Garage gable vent, 3/2026

And now, for something a little different...

I noticed that the warm air inside the garage had no way to vent to the outside, causing condensation on the smooth surfaces on the ceiling. As part of my engineering and architecture training, we always strove to eliminate moisture buildup in the interior of a building because it is a source of mold and mildew. So, I'm installing gable vents to allow the warm air to pass through to the outside. Here are some highlights:

Back of garage, without a gable vent. I can feel moisture buildup on the smooth surfaces of the ceiling. This can lead to all kinds of water damage, mold, and mildew.

Polyurethane exterior vent

The prefab vent is a block of polyurethane, but I wanted to hide the cut shingle edge with a rabbet around the perimeter. This will allow the vent to hide any miscuts or imperfections around the shingles. 

Rabbet cut using my tablesaw.

Using the vent mailing box, I created a template to trace the wall penetration.

Placing the template to locate the vent.

Since I don't own a multi-tool, I used a drill and chisel to "cut" the shingles within the template tracing. This takes longer than a multi-tool, but works well if you are careful with your drilling and chiseling.

Shingles removed, wall sheathing exposed and marked out for penetration. One hurdle is that the opening is blocked by a wall stud. I didn't want to relocate the stud, so I left it in place and modified the hole.

Sheathing cut, all exposed wood was sealed with primer.

Vent installed with construction adhesive and reinforced with screws.

I sealed the interior perimeter of the hole as a precaution for water infiltration. The bottom was not sealed to allow incidental water to drain out. 

Garage back gable vent installed and complete.

So, the next step is to install the garage front gable vent to allow cross flow for better air movement. Sometimes it's good to exercise your construction skills to keep your mind sharp and flexible.

CoWaBunGA!