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Installing a Bath Fan


Bath fan installation is an easy project you can complete in one dayBath fans are essential for removing moisture, heat and odors from the bathroom.


This project guide illustrates the basic steps required for the installation of a new bath ventilation system. When installing your new bath fan kit be sure to following the manufactures instructions.




Step 1: Cut the Hole 

 Step 1: Cut the Hole 1.  Locate where you want to place the fan, over a toilet is a good location. Do not 
     mount it above a tub or shower. 
2.  Once you have located the fan, mark the location by inserting a 16 penny nail
     into the drywall at each corner so they will protrude into the attic.

3.  From the attic, locate the nails and mark the location of the fan with a pencil.

4.  Cut out the drywall or plaster with a drywall saw or reciprocating saw. Start your  
     cut by drilling a hole in the drywall large enough to accept the saw blade.

5.  If there is no attic or if the roof is inaccessible, use a stud sensor to locate a
     joists from the bathroom. Cut the opening from below. Use the fan enclosure
     as a template.
Important: Never vent to an attic or sub-floor as moist air creates an environment for damaging mold and mildew growth. 

Step 2: Attach Fan and Block Off Insulation

 Step 2: Attach Fan and Block Off Insulation 1.  Attach the fan enclosure to the joist with screws.
2.  Cut or push back the insulation, leaving a six inch gap between the unit and 
3.  Cut pieces of a 2x4 to fit between the joists, blocking off the fan from the
     insulation, and attach lumber with screws.  

Step 3: Cut Hole in the Roof

 Step 3: Cut Hole in the Roof 1.  Trace a circle on the underside of the roof just large enough for the roof vent and
2.  Drill a hole large enough for the saw blade, then cut out the circle with a
     reciprocating saw, saber saw, or keyhole saw.
Note: If you are installing a side vent, you can skip to Step 6.

Step 4: Cut Away Shingles

 Step 4: Cut Away Shingles Remove the shingles from around the cutoff without damaging the underlying roof paper.

Step 5: Install the Roof Vent

 Step 5: Install the Roof Cap 1.  Install the roof vent by sliding the top flange under the shingles above it and
     resting the bottom flange on the shingles below. 
2.  Apply roofing cement on the underside of the flanges to seal the installation.  
3.  Secure the vent flanges with roofing nails, prior to installing the shingles.
4.  Install the shingles on the sides of the roof vent, apply roofing cement to seal the
     joint with the shingles. Starting at the bottom and working your way up to the top
    of the vent. Slip the last shingle under the existing singles above the vent.  

Step 6: Connect the Ductwork

 Step 6: Connect the Ductwork 1.  Slide clamps over the flexible duct at both the roof cap and the fan, then slip the
     clamps over the tailpieces of the roof vent and fan and tighten the clamps.
2.  Wrap the joints with duct tape.

Step 7: Wire the Fan

 Step 7: Wire the Fan 1.  Run cable to the fan and to the switch if no wiring is present. If you are installing
     a fan/light, you’ll need to run three-wire cable from the switch to the fan.
2.  Connect wiring according to the manufacturer’s instructions.
3.  Plug the fan motor into the built-in receptacle.

Step 8: Wire the Switch

 Step 8: Wire the Switch 1.  For a fan/light switch existing wiring, splice the white wires and connect the
     grounds securely with wire connectors.  
2.  Connect power to both switches through two pigtails spliced to the feed wire.
3.  Connect the red wire to one switch terminal and the black wire to the other