Vent Hood — Exterior Wall Cap for HVAC Exhaust Ducts

A vent hood is an exterior wall cap or hood that covers an HVAC or exhaust vent termination while directing air out of the building.

Vent Hood diagram — labeled parts, dimensions, and installation context

What It Is

A vent hood is the protective termination mounted on an outside wall where ducted air is discharged or, in some systems, drawn in. The hood shape helps deflect rain and reduce direct wind entry while keeping the vent opening functional.

Many vent hoods include a backdraft damper, bird screen, or flap depending on the appliance or fan they serve. The exact design must match the equipment because dryers, bath fans, range hoods, and high-efficiency HVAC systems all have different venting needs.

Types

Common types include dryer vent hoods, bath fan wall caps, kitchen exhaust hoods, and listed intake or exhaust terminations for HVAC equipment. Materials range from plastic to painted steel, aluminum, or stainless steel.

Where It Is Used

Vent hoods are used on exterior walls where a duct or vent terminates from a bathroom fan, dryer, range hood, fresh-air intake, or other HVAC-related system. They are usually placed where the connected duct can run with minimal restriction.

How to Identify One

Look for a hooded cover on the outside wall with an opening, flap, or louver tied to a duct behind it. Broken flaps, missing screens, lint buildup, rust, or staining on the siding are signs the vent hood needs attention.

Replacement

Replacement requires matching the hood size, duct connection, and appliance listing requirements. For dryer and combustion-related vents especially, using the wrong hood can create airflow restrictions or safety problems.

Vent Hood — FAQ

What does a vent hood do on the outside of a house?

It covers the duct termination and helps direct air out while limiting rain, pests, and backdrafts. Many also include a flap or damper that closes when the fan or appliance is off.

Why is lint collecting around my vent hood?

That often points to a dryer vent issue, such as a stuck flap, partial blockage, or excessive lint escaping the duct. It should be checked promptly because lint buildup can become a fire hazard.

Can I use the same vent hood for any appliance?

No. Different appliances have different airflow and safety requirements, so the termination needs to match the equipment type and manufacturer instructions.

When should a vent hood be replaced?

Replace it when the hood is cracked, rusted through, missing its damper, clogged beyond practical cleaning, or no longer seals and sheds water correctly. Damage is common on hoods exposed to sun and wind.