RV Roof Vent and Skylight Repair in Yorba Linda

Ultraviolet degradation of the plastic, first and by a wide margin. Vent lids and skylight domes are acrylic or polycarbonate, and in constant Southern California sun they yellow, become brittle, and then crack from a hail stone, a branch, or simply from thermal cycling. A crazed dome that has not cracked yet is on borrowed time.

Second, the lift mechanism. Manual vents use a scissor arm and a crank with a plastic gear that strips. Powered fans use a small motor and a gearbox, and the common failures are the motor itself, the lid position switch, and the wiring at the hinge where it flexes every cycle. Rain sensors on the fancier units fail in the closed position, which is at least the safe direction.

Third, the flange and the sealant. The plastic flange itself becomes brittle and cracks at the fastener holes, which means a resealed vent with a cracked flange still leaks. We inspect the flange before deciding to reseal rather than replace, because resealing a cracked flange is a wasted visit.

• Cracked and yellowed vent lids and skylight domes
• Stripped crank gears on manual vent mechanisms
• Failed fan motors, position switches and hinge wiring on powered vents
• Cracked flanges at the fastener holes
• Shrunken and cracked sealant around the flange perimeter
• Rotted decking around the opening from a leak that ran unnoticed

Because a shower skylight is a large opening in a location with a specific set of problems. It is usually the biggest single penetration on the roof after the air conditioner, it is often an inner dome plus an outer dome with a gap between them, and the bathroom below it is the highest humidity space in the vehicle.

That last point causes a diagnostic trap. Water on the inside of a bath skylight is frequently condensation rather than a leak, because a shower puts a lot of moisture into a small space and the skylight is the coldest surface it can reach. We check whether the water appears after showers or after rain before we start pulling the skylight apart. It is a five minute question that saves the owner money.

When it is a genuine leak, the causes are a cracked outer dome, a failed flange, or sealant that shrank at the corners. Skylight flanges are large, which means more thermal movement across the joint and more demand on the sealant than a small vent. We reseal skylights with self-leveling on the horizontal flange and we replace the dome whenever it is crazed, because resealing under a dome that is about to crack is half a job.

Roof vent and fan replacement runs $250 to $1,200 at 1 to 5 hours. A lid only replacement is at the bottom. A powered fan upgrade with a rain sensor and a thermostat, wired into an existing circuit, is toward the top. Skylight repair and replacement runs $350 to $2,500 at 1 to 10 hours, with a simple dome swap at the bottom and a full skylight replacement with flange and decking repair at the top.

Every one of those jobs includes removing the old sealant back to a clean bond surface rather than sealing over it, replacing the butyl under the flange rather than reusing it, and probing the decking around the opening for softness before the new unit goes down. If the decking around an opening has rotted, we tell you before we set the new vent, because setting a vent into soft plywood produces a leak within a year.

Powered fan work is billed at our mechanical and electrical rate of $260 per hour. Sealing and flange work is at the body and paint rate of $210 per hour.