If you have to go in your attic for something this time of year, the heat is unforgiving. Besides trying to get out as soon as possible you should be thinking about ventilation and, “Do I have enough?”
Minimum recommended attic ventilation is 1 Sq Foot for every 300 Sq Feet of attic area. Multiplying the length by the width of your home should give you the area. You should have as much intake ventilation as exhaust ventilation. Truth is you can’t have too much ventilation if you stick to the 50/50 rule. 50% intake under the eaves and 50% exhaust at or near the roof peak. However, most homes have too little. So what’s the big deal?
When I do a home inspection I’m on the warpath for moisture. We often think of moisture in the form of rain or groundwater and these are culprits but moisture in the form of humidity can be just as evil. Moisture in improperly ventilated attics can cause mold, mildew and rot. Higher temperatures can shorten the life span of building materials like your roof. Ventilation is just as important in the cold months too, but the hot weather can bring it to the forefront of our thinking, especially if you have to go “up there.”
Gable roofs are the easiest to ventilate because they have the longest ridges. Hip roofs are more of a challenge as are Mansard roofs. Dormers create their own set of challenges. Surprisingly many builders don’t understand proper ventilation and sometimes opt for the cheapest way to “Git-R-Done.”
A good Home Inspector should be looking at the attic ventilation as part of the overall picture. If you are not planning on a home inspection in the near future, pick a cooler day and take a good look at your attic ventilation. You can save money and costly repairs by simply increasing it.
A source of good information on ventilation is Lomanco.