A Storm-Damaged Roof Vent Is Part of a System

A dented attic vent can look like a simple storm repair. Remove the damaged metal, install a new vent, and seal the opening. The important fact is that the vent is not working alone. It is one part of an airflow system that should bring outside air in near the eaves and release warmer, moist air near the roof peak. Replacing the visible damage without checking that system can leave a St. Louis homeowner with a sound new vent and an attic that still holds heat and moisture.

This matters when you are deciding whether to authorize a small repair or include the vents in a larger roof scope. The contractor should identify every intake and exhaust opening, calculate how much ventilation the attic needs, and specify which openings will remain active. A line on a proposal that says only replace roof vents does not answer those questions.

Storm and hail

Hail often leaves clearer marks on thin metal than it leaves on shingles. Box vents, powered fan covers, ridge vent caps, pipe flashing, gutters, and other exposed metal may show round dents after a storm. Those marks help establish what parts of the property were struck, but a dent does not automatically mean a vent has stopped working.

The functional questions are more specific. Did the impact crack a plastic housing? Did it open a seam in a metal vent? Did it loosen fasteners or distort the flange that runs under the shingles? Is the vent cover still secured against wind driven rain? Is the screen torn or pulled away? A contractor should photograph the top, sides, fasteners, and surrounding shingles instead of treating every visible dent as the same condition.

Wind can create a different problem. A vent may remain on the roof while its flange lifts slightly on one side. Water can then enter below the surface, especially when rain is pushed across the slope. A displaced ridge cap can also expose the ridge vent beneath it. From the ground, both conditions may look normal.

The repair choice must account for the roof around the vent. Removing a box vent requires lifting or removing shingles around its flange. On a newer flexible roof, that may be practical. On an older three tab roof, the surrounding shingles may be brittle, sealed tightly together, or difficult to replace with anything close in size and color. Once a three tab roof is roughly 15 to 20 years old, a contractor should be cautious about promising that a vent can be removed without breaking adjacent material. Condition matters more than the birthday alone, but age changes what a small repair can reasonably accomplish.

Cold weather adds another limit. Shingles stiffen when temperatures fall, and their seal strips may not bond promptly after they are disturbed. St. Louis can move through freezing nights and warmer afternoons in the same week. If a repair requires lifting cold shingles, ask how the contractor will avoid creasing them and how any unsealed tabs will be secured until warmer conditions allow proper sealing.

Do not combine exhaust types without a plan

A common mistake is leaving box vents in place when a new ridge vent is added. Both are exhaust vents, but they sit at different heights. Instead of drawing replacement air through the soffits, the ridge vent may pull air through the nearby box vents. That short path can leave lower areas of the attic with little movement.

The same concern applies when a powered attic fan operates near passive exhaust vents. The fan can pull through the nearest roof opening rather than through the intake at the eaves. It may also create negative pressure in the attic. If ceiling penetrations are poorly sealed, conditioned indoor air can be drawn upward. A larger fan does not correct missing soffit intake.

Ask for an attic ventilation drawing or a simple written count. It should identify the intake vents, the exhaust vents, and their net free ventilating area. Net free ventilating area is the usable open area after screens, louvers, and other restrictions are considered. The outside dimensions of two vents can be similar while their actual airflow ratings differ.

Balanced ventilation generally means providing intake capacity near the eaves and exhaust capacity near the top. The intake should not be blocked by insulation. From inside the attic, a contractor can look for daylight at the soffits, ventilation chutes between rafters, compressed insulation, staining, rusted nails, and damp roof decking. Those observations say more about the working system than the number of vents visible from the driveway.

Why the eave matters in a St. Louis winter

Attic ventilation does not replace air sealing or insulation. Warm household air that leaks through attic hatches, recessed lights, wiring holes, and plumbing penetrations can heat the underside of the roof. Snow may melt higher on the slope and freeze again at the colder eave. That is one path to ice damming.

Adding exhaust openings alone may not solve it. The useful sequence is to check for indoor air leakage, confirm insulation coverage, keep soffit intake paths open, and then size the exhaust to the roof and attic. A storm project creates an opportunity to inspect these parts because vents and ridge materials may already be under consideration. It should not become an excuse to install extra roof openings without a calculation.

Moisture signs also need careful reading. Frost on nail tips or roof decking can indicate humid attic air condensing on a cold surface. It does not, by itself, identify a hole caused by the storm. A water stain below a vent may come from a damaged flange, wind driven rain, condensation, or an older installation defect. The inspection should separate those possibilities before the repair scope is written.

What it costs

The price difference between vent choices is not limited to the part. Labor changes with roof pitch, height, access, shingle condition, and the amount of surrounding material that must be removed. Replacing one box vent on a walkable one story roof is different from replacing several vents on a steep two story roof with limited driveway access.

A ridge vent conversion can require removing the old ridge caps, checking the width and continuity of the ridge opening, installing the specified vent, and installing new cap shingles. Existing box vent openings then need to be closed with properly supported roof decking. Covering an old opening with thin sheet metal and shingles is not the same as restoring the deck.

Deck repair should be priced clearly. Ask whether the proposal includes the sheathing needed to close abandoned vent holes, underlayment, compatible flashing, cap shingles, and disposal. If damaged decking cannot be seen until the vent is removed, the proposal should state a unit rate or another written method for approving that added work.

Permit requirements can also vary by municipality. St. Louis County contains many municipal permit desks, and a city may administer roofing work differently from an unincorporated county address. The contractor should check the authority for the exact property address and state who will obtain any required permit. Do not assume the rule at a neighboring house applies to yours.

What to ask

Before approving the vent portion of a storm repair, ask the contractor to put these answers in writing:

• Which vents are physically damaged, and what photographs show the damage?
• Which vents are intake and which are exhaust?
• Will more than one type of exhaust vent remain active on the same attic?
• What is the net free ventilating area of the proposed intake and exhaust?
• Are the soffit openings clear inside the attic?
• Will old vent holes be closed with supported decking?
• Can the surrounding shingles be lifted without cracking or tearing?
• How will cold weather affect the repair and shingle sealing?
• Are there separate attic spaces that need separate ventilation calculations?
• Who checks the permit requirement for this address?

Separate attic spaces deserve special attention. A main house, attached garage, vaulted addition, and low porch roof may not share open airspace. One long ridge vent on the main roof cannot ventilate an attic section cut off by framing, fire blocking, insulation, or a finished ceiling. Each enclosed area needs its own intake and exhaust path where ventilation is required.

The written scope should name the vent type and quantity instead of using a broad allowance. It should also say what happens to every existing vent. Terms such as remove, replace, close opening with decking, and leave in service are clear. Address ventilation as needed is not.

Keys Roofing can document the vent condition with photos and measurements and put the proposed roofing scope in the homeowner's hands. To schedule a roof and attic ventilation inspection in the greater St. Louis area, call (314) 220-2333.