attic ventilation: almost no eaves

Page 2 of 2  


vents.

soffit?

Here's some photos of 3 attic fans. The dates on the photos are wrong and not in order due to camera snafus.
Vent from inside attic, before fan installed
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/BEFORE.gif
I mounted it on 1/4-in plywood first because there was nowhere to conveniently mount it to the studs without blowing air back into the attic.
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/MOUNTED.gif
Fan installed ready for wiring
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/FAN-IN2.gif
Fan as installed
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/FAN-IN.gif
Thermostat wiring.
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/THERMOST.gif
Thermostat as installed. Ended up moving it to a hotter location and setting it at 110 deg F. Was not reliable leaving it mounting in the fan intake. I don't use leave the fan powered -- just use the thermostat to tell me when it's hot enough to run. Also it will shut the fan off in case I forget. But I don't depend on it.
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/TS-MOUNT.gif
Different vent fan - was too noisy and vibrated off center-- returned
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/NOTUSED.gif
Roof-top fan on a different house - it looked like a space ship on the roof so I painted it with Rustoleum. If you install on of these, be sure you seal it good and slide it up under the shingles properly. I wouldn't install one of these again because of the windy rains we get. Also I don't like cutting holes in the roof.
http://i249.photobucket.com/albums/gg234/sammybinsnoozin/ROOFTOP.gif
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tuesday, June 17, 2014 10:28:13 PM UTC-4, Guv Bob wrote:

s.

ake. I don't use leave the fan powered -- just use the thermostat to tell me when it's hot enough to run. Also it will shut the fan off in case I fo rget. But I don't depend on it.

seal it good and slide it up under the shingles properly. I wouldn't inst all one of these again because of the windy rains we get. Also I don't lik e cutting holes in the roof.

A key concept with soffit vents combined with a rigdge vent is that you have equal air intake down low and exhaust up high. If you choose to use a fan, you have to consider what size fan, how much air it moves and where that air is going to come from. If he just puts in a gable fan, with the existing ridge vent, it's not likely to do much good. Most of that forced air is likely to short circuit, via the ridge vent.
IDK how Derby will feel about that, but it's how I see it when you introduce a fan. Just a natural gable vent and a ridge, I can see how it's debatable, but when you have a fan, I think it's very likely to be of little benefit, unless you close off the ridge vent in the area of the fan. And I think adding a powered roof vent is not of much benefit, for the same reason.
And with a powered fan, if you don't have adequate/matching air intake, you can wind up sucking conditioned cool air from the living space via any recessed lighting, through bath fan openings, outlets, etc. because you've created a negative pressure in the attic.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Guv Bob wrote: What you have in this picture:

Is exactly what you see when you look under this "space ship":

I have two of those on my roof. For one of them, I raised the "space ship" top-hat by about 8 inches using 2x2 pieces of wood. I also installed a taller screen to match the new height. The extra height improves airflow. The wood struts are unequal length so the top-hat sits level (with the ground - not with the roof). This keeps rain out (yea, we get windy rain too sometimes).

You want a ventilated roof, you're gonna have to cut holes in the roof.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.