I have a 5 year old 2-story house in Dallas. Attic is about 1600 square
feet, and the roof is complex with a number of peaks and only a few
relatively short horizontal ridges. Ventilation is roughly to code,
using about a dozen 8 x 16 soffit vents and mushroom vents at or near
most peaks. Insulation is blow-in fiberglass and it's ok - about R-40.
I have 2 issues, would appreciate some advice.

First, in the Spring, on windy days, the airflow thru the vents pushes
loose-fill all over the place. I have to carefully rake it back into
place before the start of the cooling season each year. It's a real
pain. Does anyone else have this problem? I was thinking of installing
some sort of vertical baffles, like a thin plastic that I every 3rd
or 4th joist to help hold the heaps into place. Wouldn't fasten them
down as I do have to get to something electrical or plumbing every now
and then. Is this a good idea?

Second, in the Summer, on very hot calm days, the air stagnates in the
attic. I suspect it just doesn't have the "oomph" to make the S-turn
needed to flow out of the mushroom vents. It gets real hot up there.
The floor insulation keeps this out of the house proper, but the mile
of cheap AC flex duct soaks up a lot of heat and so does the underside
of the roof. I'd just like it a bit cooler up there, not looking for a
miracle. Was wondering if the addition of a medium size or slow moving
fan mounted a few feet off the attic floor under the highest roof peak,
with a tube extending upward to within a few feet of a cluster of
mushroom vents would help the convection along. Will this help?

Thanks!
Bill

"BillH" wrote in message
oups.com...
I have a 5 year old 2-story house in Dallas. Attic is about 1600 square
feet, and the roof is complex with a number of peaks and only a few
relatively short horizontal ridges. Ventilation is roughly to code,
using about a dozen 8 x 16 soffit vents and mushroom vents at or near
most peaks. Insulation is blow-in fiberglass and it's ok - about R-40.
I have 2 issues, would appreciate some advice.

First, in the Spring, on windy days, the airflow thru the vents pushes
loose-fill all over the place. I have to carefully rake it back into
place before the start of the cooling season each year. It's a real
pain. Does anyone else have this problem? I was thinking of installing
some sort of vertical baffles, like a thin plastic that I every 3rd
or 4th joist to help hold the heaps into place. Wouldn't fasten them
down as I do have to get to something electrical or plumbing every now
and then. Is this a good idea?

Second, in the Summer, on very hot calm days, the air stagnates in the
attic. I suspect it just doesn't have the "oomph" to make the S-turn
needed to flow out of the mushroom vents. It gets real hot up there.
The floor insulation keeps this out of the house proper, but the mile
of cheap AC flex duct soaks up a lot of heat and so does the underside
of the roof. I'd just like it a bit cooler up there, not looking for a
miracle. Was wondering if the addition of a medium size or slow moving
fan mounted a few feet off the attic floor under the highest roof peak,
with a tube extending upward to within a few feet of a cluster of
mushroom vents would help the convection along. Will this help?

Thanks!
Bill

Me thinks your a worry wart.

Installing a attic fan or turbines will help a bit. I installed a attic fan
in the last house. Even a fan properly sized for the house it still did not
really lower the temp much. I put a thermal couple in the attic before I
installed the fan.

On 31 Mar 2006 14:02:11 -0800, "BillH" wrote:

I have a 5 year old 2-story house in Dallas. Attic is about 1600 square
feet, and the roof is complex with a number of peaks and only a few
relatively short horizontal ridges. Ventilation is roughly to code,
using about a dozen 8 x 16 soffit vents and mushroom vents at or near
most peaks. Insulation is blow-in fiberglass and it's ok - about R-40.
I have 2 issues, would appreciate some advice.

First, in the Spring, on windy days, the airflow thru the vents pushes
loose-fill all over the place. I have to carefully rake it back into
place before the start of the cooling season each year. It's a real
pain. Does anyone else have this problem? I was thinking of installing
some sort of vertical baffles, like a thin plastic that I every 3rd
or 4th joist to help hold the heaps into place. Wouldn't fasten them
down as I do have to get to something electrical or plumbing every now
and then. Is this a good idea?

Would these baffles cover the insulation? So it didn't blow around?
If yes, I would think it would help. I was going to suggest
fiberglass batting to sit on top of the insulation that blows around.

Second, in the Summer, on very hot calm days, the air stagnates in the
attic. I suspect it just doesn't have the "oomph" to make the S-turn
needed to flow out of the mushroom vents. It gets real hot up there.
The floor insulation keeps this out of the house proper, but the mile
of cheap AC flex duct soaks up a lot of heat and so does the underside
of the roof. I'd just like it a bit cooler up there, not looking for a
miracle. Was wondering if the addition of a medium size or slow moving
fan mounted a few feet off the attic floor under the highest roof peak,

Just in the middle of the attic? Not on the floor but not on the
roof? Never heard of that. Remember that if it doesn't actually blow
the air out of the attic, it will be adding more heat to the attic. A
breeze may feel good on your skin, because your sweat evaporates, but
in the absence of a person who feels good, moving air is just hotter
air than the same air when it is isn't moving.

I think for a little bit more same money and effort you can put a fan
in the roof, blowing out.

with a tube extending upward to within a few feet of a cluster of
mushroom vents would help the convection along. Will this help?

Oh, I missed the tube. Yes it would help, but I think some/much of
the hot air will still end up back int he attic. Better a fan in the
roof iteself, close to the top, but it doesn't have to be all the way.

I live in Baltimroe where it doesn't get as hot as Dallas, but otoh, I
live in a little valley and don't have much normal breeze, and I don't
think I ever had the breeze you have in your attic sometimes.

After the fan went in, it was 10 degrees cooler on the 2nd floor,
maybe 30 degrees cooler in the attic. I don't know why they're not
more popular. I have a switch in the second floor hall to turn it
off in the early spring and late fall, so that the sun heats the attic
and the attic heats my house.




Thanks!
Bill