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Ventilation can't eliminate all the heat that builds up in your attic, but it can minimize the effect on your home. In order for attic ventilation to be effective, you must have equal intake and exhaust vents. Therefore, for every soffit vent installed you will have to install a roof vent, or install a ridge vent. The idea is that the soffit vents allow cool fresh air into your attic while the roof vents exhaust the hot humid air.

A general guideline for determining the number of vents you need is at least one square foot of intake vents (soffit) and one square foot of exhaust vents (roof vent) for every 150 square feet of ceiling. You will want to consult your local building codes to be sure that you are compliant. For more information on ridge vents, see our tutorial "Installing a Ridge Vent" - and remember, a cool attic is a happy attic!



Skill Level & Time to Complete

  • Beginner - 3 to 4 hours 
  • Intermediate - 2 to 3 hours
  • Advanced - 1 to 2 hours
  - Always check your ladder for structural integrity and make sure its in good shape.
  - When moving ladders always be aware of any overhead electric lines. Make sure you stay clear!
  - When using power tools always wear safety glasses.


Materials List
   Soffit vents
   Galvanized roof nails or screws
Tools List
   drill bit
   Claw Hammer
   Carpenter's pencil
   Safety glasses
   Tape measure
   pry bar


1. From inside the attic, locate the placement of your new soffit vents follow between the two rafters that are vertically close to your existing or planned roof vent. Follow it down to the soffit and mark the center between the rafters.
2. Drill a hole on the mark. If you do not have enough room to use your drill, you can hammer a nail through the soffit; the purpose being to mark the location of the soffit of your house. You might find it easier to find the hole if you poke a coat hanger out through the hole.
3. There are several types of vents to choose from. You can purchase rectangular vents, round vents or continuous vents that can run the entire length of your soffit. Which type you choose will depend on how much ventilation you need and how large your soffit is. The installation procedures for each type are really the same, but obviously you will need to cut a hole in your soffit that matches the vent you purchased.
4. Before you install your soffit vent you need to make a template. This will make your job a lot easier, especially if you are installing more than one vent. Cut out a template from cardboard or similar material with a hole directly in the center. The template should be one inch smaller than the actual length and width of your vent. This will allow a ½” mounting surface all the way around the vent.
5. Carefully position your ladder below the location of the soffit vent. Center the template over the hole that you made from inside the attic and confirm that each edge of your template is the same distance from the edge of the soffit. Trace around the template.


6. Using the hole as a starting point cut out your traced outline with your jig saw or reciprocating saw. Make sure you wear safety glasses to protect your eyes from sawdust.
7. It is very easy to actually attach the soffit vent. Center the vent over the opening you just cut out and nail it or screw it into place. If nails were not provided, galvanized roofing nails will work.
8. To be sure that you have adequate ventilation, go to your attic and test the draft through your roof vent. Wet your finger and hold it up to the roof vent or light a match and blow it out close to the vent. If your finger feels cold or the smoke from the match goes out the roof vent, you should be in good shape. If you feel that your ventilation is too slow, install additional soffit vents; or install an attic fan or a ridge vent as described in those other tutorials.

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