How to Ventilate a Detached Garage

Proper ventilation keeps your family and your garage healthy.

Ventilating a garage is a major health issue. Harmful gasses routinely build up in the garage. The car is a major culprit, contributing exhaust, gas, oil and even antifreeze and any other fluids that may be leaking. Then there are the pesticides, fertilizers, paint, cleaners and other fluids that are too smelly to be kept in the house. Add to that any moisture or mold issue, and you have the potential for very dangerous air. Installing ventilation in the garage is the only way to permanently fix the problem. Attic fans come in a wide variety of sizes and with features that make them the perfect solution.

Things You'll Need

• Attic fan
• Automatic shutter
• Level
• Pencil
• Ruler
• Drill
• Large drill bit
• Sabre saw
• Screwdriver bit
• Wood screws
• 1/2-inch plywood
• Acrylic caulk
• 14/2 w/g cable
• Wire staples
• Hammer
• Tape
• 2 box connectors
• Wiring caps
• Screwdriver
• 1/4-inch plywood (optional)

Instructions

1. Choose the best place for your ventilation fan. The fan should not be pointed into prevailing winds since this will simply blow the fumes back into the building. If possible, choose an area in the garage that is free from wiring and other obstructions.

2. Measure your garage. Fans are rated for the amount of cubic air they move. Choose the right size fan for your garage. Additionally, since this fan will not be locked away in the attic, choose a fan with a safety cage or other covering on the inside to prevent contact with the spinning blades. Purchase the automatic exterior shutter that is 2 inches larger than the diameter of the fan.

3. Hold the shutter panel up to the wall where the fan will be installed. Use the level to assure that the shutter panel is straight. Trace around the shutter with a pencil. Measure 5/8 inch inside the pencil line and draw a second line.

4. On the inside of the garage, drill a large hole near the corner of the inside line. Insert the blade of the saber saw into the hole. Cut along the inner line. Remove any insulation. Repeat the process for the outer wall, if necessary.

5. Place the automatic shutter on the outside of the garage. Attach to the building with wood screws. Seal around the outer edge with acrylic caulk.

6. Cut a square of plywood 6 inches larger than the fan.

7. Place the fan on the 1/2-inch plywood. Trace the fan. Drill a small hole near the tracing line for the blade of the saber saw. Cut the hole from the center of the plywood.

8. Look for the top of the fan. The motor has a vertical orientation and one of the mounting brackets is marked as the top.

9. Place the fan over the hole in the plywood. Mount the fan onto the plywood with wood screws. Fasten the screws through the mounting blocks on the fan. Screw the electric thermostat (if included) onto the plywood.

10. Place the fan on the inside of the hole in the garage wall. The new shutters now cover the outside of the hole. Screw the plywood frame to the studs of the wall.

11. Locate the closest wall socket circuit box. Drill a hole through any studs that lie between the fan and the closest socket. Thread the 14/2 cable through the holes and staple the cable to the wall between each stud.

12. Attach a box connector to both ends of the cable. Strip 6 inches of insulation from the end of the cable closest to the fan. Thread the wires through the bottom of the electrical box of the fan and screw the box connector into place.

13. Attach the bare, ground wire to the green ground terminal in the box.

14. Twist together the black wire in the box with the black wire in the cable. Hold these together with wire caps. Repeat with the white wires.

15. Turn off the breaker to the box. Place tape over the breaker to prevent someone from accidentally turning the power back on.

16. Remove the faceplate of the wall socket and unscrew the plugs. Pull the plugs out as far as they will go and press to one side.

17. Punch out one of the holes in the side of the socket box. Thread the wires from the 14/2 cable through the hole and screw the box connector in place.

18. Attach the bare ground wire to the screw at the side of the box.

19. Strip about 1 inch from the end of the black and white wires. Bend the ends into hooks.

20. Loosen the brass screw. There should already be a black wire held in place. Add the newly stripped black wire by hooking it around the lead. Screw the brass screw back down. Attach the white wire to the silver screw in the same way.

21. Replace the plugs and the faceplate of the box. Turn on the power at the breaker box. Turn the fan on to test.

Tips & Warnings

• Some garages are single wall construction while others have dual walls with insulation between. Line the hole on all four sides with scraps of plywood to prevent the fan from blowing insulation.

• Instead of wiring the fan to a wall socket, you can wire the fan to an overhead light. This will turn on the fan whenever the light goes on.

• There are solar models available that respond to and are powered by sunlight.

• Always use great care when working with electricity.

• Make sure that the wall is clear of all nails and wires before cutting the hole for the fan.

References

• Garage Apartment Plans: Six Steps to a Healthier Garage
• Green Builder Magazine: Green Air is Clean Air: Part 3 of 4
• Popular Mechanics: Installing an Attic Fan
• Blower Wheel: How To Install An Attic Fan