Attic ventilation mistakes to avoid

Problems arise after residing, re-roofing

By Inman News Feed
Add Comment Add Comment | Comments: 0 | Posted Jul. 15, 2011

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Problems arise after residing, re-roofing

Paul Bianchina
Inman News™

Q: I just had my house sided and roofed and the contractor closed off the gable vents except for drilling six holes in the inside bottom of the decorative half-round louvers at the tops of my house. He left insulation and Tyvek on the rest of the vent. He also installed a solar fan in the attic.

I am worried that the fan will burn out since there is not enough air to suck out of the attic because of the closing off of the vents. Plus, I thought the vents were needed for a good air flow. My contractor insists that what he did is correct. Please give me your opinion or someone to call for an unbiased opinion of this procedure. --Madeline D.

A: What your contractor did is certainly not correct.

Just as you thought, proper attic ventilation is essential for several reasons. It flushes hot air out of the attic, which prolongs the life of the roofing. It removes any accumulated moisture, which helps prevent the possibility of mold as well as moisture-related structural damage to wood framing members.

And, if you live in a cold climate, the attic ventilation flushes out heat lost from the house during the winter months, which keeps the underside of the roof colder and helps to prevent ice damming. So for a number of reasons, proper ventilation is absolutely essential to your home.

The basic formula for attic ventilation is that you need approximately 1 square foot of vent area for every 300 square feet of attic area. So if you have an 1,800-square-foot house, you would need about 6 square feet of total vent area.

Those vents should be roughly divided between high and low vents to provide air flow, so that would mean about 3 square feet of vents placed low in the attic, usually in the soffits, and another 3 square feet placed high, either in the gable ends or along the ridge.

I also completely agree with you about the solar fan. If you have enough vents and they're installed in the proper places, your attic will have a sufficient amount of passive ventilation, and any type of mechanical fan isn't necessary. That way you'll never have to worry about it burning out, or lacking power from extended periods without sufficient sunlight. And solar vents typically don't have sufficient power to compensate for a lack of other ventilation anyway.

As far as independent sources that you can turn to, you have a couple. One would be your local building department. They can confirm the ventilation requirements, and can also tell you whether or not the contractor should have gotten a permit for all this work. Some jurisdictions require permits for reroofing and/or residing jobs, while others don't.

The other place to turn would be your state contractors' board. A job this size would have required a contract, which I assume you have. So in the event of a dispute, there should be arbitration assistance available through the contractors' board.

Hopefully it won't come to that. Attic ventilation is a fairly straightforward issue, so I'd start with your local building department, get some independent confirmation from them, and then have a talk with the contractor about correcting the problems.

Q: I have a deck over a patio area. We are looking at closing [the patio] in and making it a three-season room. I am looking at putting a new floor on the deck that would drain all the water away so it would be dry below. I looked at some different drain systems. Which would be the best? --Harold R.

A: What you need to do is treat the upper deck as though it were a roof. There are several very good flat-roof coatings that are laid down in overlapping sheets and then sealed together. They form a tough, waterproof coating that will definitely keep the room below dry. Most of these coatings are tough enough to walk on if you intend to use the upper deck only occasionally.

If you plan to use the upper deck on a regular basis, especially if there is a table or other furniture on it, then you will need to install a wooden walking surface on top of the roofing membrane.

Membranes of this type need to be professionally installed, especially if it will also incorporate a deck on top. You will want to talk with at least two licensed roofing contractors who are specifically experienced in this type of work.

Q: Could you recommend a good battery timer for the hose? The egg-style timers do not work that well. --Parker L.

A: Orbit makes a couple of different styles of mechanical and digital hose timers that should do the trick for you. Their website is www.orbit-irrigation.com if you'd like to check them out.

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