Attic Ventilation

[stephensandlin]

I have a 1928 bungalow in Houston, Texas (read: hot and humid). I'm in the process of replacing my ductwork, and wanted to improve the ventilation in the attic while up there. It's getting extremely hot in the attic, and I'd like to prolong the roof's life, while getting rid of some of the hot air that is zapping my nice cold air inside.

This is a rectagular, Southward-facing, A-frame attic. Originally, there were gable vents at the front and back (South and North) of the house. 12 years ago, a previous owner renovated the home. They took out the front vent, and replaced it with a piece of glass. When they replaced the roof, they also put in a ridge vent. There are no other roof vents. There are also no soffit vents, or air intakes entering at the bottom of the roof. In fact there are no soffits, as the rafters are exposed. As for insulation, the remodeler blew in insulation, and it has settled in to a height just above the joists.

My initial thought was to add several soffit intakes along the 1x6's in between the rafters. Then stick some styrofoam baffles on the inside to hold the insulation back.

My questions:

1 Would I be better off just replacing the front glass with a vent, to get some cross-flow in the attic?

2 After adding soffit vents, is the rear gable vent going to hinder the proper airflow of whatever soffit & ridge system I am able to create?

3 Is there some sort of regional climate issue that I'm not aware... do soffit & ridge sytems not do well with hot and humid climates? I've seen some ridge vents in my neighborhood, but not mant soffits... are they hidden?


Thanks in advance... all advice is welcome!

This is what the overhang looks like... exposed rafters, no vent


This is the front gable... glass, no vent


This is the back gable... just a screened vent

[Gunguy45]

My house here is similar except stucco. Same sort of soffit or lack of soffit I should say.

I'd open up that front to at least get some cross venting going as well. Thats pretty much what I have now (larger openings)..only no ridge venting, thats on my list.

Very few ridge vents here as well except on newer homes.

How did you plan on getting ANY soffit vents in the 2 x 6 blocking? Not much room to work there it looks like. I may drill 2" holes in my 2 x 4 blocking and put snap in vents in..but it's gonna be a lot of holes! My roof slope seems a little lower than yours, but I'll still need a right angle drill I think.

[stephensandlin]

Thanks for the reply... to be honest, it is going to be a stretch to make the soffits work. Depending on how the blocks are nailed in, I was going to try to pry one off, every 4th rafter or so, and work with them on the ground before reinstalling. My thought was to use a 2"x8" or 2"x10" vent to maximize the intake, and allow me to spread them out a bit... like I said, a stretch at best.

The idea of a gable vent is much more appealling from an installation perspective, but I'm concerned about creating a bunch of dead air space by not having soffits at all. The 2 gable vents might produce crossflow, or they could just feed the ridge vent.

[GBR in WA]

Notice this on gable vents and fans: BlockTheHeat.com -Attic Ventilation Problems

You would need to drill every rafter bay with 3 holes each to get close to the required air supply. I would use this: Cor-A-Vent : IN-Vent

Block the other gable vent closed. Seal all air penetrations to attic from conditioned air space, including fan and light fixture holes. Leave any gas unit flues alone.

A good read: Audel Complete Building Construction - Google Books Be safe, G

[igneous]

You definitely need to get some soffit holes drilled if possible, and I agree to get rid of the glass pane and put up screened gable--possibly w/gable fan on appropriate end to pull air thru. Ridge vent don't do much without some air flow up thru rafters/deck. My house is newer and has the holey masonite soffits, which vent well. They are small holes actually, too small for wasps but there's thousands. Be easier for you to use larger screened vents. I'd also get some radiant barrier installed. I did this last winter and what a difference. I used the foil type and stapled to rafters in about 75% of our house. Couldn't access the west side, which needs it most (I'm working on that aspect for winter installation again-good project for my agile 14 yr old!)

We're in East DFW and on a 100+* day when we get home, our house is about 80 degrees without having air on all day.
Key to it is keeping the heat out, so your AC don't have to work so hard to remove it.