I’ve talked about attic ventilation issues before, in fact it’s probably one of the most popular posts on the blog to date. In that article I touch on this issue and in this video I decided to go a little more in depth based on the frequency this problem comes up in conversations.
What do you think? Is this a problem you’ve personally experienced in your attic? Did you have situations like the examples in the video? Tell me about it in the comments!
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Great Video. How many exterior fans do i need on a 2000 sq. ft. house?
I typically never recommend fans. I’d go with a couple of 14″ wind turbines along with installing Radiant Barrier Foil
I’ve read your many posts, Why not put reflective insulation over the floor in the attic, rather than the attic ceiling? Wont that accomplish the same thing and be much easier??? I mean, the sunlight travelled a million miles, it doesn’t matter if we stop it on the roof joists or the house joists. In fact, one might make the arguement that it might be better. Flow and radiation follow Pouiselle’s law where the flow and radiation dissipate with 1/R the 4th power. So the reflective wave energy will dissipate much faster before it reflects back through the attic joists. This is also an arguement not to insulate your attic roof, but just the room right? So maybe put down a highly reflective floor in the attic and make sure it’s air tight?
Scott, you can definitely lay the foil on top of the insulation. In fact this is the preferred method in cold an mixed climates. Here is the page on the Radiant Barrier On Top Of Insulation The main advantage of stapling up is when you have ductwork in the attic. There is a saying that “putting ductwork in the attic is like making ice cream in the oven”. So, stapling up will reduce heat both into the ductwork AND put the ductwork in a less hostile environment.
I live in a log house. 1800 to 2000 sq ft and log homes don’t have soffits. The other issue is the roof is Gambrel. There is one attic fan on one wall. Just found out I have some mold. I had mold assessor come and he found the mold is much less or none closer to the fan. Farther away is where the mold is. I had just had a new roof put on two months ago. Unfortunately the roofer screwed us by re-contracting out plus not telling the contractors about some of the issues with the roof. Lot of things were done wrong. I am not getting great input from the remediator on solving the ventilation issue. I think it’s tough getting reliable people now days. Any suggestions regarding this type of roof and no soffits. Attic is about 700 sq ft I am told. There is a ridge vent. Live in upstate NY. Don’t get a lot of sun in winter and winters ar cold, icy or snowy or just damp. Any thoughts on this?
For mold to grow, you need dark, cold, wet conditions. Since it is localized, that should help you find the source of where your warm air/water could be leaking from. I’d work to get that sealed up air tight and get everything dried out. It’s possible the fan is sucking warm air out of the house, especially since you don’t appear to have any way for air to get in the attic. The fan has to pull air from somewhere so without intake vents, it’s going to suck it out of the house. Besides being a big energy waster, it can create issues with mold/moisture. This is why I rarely (if at all) recommend attic fans for ventilation. I’d maybe try unplugging the fan after you air seal and after everything dries out, and see how it goes.