Improving attic ventilation


#1

I have a 2 story colonial built in 1980 in the Washington, DC area which has 2 A-style gable vents on each end of the attic wall. There are no soffit vents, ridge vents, or powered ventilators installed at this time. I recently removed the old insulation, air sealed the attic floor, and reinstalled the insulation. On hot days (> 72 degrees), I’ve noticed a slight odor (smells like the insulation) on the second story.

The roof was redone by the previous owners in 2008. I wasn’t prepared to install soffit vents at this time and would likely use the SmartVent when it’s time to redo the roof. For what it’s worth, there is a small 1” gap where I can see daylight in the attic where the roof deck meets the eaves. I’d like to get opinions on installing only a ridge vent to solve the odor problem? Would it be worth the effort to install the SmartVent on the existing roof?

Really appreciate the feedback as I want to get this right.


#2

Take a simple approach first. Try installing an attic fan in one of your gable vents. Create some circulation.

If you’re going to make major changes, install some kind of intake ventilation, close off the gable vents and install shingle over ridge vent. It is important to seal off the gable vents if you’re going to install some other type of exhaust ventilation. Do some google searches for roof ventilation, check out the Lomanco site. There is some good information available there.


#3

I’m strongly considering adding soffit vents as the first change. If I perforate the plywood in the soffit in each rafter bay with a lot of 1/8" holes, would that be effective?


#4

It might work for awhile. What is the soffit material? If wood, I wouldn’t recommend it at all. If you’re going to do it, do it correctly. Soffit vents are relatively inexpensive.


#5

Thanks. The soffit material is plywood. I’ll take your advice and go with vents. If I cut out strips in the plywood, do you think I could use these vents to rest in the new channel – http://www.vinylcorp.com/products/eifs-defs/eifs-soffit-vents-drips/miscellaneous-soffit-vents

I’m trying to find something that looks good while also being functional.


#6

I’m not an expert on soffit vent manufacturers but those look okay.


#7

Adequate roof ventilation reduces cooling bills, extends shingle life, and prevents roof rot and ice dams in winter. Both roof and soffit vents are easy to install in just a few hours. They’ll protect your house from expensive future repairs.

Ultimately a professional contractor can help determine exactly how much ventilation a home needs. As a rule of thumb, however, homeowners need one square foot of attic ventilation for every 300 square feet of ceiling space. Roof vents are commonly placed near the peak of the roof; soffit vents are placed in the eaves. Outside air can circulate in through the soffit vents and exit through the roof vents above. Homeowners can tell if their roof is acting like a sauna simply by touching their ceiling on a warm day. A hot ceiling indicates trouble and requires better ventilation.

The ideal attic should have an equal amount of air coming and heading out. Since heat rises, cool air can enter the attic from the eaves and remove hot air through the vents at the peak of the roof. While it may seem counterintuitive to tout home insulation and attic ventilation, it is crucial to have both for an energy-efficient home.