Attic Venting

[jatoxico]

My house is a split ranch w/ stove in a family room that is half underground on one side and walk out on the other (downside of a hill). Up a half set of stairs and you're on the main level, another 5 up and your on the "3rd" floor. There is also a basement.

There is a leaky attic stair case on the upper level. I believe the house setup cause the stove to suffer to some degree due to the stack effect although I don't have too much trouble.

There is a attic fan (not whole house) on one gable end that exhausts heat in summer. Do you think it would help to cover that in winter or better to let attic breath?

 

[DickRussell]

Here's an interesting read: http://www.greenbuildingadvisor.com/blogs/dept/musings/fans-attic-do-they-help-or-do-they-hurt

That leaky attic stair case should be tightened up. Don't let it leak air into the attic. With a decent amount of insulation on the attic floor, the exhaust fan up there isn't doing any real good.

 

[Circus]

Leave attic vents open especially if the ceiling isn't sealed very well. Moisture needs to be expelled or it will condense and drip onto your insulation and drywall. A cold attic also prevents ice dams on the roof (warm attics cause ice dams).
PS. I wouldn't run the fan.

 

[valuman]

Air seal the barrier between living space and attic, then insulate. I'm a growing fan of closed cell spray foam for air sealing. An inch of spray foam topped with as much blown in cellulose as you want, or can afford will make a nearly unbelievable difference in heat retention and keep your attic cold as well.

 

[jatoxico]

Here's an interesting read: http://www.greenbuildingadvisor.com/blogs/dept/musings/fans-attic-do-they-help-or-do-they-hurt

That leaky attic stair case should be tightened up. Don't let it leak air into the attic. With a decent amount of insulation on the attic floor, the exhaust fan up there isn't doing any real good.

Thanks I was mostly worried about cold weather months but after reading that...oh well.

 

[jatoxico]

Thanks for the replies. So seems the consensus would be seal the attic stair case but leave the vent alone. I need better attic insulation but I've seen worse. The bad thing I see up there is that they pushed insulation into the eaves which last I heard was a no no. Problem is the conventional wisdom keeps changing and some of the articles assume certain construction techniques. My place was built in the 60's BTW.

 

[woodgeek]

Bottom line, in the 60s, they built in a lot of leaks between the attic and the conditioned space. That causes all the major problems that folks report for attics: ice dams, hot upstairs in summer, basement humidity in summer, huge heating bills, mold in attic, you name it. Attic ventilation to the outside is a bandaid solution for a lack of airsealing to the heated space. Airseal the attic floor well, and everything else becomes much less problematic.

 

[jatoxico]

Bottom line, in the 60s, they built in a lot of leaks between the attic and the conditioned space. That causes all the major problems that folks report for attics: ice dams, hot upstairs in summer, basement humidity in summer, huge heating bills, mold in attic, you name it. Attic ventilation to the outside is a bandaid solution for a lack of airsealing to the heated space. Airseal the attic floor well, and everything else becomes much less problematic.

I will have to look into attic sealing. Not sure what's involved. I have no mold issues or excessive moisture but I have had ice damming in the right conditions and icicles off the gutters so I know I'm losing heat.

 

[Wilbur Feral]

Valuman has good advice, and Green Building Advisor as recommended by DickRussell is an excellent info source. Also search web for Fine Homebuilding air sealing for good videos and articles. In general, you want to:

1) Air seal the attic so that is is kept separate from conditioned space. This means not just the attic stair well (which is the place to start but not the last thing to do) but also holes where wires and pipes enter the attic. I sealed all my top plates as well using acoustic sealant, which is like caulk but thicker and stays flexible when dry. Pay attention to lighting at this stage and make sure any "can" lights are properly rated for insulation contact, or are covered properly by approved covers. This is necessary for fire safety.
2) Then make sure you have good ventilation of the attic. Your gable vent is questionable if that's the only way for air to escape, ridge vents are generally best. Roof fans are helpful but not ideal. The biggest problem, though is often insufficient air SUPPLY at the lower part of the attic, which means soffit vents are needed. If air can't get IN, you can't have good ventilation. Baffles that ensure good air flow from the soffit, up and over the insulation layer, are essential. These are cheap and installed PRIOR to installing more insulation.
3) THEN blow in insulation, or use batts. R60 is fairly easy to obtain with blown in. If attic used for storage you will need to build raised platforms to get enough space for the insulation. The idea of using a layer of closed cell foam with blown in over top, AFTER ensuring good air flow from soffit to vents, is an excellent idea but more expensive than air sealing using caulk and canned foam if going DIY. It is likely cheaper, though, if hiring it done.

Your attic should be about the same temp as the air outside, in winter. A few degrees warmer is not uncommon, but a warm attic means significant heat loss and almost certainly excessive humidity and summer heat. Correcting it is well worth the cost.