stack Effects
Bypass and stack effects are significant to the proper ventilation of a home because they eliminate stagnant pockets of air in your home. These areas are very important to ensure proper airflow through your home.
When properly installed, a roof ventilation system using the best components on the market today will allow you to eliminate moisture build-up in your home, reduce air pollution and energy costs, decrease condensation and mold formation inside and outside your home, as well as improve its overall visual appearance.