When installing a range hood, one of the most important decisions is determining whether the vent should go through the roof or the wall. Both options have pros and cons that must be weighed carefully during the planning process. This article will examine the key factors to consider when deciding between a roof vent and wall vent for a range hood.
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What is the purpose of a range hood vent?
A range hood vent serves a crucial purpose – to remove smoke, grease, odors, moisture, and combustion byproducts that occur during cooking. As these byproducts can condense on surfaces and cause damage over time, it’s important to vent them completely outside the home. The venting method should provide the shortest, most direct path outdoors while still adhering to building code.
Key functions of range hood vents
- Remove grease from the air to prevent buildup and residue on kitchen surfaces
- Eliminate odors, smoke, and moisture from cooking
- Draw combustion byproducts produced by gas ranges outdoors
- Improve indoor air quality by reducing particulates, VOCs, and other pollutants
- Prevent heat and humidity buildup in the kitchen
Proper venting is not only important for kitchen cleanliness and comfort, it’s also a safety issue. Failing to adequately vent cooking pollutants can lead to mold, damage, fires, and indoor air quality issues.
Factors to consider for roof vents
Roof vents expel cooking exhaust straight up and out of the house through the roof. Here are key factors to weigh:
Benefits of roof vents
- Provide the shortest, most direct path outdoors
- Prevent grease buildup on walls or ceilings
- Often comply with building codes for gas stoves
- More aesthetically pleasing without exterior vent on wall
Potential downsides of roof vents
- Roof penetration required – potential for leaks
- Venting through attics or upper floors can be complex
- Roof access required for inspection and cleaning
- Exposed to weather and debris
- May have greater noise from wind and debris
Roof vents are usually preferred from a performance standpoint, as the direct vertical pathway limits grease buildup and provides optimal airflow. However, installing the ductwork can be more labor intensive, and penetrations through the roof must be properly sealed and flashed.
Factors to consider for wall vents
Wall vents expel exhaust horizontally through an exterior wall. Here are key factors to consider:
Benefits of wall vents
- Often easier and less expensive to install
- No need for roof penetration – reduced risk of leaks
- Accessible for inspection and cleaning
- Less exposed to weather elements
Potential downsides of wall vents
- Indirect venting path less efficient at removing grease and smoke
- Horizontal ducts can allow grease to accumulate
- May not meet code for gas stoves due to increased fire hazard
- Requires exterior wall penetration and vent cap
- Vent on exterior wall may be aesthetically unappealing
Wall vents tend to cost less and involve simpler installation. However, the indirect venting path and potential for grease buildup can reduce performance. Wall vents should be avoided for powerful, gas stoves whenever possible.
Range hood duct type comparisons
When the vent path has been determined, the ducting material must also be selected. Here’s how common duct types compare:
| Duct Type | Pros | Cons |
|---|---|---|
| Round metal |
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| Rectangular metal |
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| Flexible metal |
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| Plastic/vinyl |
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Rigid, rounded metal ducts provide the best venting performance and easiest cleaning. Flexible or plastic ducts may suffice for short, simple vent runs, but reduce airflow over time as they sag and attract grease. Higher quality rigid metal ductwork is recommended for optimal range hood venting.
Special considerations for venting gas stoves
Gas stoves warrant extra ventilation precautions, as combustion byproducts like carbon monoxide, nitrogen dioxide, formaldehyde, and moisture are released when burning fuel. Here are key considerations for venting gas ranges:
Building code requirements
Many building codes require gas stove ventilation to be vertical through the roof. This provides the shortest path outdoors so combustion gases are fully exhausted.
Higher CFM range hood
Opt for a more powerful 700-1200 CFM range hood designed for a commercial-style gas range. This will properly capture and vent contaminants.
Vent hood 6-12 inches from range
Locate the range hood closer to the cooking surface so it can capture contaminants immediately before they spread.
Avoid long horizontal duct runs
Horizontal segments allow gases to pool and condense rather than venting straight outdoors. Use as few elbows as possible.
Use thick, rigid metal ducts only
Only use thick, rigid metal ductwork rated for the high temps and moisture levels. Flexible ducts can sag over time and lead to dangerous gas buildup.
Proper planning ensures gas stove combustion byproducts are vented fully to create a safer indoor environment.
Installation considerations
Proper installation is key to an effective range hood venting system. Here are important factors to keep in mind:
Hire a professional
Venting through the roof requires expertise to weatherproof and seal the penetration properly. A professional can also ensure the system meets code.
Plan duct runs carefully
Minimize turns and transitions. Allow access to ducts for regular cleaning and maintenance.
Slope horizontal ducts
A downward slope of 1/4 inch per linear foot will keep grease and moisture moving.
Use rigid duct elbows
Flexible elbows are more likely to sag over time or detach and lead to leakage.
Seal all connections
Use quality UL-181 tape to seal duct segments so exhaust cannot leak into the home.
Install a backdraft damper
This will prevent outdoor air from entering the ductwork and allow proper ventilation flow.
Insulate ductwork as needed
Insulation prevents moisture buildup and keeps exhaust at optimal temperatures.
Paying close attention to all details during installation will lead to improved ventilation system effectiveness and longevity.
Conclusion
Determining the best location and method for a range hood vent requires weighing several factors. Roof vents provide the most direct path outdoors but involve roof work. Wall vents are often simpler to install but have reduced capacity to remove smoke and grease. Powerful, commercial-style range hoods with 600-1200 CFMs paired with rigid metal ductwork provide the best performance for venting high heat and contaminants produced by today’s ranges. Hiring a professional installer is recommended to ensure the system meets code and operates safely and efficiently.